Fozzy asked in Science & MathematicsEngineering · 8 years ago

Powering an air conditioner via solar panels?

Does anyone know how I would go about hooking up the air conditioners in my house to solar panels? I would want just the air conditioners to be powered by solar energy. How could I hook it up where the panels can absorb energy from the sun during the day, and save and store the energy so I can run the air conditioners at night? I really feel that in the long run, this would save a lot of money with the energy bill. It's the use of the air conditioners that drive up the bill. Is this idea feasible? Is it also possible to have some sort of hybrid system where I can switch from solar to my regular local energy source when I want to?

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• 8 years ago

The simple answer is no. It is not feasible to run your AC on solar photovoltaics. Even a small AC system is about 2 1/2 ton (30,000 BTU's of cooling power). There is 3,413 BTU's per KW, which is saying 1000 watts of energy is required to get you 3413 BTU's of cooling

30000/ 3413 = 8.8 kWh .

That means you need 8,800 watts of power over each hour to run your AC while the compressor is kicked in.

If you run your AC for just 10 hours a day you need 10 * 8.8 kWh(= 88 kWh) of stored capacity to run your AC. Solar panels cost about \$10 per installed watt, so this means even if you ran your AC for 1/3 of the day, you would need 8.8 /3 = 3000 watts generated each hour for 24 hours. Sun doean't shine...means no power.

So you need about 5000 watts of panels with deep cycle batteries to run your AC even miserly.

That is a \$50,000 system.

I would suggest if you are really into alternative energy, that the most cost effective is to get a wind pump (not a wind turbine, but a pump similar to a wind water pump seen on farms) where the pump is hooked directly to the AC's compressor pump thru a torque converter.

The compressor in a AC is the big user of all those watts. It is just a mechanical pump that pumps the freon up to a high pressure and then allows it to expand to make the cooling power.

A torque converter is what is on your car transmission. This allows a spinning power source, like a wind pump, to put it's power into a compressor shaft only when the wind is blowing. When the wind is not blowing the compressor gets power from the normal AC motor.

In this way , the wind is used for assistance to lessen the power requirements to run the AC's compressor.

The best way is to convert your AC air unit to a ground water condenser, which is a "geothermal AC" or a heat pump.

Geothermal air conditioning might cut your bill by 75% because depending on your ground water temperature (55F or lower is best) , the heat from your compressor and heat of condensation is given up to the cold water instead of hot outside air. Water conducts heat about 256 times better than air, so this is very effective.

Think of this, take you shirt off in 40F weather and it feels cool. But have someone throw a glass of 40F water on your back and you will jump 3 feet in the air from the shock. That shows how much more heat water conducts from a surface over what air does from a surface.

So all in all, the most practical way to get a cheap AC electric bill is to get a heat pump using ground water. It has the added benefit of giving you free hot water if you plumb in the condenser into the how water heater

• 8 years ago

There's no need to connect only the A/C to solar, nor is there a need to use batteries. Both of those problems are solved with grid-tied solar. The solar electricity system works alongside your regular, and the A/C just plugs in normally. You never need to worry about switching.

During the day, if the A/C is drawing power, the solar goes into that, reducing your draw from the electric company. If the solar generates more than the A/C needs, the meter is driven backwards. At night, the meter runs forward again. For example, the meter may read 5000 in the morning. By evening, maybe it reads 4975. At night, it creeps back up to 5005. When the meter reader comes, you would be billed for only 5 kWh. That's the general idea.

Also, consider whether you can insulate your home more, and whether you might want to change out your air conditioners for new, DC inverter mini-split units. Those can use a fraction of the electricity per BTU of regular air conditioners.

• Fred
Lv 5
8 years ago

There are solar air conditioners. They don't use electricity. Most anyway.

The number of photovoltaic panels you would need to run a standard electric air conditioner would cover most of the homes on the block.

Read about heat pumps, Thermal storage, swamp coolers, solar heating to get an idea of what is practical.

Most solar systems are hybrid because of clouds and nightfall.

The best solar homes are designed from the ground up. With plenty of insulation, the right size and orientation of windows and collectors. Putting solar on an existing structure is going to be a misfit half donkey job unless you are very lucky.

• Anonymous
5 years ago

There is a step-by-step video guide online right now that can show you how to reduce your power bill by making your own solar panels.

Take a look at it: http://tinyurl.com/Earth4EnergyRew

Why pay thousands of dollars for solar energy (\$27,000 average cost) when you can build your own solar panel system for just a fraction of the retail cost. You can build a single solar panel or you can build an entire array of panels to power your whole house.

Some people are saving 50% on their power bill, some people are reducing their bill to nothing. But what’s most impressive is that just by following these instructions some are even making the power company pay them!

• Amber
Lv 4
4 years ago

Admittedly when efficiency is less than 20 percent it can look that way. Plants going bankrupt- While I have not read of any, other than Solaris, the reality of the marketplace is such that bankruptcy is a not uncommon occurance, and it is not a death knell to a company. Sometimes it is used as leverage against creditors, or can be the result of mismanagement. In the 1950's bankruptcy was common in the auto industry and we still drive cars. Over time, is when it matters. Innovations, new techniques, new materials will raise the efficiencies of panels, and some companies going bankrupt is to be expected. It is not a reflection on the industry as whole though. Many companies jumped into manufacturing when demand was expected to jump, and it did not. Competition from China is also a factor. If the regulatory burden was less, panels would be cheaper in the US and Canada. Will solar be around 30 years from now? Certainly. People are tired of the oil companies ripping them off and manipulating the marketplace. Then when you also factor in the high probability of carbon taxation becoming a reality when in fact all it is, is a scheme to make bankers, Al Gore, the Saxe-Coburg and Gothe Family richer, you will likely choose to install even inefficient panels as a matter of princicple. Being able to disconnect from a grid that is being re-engineered to shut off major appliances and your air conditioner in the name of "smart grid" technology and saving energy is not going to be acceptable to many people. Like it or not, "smart appliances" are here to stay and so is the "smart grid." No, the real Edsel of the energy technologies is Nuclear. We simply outgrew it, it is old technology, it is hazardous as Fukishima and Chernobyl bear testament to. And it's waste is a "forever" legacy- yet GE and Toshiba are touting it as "clean" when it isn't. "Reliable" when it is not. and :Safe- when it is not. The reason you do not see nuclear waste being talked about is due to 1) it is a highly regulated industry, 2) it is has a vocal opposition to many aspects of the industry, 3) politicians knew way back in the 1960's that transport of the waste or even the fuel was risky and the public unforgiving. But the nuclear industry has enough money to get their propaganda into textbooks to brainwash and curtail critical thought about the entire nuclear industry among the younger generation. This among many controversial issues that would have been rejected 50 years ago are integral to what we call "education" today.