3 Types of Solar Energy Systems: Which One Is Right for You?
All solar energy systems begin with a series of small photovoltaic (PV) cells that produce electricity directly from sunlight. These PV cells are combined to form a module or panel. Several panels are connected together to form an array or a solar system. Arrays can be small—from a few panels to power a roadside warning sign or a remote cabin—up to a large array covering hundreds of acres as part of a utility-scale solar farm.
If you want to learn more about how PV cells work, make sure to visit our How Do Solar Panels Work? page.
Solar systems can generally be divided into three different types of arrays based on size.
- This type of system is most often thought of as a residential system that you would see mounted on the roof of a house or on the ground in a homeowner's yard. However, private solar may also be installed on or near commercial and industrial facilities. For the most part, private solar systems are smaller in scale and, for practical purposes, have far less capacity to produce solar than other types.
- The actual amount of energy produced depends on the location. Typical home private solar systems are sized to produce between 2 and 10 kilowatts (kW). On average, 75 square feet of solar panels are needed to produce each kilowatt of direct current (DC) power during peak solar periods.
- While prices vary, residential system prices have fallen to an average of $3.50 per watt peak capacity of direct current Wp-DC. Watt peak capacity is the maximum capacity of a module under optimal conditions.
- Ownership of private solar systems can vary. Typically, the system is owned by the home or building’s owner. However, there are leased solar systems that are owned by the company who installed them.
- The energy produced by the solar energy system helps offset the energy use of the building on which it is installed or located nearby. During some times of the day or months of the year, it may produce more energy than is used within the home or commercial building.
- The number of solar panels installed on or near the building can be expanded over time, depending on the size and configuration of the building and the owner’s desire to install additional capacity.
- The size and scope of community solar systems typically fall between rooftop systems and utility-scale systems. Community solar systems are larger than residential rooftop systems but usually smaller than utility-scale projects. The capacity of these systems is typically between 20 kW and 1 MW (enough to power between 4 and 200 homes).
- Local cooperatives build, operate and maintain their own community solar systems. Often these systems are located within the cooperative’s service territory. Smaller systems are most likely to be local. One advantage: members can actually see the system “in action.”
- Ground mounting is the most common installation method, although some community solar installations have been placed on top of parking garages and public buildings.
- Ownership models vary, but in all cases, members who purchase solar through the cooperative community solar system receive credit on their bill for their share of the output from the solar system. The most common ownership method includes members who lease a portion of the system.
- Members subscribe to a unit of capacity from the project―they don’t own any part of it.
- There are significant advantages to community solar projects for both the co-op and the member. These include being able to participate in solar even if your home is not suited to supporting a solar system or if you don’t want the upfront investment. Participating in a community solar program offers economies of scale. That is, it’s cheaper per unit to build a large system rather than a small one, and there is more flexibility for members to participate. Cooperative advantages also include the economy of scale and the ability to manage the power inputs to a greater degree.
- Utility-scale systems may range from a capacity of 500 kW to hundreds of megawatts (MW).
- For perspective, a 1-MW alternating current (AC) solar array can produce enough energy to power about 200 homes (depending on location) and may cover 5–7 acres. Because of the amount of land required, utility-scale projects are often located in more rural, less populated areas.
- Because of their size, most utility-scale solar systems are installed in a fixed-tilt ground-mount configuration. This means that the panels are placed on the ground (rather than on a building) and are tilted in place to gain maximum exposure to sunlight.
- A solar array can be installed on marginal land that can’t be used for agriculture or building sites, such as brownfield sites, landfills and airport buffer areas. However, the site must be relatively flat or south-sloping without significant shading from vegetation or other obstructions.
- Utility-scale solar systems owned and/or operated by an electric cooperative usually feed electricity directly into the transmission or distribution grid. The utility provides solar power to members in one of two ways: by adding the power to the co-op’s power portfolio—which benefits all cooperative members; or by selling power directly to individual members who are motivated to purchase solar energy. Selling directly to consumers may be done in one of two methods, also. First, members may sign on to a cooperative-offered Green Power Purchase program that sells the renewable attributes of the power directly to members. Some cooperatives also support a community solar program, described below. Though utility-owned programs come in many variations, most programs feed power to the grid rather than directly to a home or business site.
- Economies of scale have a direct impact on costs. The 2015 calculations indicate that a large (20 MW-AC) solar system can be installed for an average of $1.55 per Wp-DC; the cost is even less in some areas.
11 Frequently Asked Questions About Solar Energy
Solar energy has grown significantly in popularity over the past five to 10 years. As a result, the technology becomes increasingly compelling for homeowners and business owners alike. Here, we’ve compiled a list of the most frequently asked questions we get related to solar panels and solar energy generally.
When sunlight hits a solar photovoltaic module (solar panel or PV panel) it causes electric current to flow. The current produced from the PV panels is controlled and regulated by an inverter, which converts direct current (DC) to alternating current (AC), needed for use by household appliances. The electrical panel is where the power gets distributed throughout your house; any excess electricity generated by your solar panel system may be sent from the panel back to your cooperative’s power grid. For those with residential, grid-tied solar systems with storage, any excess electricity produced by your system is stored in batteries.
