How efficient are solar power storage systems?

‘Testbench’ project improves quality of measurement results and facilitates comparison

Karlsruher Institut für Technologie (KIT)

IMAGE: With the help of batteries, power generated during sunshine can be stored for later use. (Photo: Shutterstock/Victor Josan) view more  Credit: Photo: Shutterstock/Victor Josan

More and more photovoltaic systems are equipped with batteries that store power produced during sunshine for later use. Such solar power storage systems enable operators to use a maximum fraction of the solar power produced for own purposes. The more efficient the storage system is, the higher is the economic profit. The “Testbench” project enhances the quality of efficiency measurements for better comparison of battery systems by planners and operators. The collaboration project funded by the Federal Ministry for Economic Affairs and Energy (BMWi) is carried out by Fraunhofer IEE, Karlsruhe Institute of Technology (KIT), VDE|DKE, and TÜV Rheinland. Associated partners are AIT, BSW, and BVES.

Photovoltaics directly converts sunlight into electrical energy and, thus, contributes to sustainable power supply. For operators of photovoltaic systems, it is worthwhile using a maximum fraction of the solar power produced for own purposes. This is achieved by applying batteries that store the power generated during sunshine until later use at times at which the photovoltaic power production is zero.

The market for solar power storage systems is growing continuously. In 2018 already was the 100,000th solar power storage system taken into operation in Germany. Such systems are mainly used by private households to increase their own consumption of solar power and their grid independence. “To guarantee economic profit for the operator, efficiency of solar power storage systems is crucial,” explains project head Fabian Niedermeyer from the Fraunhofer Institute for Energy Economics and Energy Systems Technology (IEE). Improving the quality of efficiency measurements of such systems for better comparison by planners and operators is the goal of the recently started “Testbench” project.

The “Testbench” (Test Method to Determine the Efficiency of Solar Power Storage Systems – From Guidelines to Standards) project focuses in particular on the reproducibility and comparability of results measured on the different test benches of the project partners. A ring experiment in the second half of the project will serve to validate improvements and confirm reproducibility of the results of the partners. As the partners play leading roles in the standardization group “Characteristics of Stationary Battery Storage Systems” (AK 371.0.9.) of the German Commission for Electrical, Electronic, and Information Technologies of DIN and VDE (DKE), the results obtained will be incorporated in standardization work. “national standard or VDE application rule would be an important step to further strengthen the market position of German manufacturers,” says Nina Munzke, Head of the Systems Storage and Analysis Group of KIT’s Battery Technology Center. Thanks to the large number of international customers of German manufacturers of solar power storage systems, the results will then also be included in international standards. “This will increase the competitiveness of German manufacturers on international markets,” Munzke says. In addition, workshops are planned for regular exchange with different German and international stakeholders.

Details on the “Testbench” Project

The “Testbench” project started on January 01, 2020 and is scheduled until December 31, 2021. It is funded by the Federal Ministry for Economic Affairs and Energy. Within the project, the Fraunhofer Institute for Energy Economics and Energy Systems Technology (IEE) in Kassel, together with KIT, the German Commission for Electrical, Electronic, and Information Technologies of DIN and VDE (VDE/DKE), TÜV Rheinland and the associated partners of the Austrian Institute of Technology (AIT), the German Solar Association (BSW), and the German Energy Storage Association (BVES), studies the adaptations and detailing required for the measurement and evaluation rules in the efficiency guidelines to improve the quality of results. The efficiency guidelines standardize characterization of efficiency, standby consumption, and control efficiency of photovoltaic battery systems. The guidelines were developed by the expert group “Effizienzleitfaden” (efficiency guidelines expert group) of BVES and BSW, together with members of different research institutes, test laboratories, and manufacturers of solar power storage systems. To facilitate comparison of various systems using basic methods, reproducibility of the results is indispensable. Preliminary studies, however, revealed that measurements of the same storage systems by different measurement institutes sometimes produce very different results. Moreover, experience shows that framework conditions of measurements still remain to be specified in more detail. In particular, this applies to precision of power and voltage sensors and the scanning rates and period durations used for averaging.


Fraunhofer Institute for Energy Economics and Energy Systems Technology (IEE)

Fraunhofer IEE in Kassel conducts research for the transformation of energy systems. It develops solutions for technical and economic challenges to further reduce the costs of use of renewable energy sources, to secure supply in spite of volatile power generation, to ensure grid stability on a high level, and to make the energy transition an economic success.

More about the KIT Energy Center:

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June 5, 2020 2:20 am

If indeed green power can be economically stored then used there is no need for subsidies and standby power stations to be employed.

Let the Market decide.


Bryan A
Reply to  Michael
June 5, 2020 4:57 am

With the help of batteries, power generated during sunshine can be stored for later use.
While the above statement (from the onset image caption) is true, the produced energy cannot be stored in the battery if it is been my otherwise used as it is being produced. To both use and store energy from PV requires that the end user has access to Twice the quantity of Solar panels necessary for half their energy needs

Joel O’Bryan
Reply to  Bryan A
June 5, 2020 6:21 am

Considering that the typical solar PV installation produces usable levels of current for less that 1/3 of every 24 hours, that number is really at least 3x PV. Then that doesn’t even consider the very real issues of frequency of cloudy days when little power is produced for 2-4 days in a row. In Central Europe such cloudy periods reach into a week or more every year. Fossil fuel backup will always be necessary, driving very high costs to maintain reliability.

The other issue is that while PV panels and inverter systems may have a useable lifespan of 15 – 20 years, a battery system typically, under daily discharge-recharge cycling will have a lifespan of at least half that, 7-10 years at best. So starting by 5 years after installation, the need of replacing batteries will drive costs to maintain the system. By 7 years after installation, when all the original actors in these Green artifices have taken their upfront money tax credits and long disappeared, the duped consumer is stuck with huge bills for maintenance and replacement.

Stephen Richards
Reply to  Joel O’Bryan
June 5, 2020 6:41 am

Remember to allow for those periods when there is very little sunshine for several days such as this year in france.

We will still get power from some light but not the maximum.

Reply to  Joel O’Bryan
June 5, 2020 6:45 am

A minor correction. Nickel-Iron batteries are still in use after 30 years and were used by Thomas Edison to make the first electric truck. They only have two fairly minor disadvantages. The energy density is low meaning they are best for stationary applications and they require twice the power to charge that they will deliver. Sounds like the perfect solution for a green application because as long as the government money keeps rolling in, they don’t need to make a profit.

