I toying with the idea of putting a few solar panels to the roof and adding a heating element to my 500 gallon water tank that I use with my Vigas 40. Has anyone done this yet?
Electric Solar water heater element in my water storage tank
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hobbyheater
Minister of Fire
If you mean just directly wiring the DC output of the panels to the heating element, it should work to give you a few extra BTUs as long as the wattages are matched reasonably enough. Make sure you have some sort of a high limit hooked up and ideally a low water cutoff too.
Many people who "have solar panels" are referring to a grid tied system, and if that's what you're doing you would get many more BTUs per watt by running a heat pump.
Many people who "have solar panels" are referring to a grid tied system, and if that's what you're doing you would get many more BTUs per watt by running a heat pump.
Whitenuckler
Minister of Fire
You may not have the right voltage if you get a 220VAC heating element. And if there is such thing as a DC heating element could be many amps.
Sure the heating element won't put out it's rated power, it will just consume whatever current the solar panels can give it. Which is why it needs to be rated high enough to not add too much resistance to the circuit and not go over its rated power when the solar panels hit their peak output.
A heating element is just a piece of resistive wire so it doesn't care if it gets AC or DC. However you may have to worry a little more about galvanic effects with DC if it's operating in a moist environment.
Whitenuckler
Minister of Fire
Vsquared/r = the power so it's not going to put out very much power without the right voltage. I never thought about the galvanic effect with DC. That could cause more problems than its worth.
You'll generally get maximum power when the load resistance is approximately equal to the source resistance which is the solar panels' internal resistance. Voltage will rise and drop with solar input, as will the heater's output power.
So you set up strings in series/parallel to match the load. Or you can place multiple heaters in series or parallel to match your solar string, either approach would work.
So what do you think. Is it worth looking into it? I don't think i want to go full solar panel array for electric but possibly one or two panels and not grid tied at all.
Whitenuckler
Minister of Fire
Do you know what options you have for the heating element? I tend to think you would need quite a few panels to build up the voltage.
One other option is a solar water heating array. When I bought this house it had two large panels on the roof and they had it hooked up to the oil boiler. I don't know exactly how it worked, as it was all de-commissioned and I had it removed when I did the roof. I think the "hose/cable" had heat trace in in.
Whitenuckler
Minister of Fire
I was looking and found this. I didn't know they had 48V 1500W.
I don't have solar panels but I believe they are 400W and 12V or 24V.
Looks like you could do it. You would need to design the circuit with a disconnect, grounding and fusing ect.
I local solar install company might be able to supply the panels properly.
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