Is Solar Heating of Pool worth it? Especially after Time of Use (TOU) electric rates are introduced

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I'm thinking of getting solar heating for my pool. We're in San Diego and the cost would be about $6000. Currently, I don't heat the pool at all as it's prohibitively expensive with natural gas. I am led to believe that the cost of running the solar heating is fairly negligible. Currently, I have to run the pump about 6 hours a day anyway to circulate and filter the water. I would have to pump the water to the roof to get heated which requires the pump (variable speed modern pump – PenAir) to work a little harder and thus use more electricity. However, this is all based on electricity being the same cost throughout the day. Obviously, the water must be pumped to and from the roof when the sun is shining (the higher in the sky the better). So my questions:

  1. How well does Solar Heating work?
  2. How many hours do you need to pump the water to the roof to heat the pool?

I'd hate to spend $6000 and find out that I can't use it. If/when Time of Use (TOU) becomes mandatory, it will be much more expensive to use electricity during the day. Right now, with no solar heating, that's not a big deal – I would just arrange to use the pump during off peak hours. However, that's not an option with solar heating (hence question #2). This brings me to my final question.

  1. Are people worried that there investment in solar heating will be not very good once Time of Use (TOU) becomes mandatory? It might be prohibitively expensive to pump water during the peak hours (typically something like noon – 6 pm). My understanding is that TOU will become mandatory in much (all) of the U.S.A. (I'm in California and 2018 is talked about as a possibility) The reasons why are a separate topic. I'm not sure if TOU already exists or is planned for the rest of the world. I'd be curious (but it's off topic 🙂 ).

Thanks,

Dave

Best Answer

  1. Heating a swimming pool is pretty much an ideal application for solar water heating. Relatively small delta-t requirements in mild weather means you can get high output from low cost solar collectors, and you can make use of 100% of the output. Payoff times for solar heating relative to equivalent natural gas heating can be as short as two years.
  2. You need to run the pump for most daylight hours, so in a San Diego summer, about 14 hours a day. You may be able to run your pump at a lower speed for circulation through the collectors, though, so this isn't necessarily a significant increase in operating cost
  3. Time of Use billing will certainly increase the operating cost of a solar pool heater, although not to the point that they aren't cost effective compared to other options, but perhaps past the point where you feel heating your pool is affordable. However, this can be effectively addressed with solar photovoltaic; aside from your standard grid tie solar PV, a DC pump can be tied to a few small solar panels without requiring an inverter, which can be cost effective even without peak TOU billing.
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