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Frequently Asked Questions
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 What is PV? : Unlike a solar hot water system that uses the sun's energy to heat water, solar electric or photovoltaic technology uses the sun's energy to make electricity. Learning from the word itself, the prefix "photo" means "produced by light", and the suffix "voltaic" refers to "electricity produced by a chemical reaction." PV technology produces electricity directly from the electrons freed by the interaction of sunlight with certain semiconductor materials, such as silicon, in the PV module. The electrons are collected to form a direct current (DC) of electricity.A complete PV system usually consists of one or more modules connected to an inverter that changes the PV's DC electricity to alternating current (AC) electricity to power your electrical devices and to be compatible with the electric utility grid. Batteries are sometimes included in a system to provide back-up power in case of utility power outages. What size system do I need for my home? : There is no one right size for photovoltaic system. Every site is different and the needs of owners vary, too. System size depends on several factors, including how much electricity (in kilowatt hours or kWh) you consume, the orientation of the system, the tilt of the system, available space and funds.The first step to determining the size of the photovoltaic system you'll need is to reduce consumption. Saving electricity is typically cheaper than generating it. Also, the smaller your overall consumption, the small and cheaper the system you'll need. The second rule is sizing is DON'T oversize. Utilities will not credit you for any excess electricity generated on an annual basis; in other words, in any twelve month period, if you generate more than you need, the excess electricity goes into the grid and you will receive no credit. You should try to size your system equal to or less than your annual consumption. An easy rule of thumb is to take your annual consumption (in kWh) and divide by 1300 kWh/yr. (1kW of photovoltaics will generate about 1300 kWh per year). This will give you an estimated system size. For example, the Smiths consume 6000 kW per year. If we divide 6000 by 1300 we get 4.6. This means the Smiths need about 4.6 kilowatts (kW) of photovoltaics to completely offset their annual consumption. How big is a typical system? : Solar PV systems range in size from fifty to four hundred square feet. A system composed of high efficiency cells will produce 1kW per hour for every 100 square feet. In order to qualify for the California Energy Commission's (CEC) "Buy Down" rebate, the maximum size cannot be more than 200% of the home's annual historical needs.How do I know if my site will work for a PV system? : Solar designers look for sites that provide an optimal southern orientation, good exposure to the sun, and an adequate amount of structural support and space for solar panels. The best location is on a south facing roof, but an east or west facing roof might also work. Flat roofs provide an environment for a variety of solar modules. Locating the PV system on the ground can work with either a fixed mount or a tracking mount system.How much space will the solar electric system take up on my roof? : A good rule of thumb is to allow 100 sq. ft. per every kilowatt of electricity the system produces. A solar electric system for a typical home will require 300-500 sq. ft.When is the best time to install solar? : The best time to install solar was last year and will always be last year. Solar electricity is getting more and mroe expensive as the rebates drop and the panel prices increase. Fortunately electricity rates are increasing at a faster rate than the price of solar.How long will my solar system last? : Most solar panels come with a 25 year power output guarantee and are expected to last at least twice that long. The power output guarantee on the solar panels is provided by the manufacturer of the panels and states that at the end of the 25th year, the solar panel will still produced a minimum of 80% of their original power output.What is a "net-metering grid-tie" PV system? : In California and many other states you may connect your solar system directly into the wires of your utility. "Net Metering Laws" allow you to do this and you will actually be spinning your meter backwars when your system is generating more power than you are consuming. Thus you can "sell" electricity back to the utility, up to the amount you would have used. Without Net Metering you would be forced to "sell" the energy back to the utility at a lower or wholesale rate and buy it back at a huch higher retail rate. Net Metering is one of the principle reasons solar electricity has become economically viable.What does the term TOU rate mean? : Time-of-Use rates: each day (weekday or weekend) is broken into four areas: Off-Peak (base rate), Morning Part-Peak, Peak, and Afternoon Part-Peak. In evaluating the system, the times each rate starts is defined and the current rate applicable for that time period is used. Your utility may change these rates or the time periods applied. TOU charges can account for a large percentage of your utility bill. Solar can reduce average cost of electricity by taking advantage of time-of-use rates. Electric rates are usually higher during peak daytime periods. This is when solar systems produce peak output and can "spin your meter backwards".What is the payback? : Payback is immediate. If you were to finance your solar system, your payments would typically be less than the electric bill that it replaces. A solar system will also add value to your property, reduce your monthly expenses and insulate you from higher and higher energy costs. If you were to pay cash for your system, at today's rates, you will typically recover all your investments withing the next 6-10 years. As rates go higher, the time it will take to fully recoup your investment could easily be less than 5 years.Does a PV system add to the resale value of my home? : The "PV System Resale Value" for your home is based upon research published in the Appraisal Journal whic concluded that "The increase in appraisal value for a home is about twenty (20) times the annual reduction in operating costs due to energy efficiency measures." To calculate "System Resale Value", the first year annual utility savings is multipled by twenty (2). Source: Evidence of Rational Market Valuations for Home Energy Efficiency, Appraisal Journal, Nevin/Watson. :How will the weather affect my solar electric system? : Solar electric systems are designed to withstand all weather conditions. Lightning, wind up to 80 miles per hour, and extreme temperatures are all things your solar system can handle. However, these conditions will temporarily reduce its energy production. Although a PV system may receive 80-90% less sunlight on a cloudy day, the modules can still generate electricity. In fact, PV systems generate more power when the temperature is lower. Because of the shorter hours of daylight and lower angles of the sun in winter, PV modules do generate less energy than in summer.What happens during a power outage? : With a grid connected solar PV system, the inverter will automatically disconnect itself from the utility grid when there is a power outage. This is to prevent back feeding the grid and putting engineers working to restore the power in danger. If you have a grid connected PV system with battery back up, it will automatically switch to backup power with little detection. Both these systems will automatically hook back up to the grid once power is restored.How is the solar quote determined? : Several things are taken into consideration when developing a PV system and quote: your utility rates, your utility usage, your lifestyle as to when and how you use electricity, the condition of your roof or property, your current electrical panel capability, the space available for panels, the effects of shade, your desired offset - percentage provided by solar, your financial goals (total offest or to find the "sweet spot"), and your overall motivation to go solar.How long can I reserve my rebate before installing the solar system? : In California, the California Energy Commission (CEV) provides you with a six month window in which to install the system. For new construction homes, an 18 month reservation period is given. If you do not install the system within that time frame, the reserved CEC rebate money is simply kept by the CEC. There is no penalty from the CEC if you decide not to install. |