Reply to  Dena
June 5, 2020 7:55 am

One word: Vanadium.

“The battery shows an energy efficiency of 80.83% at 600 mA cm−2.”
“The battery exhibits a peak power density of 2.78 W cm−2 at room temperature.”
“The battery is stably cycled for more than 20,000 cycles at 600 mA cm−2.”

Carbon Bigfoot
Reply to  Dena
June 5, 2020 9:55 am

Icarus world’s annual supply of Vanadium in 2017 was 80 kt.
Do you get the message or do I have to spelled it out for you?

Reply to  Dena
June 5, 2020 12:42 pm

Carbon Bigfoot,

Indeed Vanadium is not particularly rare but not much is refined out as it is not that cost effective at the moment — the market for it is small hence your ‘annual supply of Vanadium in 2017 was 80 kt.’ If Vanadium usage was to become larger then the price would rise and economic factors would make it more profitable to extract/refine and annual supply would rise to meet demand.
Just research how the worldwide availability, stock, supply, and price of Lithium, or Cobalt, or any of the ‘rare earth metals’ compares from the market in say 1970 to the present day market conditions.
By most measures any natural minerals’ worldwide stock (availability) is more dependant on disposition (where is it found, how difficult to extract/refine) and market price/requirement, than its absolute abundance. The market rules the amount of stock held! P.S. what is the worldwide stock of sand for building or glass making?


Vanadium is the 20th most abundant element in the earth’s crust;[32] metallic vanadium is rare in nature (known as native vanadium),[33][34] but vanadium compounds occur naturally in about 65 different minerals.

At the beginning of the 20th century a large deposit of vanadium ore was discovered, the Minas Ragra vanadium mine near Junín, Cerro de Pasco, Peru.[35][36][37] For several years this patrónite (VS4)[38] deposit was an economically significant source for vanadium ore. In 1920 roughly two thirds of the worldwide production was supplied by the mine in Peru.[39] With the production of uranium in the 1910s and 1920s from carnotite (K2(UO2)2(VO4)2·3H2O) vanadium became available as a side product of uranium production. Vanadinite (Pb5(VO4)3Cl) and other vanadium bearing minerals are only mined in exceptional cases. With the rising demand, much of the world’s vanadium production is now sourced from vanadium-bearing magnetite found in ultramafic gabbro bodies. If this titanomagnetite is used to produce iron, most of the vanadium goes to the slag, and is extracted from it.[40][41]
Vanadium is mined mostly in South Africa, north-western China, and eastern Russia. In 2013 these three countries mined more than 97% of the 79,000 tonnes of produced vanadium.[42]
Vanadium is also present in bauxite and in deposits of crude oil, coal, oil shale, and tar sands. In crude oil, concentrations up to 1200 ppm have been reported. When such oil products are burned, traces of vanadium may cause corrosion in engines and boilers.[43] An estimated 110,000 tonnes of vanadium per year are released into the atmosphere by burning fossil fuels.[44] Black shales are also a potential source of vanadium. During WW II some vanadium was extracted from alum shales in the south of Sweden.[45]

Reply to  Dena
June 6, 2020 1:02 am

Any mining or processing on an industrial level can’t be carried out by unicorn farts.

Reply to  Dena
June 6, 2020 2:36 am


No unicorns required just market forces!

Reply to  Dena
June 6, 2020 9:31 am

tom0mason, you are assuming that there are deposits that can be economically exploited if only prices were a little higher.

Tim Gorman
Reply to  Dena
June 7, 2020 5:32 am

They also generate hydrogen. I can’t wait to see the lawsuits filed by people suffering from explosions!

Pat Frank
Reply to  Joel O’Bryan
June 5, 2020 9:59 am

Also, the battery is manufactured using energy supplied by fossil fuels.

A proper cost accounting of PV/battery would be to cost the battery as manufactured using energy supplied strictly by PV.

That, after all, is the implicit scenario being pushed — an economy run off so-called green energy.

Reply to  Pat Frank
June 5, 2020 1:09 pm

So true. At a county meeting I asked how soon I would be able to get an electric combine and how many solar panels I would need to run it 18 hours per day for a harvest season. No one would take a guess so my response was “My John Deere is plenty green enough for me.”

Les Francis
Reply to  Pat Frank
June 5, 2020 5:44 pm

Not only the cost to manufacture but also the cost to dispose of or recycle.

Reply to  Joel O’Bryan
June 5, 2020 1:09 pm

1/3rd is probably a year round average. During winter, especially somewhere as far north as Germany, it’s going to be a lot less than that.

Steve Keohane
Reply to  MarkW
June 6, 2020 8:19 am

In Colorado with 300 days of sun a year, my solar panel company said to expect 4.3 Kw hours a day.

Reply to  MarkW
June 6, 2020 9:33 am

What have you actually gotten?
Colorado is less cloudy than Germany.
Colorado, is a lot higher in elevation than is most of Germany.

Reply to  MarkW
June 6, 2020 9:36 am

Is that number a year round average?
Also, Germany is further north than is Colorado.

Walter Sobchak
Reply to  MarkW
June 6, 2020 3:22 pm

Little known fact. The most southern point in Germany is at the same latitude as Bemidji Minnesota. 47°30’N The most northern point in the lower 48 of the US is near Lake of the Woods north of Bemidji at 49°23′

Almost all of Germany is north of almost all of the US. Solar is a dubious project at 40N where I live. It must be just plain nuts in Germany.

Steve Keohane
Reply to  MarkW
June 6, 2020 9:03 pm

MarkW: That seems right after several years. That number is per Kw of panels.

Walter Sobchak
Reply to  Joel O’Bryan
June 5, 2020 6:44 pm

Worse than that. out side of the tropics there is seasonal variation. For example. I live at 40 north. Insolation in June is about 2.25x the insolation in December. How electricity can be stored in the summer to be used in the winter economically has not yet been mooted.

My guess is that the only practical, although dreadfully inefficient and expensive, way to solve the problem is to use the solar power to run a chemical process that produces something like ammonia while the sun shines.

Reply to  Walter Sobchak
June 5, 2020 9:32 pm

I can’t understand why you would want to store energy when you can get more than you have to pay in non-sunshine periods by feeding it into the grid. Is this thing about storing it in batteries a way to stop people from destabilizing the grid?

