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Solar Learning Center: FAQs
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What are solar cells?
A: Solar (also referred to as photovoltaic) cells are made from silicon and manufactured to capture sunlight and convert it to electricity.
What are solar modules?
A: The modules contain many solar cells connected together and housed in a protective unit that can go on your roof and survive the elements. Solar energy modules are the key component of any solar energy system.
Each module contains small semiconductor wafers, and are made mostly from waste silicon, these wafers the convert the sun's light, photons, into direct current (DC) electricity in a process known as the photovoltaic effect. It is then the other components of the system (inverter, AC/DC disconnect, etc.) that covert this electricity into the electricity that powers your home.
The solar modules themselves are assigned a rating in watts: based on the maximum power they can produce.
What is a solar panel?
A: The modules are strung together to create a solar energy system, which combines all of the electricity produces and delivers it to the inverter and then to your home.
What is a solar array?
A. Basically a fancy name for your integrated and interconnected solar energy system.
What is alternating current (AC)?
A: A type of electrical current, the direction of which is reversed at regular intervals or cycles. In the United States, the standard is 120 reversals or 60 cycles per second. Electricity transmission networks use AC because voltage can be controlled with relative ease.
What is direct current (DC)?
A: A type of electricity transmission and distribution by which electricity flows in one direction through the conductor, usually relatively low voltage and high current. To be used for typical 120 volt or 220 volt household appliances, DC must be converted to alternating current (AC), its opposite.
What is an inverter?
A: The device that converts direct current electricity (DC) to alternating current (AC) either for stand-alone systems or to supply power to an electricity grid.
What is the lifespan of the solar modules?
A: Most experts believe solar electric modules have a lifespan of at least 25 to 30 years and most manufacturers provide a warranty for this period. However, the truth is that we don't really know for sure since most modern solar panels have not been in existence that long. Many experts believe the actual number could be much higher, possibly as much as 50 years. What is very clear is that solar modules are extremely durable and lose very little of their energy generating capacity over time. This is one of the reasons that they make sense as a long-term investment.
If there is a power outage, will I still have power from my solar electric system?
A: That depends upon whether or not you are using a grid-tied system or an off-the-grid system using batteries. If you are using a grid-tied system you will lose power but could switch to a generator as a backup. If you are using an off-the-grid system or a hybrid system with batteries for storing your electricity then you won't lose power. This is the main advantage of an off-the-grid approach.
How many solar electric panels would I need to completely power my house or apartment?
A: The obvious answer of course is it depends on how much energy you use. Another big factor is whether or not you are trying to supplement your energy supply with a grid-tied system or if you are off the grid and trying to cover all of your energy needs. Probably the easiest way to look at it is to consider a range based on the amount of roof space you have available for placing the solar panels. An installation with about 14 panels would probably provide about 40-%-50% of your energy needs. If you have a large roof area you can probably fit about 24, 125 watt solar panels and cover 75%-100% of your energy needs. If your roof is not south facing or if it is partially shaded the energy output will be somewhat lower. A reputable solar installer can help you determine what is practical for your home and the amount of power you can practically generate from the space you have.
Does it make sense to install a solar system if we are moving in a couple of years?
A: Probably. Most real estate experts currently believe that given the concerns about energy costs a solar system will significantly raise a home's value. One source, the Appraisal Journal, states that the value of your home is increased by $20 for every $1 reduction in annual operating costs resulting from installed energy efficiency measures or energy generation systems. However, this very much depends upon the local market so you should probably confirm this with an experienced local real estate agent before making this decision if you know you are planning to sell in a relatively short period of time.
When it is cloudy or foggy, will my solar electric system still work?
A: Yes. The solar electric system will continue to operate under fog or cloud cover but its output will be reduced. The solar electric system’s power output is relative to the “depth” of the cloud cover and how much light gets in, but typical coastal fog only reduces power output by 50%. Winter storm clouds will cause substantially greater reduction but the system will still produce energy.
Can you put solar on a flat roof?
A: Yes. Most commercial solar electric systems are installed on flat roofs. The solar panels are usually mounted on “tilt-racks” which put the panels at the optimum angle and face them in the right direction.
Is the weight too much for my roof?
A: No, solar modules are very lightweight. The combined weight of the rails and solar modules is only 3 lbs per square foot.
How much does a solar module weigh?
A: 23 pounds.
How durable are the solar panels? What about hailstorms?
A: Solar modules are very durable, and constructed with strong aluminum frames and high strength tempered glass designed to withstand moderate hailstorms.
How long does it take to install a solar electric system?
A: Solar electric systems usually take between two to five days to install, depending on the size and complexity of your solar electric system. However, in our experience the actual calendar time is usually longer because there are often delays waiting for the local energy company to install the electrical meter (in a grid-tied system) or waiting for local electrical inspectors.
Are there any disadvantages to using solar energy?
A: Solar energy technologies often have a higher "first cost." This means that a person is likely to pay more money up front to purchase and install a solar system. Still, in nearly all cases, the high initial cost is recovered through substantial fuel savings over the life of the product. Another disadvantage is that solar energy approaches do require some direct access to sunlight. If you live an a very shaded area and do not have the ability to remove trees or other impediments to sun access it may not be an option for you.
Do I need to install a new roof before the solar panels are installed?
A. Solar panels are very durable and most will last at least 25 years. Therefore, you definitely should consider the age of your roof before you install them. If your roof is more than 20 years old and in bad shape you will definitely want to consider replacing your roof before installing them. However, if your roof is in reasonably good shape go for it. In fact, adding the solar panels will actually reduce the wear and tear on your roof and make it last longer since the solar panels will block ultraviolet rays which can damage roof tiles and will help to keep snow and ice of your roof.
Do I need to clean the panels periodically?
A: In most areas of the country, there is sufficient rain to clean the panels. However, if you are in a dusty area (very near a busy dirt road, very urban area, etc.) you may see a performance gain from cleaning the panels monthly. If necessary, a hose stream is usually sufficient for cleaning. Do not walk on or over the panels to clean them. Do not use metal, hard, or abrasive methods for cleaning. Do not spray water on the panels when they are very hot.
