Plug-in grid tied inverters

[jimmychacha]

Has everyone seen these new inverters that just plug into a wall receptacle? What are your thoughts on this product? I think they may be a way to gradually produce solar energy for those who can't afford the initial investment. But is this a safe method of feeding the home?

[russ]

Outside of those units not being approved by any certification agency and unsafe I suppose there isn't much good about them.

I am not sure how companies like Clarian manages to try to sell the junk.

I believe you are not allowed to back feed the system such as they do - not in the civilized world anyway.

They are not cheap either. Per watt the costs I have seen are quite expensive. It looks cheap because it is under 1000$ maybe but you are getting next to nothing.

Non UL (or other similar agency) equipment can cause you big problems in the event of a fire or safety problem that comes to light. Homeowners insurance would be void if a fire was started and they determine unauthorized equipment was in service.

[Sunking]

What are your thoughts on this product?

They cannot be used in any code compliant configuration and no electric company would allow you to connect to them if they knew about it.

I think they may be a way to gradually produce solar energy for those who can't afford the initial investment.

There is the fatal flay of your analysis. Investment means putting money into something with hopes of a profit. The units are so expensive and inefficient they would never return a ROI. You would be better off just buying whiskey and drinking it. At least you will get something out of the whiskey.

But is this a safe method of feeding the home?

Nope, refer to first statement.

[jimmychacha]

Good points gentlemen. I understand backfeed may not be code compliant currently, but code is ever evolving, so let us analyze safety with our own electrical knowledge. If an AC source backfeeds into a branch circuit the only danger I can forsee is another load in that circuit exceeding the branch circuit's ampacity. However if said inverter output was fuse protected, I see that problem solved. The unit I was referring to also states that it will shut down when utility is lost, ant-island protection.

Lastly, this 600 watt unit cost $129.

[Sunking]

Good points gentlemen. I understand backfeed may not be code compliant currently.

Backfeed is not the safety issue, it is the plug with exposed live conductors. It can never receive UL certification. It has to be hardwired into the premises wiring and made inaccessible.

[russ]

Lastly, this 600 watt unit cost $129.

There is an important statement - at that price per watt something is hokey!

Not to mention the balance of equipment.

When something seems too good to be true - it usually is.

Russ

[jimmychacha]

Well I guess there is one born every minute, because I bought it. After verifying the anti-island protection, I wired this unit in parallel with an existing 45 watt array that charges (3) 12 volt batteries, which in turn supply some 12 volt accent lighting throughout my home. The existing charge controller prevents battery backfeed through the device or the array. I plugged the unit into a GFCI receptacle, on a 20 amp branch circuit. Reading the current flow through a Kill-a-Watt meter, I have 1.15 Amps backfeeding into my house this afternoon.
I know this is peanuts, or even millipeanuts, compared to some contributors projects, but it's working. It has me confident enough to increase my array power, and I can share my opinion with others who may be interested in the product.

[Sunking]

I wired this unit in parallel with an existing 45 watt array Reading the current flow through a Kill-a-Watt meter, I have 1.15 Amps backfeeding into my house this afternoon.

Something is wrong with the math because 45 watts at 100% efficiency produces .38 amps @ 120 volts.

[jimmychacha]

Show me your PE math, 45 watts dc divided by 12 volts DC is 3.75 amps. If the KAW meter measures anything but RMS it will be higher.

[Sunking]

Show me your PE math, 45 watts dc divided by 12 volts DC is 3.75 amps. If the KAW meter measures anything but RMS it will be higher.

OK, the inverter output is 120 VAC RMS. 45 w / 120 volts = .375 amps.

[Mike90250]

Show me your PE math, 45 watts dc divided by 12 volts DC is 3.75 amps. If the KAW meter measures anything but RMS it will be higher.

That's the 12V dc feed into the inverter, step it up to 10x the voltage, you get /10 amps

So the inverter is consuming much more power than it produces, or you have a portal into a universe with extra power, and the aliens will come looking for you for killing their star.

[ecusolar]

Not worth the money

I have one of those 250W suckers running since many month, I connected an old 110V wattmeter at it.

With good luck it produces 400W daily and I have a 7 hour full solar production all year long.

It's not worth the money, better invite your better half to a great dinner with that funds.

Joe

[Naptown]

They cannot be used in any code compliant configuration and no electric company would allow you to connect to them if they knew about it.
There is the fatal flay of your analysis. Investment means putting money into something with hopes of a profit. The units are so expensive and inefficient they would never return a ROI. You would be better off just buying whiskey and drinking it. At least you will get something out of the whiskey.
Nope, refer to first statement.

I'll drink to that!