March 20, 2007 4:00 AM PDT

Using solar energy to keep homes cool

SolCool One has developed what many people would expect to already be commonplace: An air conditioner that runs off the sun.

Later this week, the California-based company will launch the SolCool Millennia version 4, which it calls a hybrid solar air conditioner.

The air conditioning unit--sized to cool the space of a large room--can be run on solar panels, from a wall socket or, in a pinch, batteries.

Regardless of the power source, the system will lower electricity costs substantially, according to company executives. Potentially, if these units get used in a widespread manner, they could also reduce the odds of summer power outages, often caused because homes and buildings crank up their air conditioners. The unit operates at a maximum of 500 watts, far less than half what typical air conditioning units eat up.

"Air conditioning takes the biggest load on the power grid. We're trying to use small PV (photovoltaic solar) cells and equip them with 18,000 BTUs (a unit of energy) of air conditioning," said Roger Pruitt, the president of SolCool and GPM, the research and development and manufacturing arm of the company.

The system includes batteries that can run the unit for either 12 or 24 hours depending on the battery size.

"So if there's a blackout or if there's no sun, you can run it off of the batteries," Pruitt said.

The latest version can also heat a room and has attachments for purifying water and running other DC (direct current) appliances, like lights and ceiling fans.

The SolCool system, which has been under development for about four years, is one of a growing number of energy-efficient products gaining favor among consumers and businesses. With high energy prices and concerns over pollution, manufacturers are making energy efficiency a priority in product design.

Air conditioners in general consume a lot of power and are particularly taxing to electricity grids. Because the need for cooling is highest during the day, utilities often have to turn on auxiliary power generators during very hot days to meet demand.

These peaks in power demand, when not met, cause blackouts or brownouts. Consumers also pay the highest rate for electricity during this time of the day.

SolCool's unit can be thought of as going solar incrementally. Putting solar panels on a roof can cost $20,000 to $40,000 before subsidies, according to installers, a price tag that makes some consumers balk. But, by adopting solar power for smaller applications, sticker shock is eased.

Some companies are betting that solar water heaters, which cost about $7,000, will gain popularity in this manner.


The latest SolCool unit has an energy efficiency rating (EER) of 30, according to SolCool. (That ratio is calculated by dividing the cooling output by watt hours). Room air conditioners of similar cooling output with an EER of 9.7 meet the federal Energy Star rating standard by the U.S. Department of Energy.

Sam Little, the president of renewable energy installer EcoVantage Energy in Weatherford, Texas, has tested the previous versions of the SolCool air conditioner. He said that at 18,000 BTUs, the devices are not large enough to cool a very large house, but work well for a couple of rooms or to supplement another system. He estimated the previous version used one-fourth the electricity of other air conditioning units.

Needing 500 watts, SolCool's unit could run on five or six midsize panels, which would cost a fraction of a solar system sized for a full building.

SolCool has optimized the air conditioner to run on the direct current generated by the solar panels or batteries, rather than the alternating current that comes from electrical plugs. Building the product for direct current has allowed the company to build a very energy-efficient product which can run off-grid as well, Pruitt said. (In standard solar installations, the panels produce direct current, but then a device called an inverter switches it to AC before you use it in your home.)

The SolCool includes a sealed, two-gallon water tank that stores cooled water, which the air conditioner draws cooling from during a power outage.

Little said he regularly gets requests for solar air conditioners.

CONTINUED: Green and off-grid…
Page 1 | 2

See more CNET content tagged:
air conditioner, solar energy, renewable energy, photovoltaics, sun


Join the conversation!
Add your comment
What we really need.
Is a storage system with high heat capacities. We pump heat out during the summer and pump the heat inside (or burn gas, or run electric heater) during the winter. Since it is too late for existing homes to be rebuilt with walls of annual averaging thermal properties, perhaps a bigger heat storage system can be used. Imagine using up all the stored summer heat during the winter, and then using all the cold media from the winter.

We can then use the electricity from solar for other things. The way things are being marketed right now is that they are pricing the system like this one so that whatever money you will save is equal to the mark-up price. I hope it would go much lower than that, like at par or slightly higher with current air-conditioning systems, then that would truly help us all, including the planet.
Posted by Joe Real (1217 comments )
Reply Link Flag
I think it's the greatest thing since the light bulb.Can you imagine not having to pay for air conditioning. Well my friends the choice is yours I know it works, and I am so excited for eveyone who get's one and does not have to stress over the cost of running it. This machine runs off pixie dust.So take your savings and try to enjoy life a little more,remember we as humans have really hurt this planet and now we have to fix it for the future of our children,if we don't than who will!
Posted by superdawg1 (2 comments )
Reply Link Flag
That IS the the greatest thing since the lite bulb, but now we have the CFL's, which are even better! Let's hope everyone sees the light, before there 'ain't' none! ;-)
Posted by Charlene L. (1 comment )
Link Flag
People will buy anything....
Solar cooling is certainly possible, and even practical, but to do it with photovoltaics is sheer stupidity. PV panels have low conversion efficiency. The soloution is ages old already: Ammonia Absorbtion Refrigeration. This form of cooling can use *any* heat source, including thermal solar energy. It has no moving parts, it is proven technology, and it is extremely reliable. Power an A/C system from PV panels? That's just stupid.
Posted by timinraymond (6 comments )
Reply Link Flag
u r right but..
Posted by anil_bharti (3 comments )
Link Flag
Would like to know what is the best type of solar energy on the market currently? I plan to open a business.
Posted by sunshineman2008 (1 comment )
Reply Link Flag
sunshineman2008 - so do I... did you ever receive an answer to this question. I am trying to position myself to provide 90-100% green energy with utility backup to a specific type of buyer soon. I am doing research and have the same question.

What is the best type of solar solution for mainly cooling, then lighting and then small appliances. I am also open to wind farms and hydro/wave farms.

Going for efficiency and this ac unit is attractive but as you pointed out has its limitations and CONS.
Posted by hrhkee (4 comments )
Link Flag
Very intelligentelly designed product! If you still need to refine it further .. just give me a call.. 09463495098
Posted by anil_bharti (3 comments )
Reply Link Flag
People will buy anything....
by timinraymond July 16, 2007 11:20 AM PDT

You are absolutely right, but ammonia vapor absorption system is quite toxic and dangerous for homes unless you install scrubber along with it. Let them do the experiment. Necessity is mother of invention! One day it will be possible.
Lets makes things better... just help them!
Posted by anil_bharti (3 comments )
Reply Link Flag

Join the conversation

Add your comment

The posting of advertisements, profanity, or personal attacks is prohibited. Click here to review our Terms of Use.

What's Hot



RSS Feeds

Add headlines from CNET News to your homepage or feedreader.