Build Your Own Solar Evaporative Cooler By: Jim Eddy - Susanville, California

I live in an all solar house in Northern California. It is a passive design so the sun heats it by shining in the windows. I solar heat our water and have a 1 kilowatt solar electric charging system providing 110 volts of AC power. The one thing I could not do was cool the house easily in the summer without taxing the system. I purchased an evaporative type unit for indoors but it did not do much good. A compressor type air conditioner would use more energy than I could supply and a regular evaporative cooler would use a lot of energy. I figured that some sort of solar cooler could do the trick. I spent sometime looking for a solar evaporative cooler on the Internet. Those that I found were bulky, ugly and expensive. Most cost around $ 600.00 and up. The above pictures are of a Solar evaporative cooler that I made using easily purchased components to cool our 1600 square foot house. I spent roughly $300 to make this unit. It is in it’s fourth year of use. If you have some of the components already you could spend much less. The cost of a new solar panel to power the unit is around $550 and can be purchased at many local or on line stores. Afternoon Summer temperatures range between 85° to 95° in this part of California. The cooler that I purchased is smaller than I should have for my house size, but it does a good job of keeping the house cool. With the fan and pump modifications, it maintains a temperature difference of about 15° between the outside and the inside. As I am writing this it is 4:30 in the afternoon. The outside temperature is 92° and the inside temperature is 77°. Anyone with an existing evaporative cooler of any size can make a similar looking cooler, or you can buy one like I did.

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I decided to use an existing evaporative cooler because I didn’t want to reinvent the wheel. All the components are already there, the cooler pads, a trough to hold water, a float valve to let more water in and a water distribution system. As you can see from the pictures I mounted a 12 volt radiator fan in front of the existing opening and I opted to leave the existing AC pump, motor and squirrel cage intact. Since I have 110 Volt AC power available at my house, on occasions, I use the existing AC pump and motor after the sun has gone down to continue cooling the house. I was concerned that leaving everything there might significantly block the airflow, but it seems to work just fine. You could remove the existing motor and pump and It might work even better. If you do use the AC fan, make sure the 12 Volt fan does not turn as it could cause it to burn out. I use a coat hanger inserted through the front and placed between the 12 Volt fan blades and it’s housing. It seems a little hoaky but it keeps the fan from turning. I purchased the electric radiator fan at a local auto parts store. I paid around $80 for it and have seen similar fans on the Internet for $35. The pump is a 12 volt bilge pump that I purchased at Wal Mart for around $14. Make sure that you don’t use too strong of a pump or you will blast the water into the feeder tubes. At full speed the fan pulls 5.5amps @ 12 volts. The bilge pump pulls around 1.5 amps @ 12 volts. A 100 watt solar panel will power the fan and pump nicely. I am using a Mitsubishi 110 Watt panel that is mounted on a solar tracker that I made. The panel and tracker are mounted on the ground in front of the cooler. In previous years I have placed the panel flat on the roof just above the cooler. That worked fine for most of the day. The tracker extends the time in the afternoon when the summer temperatures are keeping things hot. You can decide for yourself how you want to mount the fan. I drilled holes in the sheet metal and used sheet metal screws to attach it. I did have to do some cutting of the sheet metal with a Dremel tool to make it fit. Radiator fans can be 2 www.livingonsolar.com

hooked up two ways electrically so the fan can blow air in either direction. Make sure you hook it up correctly to blow the direction you want.

I removed the existing front cover to expose the opening. I then placed the fan over the opening to determine the best fit and drilled holes in the sheet metal.

I opted to leave the cover in tact as much as possible so I had to fit the fan back into the cover before mounting everything to the main housing. It was a tight fit!

After sliding the fan into the cover, I mounted both onto the main housing with the existing sheet metal screws and 4 new ones for the fan. 3 www.livingonsolar.com

The bilge pump can be placed in the water right alongside of the existing AC pump. You can disconnect the hose from the existing pump and place it on the bilge pump. You may have to use additional hose and an adapter like I did.

I mounted two new rocker switches to the front of the existing cover on the side opposite of the existing switches. I was able to drill holes in the plastic and they mounted nicely.

The finished front installed inside.

The panel and tracker that I use.

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Wiring the solar panel to the fan and pump is relatively easy if you have some experience. Solar panels have different types of connectors depending on which kind that you have. Some have junction boxes that allow wire to be placed into the box and a secure connection made. Newer panels have MC connectors which allow for a snap fit for multiple panel connections. These would probably have to be cut to connect the wire. The better way to do this is to buy an MC extension which has both male and female ends on it. It can be cut in half and then connected to the panel and then to the wire. I used wire connectors that were crimped to the positive and negative wires and then to the fan and pump wires and switches. When I placed my panels directly on the roof I ran the positive and negative wires over the eave and along the outside wall to the cooler. I placed the wire in flex tubing to make a neat job. There was an existing hole on the top corner of the cooler that I could run the wires into. The negative wire went to a common ground which then went to the fan and pump. The positive wire was run to the two switches that control the fan and pump. The wires were passed through an opening between the inside of the cooler and the portion that goes into the window where the existing 110 AC volt wires were run. They were connected to the switches and back to the fan and pump. I used tie connectors to keep the wires in place and neat. I do not use a voltage regulator on my cooler. The fan and pump seem to work fine without it. There are some panels that have built in regulators. They might function the best. A LITTLE ABOUT EVAPORATIVE COOLERS Evaporative coolers perform best when the humidity is low. On days when the humidity is really high, the house can feel muggy inside. For those who have another type of air conditioning system, that will be the time to use it. For the drier days the evaporative cooler can do quite well. If you can, place the cooler in a window that is shaded. The sun baking on the metal surface can reduce the effectiveness. I actually don’t have mine shaded, but you should do what I say and not what I do. Evaporative coolers draw air from the outside and as it passes through the pads it is cooled and blown into the house. It is best to close all the windows in the house except for one that is farthest from the cooler. I open the back bathroom window about half way. You can feel the air exiting the house at the window. I place a piece of toilet paper up to the screen and it will stay in place from the exiting air. The cooler is a little noisy and it can be irritating when the sun goes behind a cloud and the fan slows down and then speeds up when the cloud goes away. 5 www.livingonsolar.com

The following is a partial list of items that you will need. Materials:

Purchased at:

Price

New Evap cooler 3000CFM

Wal Mart, Lowes, Home Depot Home Internet, Kragen’s Wal Mart Radio Shack - Kragen’s Radio Shack - Kragens Hardware store Internet

$ 200-300 $0 $ 35-80 $ 14 $ 4 ea $ 10/25feet $2 $ 400-600

Evap cooler you have 12 Volt radiator fan 12 Volt bilge pump (2) 12 Volt switches 12 gauge wire Additional hose for pump 75 to 125 watt 12 Volt solar panel

Wire connectors, flex tubing to cover wires, sheet metal screws, fuse and fuse holder, tie straps to make a neat job and keep wires in place. Good Luck!

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