[workerIbe]

I have built a system that cost just under $2k and should pay off in about 3-4 years (depending on battery lifetime). 2.4 Kw (8 panels) of used panels @ $.32/Watt, Charge controller, 3Kw inverter, transfer switch and 320ah@48v used Golf Cart Batteries. System is offgrid and supplies all my convenience outlets, kitchen and 240v circuits are on still on the grid. Panels are on top of free standing structures and being off grid permits are not required and only the transfer switch installation needed to be done by an electrician. Bonus is being offgrid it acts as a big UPS in a power failure.

[matt_wulfeck]

This is a great plan. PG&E here in California forces solar customers onto a more expensive plan. If you can avoid that switch and use solar to dramatically reduce (but not eliminate) your total kwh load then you'll definitely come out way ahead, because you'll be on their cheapest tier.

[njarboe]

California will be changing dramatically how it charges for electricity in the next few years[1]. I was talking to a person Tesla today about putting solar on our house and he mentioned in passing that Time-Of-Use Rates will be the default for everyone in California in 2019 by law (AB 327 in passed in 2013). For your net metering you will get credit/pay for power to/from the grid at the rate for the time it happens. A good up-sell for the powerwall. If the rates get way out of wack due to high solar input, one could do well charging your powerwall during the peak solar production hours (see duck curve [2]) and putting them back on the grid a 3-6 hours later.

[1] https://cleantechnica.com/2015/06/08/california-rolls-out-de... [2] http://instituteforenergyresearch.org/solar-energys-duck-cur...

[workerIbe]

Yes, most of the electricity I have generated has been what would have been tier 2 @ $.26 kWh, with the climate stuff going thru Sacramento atm I expect the price to go even higher soon.

[grw_]

I've wondered about the 'used panel' market for a while. Do you know why your seller didn't just increase the price of the property or move the panels? Does the second-hand price of panels decrease linearly with the amount of lifetime left, and how can you verify?

[workerIbe]

I got mine from a recycler, he said they failed inspection after installation for scuffs and scratches. Mine produce very close to spec. I have read that most panels degrade at about 1% per year, the ones I got were 3 years old. I checked them all to see that the open voltage was close to the specs when I got them, worked out great.

[bainsfather]

In the uk most solar installations get a generous subsidy for power produced. The fixed subsidy was set 5 or more years ago at e.g. 44p/kWh for a specific installed capacity.

The high price per kWh means it is economic for these places to upgrade their panels to newer ones that get closer to their rated output (e.g. in low light conditions etc). Hence the market for used panels.

Source: looking at the explanations on used panel shop's website - I think it is reliable.