Walter Sobchak
Reply to  Walter Sobchak
June 5, 2020 10:25 pm

” Is this thing about storing it in batteries a way to stop people from destabilizing the grid?”

It doesn’t make any difference if I own the solar cells and feed the surplus energy to the grid, or of the power company cuts me out of the equation. The problem is the same. if you want to power the system with solar power you have to find a way to match supply and demand. Supply fluctuates diurnally and seasonally. Demand is on a different set of cycles.

The question is how will the solar power generated in July keep me warm in January.

willem post
Reply to  Joel O’Bryan
June 6, 2020 7:05 am


the KIT is notorious German solar hyping source.

The article is TOTAL BS.

No numbers of any kind.

Remember to allow for losses, as electricity out/electricity in is about 0.85, WHEN NEW.

Even at turnkey $100/kW (keep dreaming), lasting 10 years, the cost/kWh of electricity passing through the battery, would be off the charts, because we are talking about EXPENSIVELY SUBSIDIZED dc solar electricity being fed into the battery, which has to feed ac to your house grid, with leftovers, as dc, to your electric vehicle, and with other leftovers, as ac, to the distribution grid, etc.

Reply to  Joel O’Bryan
June 6, 2020 5:27 pm

There were calculations on the JoNova site some time ago that even in Australia with its higher amounts of sunlight, an off-grid system for an average house would cost in the region of US$110,000. With the component lifetimes that you have mentioned, nobody could save any money by installing such a system.

Reply to  Bryan A
June 5, 2020 9:30 am

and the same for Wind. Note that even Pumped storage is very nearly the cost for any equal amount of coal-fired electricity generation.
There is no free lunch…

Reply to  Enginer01
June 6, 2020 6:54 pm

It should noted that Wind power doesn’t need to generate electrical power to drive electrical motors.
Wind power could transfer it’s mechanical power to mechanically power pumps.

Reply to  Michael
June 5, 2020 8:58 am

“Sure we’ll lose money on every unit we make, but we’ll make up for it with quantity.”
Every optimists poor math equation.

A C Osborn
June 5, 2020 2:30 am

Well we all know you won’t get out all of what you have put in.
Surely this has been done before?

Carl Friis-Hansen
June 5, 2020 2:42 am

I like the idea of standard performance measurement. It is good for the customers, it makes comparison between various manufactures easier.

What concerns me, the scale and duration of such a standard.
Germany already has a consumer association, which could evaluate the products and advice the customers, as they already do with so many other products.

June 5, 2020 2:42 am

Well, yes.
It is very reasonable to make your roof from solar panel tiles instead of usual tiles.
The energy costs of producing the both are comparable.
I would even demand it by law.
All new properties MUST have solar panel tiles
Tesla Solar Roof is just the right thing.

Reply to  Alex
June 5, 2020 3:08 am


If you propose “demanding it by law” you’re one of the fools who got us into the state we’re in right now.

When have governments ever been good at picking technology?


If solar tiles are truly competitive with conventional tiles (very doubtful) then they will naturally evolve as the dominant roof covering. But they’re not.

And by demanding something by law, you stifle other emerging technologies.

Every time someone, somewhere in the world says “The government ought to do something about this” is the moment we all surrender a little more of our Liberty.

Reply to  HotScot
June 5, 2020 3:42 am

Here in North Queensland Australia we get 650W/m2 coming down. If solar is going to work it would work here. Trouble is, maximum generation occurs at minimum demand times, and the number of installations (about 30%) are close to destabilising the grid.

Reply to  Martin Clark
June 5, 2020 4:09 am

the next cyclone will adjust that

Reply to  yarpos
June 5, 2020 5:35 am

Here in the not quite so sunny UK, I’d expect a well installed roof to last 60-80 years, quite possibly more. Good quality retrofit solar panels should last 20-25 years, after 15 years they will be down to half their original rated output. As for the cheap ones, I don’t care to think.

To be of any use beyond keeping the rain out of my house, I’d be replacing those solar roof tiles every quarter century, whereas I’d expect my new roof to comfortably outlive me.

If I was to forced to spend on any ‘green’ improvement to my existing house, or indeed a new house, I’d rather insulate the bejeesus out of it and save more over the year more than the value of the energy generated by the solar tiles.

Then factor in the cost of replacing the battery pack after, say 10 years, tiles after 20 years.


Reply to  Martin Clark
June 5, 2020 5:51 am

It must have been cloudy in Eastern Australia today because at mid day the solar capacity factor was 38%.
I wonder what the capacity factor is 12 hours later?
These batteries must be amazing when overall capacity factor for solar is , 20%.

Gary Pearse
Reply to  HotScot
June 6, 2020 4:49 pm

Hot Scot, Am I wrong to think that people in UK that think like you are sadly in a minority? UK basically invented freedom and justice for the world and have over the years backed away from it.

I recall about 50 years ago in a discussion with International Nickel executives who needed to import considerable labor for expansion of production from a few new large mineral deposits they had discovered. They were considering advertising in UK for mining, milling and smelting workers. I advised that UK labor was socialist-activist anti-corporate and would screw things up with strikes, go slow, inter-workman trade disputes, sabotage and the like. I suggested Brazil, Potugal and Italy if they wanted productive, trained workers.

Reply to  Alex
June 5, 2020 3:08 am

Until the hail storm!

Reply to  Alex
June 5, 2020 3:51 am

No it’s not. You have North facing roofs. You have trees nearby blocking the Sun.
Explain why you would demand it by law? I would demand you never use anything shipped using fossil fuels. People have problems. Solar panel tiles are expensive toys not helping with that. They are a virtue signal. A fraud.

Reply to  Alex
June 5, 2020 4:06 am

Tesla solar roofs, like their cars, cost a small fortune. There is also no data as to the comparative lifespans of the roofs versus the photovoltaic portion – any mismatch means extra costs.
This is a really stupid way to make power when molten salt reactors are just around the corner. Far cheaper and a WHOLE lot safer. We have to stop subsidizing the cost of install and the cost of power taken and supplied to the grid. There is no such thing as an independently powered house.

Beta Blocker
Reply to  ColMosby
June 5, 2020 7:06 am

If you can’t answer these basic questions, then you can’t claim that molten salt reactors are just around the corner.

