@wall0159 @smallsolar I wonder if you can pick up a #recycled #doubleglazed window panel to make the heater box? There are plenty of foam panels available now to #insulate the sides and back of the box now. Even the local hardware stores sell them here.

The insulating the pipes into and out of the house.

Hmmm... folks I think you are onto somthing!

The other thing I have seen folks #experiment with was passing a small garden irrigation pipe along the back of #solar #panels to cool them down.