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12KW Solar gen for $2699 what is the Gimick?

3505 Views 9 Replies 9 Participants Last post by  Cord
Hello Solar experts. What is the Gimick in this add? Two weeks ago there was a similiar one for $1800 at 12KW.
This makes no sense as some people pay about $20K+ for a house system. Maybe $8-15K if they do it themselves. I googled it but did not find anything on these solar generators in my searches.
I use 4000 KW-HR a month. So even if this Generator system operates at 50% during a 8hr sun day that would be: 12KW x 8hrs x .50 x 30=1440KW-HRS a month. Or about 36% of a monthly bill.
I am sure alot of factors are missing. Ie cost to wire into house. It would probally only be able to work off grid.
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Run Time on Typical Applications before a recharge is required 70 Amp unit:
Those are make believe numbers.

1) The inverter produces a modified sine wave so many of those things listed won't work properly (trust me on this, you would find many of them burning up [at least stinking up the place] after running not very long).
2) You are not going to get more than a couple hundred watts out of that inverter with those tiny wires connecting it to the battery as shown in the pix. You'd need to replace them with some very heavy gauge wires to get anything reasonable out of it.
3) Although it's true 135AH x 12v = 1600WH, it is not true you can draw 1600 watts for one hour. Lead acid batteries don't work like that. Expect the reality to be 160watts for 10 hours best case. You could probably push it to 320watts for 5 hours and it might work (but probably only for maybe 4 hours). 320 watts to the load is probably going to be 30+ amps out of the battery with losses, so you'd probably want to use some really short 6ga or larger wires to keep the voltage drop at a minimum.
4) Inverters of that size will have a parasitic load, probably pretty large. I don't know what that particular one has, but would not be surprised if it is up around 75 watts or more. You will need to adjust your expectations of total run time accordingly.
5) Lead acid batteries do not charge at a linear rate. If you were very lucky and your panels could actually produce a maximum of 200watts for 8 hours, you still would not get 1600WH into the batteries. The batteries would accept 200watts until they were about 80% full, then gradually slow accepting less and less over the next several hours until they reached 100%. In reality, I think you'd need two full sunny days to get the batteries from empty to full.

But good luck with it. I built something similar a few years ago for my camping rig: 2 12v batteries, 2 100watt panels, an inverter. My first inverter was a simple 1500watt modified sine wave unit that liked to burn up all the things I plugged into it. It would not run an electric fan (for long; something about motors and modified sine waves don't like each other). I replaced the inverter with a small 150watt true sine wave and that worked fine running everything I needed it to without incident. It just wasn't easy to find spots that were sunny all day to place the panels, so I had to be quite conservative with electric use during my travels.
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