— When is the first commercial-scale molten salt reactor scheduled to go into service?
— Which specific design will be used?
— Where will the first commercial plant be located?
— Which utilities have signed on as firm customers for its power?
— Who is supplying the financing for that first commercial plant?
— Has the design been submitted for regulatory review and a license to begin construction?
— If the design is now under formal regulatory review, when is approval expected?
— Who will be the prime contract’s architect-engineer-constructor?
— Who will be the EPC’s subcontractors and its component suppliers?
— Who will be supplying the nuclear fuel?
— How will the molten salt end-to-end nuclear fuel cycle be managed?
— Who specifically will be supporting the molten salt end-to-end nuclear fuel cycle?
— Have the regulatory review processes been initiated for all players in the end-to-end molten salt fuel cycle?
— How soon are these regulatory review activities expected to be completed?
— How soon are the various components of the end-to-end fuel cycle expected to be ready for commercial operation?

If you can’t answer the specifics of the who, the what, the where, the how, and the why of the first utility scale molten salt reactor, then any claim that molten salt reactors are just around the corner is completely baseless.

John F. Hultquist
Reply to  Beta Blocker
June 5, 2020 8:16 am

I’ve tried to get ColMosby to at least acknowledge that “just around the corner” is similar to “real soon now.”
These phrases are Newsspeak that indicate the person doesn’t have a clue. Don’t expect any answers. Do expect ColMosby to make a similar statement on the next appropriate thread.

Reply to  John F. Hultquist
June 5, 2020 8:42 am

I’m always reminded of the fusion enthusiasts who have been telling us that fusion power is less than 20 years off, for at least 60 years.

Tom in Florida
Reply to  John F. Hultquist
June 5, 2020 8:50 am

Kind of like the sign in many bars: “Free Beer Tomorrow”

Douglas Lampert
Reply to  John F. Hultquist
June 5, 2020 9:51 am

Hey! About 10 years ago Lockheed announced that they were then only 5 years from a practical fusion demonstrator reactor.

So, in circa 50 years we went from 20 years away to 5 years away, surely based on the passage of 10 more years since, we must have it by now. Or maybe not.

Smart Rock
Reply to  John F. Hultquist
June 5, 2020 11:15 am

Mosby is a fixture, with a bit of a one-track mind, and we shouldn’t pay him any mind. It wouldn’t surprise me if he was a shareholder in one of the MSR companies, which tend to promote their developing technologies, well beyond proven facts and into the area of possibilities, potentialities and optimistic anticipation. They have to hype, because they depend on risk capital investment. Nothing wrong with that – we do the same in the gold exploration business – but it does require a hard-nosed appraisal, not simple repetition of promotional claims.

The same goes for fusion developers.

New technology developers and “upstarts” using risk capital to pursue potential future visions are an integral part of the free-market system. Without them, our industrialized societies would never have reached the level of prosperity that we enjoy. The lucky investors who fund winners get rich, which is the whole point of investing.

When governments try to pick winners in the new-technology sweepstakes by offering subsidies or preferential purchase contracts, or (worse still) compelling consumers to use their preferred products, they distort the operation of the free market, and this, of course, is what we’re experiencing in the “sustainable energy” sector now.

What the MSR folks are going to find, when they finally try and get approval for a market-ready product, is that our governments are totally, obsessively risk-averse with regard to anything remotely “nuclear”. They will probably get sucked into a decade(s)-long approval and permitting process – the same one that has made conventional nuclear plants almost impossible to build. They will have to pour billions into the pockets of consulting engineers and lawyers and any hope of cheap, easily-accessible, transportable power generation will wither, just as conventional nuclear energy has withered.

Reply to  Beta Blocker
June 5, 2020 8:44 am

I’ve lost track of the number of “miracle” technologies that worked great in the lab, but never made it to commercial production.

Beta Blocker
Reply to  MarkW
June 5, 2020 10:16 am

To be fair about it, there is considerable interest in exploring the potential of molten salt reactors.

The problem with these reactors is that much work must still be done in moving the technology into a commercial environment, one which is capable of making a profit for all those who invest in it.

On the other hand, NuScale out of Portland Oregon and its partners have been exceptionally patient and diligent in covering every requirement needed for commercializing their SMR design, one which uses half-height conventional fuel rods.

NuScale and its partners are dotting every ‘i’ and crossing every ‘t’ with all the industrial and regulatory players needed to make their 60 Mw SMR design commercially successful. Nothing is being left to chance.

Bryan A
Reply to  Beta Blocker
June 5, 2020 8:50 pm

Cold Fusion is just around the corner though

Reply to  Bryan A
June 6, 2020 5:55 am

Much like “hot fusion” it’s just 10-20 years away-still.

Walter Sobchak
Reply to  Bryan A
June 6, 2020 3:12 pm

I knew the father of the chemist who claimed to have discovered cold fusion ~30 years ago. He was a man whose business dealings could not be characterized by scrupulous honesty.

David Guy-Johnson
Reply to  Alex
June 5, 2020 4:58 am

Alex. That’s probably the most inaccurate claim I will hear this year. You need a new tiler. I recently had my roof retailed with Welsh Slate. This will last for 60 years or more. The cost was one fifth of a tesla installation. In addition the tesla set up will last nowhere near as long as the slate

Reply to  Alex
June 5, 2020 5:09 am

The cost to purchase and install solar tiles on a 2,000 ft2 roof would be about $42,500 US.

Mark Luhman
Reply to  DHR
June 5, 2020 9:11 am

When my house was constructed it did not coast 42,000 to replace it today would be about double that. The property my house sits on is worth about three times what my house is worth. I live in Arizona and what I spend to heat and cool my house is little, a solar system would never pay for itself period. It would wear out before I would recover my cost. Yet according to the solar companies I would have a eight year pay back, funny they somehow figure the base cost for electricity is twice what I am paying and I would be paying less it it was not for solar mandates.

Reply to  Alex
June 5, 2020 5:59 am

I do not know about the U.K., but here, in Germany, there is no single house that would last for longer than 50 years.
Houses built in 70-ies are already subject to mandatory sanation: they do not satisfy energy saving requirements.
You cannot sale them, you cannot give them for rent, nothing.
You have to renovate.
Exchanging solar roof tiles for more efficient ones will be your least problem in 50 years.
And you get a lot of electricity for free in these 50 years.

Gunga Din
Reply to  Alex
June 5, 2020 7:06 am

Sounds like the problem in Germany isn’t the houses not being built properly but the government “going green” regulations.
And you would add even more such regulations!?

