Too much hot water!

I’ve had my solar water heating system in operation since May 2011. It works really well. In over a year, I’ve turned my electric water heater on for part of 2 days. Once, we had experienced about 7 heavily overcast days in a row, so I was just running out of hot water. The second time, I had to drain and recharge the collector loop because I didn’t have enough antifreeze in the solution. That means that my electric water heater has been powered up for less than 24 hours in over 400 days. The solar water heater is providing 99.75% of my hot water. I even do some of my laundry in hot water and rinse my dishes in hot water because the heat is free.

solar water heater panel partially covered with a sheetWell, now that summer is upon us, again, I can’t use enough hot water to stay ahead of the sun. The primary tank will reach 185F in a day of full sun. The water is so hot, even with R30 insulation on the tank, it’s heating my utility room.

I can set the pump controller to stop circulating the collector loop once the storage tank reaches the desired temperature, but then the collector gets really hot. It reaches temperatures of 300F, and I am pretty sure that’s not a good thing. So, yesterday I enlisted a friend to help me put a sheet over about two thirds of the panel, to deflect some of the sun’s heat. We had a day of full sun, today, and the sheet worked well at moderating the amount of heat. It’s a good temporary solution, but I’m going to have to work on something more permanent and easy to control. It would be really nice to have an automatic louver system, but I’m not that ambitious, and I’m pretty sure that would cut down on the effectiveness of the panel when I actually need it to work at 100% capacity.


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