Solar Power For Homes

Solar Power For Homes

Solar power, when converted to AC electricity, can be used to supply almost any electrical device(s) in a household. In addition, the sun’s energy can be used in the form of heat for other home uses. It’s really just a matter of scale.

More of the sun’s energy being collected means more energy available for use. When a solar panel system is connected to a home it usually takes one of two forms. A system that is set up to be “on-grid” is hooked into the local utility system and the home runs from both solar and conventional power. Many times this system also has a battery to store excess solar energy for use when the sun isn’t available.

The other set-up is “off-grid”, and this is usually used for off the grid homes in remote areas not easily supplied by conventional power. Essentially, all of the power to the home is supplied by solar energy. A battery is always used in this system or there would only be power during sunlit hours.

Along with the supply of general household electricity, major home systems supported by solar power for homes include a solar hot water system, air heating and cooling, and pool heating.

A solar hot water system does not simply supply electricity to a conventional hot water heater. Instead, the sun’s energy is harnessed directly in the form of heat and then either applied directly to water (“closed-loop”) or to a heat-transfer fluid, which then in turn heats the water through a heat exchanger (“open-loop”).

A solar heating system can be somewhat similar and is usually either “passive” or “active”. In a passive solar heating system solar energy is absorbed directly into specific building materials that have the property of slowly releasing the heat throughout the day. Examples of building materials used for this purpose are concrete and tile. On the other hand, in an active solar heating system heat is absorbed  directly into solar collectors and then sent throughout the home using fans and/or pumps.

Solar air-conditioning, though, is a little more complicated. In one version a material is used, called a “desiccant”, to draw moisture from the air. That moisture then evaporates, thus cooling the surrounding air which is then sent throughout the home. (A similar principle is in force when you are sweating outside and feel a breeze. You feel cooler because the water is evaporating off of your body.) Solar thermal energy is then used to dry out the desiccant so the whole process can start over and repeat. This is a surprisingly cost-efficient method of cooling air.

Finally, the benefits of a solar pool-heating system seem fairly obvious, but beyond simply heating the pool water the solar energy can also be used for running pool pumps, and even heating water for an outdoor shower. Solar pool-heating systems are also much quieter than conventional systems and can even work when the power is out.

Cost

To estimate the real cost of electricity over the lifetime of an installed solar power home system, a couple of calculations will need to be made. As will be explained, to arrive at cost of electricity per Kilowatt-hour we will need to divide what is called the “life cycle cost” by the combined power generated over the lifetime of the system.

In simple terms, the “life cycle cost” is the total cost of all components that will EVER be used during the lifetime of the system. As a benchmark, choose the component that will last the longest. Let’s say you choose the rooftop solar panel itself and then estimate how long do solar panels last. For this example, assume they will last 30 years. We now say that the life of the system is 30 years and you will only have to pay for solar panels once. So, if the totality of your solar panel cost is $10,000 then your total life cycle cost for the solar panel component is the same $10,000 since, again, you only count it once.

Now, consider all of the other components of the system and their average life spans. Let’s say you expect your battery to last 15 years. Accordingly, over the life of the system you will need two batteries, so that cost should be counted twice. Then add that number to the
$10,000 for the solar panel component and keep going in likewise fashion until all the parts are correctly accounted for and you arrive at a total life cycle cost.

It is the total amount of money you will expect to ever pay to run the system for its entire lifetime, including all replacement parts. Of course, this number may be adjusted to account for any rebates, government subsidies and/or tax breaks which you expect to receive and to which you would otherwise not be entitled.

Next, to estimate the combined power generated over the lifetime of the system, take the rated power of your entire system measured in Kilowatts, and then estimate the total hours of usable sunlight per year in your location. Multiply these together and then multiply that number by the lifetime of the system, in this case 30 years. This will give you the total amount of Kilowatt-hours produced by your system over the 30 years.

Finally, we simply divide the total amount the system will ever cost by the total power ever produced by the system, and that will give us a cost per Kilowatt-hour over the lifetime of the whole system. You can then compare that number to the cost per Kilowatt- hour you are/were paying for conventional electricity and immediately see the profound savings you will enjoy.

Calculator

Another option in your cost analysis is to use an automatic calculator. Typically, instead of estimating the total cost of electricity plus installation over the entire lifetime of the system, these calculators just try to estimate an appropriate size of system for you, the initial cost of installation, and savings to be expected immediately. These calculators are very useful too, but just remember that they do not attempt to come up with a number as precise as we calculated by hand above.

Having said that, in the U.S. a typical automatic calculator will begin by asking for your zip code. This is to determine the average amount of sunlight for your area. It will then ask for the specific name of your local utility company in order to compare costs. Finally, it will ask about how much electricity you use in a month to determine the scale of their recommended project size and monthly initial cost savings.

One advantage of using these automatic calculators is that they are pretty good in accounting for all the incentives and government rebates, etc., to which you would be eligible. Those are automatically accounted for without you having to do any research.

One disadvantage is that the final numbers are not as exact as the calculations we did by hand because they do not take into account for the expected life span of the entire system and thus the cost of replacement parts. The automatic calculator will only give immediate results, whereas the calculation by hand will give you the whole picture for many decades.

Texas

One of the fastest growing users of solar power is the United States. In order to encourage people to switch over to solar power, local, state and federal governments, and even utilities offer a variety of incentive programs, rebates, and other monies. Every state has different programs, and here we will see some of what is available in Texas, a large, populous state with greater-than-average access to sunshine.

Citizens of Texas would be eligible for all national incentive programs provided by the federal government. These include several grant programs, home building tax credits, renewable energy tax credits, energy efficiency tax credits, other tax reductions for renewable energy use, an energy efficient mortgage program, and a residential energy conservation subsidy.

Texas also has several incentives built into its state tax code. These include a tax exemption for solar and wind powered energy devices, a “Deduction of Cost of Solar Energy Device From Taxable Capital” statute, and a franchise tax exemption for solar energy devices used by businesses.

Several large Texas cities also have local programs which promote solar use. These include Austin, San Antonio, and Houston. This is just a small snapshot of what is available in just one state. The point is that no matter where you live, there are probably multiple opportunities to take advantage of monetary benefits offered by city, state, and federal governments. It is well worth the time to investigate these programs and figure their savings into your decision to go solar.