JohnM de France
Reply to  Alex
June 5, 2020 8:24 am

My house is about 350 years old. The walls are 0.75 meteres thick. In summer when, outside, it is in the upper 30s C ; inside it is 24 – 25°C.
Should I demolish it, and why?

Reply to  Alex
June 5, 2020 8:47 am

It’s not so much that the houses don’t last, it’s that the government has decided that old houses no longer meet modern requirements.
Either that or the carpenters union has bought the local council.

Reply to  Alex
June 5, 2020 8:48 am

Actually you would get very little electricity for about 10 to 15 years (especially in Germany), after which you will have to pay to replace those panels.

Reply to  Alex
June 5, 2020 4:37 pm

“I do not know about the U.K., but here, in Germany, there is no single house that would last for longer than 50 years.”

One of my friends in the UK lives in a house that was built in the 14th century. So it’s lasted something like 700 years already.

Of course, it was built without government regulation imposing construction methods that would ensure it couldn’t last more than 50 years.

Walter Sobchak
Reply to  MarkG
June 5, 2020 6:52 pm

I live in the US. The town I live in is 115 years old. My house is a pup compared to JohnM’s a mere 107 yro. but, we have kept it well maintained, and I amsure it is good for another 107, unless the ecoloons take over and force us to tear it down.

Brooks Hurd
Reply to  Alex
June 5, 2020 6:50 am


Have you gotten a quote on installing a Tesla Solar Roof with Power Walls to store power for the evening high use period? The current cost is not close to comparable for even the highest cost standard roofing.

The solar roof cost should come down over time, and Tesla’s new battery technology should lead to less expensive and much longer life batteries. Today, however, the Solar Roof is considerably more expensive than standard roofing.

Walter Sobchak
Reply to  Brooks Hurd
June 5, 2020 7:01 pm

My roof is covered with asphalt shingles. Not like David Guy-Johnson’s welsh slate, but serviceable.
In what universe do think that solar cells will ever be cost competitive with asphalt shingles? $0.72/sq.ft. at Home Depot right now.

Reply to  Alex
June 5, 2020 8:39 am

1) You claim that energy costs are the same, I doubt that very, very much. To make solar cells you have to melt glass.
2) Even if energy costs were close the same, monetary costs are much higher for the solar panels.
3) Life expectancy for a standard roof is years longer, so you have to factor in the cost of replacing your roof every few years.
4) I love the way socialists automatically turn to government to force other people into the choices that the socialists prefer.
4a) If the cost was as low as you want to believe, then there would be no need for a law.

Tom in Florida
Reply to  Alex
June 5, 2020 8:57 am

When a part of the panel that is in the middle of the roof goes bad or gets damaged, how do you get to it for repair?

When you have 4 straight days of clouds and rain as we are now experiencing on the central west coast of Florida, what is the alternative for power?

Reply to  Alex
June 5, 2020 10:32 am

Alex, that is a terrific idea! No need to stop at solar panels, though. Let’s mandate that everyone drive a Tesla M3, or a Prius, those are much better for the environment, right? We can restrict meat consumption because that is bad for you too. And families in the suburbs don’t need such big houses or to be so far away, so let’s make a law that everyone move to the city. Everyone needs to turn in their guns, of course. While we’re at it, let’s just collect 100% of everyone’s salary and then pay a minimum living wage. More than that is just excess and privilege, right? We could be much more efficient with healthcare if we dole it out sparingly to those who need it, that’s the fair way to do it. Everyone will have a job, except those that are unable to work because of disability, or stress, or inconvenience. Free education for all and we can let the government pick who goes to university or into the trades. Universal service for everyone (barring the special classes mentioned above) but we won’t need an army so everyone can work in the food kitchens or the abortion clinics.

I’m sure if you put your mind to it you can invent some other collective benefits of a strong but benevolent government.

And for those who have difficulty understanding these benefits we can create fun summer camps where people will go to learn how wonderful everything is.

Sounds perfect, doesn’t it?

Reply to  Alex
June 5, 2020 4:31 pm

“All new properties MUST have solar panel tiles”

It’ll work real well here for the 50% of the time the roof is covered with snow.

And it’ll be real good fun for firefighters when the house catches fire because of a short in the panels, and they can’t risk getting close to the roof if they don’t want to get electrocuted.

Ever considered it might be a good idea to let engineers do the engineering, and not politicians?

Reply to  Alex
June 5, 2020 5:07 pm

Given the hail we get periodically, it would need to be “as well”, not “instead”. And gawd knows what the accident rate of old codgers like me getting up to clean them off every second month would be. Come to think of it, how the heck would you even walk around on a roof that was 100% PV tiles.

As is usually the case, practical considerations run rough shod over theoretical pipe dreams – in the absence of Government regulation and subsidization.

Walter Sobchak
Reply to  Alex
June 5, 2020 6:47 pm

Of course it costs nothing. /sarc.

Bloke down the pub
June 5, 2020 2:51 am

If I was to invest in a storage system to go with my PV, I think I’d rather go down the route of heat batteries like those from , as they have an almost unlimited lifespan.

June 5, 2020 2:52 am

What took them so long ?

June 5, 2020 2:52 am

Sun is awaking. In May there was a single sunspot-day (May 1st) followed by 30 blank days, but the June SC25 activity is picking up, with SSN count:
2020 06 01 2020.417 5
2020 06 02 2020.419 0
2020 06 03 2020.422 10
2020 06 04 2020.425 11
2020 06 05 2020.428 11
It looks as the SC24 minimum will be following the last one (SC23)
If so than no the Maunder type Grand minimum this time, which is a good news, since cold weather kills people and retards biosphere’s activity.

Moderately Cross of East Anglia
June 5, 2020 3:04 am

As long as the tested panels/tiles are run in real world conditions, not some sterile lab. So exposed to the full gamut of bird crap, leaf debris, summer and winter extremes for the proposed siting latitudes, mould growth and all the other conditions in which they would really be expected to work. Oh and don’t forget if you are talking panels you will possibly have to put up with pigeons roosting underneath and covering your roof with filth.

Reply to  Moderately Cross of East Anglia
June 5, 2020 5:26 am


Dirty panels lose a lot of efficiency.

They stay dirty until someone cleans them.

Reply to  Richard Greene
June 5, 2020 7:27 am

“They stay dirty until someone cleans them.” Or until it rains, whichever comes first.

