Solar Window Heater | Solar Space Heater
|Solar Window Heater
(32"H x 20"W x 5.5"D)
If you live in a home or apartment with southern
exposure you have the perfect opportunity to transform
day long sunshine into free heat with an inexpensive,
portable solar window heater.
Manufacturers of solar window heaters state they
provide supplemental heat for up to 1,000 square feet
or can function as a primary heat source for smaller
areas less than 400 square feet.
How a solar window heater works
Using the picture on the left as a reference, the air from
the room is drawn into the box by the small fan located
in the bottom right corner of the back panel.
Solar Window Heater Installations
The heater pictured on the left is installed inside the window
and is constructed with metal components instead of wood
and measures 42"H x 23"W x 4"D.
The amount of heat generated by this style of solar heater
relative to its size makes it a popular choice for boat and RV
The next photo shows an outdoor installation of a solar
window heater. This unit has vent at the top - back to
channel the heated air into the room. A flange on the vent is
used to secure the heater to the inside of the sash.
Depending on the width of the window frame, it might be
necessary to fill the gap between the vent and the window
jamb much like you would with a window air conditioner.
The outdoor version produces the same amount of heat as
the indoor model but doesn't obstruct the view or the natural
sunlight which is an additional source of free heat.
Another type of installation is engineered by U. S. Solar
Heating specifically for double hung windows and is equipped
with a fan.
They're lightweight, easy to install, and available in sizes
ranging from 27" x 18" to 32" x 26".
The intake air from the room is heated up to 130 F (54 C) and
redistributed by the fan at a rate of 70 cfm (cubic feet per
Build Your Own Window Heater
Instead of buying a ready made window heater you could
always build your own. Solar window heaters are a popular
DIY project and the results vary according to the imagination
of the builder.
There are many DIY solar window heater videos on the web
but the following video shows you how it's done by a pro.
Outdoor solar heater
|U S Solar indoor
|Solar window heater for
double hung windows
Within the box are baffles configured to look like a maze. As the air flows
around the baffles it is heated to a temperature of around 120 F (49 C) and
then returned to the room through the exhaust port in the upper left corner of
the back panel.
The inside of the box is lined with a thin sheet of aluminum to ensure that
radiant heat from the sun is distributed evenly throughout the box when the
sun hits it at an angle early in the morning and late afternoon.
Further along in the construction process the inside of the box will be painted
with Hi-Temp flat black spray paint to increase heat absorption and a sheet of
Plexiglas will cover and seal the front of the box.
Not all manufacturers of solar space heaters use the baffle/metal lining system
but instead substitute vertical half pipes or recycled aluminum cans as
Most, but not all indoor window heaters are thermostatically controlled. Those
that aren't usually have a digital display showing the air temperature inside the
The 4" intake fan runs on 12 volts with a 120 volt adapter and requires very
little power to operate. You could even eliminate the expense of running the fan
with a small 10 watt solar electric panel and own a system that heats for free.