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I have 1200w of solar panels hooked directly to the lower element of my hot water heater. I sized the element to match the source impedance of the panels in fu
by opwieurposiu 5y ago
I have 1200w of solar panels hooked directly to the lower element of my hot water heater. I sized the element to match the source impedance of the panels in full sun. If you use a MPPT system you could get 50% more power in partial shade but panels were so cheap it was not worth the complexity. The top heating element is still on city power as backup but I rarely use it.
The water will get up to 80c on a sunny day, so it can store enough heat to last a couple days without sun. There is a mixing valve so the water coming out of the tank is mixed with cold to stay below 50C for safety.
- jojohohanon 5y agoWhen hooked up to the grid, converting from electricity to heat for storage makes alot of sense (to me). But I'm curious about your case: why not use the old-fashioned solar water panels to create hot water directly?
- opwieurposiu 5y agoSolar hot water panels would make 4x the heat for the same area, but are too complex and expensive to install. They need pumps, expansion chamber, control system, antifreeze, new larger hot water tank. They are too heavy to get on the roof by yourself. My non-grid connected solar cost about $1200, and was easy to DIY. No $1000 permit needed since it is not connected to the grid. No moving parts and almost no electronics. House now uses only 8-12 kWh a day.