We had a good hard rain last night, the kind they call a gully washer. If it can was a gully…

Reply to  mcswell
June 5, 2020 8:41 am

Not true macswell except in your optimistic imagination, but funny.

Rain, I never thought of that !

I would love to wash my cars by simply parking them outside in the rain – car washes would go.out of business.

In fact, scientific experiments show particulate matter bakes onto the panel and can not be removed by merely spraying a solar panel with water.

I summarized a study in my climate science blog a year or two ago, and was surprised the dirt vs. efficiency problem for solar panels was much worse than I had ever imagined.

michael hart
Reply to  Richard Greene
June 7, 2020 5:22 am

I’m also trying to think of what other electrical devices still work when you park them outside for a few decades without maintenance activity. Not counting bulb changes, our garden flood light installations seem to break in about five years.

Ron Long
June 5, 2020 3:12 am

Going Green! I have my own energy storage system. It’s a 10 gallon container full of gasoline. I put it into my little Honda generator, start it up, plug in the refrigerator, the furnace control, and some lights, and off we go! Renewable? Yes, every few months I pour the remainder into my SUV and fill the container with new fuel. Works great!

Reply to  Ron Long
June 5, 2020 5:00 am

Oil, organic, renewable, green, high-density energy storage, and what excess the sun doesn’t break down, the bacteria will digest.

Ron Long
Reply to  n.n
June 5, 2020 6:21 am

Black Gold!

Reply to  Ron Long
June 5, 2020 6:40 am

Nature’s solar power storage system, accessible, affordable, convenient, environmentally friendly.

Reply to  Ron Long
June 5, 2020 1:07 pm

Texas Tea!

Gerard Flood
June 5, 2020 3:27 am

“Preliminary studies, however, revealed that measurements of the same storage systems by different measurement institutes sometimes produce very different results.”

So, at this stage, can anyone predict whether there will be any scientifically definitive standard measurement systems found, proposed, agreed, applied and subsequently, whether authoritative measurements of plants and installations be publicly announced?

My bet is that politics will again confound the capacity of the paying public to be fully informed of the realities. There is far too much money, personal advantage and political “investment” at risk – if truth were ever to be admitted onto the agenda.

Eric Vieira
June 5, 2020 3:32 am

Efficiency is nice to have, but in the long run it’s about how much does the current cost per kWh, and when has the system paid for itself, including maintenance and replacement costs. With batteries, the break even time is much longer (40Y instead of 10Y?).

June 5, 2020 3:59 am

Like commerical solar, commerical storage is going to be cheaper than homeowner storage. We don’t have much need for more ‘off the grid’ survivalists.
The article is in the neighborhood of admitting to some of solar’s problems.
I propose all homeowner and community solar have 24 hours of solar back up. This is to level the playing field some by shifting costs back to where they belong. Solar as it most often exists is a parasite on the grid. I wish to make all these solar panels owners less of a parasite on the rest of us. Let them put on their big boy pants. They’ve been at this deal for over 10 years. Time for them to grow up.

Leonard Weinstein
Reply to  Ragnaar
June 5, 2020 5:34 am

The point of being off the grid is not survivalists, but eliminating power transmission losses, removing power lines (subject to storm downs), and cutting costs in locations where power is expensive. PV cells and wind turbines are not practical due to not being despatchable when needed, and bad overall economics. Newer developing technologies are being developed that likely will satisfy price and capability, but until then, wait.

Michael Talcott
June 5, 2020 4:05 am

Entropy losses in.
“Bleed” losses while in storage.
Entropy losses out.
Original capital costs.
Replacement capital costs (like your car battery.)
Reclamation costs for the nasty materials of dead units.
Accelerated environmental costs for rare earths when demand is pushed to millions of units a day.

*Now* do your calculation.

Recall this is all net new costs as there is no need for these units currently.

June 5, 2020 4:10 am

I agree tht solar powered roofs should have storage capacity – this minimizes (but does NOT eliminate
taking power from the grid, or suplying same, both of which disrupt the grid.
Batteries do not produce power, they only store power and during cloudy days, they are pretty much useless. All-in-all, it is very inefficient to have each house maintain its own power supply.

June 5, 2020 4:34 am

The batteries cost more than the total storage energy potential. They are pushing on a string with these types of applications. What folly.

Just Jenn
June 5, 2020 4:39 am

Does anyone remember the Stephen King novel, “The Tommyknockers”?

In it the protagonist remarks that they are powering a space ship with D batteries instead of just using a more powerful battery system.

Somehow this is a parallel to that book.

To draw another, why are we not building a better mouse trap instead of throwing pennies to see where the other traps lie in the field?

I have no problems using solar panels to offset electric costs from the grid, I have in the past and may do so in the future if it actually is cost effective(determines where I’ll be living, in the tropics, you bet it would during the day). But the use of solar panels should be thus, to offset the cost not to replace that grid. If you are so bent on replacing that grid, then build a better mouse trap to do it. And solar panels are not the way to go, they are subject to a narrow band of efficiency in order to work. We don’t need to restrict ourselves to the fantasy of only 1 technology, we are creative beings, we can imagine something better. So lets start focusing on that and not on this…..JMO.

June 5, 2020 4:48 am

I get the impression that Greta’s disciples have little concept of what a kilowatt is and the effort needed to generate it. Those folk who have been on a building-site with no mains power and only a 2.5kVA petrol generator will know the saga. You have a wall to chase, the cutter tool says 1.6kW so you take a chance, start and warm the engine, plug in and squeeze the switch. The generator jumps in the air and stalls with the inrush. Eventually you catch it right and do the job. Note to self, next time hire a 3.5kVA diesel generator with a heavy flywheel.
Private and commercial renewables often produce electrically noisy power from inverters which can be electrically frail and fall over, an expensive replacement adding to TCOA.
Small scale nuclear surely is already here, there are quite a few units parked in the River Tamar, idle.

