5watt 12volt heater?

Assuming you're thinking of one solar panel, you're proposing to use a heater drawing 16-17 amps and recharge the battery with a current source of less than half an amp. So, assuming 100% efficiency, which you won't get by a very long margin, you would need 35 minutes of sunshine to cover one minute of heat. Or six hours for ten minutes. Hmmmmm

John

In theroy the heater would run very rarely. Just to keep the super insulated box above 32 degrees. Are you recommending more panels? Or is there a bigger one you see that would work at the site I linked to?

Thanks very much!

Elijah

You don't say how long your pipe run is or what external temperatures fall to in your neck of the woods. If you insulate well I think rather less power will be needed than you are proposing.

You ought to look into heating tapes like these:

You wrap the stuff round the pipe and then enclose in insulation.

It's a very short run about 12" sticking out. Brooklyn ny, maybe down to 0 once and awhile but mostly 20s

I'll look at that heat tape, thanks for you help!

It's a very short run about 12" sticking out. Brooklyn ny, maybe down to 0 once and awhile but mostly 20s

I'll look at that heat tape, thanks for you help!

I've seen it done with a power resistor clamped to the pipe. A 30 Ohm resistor will dissipate about 5 Watts when powered from 12V and can be had for little or nothing. As someone else said though you can buy heat tape specifically for this purpose.