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I don't se how it includes the cost of a new system in 30 years. 2.3 * 30,000 = $69,000 and your cost listed is only ~$59k. 8% over 25 years is much better than
by gibybo 8y ago
I don't se how it includes the cost of a new system in 30 years. 2.3 * 30,000 = $69,000 and your cost listed is only ~$59k. 8% over 25 years is much better than I thought for the panels, but you still need to include about 10%/year depreciation on the inverters since you'll need to replace them every 10 years or so (at least that was about their lifetime last time I checked in Arizona, it may be different in cooler climates)
- aoeusnth1 8y agoI'm including the 30% tax rebate and assuming solar panel installations will be 50% cheaper in 30 years which is pretty conservative given their price history. Microinverters last 25 years.
- gibybo 8y agoStill not seeing $59k. 2.3 * 30.000 * 0.7 = $48,300 (30% tax credit) 2.3 * 30.000 * 0.5 = $34,500 (50% cheaper) Total = $82,800 Regardless, adding up the cost of the second one in 30 years doesn't make sense for calculating kWh prices, depreciation and cost of capital are the only factors that matter and you are only including one of those.
- aoeusnth1 8y agoSure, looking at my spreadsheet I also discounted the cost by the same interest rate after 30 years, (1/1.04)^30. Agreed that including the second system doesn't really make much sense, but I wanted a quick-and-dirty estimate without having to individually discount each year's production (as you would if you had a finite time horizon).