As you might imagine, the amount of power a solar panel system can generate depends on several factors:
- The size of your system. You can determine how much electricity you want to produce; then size your solar panel system accordingly. Note that you can start out with a small array of panels and add on. A system that will generate 100% of your energy needs is expensive, so most systems are sized to generate only a portion of your home’s needs.
- Your site. If you have a shade-free area from 9 a.m. to 3 p.m., you’ll be able to collect more sun and produce more energy than if your site is shaded.
- Your region. The more sunny days in your area, the more electricity you’ll be able to generate from your solar panel system. For example, systems in the Southwest produce more electricity per year than in the Northeast.
You can find online calculators to help answer this question in more detail; PV Watts is a good one: https://pvwatts.nrel.gov/. Your co-op and reputable installers can also help.
Your system will not generate the power you need at night or on cloudy days, so you need an alternative energy source. Battery-backed or grid-independent solar panel systems use on-site energy storage to store excess energy produced during the day for use when the sun is not producing enough power, whether that’s at night or when it’s cloudy. Choosing this option will add significant cost and maintenance to your system. Most people opt for grid-connected solar energy systems for reduced cost, maintenance, and high reliability. With this type of system, your cooperative continues to provide energy to you when you need it 24-7. Your solar panel system will produce energy, and even excess energy, on sunny days. Your system will not collect sunlight at night and on cloudy days. That means you will continue to draw electricity from your cooperative during these times.
No, unless they have batteries and are isolated from the grid. All grid-connected solar panel systems must shut down to prevent back-feeding electricity into de-energized power lines that may have fallen or that line crew members may be working on. It’s important to have this shut-down feature built into your solar power system to prevent injuries—and even death—to those working on the line.
Grid-connected solar and other distributed energy resources are connected to the cooperative’s power lines. That means electricity can flow both to your home from your electric company or cooperative and from your solar energy system back to the electrical grid. Particularly on sunny days when energy goes unused, your system may generate excess energy that can flow back to the grid and may be sold back to your cooperative. This is known as “net-metering." Many cooperatives and electric companies purchase energy generated by a solar panel system above what the homeowner uses. Check with your cooperative or utility provider to get specific details for your area, including requirements for interconnection, safety, metering and applicable rates.
The price of solar energy system components varies depending on the size of the system (generating capacity), type and quality of the components purchased and complexity of the system selected. The good news for members is that the cost of solar panels and their corresponding components has declined dramatically while the technology has improved.
Installation costs depend on the size and complexity of the system but also on the home layout and construction. For example, a simple, south-facing roof allows for easier installation than a roof with hips and valleys. In addition, some homes require structural or wiring upgrades to accommodate a solar panel system. An average 4 kW system may cost between $10,000 and $20,000, before credits and incentives. This is based on a typical installed cost of $2.50 to $5 per Watt of distributed generation capacity. To determine your costs, look for online calculators to help you estimate your pricing. It's also wise to get bids from reputable installers.
State and federal governments and some utility companies offer certain incentives, rebates and tax credits to those who install solar panel systems. There is a federal tax credit of thirty percent through 2032. In addition, there may be state or local income tax credits, property tax exemptions and rebate programs from government agencies. These vary by state, city and utility, and rebates may also depend on whether the solar energy system is purchased or leased. Find information about available programs: http://programs.dsireusa.org/system/program/maps. Be sure to consult with your financial and tax advisor.
One of the most common questions surrounding solar energy is, “How long is it going to take to pay off the solar panels I just installed?” On average, the payback period can range from fewer than 10 years to more than 20 years, depending on the following factors:
- System costs
- Available rebates and incentives
- Operation and maintenance costs for the system
- The amount of electricity produced
- The retail price of electricity you purchase from your cooperative.
Check with your cooperative for more information.
Certified PV products and solar panel systems generally are reliable and can work for 30 years on average. Manufacturers test solar panels for hail impact, high wind and freeze-thaw cycles to represent real-life situations. Most manufacturers offer 20- to 25-year warranties for panels; extended warranties may be available at an extra cost. Maintenance is required, and you should talk with your system provider about proper care. On average, solar panels degrade at a rate of 1 percent each year. Additionally, you need to make sure your roof is in good shape before installation. Other components like inverters may have a shorter life. Solar panels may outlast the roof they are attached to. Make sure your roof is in good shape or budget for replacement during the life of the system.
To determine if solar is right for your house, you can look at factors such as which direction your home faces, the condition of your roof, and obstructions such as trees and other buildings that may block the sun during the peak generation period of 9:00 a.m. to 3:00 p.m. Solar contractors can provide a more detailed analysis on whether or not your home is suitable for a solar panel system, and your cooperative can offer advice, too.
If your house is not ideal for solar, you rent your home or you just aren’t ready to make a big investment, there are other options. Talk to your cooperative about community solar or green power program options.