About Us

What's New

Solar Power Basics

Solar Videos

Save Energy

A Solar Window Heater

How and why to use a solar window heater. Find out how it works and if it is worth building one yourself.

Solar window heaters, some times called window solar air heaters, are an eco-friendly product that can help to supplement your home heating system. If you have several windows with a southern exposure you might want to consider some free solar heat.

A window solar air heater will not eliminate all of your heating costs, but it can reduce some of your monthly electricity costs. The more windows you place a solar heater in the bigger your heating savings will be.

Window solar air heaters will help warm your room during the winter season. The basic concept of a solar window heater is simple; anyone who enjoys taking on a simple project can build one quite easily.

Is it worth building your own to save money? Well, that is not quite as certain. While you can save by carrying out a DIY window solar heater project, they are not very expensive even when bought ready-made, so only if you need many solar window heaters wil you actually make significant savings. Well more about that below.

A Solar Window Heater Described

A solar window heater is basically comprised of an insulated flat box with divider panels inside that creates two shallow chambers, one above the other. The box has a clear top, and the two chambers are connected at the outdoor end. One end of the box slopes downwards outside with the clear top of the box facing the sun's rays and other end mounted in your window opening and sealed with weather stripping against the window frame and the sash.

Since it is powered by the sun, and heats with hot air, the only mechanical or moving part is a fan that draws room temperature air into the heating panel through a series of heating channels, and then exhausts the heated air back into the room.

Think of it as a box with an aluminum panel (collector) behind a sheet of air tight Plexiglas on the outside, and a sheet of thin wood on the inside to trap the collected heat. Within the box are two baffles constructed to look like a maze. This allows for a continuous stream of air to be heated as it is drawn through the box by the fan. The aluminum collector panel is finished in flat black paint to maximize heat absorption from the sun. On a day with full sun, the panel will reach a temperature of between 140 - 170 degrees F.

A newer version of the solar window heater replaces the aluminum panel with high quality copper which is also finished in flat black.

Located inside the panel is a thermostat switch. When the temperature of the heated air reaches 120 degrees, the switch automatically turns on the fan. When the air temperature cools to 90 degrees or less, the fan shuts itself off. The small, efficient fan will move 102 cubic feet of air per minute or about 6,000 cubic feet per hour. The cost of electricity to operate the fan is around $3.00 per year. Not too bad, right?!

If you would like to build your own window solar air heater, the electrical components like fan, thermostat, transformer and junction control box are available in stores like Home depot or on the internet.

The basic solar window heater model sells for around $150.00 but you can build one yourself for around $100. In percentage, that is quite a neat saving but in dollars - I don't know if I think it is worth it. You need to somehow consider your own time as well, including the time (and gas!) to shop for the components and possible additional tools you need to buy.

Below you can see how a solar window heater works in principal.