NYT, Robert F. Kennedy Jr., and David Crane have no clue about how grid tied solar power actually works with the grid

Hurricane Sandy seems to have brought out the latent stupidity in just about everyone in their zeal to get in on the climate alarm resurgence. I laughed out loud when I read this op-ed in the NYT by DAVID CRANE and ROBERT F. KENNEDY Jr. published, December 12, 2012, because it becomes immediately obvious that these two “experts” don’t have a clue about how grid-tied solar actually works, and their ideas actually can cause deaths, injury, and additional property destruction if people try to follow their lead and then try to circumvent safety features when they find out their solar system won’t do what they claim. How embarrassing for them.

Excerpts:

Solar Panels for Every Home

[…]

Residents of New Jersey and New York have lived through three major storms in the past 16 months, suffering through sustained blackouts, closed roads and schools, long gas lines and disrupted lives, all caused by the destruction of our electric system. When our power industry is unable to perform its most basic mission of supplying safe, affordable and reliable power, we need to ask whether it is really sensible to run the 21st century by using an antiquated and vulnerable system of copper wires and wooden poles.   

Some of our neighbors have taken matters into their own hands, purchasing portable gas-powered generators in order to give themselves varying degrees of “grid independence.” But these dirty, noisy and expensive devices have no value outside of a power failure. And they’re not much help during a failure if gasoline is impossible to procure.

Having spent our careers in and around the power industry, we believe there is a better way to secure grid independence for our homes and businesses. (Disclosure: Mr. Crane’s company, based in Princeton, N.J., generates power from coal, natural gas, and nuclear, wind and solar energy.) Solar photovoltaic technology can significantly reduce our reliance on fossil fuels and our dependence on the grid. Electricity-producing photovoltaic panels installed on houses, on the roofs of warehouses and big box stores and over parking lots can be wired so that they deliver power when the grid fails.

That last sentence in bold is my emphasis, because it shows just how clueless these people are when it comes to real world solutions. They want to give readers the impression that they can use their grid-tied solar power system after a storm to get electricity, I’m here to tell you that claim is absolute bunk.

Full disclosure. I have a grid tied solar power system on my home. I had one on my previous home, and I orchestrated the first ever solar power system for our local school district. I know a thing or two first hand from an engineering and use standpoint. Here’s my current home installation:

IMAG0430

IMAG0431

Top: the solar panels. Bottom: the DC to AC inverters and the grid tie and SmartMeter.

Note the red labels, particularly under the SmartMeter. They are required by law. The red one under the meter (along with the new yellow one added by the utility company after inspection for the grid tie certification) reads:

IMAG0283

“Possible danger of electrical back feed” is the key phrase, one completely lost on the NYT, Kennedy, and Crane.

The issue is this, if you have grid tied power sources running in your neighborhood, and they are producing power, anyone who isn’t careful doing electrical work could get electrocuted thinking that after they pulled the main breaker, there is no power in the wires. Imagine if you have a bunch of these pumping power into power poles laying on the street after a storm; it becomes an instant fire starter.

But that’s been taken care of too, because the DC to AC inverters won’t function due to this (also required by law and code) safety feature built in.  Here’s the relevant code from the inverter installation manual:

Electrical conformity according to U.S., Canadian and

international safety operating standards and code

requirements:

– UL 1741 – Standard for Inverters, Converters, and

Controllers for Use in Independent Power Systems

And this:

4.2 Protective concepts

The following monitoring and protective functions are

integrated in blue planet inverters:

– BiSI grid monitoring to protect against personal

injuries and avoid islanding effects according to UL 1741

What is “BiSI grid monitoring”? According to E DIN VDE 0126, which is a year 1999 standard developed in Europe specifically to address the problem:

The automatic disconnection device is used as a safety interface between the generator and the public low-voltage distribution net and serves as a substitute for a disconnecting switch accessible at all times by the distributing network operator. It prevents the unintentional supply of electrical energy from the generator into a subnetwork disconnected from the rest of the distribution grid (islanding), thereby offering additional protection to the measures specified in DIN VDE 0105-100 (VDE 0105-100), 6.2 to

– operating staff, against voltage in the disconnected subnetwork

– equipment, against inadmissible voltages and frequencies

– consumers, against inadmissible voltages and frequencies

– equipment, against the feed of faults by the generator.

