What is solar electricity?
The sun's energy is captured and converted into DC electricity through a device called a photovoltaic (PV) panel system. A PV panel system converts sunlight directly into electricity anytime the sun is shining, but more electricity is produced when the light is more intense (a sunny day) and is striking the panels. Solar electric panels do not use heat to make electricity. Instead, electricity is produced as electrons are freed by the interaction of sunlight with semiconductor materials in the solar panels.
Solar electric systems use PV cells to convert sunlight into direct current (DC) electricity. PV cells are made from silicon and were originally developed to power spacecraft and space stations. The cells come wired together in panels. A group of panels mounted on a frame is called a PV array.
To provide electricity reliably and safely, PV systems include several pieces of equipment in addition to the PV array. This balance of system components typically includes a charge controller, an inverter, wiring, safety breakers or fuses, and a form of electricity storage (typically batteries).
What are the benefits of solar electricity?
A PV system reduces or eliminates the amount of electricity you purchase from your electric service provider, or it can provide power for sites where no power is available, or where the cost to bring in utility power is prohibitive.. The electricity generated by your PV system is clean, renewable and reliable. Solar technology produces no air or water pollution, is emission free, silent and unobtrusive. It makes it possible for home and business owners to generate their own power from a 100% renewable resource - the sun. It will immediately lower your utility bill, act as a hedge against future price increases, and even add to the resale value of your structure.
Additionally, you help your community by reducing the load on the utility grid and you can provide additional electricity for the grid when you generate more than you use during the day, when electricity demand is highest.
How much solar electricity do I need?
Accurately sizing the components of your solar electric system helps ensure that your system will produce the amount of power you want it to produce at a reasonable rate of return on your investment. Consider what portion of your current electricity needs you would like your PV system to meet. A system should be sized to meet no more than your whole load on the sunniest day of the year, and rely on some grid power or battery backup during winter or on cloudy days. If you reduce your electricity loads, you can generally buy a smaller, less expensive PV system.
In addition to how much electricity you'd like to generate, the size of your system also depends on these factors:
The site's solar resource or available sunlight;
The system's orientation and tilt;
The system's efficiency at converting sunlight to electricity;
Other electricity sources, like a utility, a wind turbine, or a fossil fuel generator.
PV systems are classified by their rated power output (the peak power they produce when exposed to solar radiation of 1000 watts per square meter at a module temperature of 25°C). Systems rated between 1 and 5 kilowatts are generally sufficient to meet most of the needs of home and small business owners.
Is my site a good place for a solar system?
Your site must have clear, unobstructed access to the sun. Buildings, trees or other vegetation should not shade your site. South-facing roof exposure is best, but roofs facing east and west may be OK. If a rooftop is not available, your PV system can also be mounted on the ground.
Does a PV system replace an electric utility?
PV systems are typically used as either stand-alone systems or grid-connected systems (also known as grid-interactive or grid-tie systems). The role of photovoltaics in these two types of systems is very different, and the design decisions and performance requirements are very different as well.
Stand-alone PV systems generate all of the on-site electricity needs of a home. Therefore, they are not connected to any electric utility. Stand-alone systems can provide AC or DC electricity, and typically include batteries to store electricity for use when the sun is not shining. Stand-alone systems are often cost-effective when installed in remote areas where access by electric utilities is difficult and expensive.
Grid-connected PV systems are typically sized to meet 50% or more of a home's electrical load. These systems are not always sized to meet all of the electricity loads of a house because of the higher upfront costs associated with purchasing a larger system. A larger system will cost less per kilowatt-hour generated due to the economies of scale associated with manufacturing processes. Thus, a grid-connected system will generate all or part of the electricity required in a home, while the remaining electricity loads are met by the utility.
Isn't solar expensive?
At first it may seem that a solar electric system is expensive, but solar is actually much more economical than utility power. Many states and utilities have incentives and/or rebates, and the Federal government offers deductions for installing an alternative energy system.
Do I need to buy a system that will eliminate my electric bill?
No. Many people buy systems that only eliminate part of their electric bill. The utilities have adopted a rate structure that increases the cost of electricity as you use more of it. Many people choose a system that will only eliminate the most expensive electricity. This increases the return on your investment.
What's the payback period?
Payback is usually used to describe the time it takes for an investment to pay for itself, similar to Return On Investment. However, the basic assumption behind a payback calculation is that this is a discretionary expenditure, I can choose to invest in this energy equipment, or not, and if I don't, I can put that amount of money in the bank and with no risk, make some 3-4%.
Paying an electric bill is not a 'discretionary' expense for most people; they have no choice! By buying a solar electric system you are taking money that you would be "giving" to your electric utility and investing it in your home.
What is the lifespan of a PV system?
Solar Electric systems last a long time depending on the amount of active use, or the amount of sunshine converted into electricity by the PV cells. Most systems are only in use for 6 to 8 hours per day. Manufacturers will usually provide 10 to 20-year warranties, but PV modules will likely last longer than that. The balance of system components, however, will have a shorter life.
Can I use solar electricity to heat water or to heat my house or office?
It is impractical to use solar-generated electricity to heat water-a solar water heating system is a far more cost-effective choice. Similarly, space heating is best accomplished with solar thermal strategies or equipment designed for the task-passive solar designs or transpired collectors, for example.
What is involved in maintaining and operating a Solar Electric system?
Without any moving parts, maintaining a PV system is relatively simple. For grid-connected systems, minimal maintenance is required, including keeping the panels free of any debris such as fallen leaves, bird droppings, etc. For stand-alone systems, the batteries usually require the most maintenance. Contact your PV system retailer for more information on maintaining battery banks.
Does my electric meter really spin backwards?
When a grid-connected solar electric system generates more power than the appliances within the home are consuming, the excess electricity goes back out into the utility grid. Excess power going back into the grid spins your meter backwards and your neighbors are using clean quiet solar power. This is called "net metering", and allows the utilities customer to only be billed for the "net" electricity purchased over the entire billing period. At the end of each billing cycle your meter will not have spun as far forwards as compared to not having solar electricity.
Will I have power if the utility grid experiences a blackout?
A battery option is available to provide electricity in the event of a blackout offering you greater security and convenience.
Are there any incentives or rebates available? Many states and utilities offer incentive programas. For more information on incentives available in your area, follow this link to the Database of State Incentives for Renewable Energy (DSIRE
