ECN Forum Forums General Topics of the Trade General Discussion Area Solar: The Ghost of Carter

I have always held the position that any kind of tax credit, rebate or refund program is just a mechanism to convince you to make what is (in reality) the wrong decision.

If something is a good idea...you'll subscribe to it without any sweetener.

Greg:
Personally, I feel that without incentives the solar industry would face a massive reduction in 'solar companies'.

Well, as the news link I started with made clear, the reductions happened instantly, at the first hint of trouble.

There's a business lesson in this. What happens to you when the rules change in mid-stream? Or, worse, after the game is over?

Imagine .... what if you completed a job, and two years later the customer was able to walk into your bank and get the money back- AND keep the work?

That's exactly what's happening here. Systems were sold, based upon a fare structure that supported the sale. Now, years later, the rates change - turning a 'money maker' for the homeowner into an extra expense ..... an expense they can't eliminate. Any remaining construction loans still have to be paid off. Any service issues and warranties are up for grabs, as the vendor is now gone.

I could say "I told you so," but that would suggest that I'm happy with this outcome. I'm not. This sort of outrage is, alas, far too common these days. I don't think it can be avoided as long as we attempt to 'steer' economic choices with goals that are not economic themselves. Adam Smith's "invisible hand" can't work in handcuffs.

Reno:
I have to stir this pot a little......
You said....
"Installing a micro-inverter is so easy, it can be done in minutes, by most anyone, without interrupting household supply. The only question is whether the meter will run backwards or not.

Separate meters? Simply not possible, when the micro-inverter ties directly to a breaker in the common panel. There is NO separate panel needed for them. The breaker is all the disconnect you need."

Are you talking about one panel, and one micro? Like a 235 watt panel & micro going straight to the existing service panel with a backfed 15 amp, 2 pole cb??

Please enlighten me a little.

You're not stirring the pot at all .... I suppose (considering how new solar is), I ought to make sure everyone knows what I'm talking about.

We all understand the conventional way to do solar .. a bunch of panels feeding an inverter, then there being some manner of tying the generated power into the main service of the house.

That's all now as obsolete as the Model A Ford. Micro-inverters are here.

"Micro-inverter" actually refers to an entire unit, of which the inverter is but a small part. Let me describe it ...

Each solar panel has, as part of it, a small inverter. The power is changed into AC right up there, at the panel. Usually, these panels are capable of generating only a few amps each.

The "output" wires of several such assemblies are connected together right at the array, and a single, small cable is run from the array to ANY panel in the house. These arrays are usually limited to a total of 20 amps.

When the cable reaches the panel - and it can be any electrical panel - it is simply landed on an ordinary, dedicated breaker. These breakers are often single-pole (120v) breakers. The generated power is backfed directly into the panel.

It's up to the PoCo meter to know when there's more power going 'out' than 'in,' and adjust accordingly. Under the original "net metering" laws, the meter simply ran backwards (with the limitation that the PoCo would never actually pay out if you made more than you used). When I left Nevada in 2009, this was the law there.

Safety? These assemblies are UL listed. They operate only if there is PoCo power present, Through some technical magic, somehow all the panels generate AC that is synchronized with each other, as well as the PoCo. These are among the conditions of the UL Listing.

That's ALL there is to it. Harry Homeowner simply need buy an assembly, run a wire, and land it in the panel. Period. That's why I say regulatory approaches are doomed to fail.

The 'magic' of which you speak is actually a relatively simple thing.

The microinverter only works when it has something to synchronize to. As long as the Utility is present, it will synchronize to that and convert the solar DC power to AC. Since each microinverter is synchronizing to the same thing they end up being synchronized with each other as well.

One of the best safety features of this design is that once the power to the structure is cut, the PV panels stop outputting power since they have lost their synchronizing signal. Under the older system there were a lot of live DC cables running around on the roof ahead of the inverter that the firefighters would have no way to shut down.

The micro inverters I made the mistake of investing in had a NEMA 5-15 plug on them and you just plugged them into a convenient receptacle. Lowes was supposed to sell them
Unfortunately, nobody did and the stock dropped to pennies.

Will they sync to a UPS running on batteries?

I wondered that myself. If you had the right transfer equipment and tickled the collectors with an inverter, I think it should work. I am not sure a regular UPS would work tho because it might see the solars as being the utility and shutting down, starting a painful oscillation.
I bought the stock but I never bought a plug in micro inverter setup to test the theory.
You could test it without actually involving the utility power at all.

Greg:
Following the comments from you, and Reno, you guys are talking about micros that have a 120 volt nominal AC output, correct??

I have only seen 240 volt nominal micros, that are common on solar installs.

I guess if you had a 240 volt UPS, and a compliant way to connect it as a 'utility' source, it should trick the inverter to provide solar power?? What say you??