In a nutshell, when the power poles go down, the inverters lose connectivity to the grid, sense this automatically, and shut themselves off.

Never mind the fact that grid-tied solar power doesn’t work at night when you need it most, never mind the fact that during and after the storm, solar insolation is drastically reduced due to rain and cloudiness, and never mind the fact that all electrical systems, solar or otherwise, are just as susceptible to storm damage as conventional power infrastructure, there is one important point that kills the entire idea.

Assuming the solar panels aren’t ripped off the roof by the hurricane/storm, they are of absolutely no use because the grid-tie is broken, and the mandated grid-tie safety features prevent the homeowner from using the inverters to get power locally.

You’d think “experts” like Kennedy and Crane would understand this basic concept…but they probably never got any closer to a solar power system than a photo op.

Some might claim that a battery backup with an automatic transfer switch might solve the issue. But, battery systems double to cost of most solar installations, and need to be replaced about every four years on average (for lead acid batteries, the most common solution), and they need to be maintained, checked, etc, plus require significant space. Compare all that to a $699 generator available from a local hardware outlet that has none of these problems and you’d understand why that is currently the solution of choice for most homeowners that want backup power after a storm.

Hopefully people following their lead for solar systems won’t try to hack their solar power system inverter safety features in time of crisis.  The first person to try defeating this safety feature after a storm may get themselves or others killed or injured, either by electrocution or fire. Hopefully the solar power industry will join me in condemning this foolishness propagated by Kennedy and Crane.

h/t to WUWT reader Charles Carmichael for the NYT story link.

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Larry in Texas
December 15, 2012 12:35 am

Anthony, a very good job exposing another canard from the Kennedy clan and the solar fools. My dad had a huge knowledge of electricity and could do a lot of things around the house with electrical systems, but his knowledge didn’t rub off enough on me to enable me to do my own work. So I sure don’t mess with it in my house; I call the electrician when needed. Your post is an excellent way of telling people to NOT mess with electricity. Either get the right generator or find another way if you need a little power in your house when the grid goes down. Because you are either on the grid or you are off. There is no half-way on this one.

Massimo PORZIO
December 15, 2012 3:19 am

Steve Richards,
“If you do not ‘use’ the output of the panel/invertor it is not dumped into resistors etc, it is simply not used. You can have 240VAC or 120VAC produced all the time, if you do not switch on your heater, the take no current, it remains available till you need it (or darkness falls)”
Not really so, you must provide a device which converts the unused energy in something else (typically chemical work, in accumulator or capacitors) when your accumulator reaches its maximum capacity your inverter must have have an additional device (here in Italy we call it “braking resistors” , the term comes from the industrial control, where inverters are widely used to control motors) which keeps the voltage under the maximum allowed by the accumulator.
So when you accumulators are full, the unused energy is finally dumped into resistors indeed.

Massimo PORZIO
December 15, 2012 5:30 am

Richards.
Hops… I missed a thing
Many solar panel system power-grid-coupled without any accumulation device haven’t braking resistor at all, because it’s the same solar panel string which works that way. That is, when the panel surface is irradiated but the inverter doesn’t supply the grid, the voltage across the panel rise directly polarizing the solar panel junction which dissipates, heating up itself.