Leonard Weinstein
June 5, 2020 5:25 am

Germany is a particularly bad choice for solar due to their average solar intensity. In general, present batteries store energy and have number of useful cycles resulting in average cost of delivered energy of about $0.25 per net kW-h. This is true for lead acid and lithium types. Future costs could come down, but likely not much. The solar cells produce energy (based on average actual use and lifetime) for about $0.05 per delivered kW-h. The mix need (batteries and PV cells) to deliver 24 hr reliable requirements, independent of external electric hookup, with several day storage for cloudy periods, has an average cost near $0.20 per net delivered kW-h. If external power is used rather than large systems with many batteries, cost is much lower, but this destroys the income for the power company, and would eventually result in LOSS of the power company, removing that backup. In addition, the batteries and PV cells are mostly up front costs for the entire use period, and if paid on time, interest would likely increase the actual cost to over $0.30 per kW-h. Present power company costs using coal, gas, or nuclear are close to $0.10 per kW-h most places. There are new technologies being developed (e-cat SKL and Brillian Light Power) that may make external power generation companies not need for homes while still being economical, but until they are available, solar and wind systems are a bad idea unless cost is no limitation.

John Shotsky
June 5, 2020 5:28 am

All this ‘renewable’ energy is such a farce. Anyone that knows anything about efficiency knows that energy is lost at each time work is done. With solar panels, batteries and windmills, there is first the work of getting the raw materials. Energy is lost in that process. Then, there is the transport of the raw materials to where they are assembled. More loss there. Next is the process of refining the raw materials into a usable form. More loss there. Then there is the process of assembling and testing the end product. More loss there. Next is the transport of the finished product to either a distribution system or to an end user. More loss there. Now, it has to be assembled into a working system. More loss there.
So, the end user says ‘Looky here, I’m going green’. There ‘renewables’ are unlikely to EVER produce enough energy to account for the energy it took to GET THEM THERE.
Anyone think any of the preceding is done with ‘green energy’? No, I thought not.
Oh, and that renewable part? Does anyone think there is an infinite supply of the rare earth materials it take to MAKE these things? Do we REALLY need to run completely out of cobalt before we realize that there is NOT an infinite supply, so that it cannot be said to be ‘renewable’. There is far more petroleum than there are the rare earth materials, and in case anyone isn’t watching, China has been cornering the market in rare earth materials for years…

June 5, 2020 6:23 am

Electrochemical storage and recovery of energy with it’s expense and 2 way losses will never cut it without some fantastic technological breakthrough but so far we only have a limited table of elements although we know how and where the most energy comes from already (Hint: It powers the solar panels). So with the pitiful history of mankind’s capacity to store energy other than in the form of pumping water uphill or in the form of calories what’s the best use of the free but intermittent energy from the sun?

Well for most with an all electric household around a third of energy is used to heat water so that’s what you should do with an inexpensive electric element mains pressure HWS and a solar diverter like so-
Then any spare during the day you should use to RC aircondition the home to store heating or cooling for the evening which of course with the demise of coal will mean no off-peak power rates. No batteries in the market would get within cooee of that for economic energy storage and remember with water supply you’re already paying for the energy in water pressure. Wind and solar are useful for pumping and desalinating water too providing there’s no urgency required so they have another role to play.

Peter Morris
June 5, 2020 6:48 am

I read through all that to read at the end that they don’t know what the hell they’re doing?

I’m getting so sick of this garbage.

Reply to  Peter Morris
June 5, 2020 11:07 am

Of course they know what they are doing. They are doing “something” and we must do something because…..

June 5, 2020 8:31 am

“The more efficient the storage system is, the higher is the economic profit.”

That’s only true if you ignore the cost of a more efficient system.
Going from a 95% efficient circuit to a 99% efficient circuit usually comes with a huge increase in cost and complexity. (Complexity usually decreases the mean time between failure as well.)

June 5, 2020 8:56 am

“Lithium Batteries at Huge UK Solar Farm Could Explode With Force of Small Atom Bomb”

Don’t make them batteies too big

Reply to  mwhite
June 5, 2020 9:21 am

They could only explode like that if all of the energy was released over a couple of milli-seconds.
Since that can’t happen, comparing the energy to that of a small atomic bomb is scare tactics at best.

Frightening the scientifically illiterate is the game plan of the alarmists.

Mark Luhman
Reply to  mwhite
June 5, 2020 9:38 am

70 KW battery losing all that power in a few seconds make very large boom. Once watch a blizzard take sheet metal pieces off a building and blow them into a power distribution station. Each time on of the pieces of sheet metal shorted out the power lines it was instantly vaporized with a flash and a very loud boom. I would assume much the same result with said batteries. Although said batteries do have a larger internal resistance than a power line.

Reply to  Mark Luhman
June 5, 2020 10:31 am

About the only way I can think of to release all that energy in just a couple of seconds would be to plant enough explosives inside the facility so every cell could be ruptured at once.

A fire would take time to spread from one end of the structure to the other. Though given the nature of lithium, once it starts about the only thing the fire department can do is protect the surrounding structures.

Reply to  Mark Luhman
June 5, 2020 2:15 pm

A thermal runaway of a lithium battery is not an explosion, but it may look like one to a layman. The electolyte in the cells is a flammable hydrocarbon compound and when a cell bursts it sprays the stuff around and it ignites on contact with air. Think a gasoline tank with a burster charge (or a napalm tank for that matter).

Reply to  Mark Luhman
June 5, 2020 4:14 pm

The proposed battery size is intended to deliver 350 MW for 2 hours.
Ignoring conversion loss, call it a 700 MWh battery.
That converts to 2.5E12 Joules.
At 1E9 Joules per cubic meter for Li-ion, a 1 meter tall battery would have a floor area of 2500 square meters. A US football field has an area of 5350 square meters.
If the specific power is 350 kW per tonne, the battery would weigh 1000 tonnes.

A couple sources claim the Hiroshima bomb energy at 63E12 Joules.
About 50 percent kinetic (blast/shock wave), 35 percent thermal, 15 percent ionizing radiation.

2.5 divided by 63 is about 4 percent.

June 5, 2020 9:08 am

The caribbean island Sint Eustatius has a solar battery buffer which seems to work quite well.

It doesn't add up...
Reply to  Hans Erren
June 7, 2020 10:02 am

Some parameters on that. System installed and commissioned in November 2017. Island load (I suspect peak rather than average, which is more like 1.6MW) about 2MW. 4 MW of diesel generators (allows backup and maintenance) 4.15MWp of solar PV. 5.9MWh battery – about 3 hours of demand and 3 hours of midday charging. Solar provides 46% of power (but likely varies year on year). Battery also used for grid balancing. Allegedly saves about 1.7million litres of diesel p.a. (currently worth about $250,000 p.a., but obviously more at higher oil prices). About 18% capacity factor on the PV.

Interesting to see how it fares as it ages.

