Solar thermal on the cheap

[mountain]

Crystal clear cold winter days... perfect for building another solar-thermal heater. The goal this time was to see how well a minimum cost ($100), minimum fuss system would work on this small well insulated building.

http://www.mountainelectric.ca/hotbox/#HB_junior

The performance is tremendous, in thank part to the fact that the building is otherwise completely unheated. The temperature rise inside the panel is thus large (during sunshine), and the measured energy harvested is up to 6kWh/day. Not bad for 16 sq ft.

control & measurement is with a homebrew electronic differential thermostat w/display.

M

[Mike90250]

WOW !! Are you going to put up any sketches, or plans for your controller ? I want one for my shed !!

Mike

[netttech]

ALthough your box was smaller, it's basically the same as my solar space heating panels. Although I was trying to heat my house.

I see you intend to add rocks at some point which should extend the heat transfer after peak solar time. Curious, how are you stopping the reverse affect after the sun sets? I manually opened/closedregisters to keep cold air from entering in reverse?

You can try suspending a piece of flat rolled Aluminum facia (painted black) just above your cold air intake. The facia heats up very quickly & gets very hot. Supend the facia so the air flow can travel equally on both sides (front/back). It could boost the air temps significantly.

My panel was basically an 4" deep rigid foam air duct with the facia supended, allowing the air flow/heat up on both sides.

On sunny days, it would heat the air to 158 + degrees (thermometer maxed at 158) with constant airflow from 350 cfm fan.

Looks like you have a winner design already though.

Jeff