Ygor
December 15, 2012 5:54 am
December 15, 2012 7:04 am

Ygor: This may work for some large scale applications (it still runs off the grid, it looks like, or may require a separate grid) but while some of the commentors said they run duel systems already and I use DC backup for power outages, I can attest to the fact that it is very difficult to get people to use DC. We use it at our cabin, but all the others in the area use wind and solar, then an inverter and AC power. No amount of explaining how much energy is lost in the inversion, etc, makes any difference. People want AC and little black boxes on their electronics cords. It won’t be an easy sell. Personally, I prefer DC (we use 12 volt since there are all kinds of devices that run on 12v systems). It’s easier to understand and you can set up your own 12 volt system.
Dependence on the grid will remain, I think, because people simply do not want to learn how to deal with electricity. Solar and wind on a personal level requires troubleshooting, constant maintenance, etc.

Lemonade
December 15, 2012 9:25 am

I see The NYT has posted an online correction underneath the oped but it’s not the error you mentioned on MediaBugs (and here).

steverichards1984
December 16, 2012 1:02 pm

@Massimo PORZIO,
A PV panel is just like a battery, if you decide not to use the potential within a battery, you do not and the power is available for another time.
If you do not make use of the voltage produced by a PV panel then you don’t, and need worry no more.
Inverters are designed to make the most of the output from a PV panel, they constantly adjust how much current to take because when you take more current, the voltage falls slightly.
The inverter produces as much power capacity as it can, if you do not wish to use it at anytime, don’t, the inverter will take less from the panel.
There is no need for resistors or other loads.

Steve Richards
December 17, 2012 4:32 am

@Massimo PORZIO:
Your “breaking resistors” are used in motor drive systems, when the inverter has stopped providing power to the motor, the load (a machine, a conveyor belt etc) runs due to kinetic energy and you want to stop it by allowing your motor to run as a generator, provide the generator with a load, ‘breaking resistors’ and your machine will come to a stop as the ‘breaking resistors’ absorb the power of your machine.
In cars etc they call it regenerative breaking, where the generated electricity is fed back to the battery rather than wasted in resistors.

Massimo PORZIO
December 17, 2012 6:29 am

Richards
“A PV panel is just like a battery, if you decide not to use the potential within a battery, you do not and the power is available for another time.”
False: the unused power is converted in heat by the junction of the solar panels that, when irradiated by the Sun, increase the voltage at their contacts this voltage higher than the nominal P-N junction at the environmental temperature generate the current across the junction which heats up the panel, this way the panel works as the breaking resistor I referred.
“The inverter produces as much power capacity as it can, if you do not wish to use it at anytime, don’t, the inverter will take less from the panel. There is no need for resistors or other loads.”
Yes, you are right here. No need for them, because the panels themselves dissipate the unused power heating up.
But heating up they lose efficiency.

steverichards1984
Reply to  Massimo PORZIO
December 17, 2012 7:10 am

@Massimo PORZIO:
I feel that we are getting closer!
There is no mechanism that I know of for an unused PV panel to heat up other than by direct application of the suns rays. In just the same way that a plate of steel would warm up if exposed to the sun.
If it is not providing electrical power, its temperature depends upon the amount of power from the sun and the figure for its reflectivity (or albedo if you wish) plus other heat transfer mechanisms such as conduction and radiation.
Now, when you draw current from a PV panel, the panel will experience a temperature rise due to P=VI or P=I^2R etc.
The more power extracted, the warmer the panel gets.
I agree that the warmer it gets, the less efficient it becomes.
Still no breaking resistors though.

Massimo PORZIO
December 17, 2012 8:04 am

Hi Richard,
Not really so, The more energy you convert to electricity and extract from the PV the more it cools.
If you leave the produced current there on the panels electrodes without using it, that current is converted to heat. The temperature rise due to the Joule effect you refer exists but its another issue.
Energy must go somewhere, if the inverter doesn’t sink it from the panels they became more warm than otherwise.
This is the reason I don’t agree with your “A PV panel is just like a battery, if you decide not to use the potential within a battery, you do not and the power is available for another time.”