Brooks Hurd
Reply to  It doesn't add up...
June 7, 2020 1:49 pm

18% capacity factor is on the high side for PV. Do they track the sun?

June 5, 2020 9:10 am

“Such systems are mainly used by private households to increase their own consumption of solar power and their grid independence. ” You are either independent of the grid or you are not. If you are you will be in the dark a lot.
I have two solar installations at a remote farm site that are primarily used to run security cameras and the required wireless internet. It is EXPENSIVE maintaining them. I have “high” voltage/low current panels which are supposed to outlast ~12 volt panels by 10 years. I don’t even want to know how much I am paying per KWHr. I will be replacing $1,000 batteries this year. ARGH! I will be there today washing the panels.

June 5, 2020 9:18 am

Few transportation fuels surpass the energy densities of gasoline and diesel

Gaia knows that you can’t beat oil for optimum solar power storage.

Kit P
June 5, 2020 9:24 am

I have 50 years experience making electricity. When (most likely never) solar is a good idea I will use it to power my house.

I do own 3 small solar panels since retiring. I maintain the two marine batteries on my sailboat with small harbor freight solar panels because I am not up north in the winter.

I live in a motorhome. It has a 40 watt solar panel to maintain the 4 golf cart (GC2) batteries when in storage.

So using solar to maintain batteries when recreation things are stored off grid is a good idea because properly charged batteries last longer. Making $600 batteries last twice as long is cost effective.

On a daily basis I use 1200 watts of power that require me to run a generator (I have 3) one hour. I estimated 600 watts is lost due inefficiencies of using batteries.

A few who have RV spend upwards of $5,000 to $10,000 on solar and lithium batteries systems to do things that are more practical with fossil fuel.

I understand. I have a sailboat. It is not practical way to get from point A to B. I enjoy getting from Point A back to Point A.

There are practical ways of doing things and hobbies for people who do not have to choose between their medicine and food.

No study is needed. Storing electricty is ineffeicent.

Reply to  Kit P
June 5, 2020 11:04 am

For those who don’t understand the difference between watts and watthours

My monthly utility bill shows about 220 kWh.
At 720 hours per month, that’s about 305 watts.

Gunga Din
June 5, 2020 9:28 am

Sometime ago there was a post about the extra hazards solar panels present to firefighters.
They can cut the power to a house and so avoid the threat of electrocution but a solar panel on the roof is still producing electricity. Firefighters often have to break through the roof in the process of putting out a fire.
And there is the battery backup to consider in a fire.
Ever buy a battery that didn’t warn against putting it in a fire?
(Or maybe in “Green Utopia” houses never catch fire because a regulation forbids CO2 emissions?)

Robert of Texas
June 5, 2020 10:01 am

I am going to submit a proposal for a grant to study the feasibility of installing huge arrays of Moon Panels. This feasibility study will last 10 years and pay all researchers (i.e. me) $1,000,000 per year for my dedication and creativity towards this study. The end result will not be any real working system, but instead a paper describing the original proposal, testing the efficiency of the design, and a final recommendation to perform another 10 years of research.

As soon as this study is complete, I will then move on to Cloud Panels. Then Star panels.

Once all of these are researched, I can build a proposal for a huge Solar/Moon/Cloud/Star solar array that will not need any backup power sources. It will be rated for worst case – that is on a cloudy night when the moon is not up. (i.e. it will be rated to not produce anything useful reliably)

Just a heads up, I don’t want anyone out there trying to steal my future employment opportunities.

Gunga Din
Reply to  Robert of Texas
June 5, 2020 11:11 am

You forgot about potato power!
Just replace a couple of your power panels with potato growing boxes!
Now all we need is a way to replace the potatoes with mushrooms. They can be kept in the dark and fed BS and then, Voila! Green Power!
(Psilocybin mushrooms have the greatest effect on the public.)

June 5, 2020 10:18 am

What am I missing? This post seems to just be a KIT advertisement which readers use as a vehicle to talk about whatever is on their mind. Where is the information?

June 5, 2020 10:25 am

We’ve optimized electricity generation and use for over a hundred years. It was relatively inexpensive until ‘they’ tried to improve it with expensive, unreliable, and little tested new technology. Then ‘they’ convinced the people they were causing AGW and this would be better for them using the force of the media and laws to make them comply. When will the people realize they’ve been had by ‘them’?

June 5, 2020 11:53 am

Photovoltaics directly converts sunlight into electrical energy and, thus, contributes to sustainable UNRELIABLE power supply.

Reply to  tom0mason
June 5, 2020 7:47 pm

Where is the study to turn the neutrons released in Fission Directly into electricity? Immediately gain at least a 100% increase in efficiency by getting 60% of the released energy instead of 30% which is MAX in the steam cycle. And there is another 30% possibility. Then work on conversion of ALL of the fission particles released achieving an order of magnitude more power. Design the reactor to run dry, Un-pressurized and greatly reduce the mechanics of inserting safety control rods and providing the cooling of the shutdown reactor.

June 5, 2020 6:06 pm

Instead of determining how efficient Solar/Battery systems are they should do the simple calculation showing that they NEVER pay back what they cost. Even with government subsidies the home owner is losing money over their lifetime.

Geoff Sherrington
June 5, 2020 6:30 pm

The article from Germany sounds better when read with a John Cleese voice, especially the 57 abbreviations for bodies sucking on the public teat but oh! so seriously intent on pushing the message of “You will obey”.
In the several times I have been to Germany I met a few nice people and many tiny dictator minds.
They are collectively a bad mob at the centre of the anti-science demands to kill fossil fuels.
They are not even forgiven for making the BMW, another abbreviation like those that make up most of the article above. RIP.
The Energiewende has proven to be a failure, over and over. Give it up, guys. That name Energiewende is now used far less than before. You can hide things you are ashamed of in the modern post-normal way, but the huge harm still has to be paid for. Do not try to export it to fine countries like mine. For you, like PIK, this war is over. Geoff S

Bryan A
June 5, 2020 8:52 pm

Cold Fusion is just around the corner though

Rainer Bensch
Reply to  Bryan A
June 6, 2020 6:03 am

Yeah, outside. But we are inside.

June 6, 2020 3:26 am

Wasn’t the best one an electric train moving uphill?

June 6, 2020 1:15 pm

We have these installed at our office. Unfortunately we are lucky to get sun here in the UK!

June 7, 2020 7:24 pm

Free quantum point energy is just around the corner

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