Considerations on using SOLAR ENERGY in the Home
By Barrett Hazeltine
Solar energy for residential use is used either for water heating or for generating electricity. One reason for using solar energy is to reduce one’s gas or electric bill—typically solar systems reduce the amount of gas or electricity used by 50% or more. Another reason is to reduce carbon emissions. A typical solar electric system avoids putting 1700 pounds of carbon into the atmosphere annually. (A typical automobile emits about twice that amount each year.) A third reason for using solar is conservation of non-renewable fuels. Of course, a homeowner using solar energy is somewhat insulated (excuse the word) from fluctuations in the price of oil.
How it works
A solar heating system consists of a collector, usually mounted on the roof, containing a fluid that does not freeze. The fluid, heated by the sun, is used to preheat domestic hot water. The collector should last 25-30 years and the various pumps and plumbing longer. Because the solar heated fluid is used only to preheat, the homeowner is not inconvenienced, except financially, by a long string of cloudy days. Snow on the ground reflects sunlight onto the collectors so the solar heater is more efficient after a snowstorm. A solar heating system costs about $10,000 and the payback period is about 12 years.
A solar electric system consists of several panels of photovoltaic material, which create voltage and thus current when illuminated. Although systems can be built which allow users to totally disconnect from the power company most homeowners remain connected and use the solar generated electricity to reduce their electric bill. If the solar system is generating more power than the home is using, electricity is sent from the house to the electric grid, driving the electric meter backwards. Remaining connected to the grid means that the homeowner does not need to store electricity for use at night. The system is somewhat complicated because solar electric panels generate DC as used, for example, in flashlights, while the power company and nearly all appliances use AC. A so-called “inverter” is used to convert the DC into AC, suitable for interchange with the grid. Because no moving parts are involved the life of the system should be at least 30 years. Solar electric systems cost about $35,000 or more, depending on how much of a home’s electric loads are to be covered by solar. The payback period is around 8 years but will be shorter if the price of oil increases.
How to get started
Before installing solar energy systems a homeowner should probably go after the low-hanging fruit first; seal air leaks, install quality storm windows, use compact fluorescent bulbs, turn down the temperature on the water heater, and install insulation in the attic and walls. Each of these will reduce energy use and thus carbon emissions significantly
Tax credits are available to reduce the cost of solar systems. Rhode Island offers a personal and corporate tax credit for residential solar systems equal to 25% of the system cost. Systems with a cost of up to $15,000 for solar electric, and $7,000 for solar hot water, are eligible for the full 25% credit. All solar energy systems are eligible for a 30% Investment Tax Credit (ITC) from the federal government. The American Recovery and Reinvestment Act of 2009 eliminated the previous maximum limit of $2000 per system, allowing home-owners to recover a significant amount of their expenditure.
A well regarded company in Rhode Island that installs both solar heating and solar electric systems is
ALTERIS RENEWABLES
28 Wolcott St.
Providence, RI 02908
For more discussion or to explore your interest further, see Barrett Hazeltine.