steverichards1984
Reply to  Massimo PORZIO
December 17, 2012 9:16 am

@Massimo:
You will have to give me a technical reason as to why PV panels cool when in use, it does not make sense to me.

dmacleo
December 17, 2012 9:58 am

I have generator set here inn outbuilding with no isolators. I also follow a well defined procedure.
if power out I first flip main breaker in house to OFF.
I then go out to incoming at meter and flip that breaker to OFF
I then start gen and let it stabilize by running a light in outbuilding, its well ventilated.
I then flip the 220 breaker to send power back to house.
but house still has nothing because, yup you guessed it, there is a fourth breaker that needs to be flipped on to allow power to go into panel.
can run heat and water pumps ok, nothing fancy but when its below 0 F and power is out you need heat. actually I can run anything I want but gen is getting old so I do not push it.
when I see evidence that power is back on, which in rural maine is hard to do actually, I then shut off the breaker from outbuilding to depower the panel.
then I flip breaker in outbuilding to remove all draw from gen, let it idle a few and then sut it down.
I then flip the breaker on meter on and then flip main on inside house.
under NO conditions is the generator running w/o the 2 breakers to utility being thrown and isolated. even when just starting the gen to run it a few for checks I will not do that.

Massimo PORZIO
December 17, 2012 4:16 pm


Hi,
maybe I’ve been not clear, I try to explain now.
Any photo-voltaic panel is made of P-N semiconductor junctions. Any semiconductor junction present a nominal voltage at its extremities which is function of the environment temperature. If you apply to the P-N junction a voltage equal or greater than its nominal value the P-N junction allow a current to flow through it. This is the very same behavior of a directly polarized semiconductor diode. For diodes, that nominal voltage is named Vf which stand for forward voltage. The P-N junctions of a photo-voltaic panel when exposed to a considerable flux of radiation which wavelength is close to the Planck’s black-body of the material which the P-N junction is made (for silicon it’s around 850-950nm) the P-N junction starts to exhibit a voltage. If that voltage rise over the nominal voltage of the junction polarizes it directly making a current flow across the junction. If instead you connect an external load to that junction, the current will flow in the load avoiding that current in the P-N junction which cools respect if it was unloaded.
By the way, just imagine the solar panel as a close system which receive the energy from the Sun. Since it’s albedo is independent by the load connection or not, that system must release the energy in one way or another, otherwise you should identify a work on the panel structure which justify the accumulation of energy along the exposition time. Since that work doesn’t exist at all, the only way it has to release that energy when no load is attached is heating up (that’s the thermodynamic work indeed of course).
An another example:
imagine to put the solar panel with a resistive load attached to it, both into a greenhouse. Then the Sun heats up all the inner thing of the greenhouse at a temperature that depends only on:
A) the solar flux which impinges the greenhouse
B) the greenhouse glasses transmittance in the solar radiation band,
C) the inner objects albedo
D) The greenhouse walls insulation coefficient.
The inner temperature it’s absolutely independent by the fact that the load is connected or not to the solar panel, because there is no other energy than the solar radiation that enters the greenhouse. So, when the load is disconnected the solar panel must be warmer than when the load is connected otherwise there is creation of energy, that we know is impossible.
By the way the reason a PV lose efficiency when its temperature rise it’s also because its nominal P-N junctions voltage decreases as the temperature increase.
I hope I’ve been a little useful with the above.
Sorry, my English is not so good.
Have a nice day.
Massimo

Massimo PORZIO
December 18, 2012 12:04 am

Hoops! I wrote:
“This is the very same behavior of a directly polarized semiconductor diode”
No, it’s “This is the very same behavior of a INVERSE polarized semiconductor diode”, because it is the current of recombination of the charges into the depletion layer of the junction.
(It was about 2:00AM here in Italy and I was very tired, sorry).
It is the very same current experienced in the zener diodes, which is very high in the case of the PV junction because they are made with highly doped semiconductors to get the direct resistance very low.
Have a nice day.
Massimo

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