alt Hacker NewsAside from power-independence, does solar on residential roofs ever make sense? For all the complexity of doing a few houses, you could do an entire parking lot (or empty land) and power the whole neighborhood.
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Yeah if you can do it cheap enough. Here in Australia a standard 6.6 kW system (but with a 5kW inverter, maximum most utilities let you export with single phase) costs around $US6000 before subsidies, but around $4500 after. The systems are all basically exactly the same components, and these installers can probably do two houses a day with a stock standard system.
I have a system this size and it's fairly rare for me to make less over the day than I use (we have pretty sunny winters where I live and at -27 degrees latitude am not super far from the equator). In summer I tend to produce at least twice as much energy than the house draws.
The economics have skewed a bit as export tariffs have dropped (due to there being so much solar) but batteries have become so cheap and are now subsidised quite a bit too that most people aren't getting just solar systems anymore but now are doing solar+battery.
It would probably technically be a bit more efficient to do larger neighbourhood arrays and batteries, but if they're cheap enough it works fine to do individual homes.
It's central vs decentralisation.
The electricy is consumed in the houses and not on the empty land.
Parking lots become a win-win with electric cars. They also keep the cars cleen and sun protected.
Power Independence isn't even a given, most systems aren't eqipped or designed that you can turn off mains/street power to your house and still have power.
E.g. Disconnecting your energy supplier or a power outage will still result in no power usage, despite solar panels generating power.
More expensive inverters and battery systems allow this, although this is far from the norm.
Clearly they make economic sense or people wouldn't buy them.
Big picture society wide economics make no sense because utility grade solar costs half as much per installed watt.
On the other hand it can make sense based on arbitrage. In a lot of markets the cost of the system is unfairly subsidized. People on the losing side of that can lower their costs with roof top solar.
I've got a consultant coming over on tuesday to take measurements and give a more solid quote for installation.
We'll see. But I have an outbuilding with a large two plane roof and the south facing plane has no penetrations and is pretty much unshaded. Our utility rates have pretty much doubled over the last three years, and there's another ~30% increase scheduled over the next three years. Said roof is coming up on the end of its expected life, so it may be a good time to put on a new roof and put on solar at the same time.
Could someone get better ROI doing a larger solar project somewhere else? Probably. But if it maths for me, I'm going to do the project on my roof, because I don't have anywhere else to do it (well I could do a ground install, but I'd lose aesthetically)