Friday, October 1, 2010

It's hot in here

As you may recall, we had a solar water heater system installed about a month ago. It definitely took longer than we expected to complete, but I think it's been worth the wait. Based on our experiences in the last month, I would highly recommend considering a solar system if you live in a sunny part of the country.

A couple of oddities you might note. First off, the plumbing required for the water heater tank is a little... convoluted.
It would be an epic plumbing kludge, except that it works.

The cylinder you see on top of the tank is a heat exchanger. Our system is an active, closed loop system, which means that the solar panel has loops of tubing filled with distilled water, and the distilled water circulates through tubing into the exchanger, where it heats water in the exchanger that is then circulated into the holding tank. Kind of a nifty system, if you ask me. Ours is guaranteed for 30 years.

The exchanger is kind of loud when it's circulating. It doesn't bother me, but you can definitely hear that the exchanger is working. If you're the type of person who wants things ultra-quiet and your water heater is in your house, you probably shouldn't get a solar heater.

Because the temperature of the water in the tank varies, you can't always set the dial on your shower in the same place and get the same temp. If it's been sunny, the water will be hotter, so you'll need to run more cold. If it's been cloudy, it will be cooler, so you'll have to move the dial warmer. Not difficult, but different if you're used to water that's always 105 degrees.

It can be entertaining to see how hot the water in your tank actually gets just from the sun. We have a little electronic doodad that shows the temperature both on the roof in the solar panel and in the bottom of the tank. I took these pictures over the weekend, when the high was 95 degrees.

See the little dot at the top of the graphic? That tells you the temperature on the roof, in the solar panel. In this case the temperature was 143 degrees.

The temperature at the bottom of the tank (denoted by the dot in the water tank) was 136 degrees, but since hot water rises, the temp at the top of the tank was likely higher. Any time there's more than a 10 degree difference between the temperature on the roof and the temperature at the bottom of the tank, the water will circulate, exchanging hotter water for cooler water.

So far we have not noticed a change in our electric bill, but we have been running the A/C more in the last month since August/September is usually the hottest month. If we continue to have sunny days, we will likely be able to leave the breaker for the water heater off completely until October! I am certainly hoping that is the case - it's very neat to have your water heated by the sun!


  1. This place had a broken solar hot water heater system when we offered on it - we had them take off the roof part when they reroofed the south side, and we got a junk guy to come take the tank. I'd love a modern system one day! This is also the ideal climate for solar.

    136* hot water is almost dangerous, eeeek.

  2. Funder, it's unfortunate that the solar water system on your house was broken, what a bummer! You are definitely in the perfect spot for a solar system. One of the reasons we went with solar was frankly because of the rebates and tax credits - our system was almost free because of it.

    Yes, if the water came out of the tap at 136 degrees, it would be dangerous. However, it's modulated down to (I think) no more than 105 or 110, more or less, out of the pipes. As I said, it's a bit less exact than a standard electric or gas heater, but it's definitely not set up to scald you when it comes out of the faucet!