DIY Solar Control

[launboy]

Anyone think this could work? Mainly I'm trying to find a cheap way to control my solar heater.

Get a 1.5" Sprinker valve that runs on 24vdc, then connect that to a cheap furnace(or other kind if it will work better) thermostat. Find out how the thermostat senses temp and move it up by the solar panels so it senses the panel temp. When the thermostat senses the panels are hot(like sensing a room is hot in a house), it will send power to the sylinoid valve which will open and let the water flow to the panels. I figure I could gather all this stuff for <$100. :idea:

Any thoughts? I just don't want to shell out $200+ on a "real" solar control. I've also though about using the thermostat already built into the Spa pack to do this. Either disconnecting the terminals from the heater and to a pump, or to a valve. Then when the Pack would normally send power to the element it would go to the valve or pump. :idea:

Adam

 

[Bama Rambler]

That could work. You can get a Hunter t-stat at Wally World for about $25. I don't know how well it'll hold up but it wouldn't be a lot wasted if it didn't. We use that t-stat in RV's because it's powered by AA batts and the control is just a relay output.

 

[mas985]

A standard solar controller uses both water temperature and solar temperature to decide when to turn the panels on and off. First, temperature difference between the two determines if there is enough heat transfer and second, to determine if the water has reached desired temperature.

By using only the solar temperature, you have no way to auto shutoff when the water gets too warm. Also, it is the relative temperature between the water and the panels that determines heat transfer so using only absolute temperature of the panels may tricky to set up for all conditions.

Check out Ebay, they sometimes have simple controlers like this. It uses temperature difference which is a better to do it.

Here is another for hot water heating but it might work for solar pool as well.

 

[launboy]

What about this one? Here

The thing I'm worried about is the temp. difference. It says it turns on when the panels are 10* above, and off when panels reach 3* above pool/spa water temp. Will the control still control black mat panels with these settings?

Adam

 

[JasonLion]

Sure, 10 degrees is just a little higher than I would use, but it won't make a big difference.

 

[mas985]

You might ask the seller if temp difference can be adjusted. I think someone on this forum is using the same controller and I remember them saying that they can be adjusted but it must be done before shipping.