Using Free Solar Energy To Cool Your Home
Solar power for air conditioning refers to using the sun’s power or energy to cool your home. Solar power for air conditioning is only one use for the panels that have extended their ability to be used for almost all the equipment in a house. Even appliances used in boats, vehicles and a large number of commercial establishments have been adapted for using solar power. Many of the appliances can be plugged into DC and fed directly from the solar panels and batteries.
The U.S. Energy Independence and Security Act of 2007 generated funding for solar air conditioning research and development program. The aim of the program was to bring forward new technological innovations being developed and in particular those applying to solar air conditioning.
Using solar power for air conditioning can be done in three different ways. The ways are:
- passive solar
- solar thermal energy conversion
- photovoltaic conversion, which is a simple conversion of sunlight to power
The best part about using solar power for air conditioning is the comfort it provides you financially by reducing your electricity bills while cooling your home. Another benefit is the effective utilization of a natural resource to generate power, to protect you from heat created by the same natural source, which is the sun.
Some features of solar power for air conditioning are:
- They save almost all of the 40-80% of your electric costs attributed to air conditioning.
- Solar power for air conditioning systems qualify to get you a 30% Federal Tax Credit.
- There is a reduced load on the compressor.
- The air conditioning system targeting solar power produces less noise when it is connected to solar power.
- Air conditioning controls and improves the inside humidity.
- A fall in the prices of Photovoltaic panels has made using solar to cool your home a viable option.
How Using Solar Power For Air Conditioning Works
Let’s see how the cooling mechanism works inside a typical air conditioner. There are three parts or components that make up the air conditioner; the compressor, condenser, and evaporator. Another key ingredient that binds these three component together is the refrigerant, which moves from one part to the other, creating the cooling effect.
The refrigerant is contained within a sealed system. It starts flowing as a cool low-pressure gas in the compressor, where an electricity powered compressor compresses the refrigerant into a pressure heated high-energy gas. The electrical compressor does the major part of the work in the air conditioner and is the component that uses the majority of the electricity.
The second phase of the process happens when the refrigerant moves into and through the condenser. The condenser helps dissipate all the heat from the refrigerant and at this stage, it changes into a very cold liquid, albeit still under high pressure.Lastly, in the evaporator the cold liquid refrigerant cools the air as it is being blown out in the room. The refrigerant as it passes through radiator coils absorbs heat from the air passing through the air conditioner’s evaporator vents. The cold liquid inside the vented coils warms and the air is cooled.
Which Solar Technology Fits The Bill
When using solar power for air conditioning to cool your home, the choice is generally between a Solar Thermal and a Solar Photovoltaic system. There are particular differences between the two technologies. In the case of solar thermal applications, like the one used in a solar cooker or thermal solar water heater, heat from the sun is collected and utilized in the heating and compressing of the refrigerant. There is no electricity generated, as happens in a Solar Photovoltaic System. A solar thermal solution is more efficient and cost-effective than a Solar Photovoltaic system, for air conditioning applications but solar thermal has the limitation of being used only during the day.A Photovoltaic system requires an inverter to be installed as well if it is to be used for powering an air conditioner or an inverter-battery system if you want to use the system after sunset. To take the load of an air conditioner, a powerful inverter is required. There are several variants of inverters now available on the market. You might consider the improved technology now available for this purpose, that means using compressors that can operate on DC. A combination technology involves a direct current (DC) air conditioning system that has been integrated with a photovoltaic (PV) system. The solar PV system is made up of PV panels, solar charger, inverter, and batteries.
Using Solar PV System For Air Conditioning
A typical central air conditioner requires 220/240 VAC for running the refrigerant through a heat exchanger, for the fan of the air conditioner to operate. A large unit like this can be used to cool entire homes up to 2200 ft2, unlike, a room air conditioner that runs off of 110 V and is capable of cooling a house of up to 300 ft2. You can have these smaller room units easily connected to provide solar power for air conditioning. An efficient solar power system is capable of covering up its initial cost in a few years through the savings made on electricity bills. The older models of air conditioners that used about 1200 Watts of power would have cost to much to operate with solar power. But, the newer efficient air conditioners are built to consume only 600 watts of energy per hour.The first step to installing solar power for air conditioning is to find an efficient air conditioning system or unit that uses small amounts of electrical power without compromising on the quality of air conditioning. With smaller power consumption for the cooling you would need less additional solar panels for the heat loading. Select the air conditioning units the you need, calculate the electrical load to run them and calculate the number of solar panels required when using solar to cool your home.
