How Solar (PV) Systems Work
Will a Solar (PV) System Work for Me?
- Is my roof facing the best way to make power? See Solar Panel Orientation
- Does my property have enough sun exposure? See Solar Exposure
- How much power do I use? See Below
- How much power do I need to make with solar panels? See Solar Panel Power Production
- If my roof has shade or isn't ideal for panels, can they be put on the ground? See Roof vs. Ground
- Is a tracker right for me? See Fixed Systems vs. Trackers
- Will I have power when the utility goes down? See Power When the Utility Goes Down
- I don't have utility service to my property. Can solar help? See No Utility Service
- How does a system work? See How a Solar Electric System Works
Solar Panel Orientation - In our area of Wisconsin, fixed solar panels work best when they are placed facing due South. When placed on fixed surfaces that are off of south, a system will make less power than the same system facing due South. Some incentive qualifications require panels to face within 45 degrees of due South.
Solar Panel Power Production - Solar electric systems can be sized to any size. Systems are sized by the total wattage of the panels. A 1,000 watt system in Northeast Wisconsin will produce approximately 1,200 kWh in a year if placed in a good solar location (South facing with no shading.)
It is up to the customer to decide what percentage of their usage will be made with solar. Utilities do have limits in place and some utilities require the system to be sized under your yearly usage. Off-grid systems can be much smaller and will be sized to the loads that will be powered (See Below: No utility service.) Roof vs. Ground - Roof installations should coincide with 'newer' shingles. Roof installations allow for seamless integration into the building structure. The roof can provide shelter and electricity.
Adjustable ground mounts offer the ability to change the pitch of panels to improve production over the year, shed snow in the winter, and when off of a hot roof, the systems are cooled more effectively thereby improving power production. Power When the Utility Goes Down - Solar electric systems will ONLY provide power during a utility outage when they are installed with a battery backup system OR they have a Secure Power Supply that is available on some central inverters. This is a safety requirement so power does not go back to the grid when it is being serviced.
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Solar Exposure - Places that are unshaded between the hours of 9AM - 3PM throughout the year will have a good solar exposure for a system.
How much power do I use? - On your utility bill there is a charge for all the kilowatt hours (kWh) that you consume every month. Solar electric systems' power production is measured in the same units (kWh.) As your power consumption changes over the year, solar electric systems will produce more power in the summer than they do in the winter in Wisconsin. It is important to know how much power you use in the year, so you will understand how the solar electric system's monthly power production will offset your bill.
Fixed Systems vs. Trackers - Most systems are "fixed" since the panels are mounted to a roof structure and do not move. Costs for "fixed" or roof mounted systems tend to be less than a ground mounted system as the structure is all ready present.
Tracking systems include solar panels that are mounted to follow the sun throughout the day (East to West) and over the year (high to low in the sky) will make more power than fixed South facing panels. Trackers involve placing panels on top of poles that have a motor beneath them to automatically turn the panels toward the sun throughout the day. These systems have moving parts so maintenance is required and carry additional costs for the tracking mechanism and installation. No utility service - Solar can provide power in this situation. A detailed list of the appliances to be powered, the length of time and the time of year the appliances will operate is essential to design a robust off-grid system. In Wisconsin, with snow and stretches of cloudy days, the number of solar panels will affect how quickly batteries can be recharged. A generator is normally suggested for such a system if there are critical loads that must be powered.
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How a Solar Electric System Works - A solar electric system "turns on" when there is enough ambient light to get electrons flowing. It shuts down at night when there isn't enough light to keep the electrons flowing. Grid-tied systems do not need any interaction from the owner on a daily basis to make solar power.
A solar electric system is a collection of photovoltaic (PV) panels connected together to generate a desired size (wattage). For example, an array may be composed of ten, 410 watt panels creating a 4,100 watt (4.1 kW) system. Framed PV modules sit side-by-side on rails and the wires from the individual modules are connected together (for central inverter systems) or connected to microinverters. The power runs to the balance of system components typically located within the home. The PV panels produce DC power which, in a normal grid-tied application, is converted into AC power by an inverter and then connected to a utility meter or your load center (electrical service panel) to power the loads in the home. If more power is being produced by the solar electric system than consumed by the home’s loads, the excess power flows out to the power grid. The utility credits the homeowner’s account in a relationship called net metering.
A solar electric system is a collection of photovoltaic (PV) panels connected together to generate a desired size (wattage). For example, an array may be composed of ten, 410 watt panels creating a 4,100 watt (4.1 kW) system. Framed PV modules sit side-by-side on rails and the wires from the individual modules are connected together (for central inverter systems) or connected to microinverters. The power runs to the balance of system components typically located within the home. The PV panels produce DC power which, in a normal grid-tied application, is converted into AC power by an inverter and then connected to a utility meter or your load center (electrical service panel) to power the loads in the home. If more power is being produced by the solar electric system than consumed by the home’s loads, the excess power flows out to the power grid. The utility credits the homeowner’s account in a relationship called net metering.