How to Create a Solar Grid

Solar panels may help a home become more energy efficient.

Solar grids harness the energy of the sun to help power a home or business building. Also called photovoltaic systems, solar grids consist of solar cells or panels that absorb sunlight and convert it into electricity. A solar system comprised of about 10 to 20 solar panels may provide 250 kilowatt hours (KWH) of energy per month, offering supplemental electrical power to a home. Panels can either be fixed in a southern direction or mounted to a moving track that follows the path of the sun. Solar grid systems can be attached to a home's existing utility grid connection to supplement power supplied by the utility.

Things You'll Need

• 10 to 20 solar panels
• Inverter
• Solar energy survey
• Roof or ground mount
• Building permit

Instructions

1. Perform a solar energy site survey to determine if your location gets enough sun to warrant the cost of installing a solar grid. Conduct a manual site survey using a printable sun path chart and solar elevation/azimuth angle gauge. Or, conduct an online site survey using the free Google SketchUp 3D modeling program. Use these tools to track the sun's path over your home and determine when and where the sunlight shines strongest on your property. Use the data to place your solar panels in the spot on your property which receives the strongest, longest and most unobstructed amount of sunlight, soyou can maximize the productivity of your solar system.

2. Decide on a "grid-tied" or "off-grid" system. Grid-tied systems are connected to the utility grid and run power back into the electricity meter when the house produces more power than it consumes. A grid-tied system allows your house to receive power from the city utility system as needed to supplement the power generated by your solar system; on days where your solar system does not provide enough power to meet your energy demands, you can rely on city power to fuel your home. Off-grid systems rely on batteries to power the house when the sun is not shining. A small off-grid system is the easiest to create and install.

3. Determine your current power usage, your budget and how much space you have to install a solar system. Use a PVWatts system-sizing calculator to determine what size of system you will need to produce a desired amount of kilowatt hours (KWH) per month.

4. Decide where to put your solar panels. Use the information gained in step 1 to determine the location on your property that receives the most sunlight and place the panels there. Commonly, this will be on a roof or in a yard.

5. Construct a roof or ground mount. Ground mounts require building a structure of wooden beams tilted at a 45-degree angle to connect the panels to, while roof mounts can just have the panels attached directly to the roof. Ground mounts also require running wire underground to connect the electricity from the panels to the home. If you install a ground mount, you will need to dig a 30-inch deep trench running from the panel site to your home. A depth of 30 inches is required to safely install the electrical wiring running from your solar system to your home.

6. Select an inverter to tie your solar panels together. An inverter converts direct electrical currents produced by your solar system into alternating currents that your home can use for energy to power electrical appliances. The voltage produced by a string of solar panels can be several hundred volts and inverters are designed to handle these voltages. Fronius, SMA Sunny Boy and Xantrex are a few inverter manufacturers.

7. Choose solar panels that are compatible with your inverter. Your inverter will include a list of compatible panels. Install rails first, then attach the inverter to the rail. Rails form the frame which the solar panels will attach to; rails will hold your solar panels together and in place, forming a sheet or wall of solar panels. Finally, attach panels and have a professional help you wire the system to your home.

Tips & Warnings

• Check with your city and county before you begin construction of a solar grid on your property. You will likely need a permit to install it and will not be legally able to begin work on your system until you have it.

• Unless you are extremely familiar and comfortable with electrical wiring, enlist the services of a professional to help you complete the final step of wiring your solar system with your home.

References

• National Renewable Energy Laboratory: Solar Photovoltaic Technology
• University of Oregon: Sun Path Charting Program
• Build it Solar: Elevation and Azimuth Gauge
• Build it Solar: Designing and Installing Your Own Grid-Tied PV System
• Build it Solar: Using Google SketchUp to Model Sun on a Home, Collector

Resources

• PV Watts: Performance Calculator for Grid-Connected PV Systems