Most people would calculate this against the term of the loan. So if you have a 10 year loan vs a 20 year loan, that would change the price. The price is what you actually pay, which in many cases would just be the cost of the loan divided by the amount of energy produced.
Interesting. I would have thought that you do it by (expected) lifetime of the panels. I haven't had my system for a full year yet so I don't have complete numbers, but it seems to be anywhere from .5 (winter) to 1.1 MWh per month.
Assuming I end up generating 8 MWh per year, I'll use that number along with an expected lifetime of, say, 20 years. So: lifetime production of 160 MWh, and my system (after incentives) was something around $18K.
$18,000 / 160,000 kWh = $0.11 / kWh.
If my system lasts 25 years, that goes down to 9 cents per kWh.
(note: I think I have a 10 year loan but will likely pay it off way earlier than that, but it wouldn't factor into this calculation other than interest)
> I would have thought that you do it by (expected) lifetime of the panels.
That would certainly make the most sense to me, and maybe even based on the warranty period, with accounting for replacing failing or underperforming panels after that.
That way, the statement, which sounds too good to be true, "and then the cost drops to zero" doesn't enter into the conversation. Sure, the monthly cashflow cost may be zero for a while, but that might just be accounting trickery.
In some cases it is expected to have less power as time passes by. My manufacturer says to expect a .72% decrease each year, so the total ammount during those 20 years will be smaller.