Savings on Air Conditioning Costs
Try using your past year’s electricity bills to give you a fair idea of what your energy usage has been. Energy requirements differ according to seasons, with summers using the energy for cooling and winters requiring energy for heating the house and heating water. The energy generation through a solar power system will also differ depending on the sunlight received by the area.
An estimate of the energy required by individual appliances summed up together provides you with a ballpark figure. For instance, a 16 W bulb that is on for 10 hours requires 4.8 kWh/ month (57.6 kWh/ year). On the other hand, a 100 W bulb that is on for 10 hours will use up 30 kWh/ month (360 kWh/ year). A Refrigerator uses 36.7 kWh/ month (440 kWh/ year) and a Dishwasher uses 41 kWh/ month (492 kWh/ year) and so on and so forth.You can see a video on how to run an Air Conditioner on solar power at
The energy requirement calculated will give you the number of solar panels required. You can check the size of each solar panel that is available for the required power output and establish how many panels are needed for the system size. You can then check and see if your roof will give you enough space to fit them.A solar power system generates direct current (DC) which is inverted to alternating current (AC). This kind of system suffices the cooling requirements during the day. To get the benefit of running the the solar power for air conditioning at night, you will need to add batteries to the solar system and store sufficient extra charge generated during the day for the night operation. You will need to add extra solar panels to the existing array for this. This will generate sufficient energy to run the air conditioner during the day with sufficient extra energy available to recharge a battery bank for use at night. Extra panels can be added only if you have sufficient room on the roof for them.
Cooling Your Home The ‘Vapor Absorption’ Way
An energy efficient way of using solar power to cool your home is evaporative air conditioning or the evaporative coolers. Air conditioners operating on this technology work using the cooling effect of water evaporation. They do not use a refrigerant so no potential of CFC makes them harmless for the environment. These air conditioners do not have a compressor, which is the most electricity-consuming unit. There is a water soaked evaporator pad, which acts as a heat exchanger, and a fan assembled together. They use water and absorbents like Li Br or NH3 for the air conditioning.
Absorption coolers work on a completely different technology than a regular air conditioner. A liquid is injected into a chamber containing a gas, where it gets evaporated. The evaporation creates a cooling effect inside the chamber, and this cooling is then used to extract heat from the space that is being refrigerated. A second liquid having a higher boiling point is used to dissolve the evaporated refrigerant. Heat is used to boil the dissolved first liquid from the second liquid.
The evaporated liquid re-condenses and returns to the first stage of the process. These coolers use relatively lesser electricity and that too only for fans, chillers, and hot water pumps. The absence of a compressor makes these units a little quieter. The only drawback of these systems is their inability to work for extended hours, thus limiting their night usage.
An evaporative cooler is more suited for areas experiencing a dry climate in summers. They work on only a 1/4 the electricity used by a conventional refrigerant-based air conditioner, for the same level of cooling. A combination of an evaporative cooler and photovoltaic electrical generation system can also be explored.
This method is much more cost effective than connecting a standard refrigerant cooling based air conditioner to an array of solar panels. Solar panel array does require a sizeable investment and this hybrid method requires only a quarter as much of electric generation capacity than in a conventional refrigerant-based system.
Knowing the amount of sunlight received by your area and adding in the energy-saving grants applicable to your state or province will help you decide if using solar to cool your home is a good option. It will then be up to you whether a system of solar power for air conditioning based on PV or absorption cooling will give you a faster payback period.
Hybrid Solar Air Conditioner
Using solar power for air conditioning to cool your home can be achieved with a hybrid option as well, which will save up to 80% on your electric bills during the daytime hours. Peak electricity hours are during the day and that is when the cost of electricity tends to be the highest. This combination generally works well for business establishments that need air conditioning only during the day. The hybrid air conditioner does not require any batteries or an inverter since it is powered by mains power electricity at night.
I hope this article has provided an insight into how you can cool your home or business during the extremes of the heat of the day using the sun’s power.
Feel free to share this and comment below with your own experiences.
This article is one of many on using solar power to benefit the environment and your level of comfort and make savings in the process.
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