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FREQUENTLY ASKED QUESTIONS
How many solar panels and what size are enough to meet my needs?
Each energy consumer has different needs, dependent upon the electric appliances being run. For instance, if you are powering two 27 watt compact fluorescent light bulbs for two hours, you would need to supply 108 watt-hours of energy (2x 27x 2 hours). In San Diego, which has a yearly average insolation of 5 hours a day, one Unisolar 32 watt photo voltaic (PV) module is more than adequate (32x 5 hours=160 watt-hours).
To find out how much energy you use, contact us directly.
What if there is hardly any sunshine for several days?
In a typical PV system, the solar modules are used to charge a battery bank. Different geographic regions provide various amounts of daily sunshine. It is recommended that a system has enough battery power to account for five days of inclement weather. More solar panels will increase the amount of power generated when the sun is shining.
How long do solar panels and batteries normally last?
New solar panels have a manufacturer's warranty of 20 years. With proper care, however, the panels should last many years beyond the warranty. In the case of batteries, basic routine maintenance and discharge rates of no more than 10 -20% means your batteries should function effectively for 10 years or more.
What maintenance is required for a solar electric system?
Solar electric systems are elegantly simple. Maintenance includes:
Checking your deep cycle batteries every few weeks to make sure they have enough distilled water
Occasional checks of the connections between the solar modules and the inverter(s), and to tighten them when applicable.
How can I find out how many watts my appliances use, such as computers and stereo etc.?
There are a few ways to determine how much energy your household appliances use including the following:
The easiest way is to look at a monthly utility bill. This has the amount of kilowatt-hours consumed during the billed month. From there, a consumer can determine how many average kilowatt-hours were used daily.
Additionally, a typical electronic appliance should have an energy rating sticker somewhere on the product.
There are devices available including the Kill-A-Watt <link to Kill A Watt in store> that can be used to determine the energy usage of a specific appliance.
How long does it take for a solar system to pay for itself?
The payback period for a solar system is roughly 20 years, based on calculations assuming the cost of energy obtained from the utility grid is 10 cents a kilowatt-hour.
Should I use a sine-wave or modified sine-wave inverter?
A modified sine-wave inverter is appropriate for most stand-alone household applications. However, for certain technical appliances or for grid-intertied PV systems, a sine-wave inverter is necessary. In grid-intertied systems, energy can be bought and sold to the utility company by the end user.
What voltage should I consider using 12, 24, or 48 Volts?
Solar systems can be sized in 12, 24 or 48 volts. As a general rule, smaller PV systems are run on 12 volts. 24 or 48 volt equipment can handle 4,000 watt systems. 48 volt systems are designed for energy consumption needs of over 4,000 watts. Higher voltage systems use smaller wiring.
What special considerations should be observed where the batteries are placed?
Ideally, storage batteries would be placed in cool, dry and vented locations (batteries release hydrogen gas). <link to battery storage in the storage> Sheds or garages are good places. The contents of batteries should not be subjected to boiling or freezing. Freezing will only occur when the batteries are in a state of discharge.
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