Passive Solar Birdbath

This is a nice simple design for a solar heated bird bath developed by Jim.

The sun shines through the glazed panel on the south side of the pedistal and warms a solar absorber which heats the bird bath from below during the day.

solar bird bath

Thanks very much to Jim for providing this matieral.

From Jim:

Passive Solar Bird Bath

In the winter in PA my bird bath freezes and the birds can’t get a drink, so I built this passive solar bird bath. I got the idea from passive solar horse watering troughs which keep the water from freezing in below freezing weather.

It actually works. No matter what the temperature, if there are two hours of sun the ice in the pan melts and the birds have water to drink. If the ambient temperature stays below freezing the ice in the pan does not melt completely, usually leaving a small disc of ice floating in the pan.

In freezing temperatures birds do not use it as a bird bath, just a drinking dish.

There is no heat storage so the water freezes when the sun goes down, and melts when the sun comes up. If I had known the birds would just use it as a drinker, and not a bird bath, I would have designed it so there isn’t so much surface area. With less surface area and less heat loss the ice would melt faster.

The temperature never gets more than 20 degrees F above the ambient temperature. I don’t plan to use it in the warm weather.

If you have any thoughts about how my passive solar bird bath could be improved I’d like to hear from you. Use the comments section below, or send me an email Send photos or drawings if you have them.



Materials: Passive Solar Bird Bath

-- ¾” exterior plywood.
-- 1/8” galvanized steel plate, for heat absorption. 
-- 9” pie pan (K-Mart).
-- ½ foil-covered foam insulation. (Lowes)
-- Insulation adhesive. (Lowes)
-- 1/8” Plexiglas. (Lowes)
-- Lots of clear silicon sealer. (Note: you can’t paint over the silicon so you have to paint the
    wood before you seal it on the outside.)
-- Drill bit to pre-drill holes in Plexiglas so corner molding can be screwed on. (I drilled through
    the molding and the Plexiglas at the same time.)
-- 2” finishing nails and carpenter’s glue.

Photos: Passive Solar Bird Bath Construction


solar bird bath

The finished birdbath.
The sun shines in the south facing glass pane and warms an absorber plate, which warms the bird batch bowl.

This cross section shows the internal details of the solar bird bath:

cross section solar bird bath


solar bird bath details

Showing the internal details of the bridbath.

blog comments powered by Disqus