Hot water circulating pump

What a great forum with such helpful people. I’m pretty new to solar and most of all this is going right over my head. Like I know what 12v is but what is 24v and 48v. I have a few projects I would like to do. Right now I'm working on an Open-Loop Direct Systems here in Phoenix AZ. I added a standard, 50-gallon electric tank for a storage tank and wondering the best way to get it together. I was ready to add an electric pump and use the Goldline gl-30 temp control. But now think maybe a DC pump would be better, wouldn't cost any electricity. I have some 75w panels, would a 75w panel be too much for this pump? They say a 10w panel will run it. And if I went with a DC pump is there a temp control unit I could use, so it just doesn't run all the time. Most I have read has the circulating pump just circulating between the 2nd tank and the collector. Can I have the pump circulate between the 2 tanks? Also in the winter I’m sure I won’t get much heat so if put 1 or 2 DC element on the storage tank how many 75w panels would each element take and is that something I should do?  I’ll also put a timer on the main tank and have it turn on a little bit a night.  Thanks for any help

Kim

Comments

  • FrankFrank Posts: 54Solar Expert ✭✭✭✭
    Re: Hot water circulating pump
    azaware wrote:
    What a great forum with such helpful people. I’m pretty new to solar and most of all this is going right over my head. Like I know what 12v is but what is 24v and 48v. I have a few projects I would like to do. Right now I'm working on an Open-Loop Direct Systems here in Phoenix AZ. I added a standard, 50-gallon electric tank for a storage tank and wondering the best way to get it together. I was ready to add an electric pump and use the Goldline gl-30 temp control. But now think maybe a DC pump would be better, wouldn't cost any electricity. I have some 75w panels, would a 75w panel be too much for this pump? They say a 10w panel will run it. And if I went with a DC pump is there a temp control unit I could use, so it just doesn't run all the time. Most I have read has the circulating pump just circulating between the 2nd tank and the collector. Can I have the pump circulate between the 2 tanks? Also in the winter I’m sure I won’t get much heat so if put 1 or 2 DC element on the storage tank how many 75w panels would each element take and is that something I should do? I’ll also put a timer on the main tank and have it turn on a little bit a night. Thanks for any help

    Kim

    Kim - 24 volt and higher voltage systems are constructed by connecting batteries in series. Three 12 volt batteries in series make a 36 volt system. Series connection means the +'ve terminal of one battery is connected to the -'ve terminal of the next one in line and so on. Higher voltage systems means that less current flows for a given power requirement. This typically means smaller wires and extended battery life.

    I'm not sure I understand your system: are you talking about a drain-back type of collector where water can be circulated but will empty itself at night? Regardless, the typical DC pump setup runs with a 10-20 watt panel (I use a 20 w panel here in Maine with an El Cid pump). 75w is too much and a waste. Using a separate panel to drive the pump means that when the sun is out the pump runs and no control is really needed. Using a control might be more efficient but means higher cost and a bit more complication.

    How many 75w PV panels do you have? You have pretty good sun in Phoenix, even in winter! It's possible to hook the panels to a DC heating element but not sure if it's worth it or not. Post some more details about what your goals are and someone else will probably chime in; lots of people can offer advice.

    good luck
  • mike95490mike95490 Posts: 7,611Solar Expert ✭✭✭✭
    Re: Hot water circulating pump
    azaware wrote:
    if put 1 or 2 DC element on the storage tank how many 75w panels would each element take and is that something I should do?

    Kim

    Forget trying to heat water with electricity from a couple of 75 watt panels 75 watts is about the wattage of an aquarium heater, and trying to heat household water with 75 or 300W is a wasted effort. A water heater has 2, 1500w elements in it, usually. Run a LED porch light or something you can have fun with.
    A solar water heater panel, pumped by a PV panel is a reasonable thing to do.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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