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There are also solar water heaters that are a bunch of black pipes on a roof. Napkin math based on Amazon/Home Depot prices You can get a 80"x90"x95% = 2kW ou
by pvillano 22d ago
There are also solar water heaters that are a bunch of black pipes on a roof.
Napkin math based on Amazon/Home Depot prices
You can get a 80"x90"x95% = 2kW output solar heater for $2000
or eight 45"x70"x25% = 1.8kW solar panels for $2800
A regular water heater needs about 12kWh a day, which is about what both systems would produce.
However, a heat pump water heater is 4x as efficient, so you could get by with $700 of solar panels.
Except, a heat pump water heater costs $2000 instead of $500 for a regular electric heater.
There's also install, maintenance, and the fact that we're talking about grid prices, not home panels, but those won't fit on my napkin.
- turtlebits 22d agoSolar water heaters (including evacuated vacuum tube) are great for efficiency, but PV has gotten so cheap and reliable that it's almost never worth a dedicated solar water heater unless you're extremely constrained for space.
- frankus 21d agoPV also (usually) lets you export generation in excess of what you're using, is ~immune to freezing, and can be pretty darned efficient if the PV is driving a heat pump.
- lostlogin 21d ago> A regular water heater needs about 12kWh a day, For reference: I’m in a household of three. Over the last month (winter, when n case that matters) we averaged 7.9kwh per day. I recently did the maths on switching to a heat pump hot water cylinder and the payback was surprisingly long at 5-7 years.