solar electric pump for hot tub.

System

Ok I am new to all of this so please bear with me. I have a hot tub. I am going to run the jet pump off 110volt system of the house. I want to run a 12 volt electric water pump to flow water from the hot tub to my roof where I plan on installing solar water heating panels. Does anyone have any suggestions as to how large of a panel I will need. I currently am looking at 12vdc pumps rated at about 10 amps. I do not know how to convert the amperage to wattage to figure out if this will work for a reasonable price.

My roof is a single story roof, approx 10 feet high. I would like to run plastic piping if possible due to cost of copper but I understand the heat might be too hot for the plastic.

if anyone has any ideas please let me know.
thanks
keith

mike95490

Re: solar electric pump for hot tub.

keimini wrote:

I do not know how to convert the amperage to wattage to figure out if this will work for a reasonable price.

Volts X Amps = Watts

So your 12V pump, at 10Amps (10 ga wire needed) is 120W

Like EPA Mileage Est. the ratings of a solar panel fall short of real life power delivery, a rule of thumb would be to expect about 75% of the label output. (Volts will be a little lower, depends on temperature) Amps will vary according to brightness

Once you know the "head" (altitude) required, and the volume (gallons) you can select the pump, and then locate a panel to power it. Don't forget to evaluate a 24V system too - save on wire thickness.

System2

Re: solar electric pump for hot tub.

Thanks for the information. What do you think about running 2 car batteries as reserve. Do they make a 12 or 24 volt timer like they do for regular electric hot water heaters to allow the pump to run off the batteries for the second half of the day and allow the pump to remain off during the morning hours to charge the batteries?

thanks for any more information.

looks like a 120 watt panel is $600

would I be able to get by with a say 40 watt panel as a battery charge panel but run mostly off the batteries? I have installed moving roof panels powered by a 12 v battery to a window regulator motor to allow the roof to open. it comes with a very small solar panel to recharge the battery. I know you only use the battery when you hit the switch to open the roof but same idea.
www.vergola.com/au

mike95490

Re: solar electric pump for hot tub.

No switch needed, keep it simple, mount the solar panel next to the heater panel, and when the sun shines, the pump runs. No sun, water drains back automaticly for frost proofing.

You need to figure how many BTU you need to heat x gallons of water, heat loss of open top tub, at ?? ambient temp. and likely rely on heating the tub hotter then needed at daytime, and then when you fire up the jets, and suck in all that air, it will quickly cool. Or you may enjoy it as a soaking tub too.