Community solar farm
A community solar farm or garden is a solar power installation that accepts capital from and provides output credit and tax benefits to individual and other investors. In some systems you buy individual solar panels which are installed in the farm after your purchase. In others you purchase kW capacity or kWh of production. The farm's power output is credited to investors in proportion to their investment, with adjustments to reflect ongoing changes in capacity, technology, costs and electricity rates. Companies, cooperatives, governments or non-profits operate the farms.
Centralizing the location of solar systems has advantages over residential installation that include:
- Trees, roof size and/or configuration, adjacent buildings, the immediate microclimate and/or other factors which may reduce power output.
- Building codes, zoning restrictions, homeowner association rules and aesthetic concerns.
- Lack of skills and commitment to install and maintain solar systems.
- Expanding participation to include renters and others who are not residential property owners.
The Solar Gardens Institute maintains a national directory of community solar projects and organizations. As of 2011, farms encompassed both photovoltaic and concentrating solar power technologies.
Community solar in the United States
An estimated 85% of U.S. residents can neither own nor lease systems because their roofs are physically unsuitable for solar or because they live in multi-family housing. At least 52 projects are under development in at least 17 states, and at least 10 states encourage their development through policy and programs.
Federal and other tax policies are necessary to finance community solar farms. U.S. Senator Mark Udall introduced the SUN Act (Solar Uniting Neighborhoods) to extend the existing 30% tax credit to community solar farms in 2010 and 2011.
The bill would enable groups of individuals or homeowner associations to develop utility-scale solar power facilities in collaboration with local utilities that would distribute the power and credit owners based on their percentage of investment in the solar farm, extending the tax credits accordingly.
“These projects have the potential to drastically increase the adoption of clean energy nationwide, but the tax code hasn’t kept up,” Udall said. “You can get a 30-percent tax credit for putting a solar panel on your house, but not for investing in a solar farm.”
SolarShares (2007) offers customers of the Sacramento Municipal Utility District the opportunity to buy "shares" in its solar farm. The electricity generated by each customer’s “shares” appears as a credit on his or her energy bill, a savings expected to average between $4–$50 a month, given sunshine variability. For a monthly fee—starting at $10.75 a month (averaging 9%) for a 0.5 kW system—participants opt into solar power production. The current phase is sold out, although plans are in progress to expand capacity.
The PVUSA array in Davis, California (2001) provides virtual net metering for city-owned meters. The California legislature passed a law specifically allowing this for this individual array. Senate Bill 43 was signed by Governor Brown on September 28, 2013 
Colorado legislation passed in 2010 that requires the Public Utilities Commission to rewrite rules to direct investor-owned utilities to offer rebates for community solar gardens. 
HB10-1342, the Community Solar Gardens Act specified:
- Energy must be sold directly to an investor-owned utility.
- Utility pays retail + REC’s.
- Utility provides Virtual Net Metering credit on the subscribing customer’s bill.
- System size limited to 2 megawatts (MW).
- 6 MW total limit on the program for first three years.
- There must be at least 10 subscribers.
- Subscribers must be located in same county or city as the solar garden. Subscribers whose county has a population less than 20,000 may subscribe in a neighboring county.
- Subscribers may buy up to 120% of their own power use worth of solar power.
- Either a for-profit or nonprofit entity may own and administer the solar garden.
In Colorado, Xcel Energy customers continue to pay the standard non-energy fees, but can buy enough solar shares to offset 120 percent of their load.
Orlando Utilities Commission (OUC) has a solar farm that began producing power in October 2013. The municipal utility, which has approximately 55 percent of its 230,000 electric customers living in multi-family housing, sought a unique solution for those wanting to use solar power, but unable to modify the homes they rent or lease. This project also allows those customers the ability to buy into solar without all of the upfront costs. Subscribing customers volunteered to pay a higher rate on their power bill, but they were also able to lock in that rate for the estimated life of the project – 25 years. Today, 1,312 solar panels are generating up to 400 kilowatts (kW) of electricity at OUC's Gardenia Operations facility next to Interstate 4. The panels are on three canopies, which have created 151 covered LED-lit parking spaces over about 2.5 acres. A total of 39 customers have subscribed to the project. Each kW of the array’s 400 kW was sold in blocks, with a limit of 15 blocks per customer. Each block represents 112 kilowatt hours (kWh) on a customer's monthly bill, so the maximum benefit per customer is 1,680 kWh. The average OUC residential customer uses around 1,200 kWh. Any unused power is credited on the account for the next month.
The Green Communities Act of 2008 authorized what was formally known as "neighborhood net-metering", which allowed a group of residents in a neighborhood/town to pool resources to cover the capital cost of a renewable energy installation.
Residents of Brewster founded the first cooperatively run solar garden in Massachusetts. The solar garden was built by solar installer My Generation Energy Inc. Each member of the cooperative was to receive benefits from the co-op; including the net-metering credits from the solar garden through Nstar. Known as the Brewster Community Solar Garden, it is a 345.6 kW community solar farm located on Cape Cod.
Massachusetts and the Federal government each offered incentives to improve solar economics. A traditional investment in photovoltaics without incentives would take 12 or more years to pay back the initial cost. The incentives lowered the payback period to 6–10 years.
Gardens built by developer Clean Energy Collective started producing power in Newton, Massachusetts in July 2014. The company originally partnered with now-defunct energy efficiency firm Next Step Living and is currently working with the startup Solstice Initiative.
Electric utilities in St. George built a large photovoltaic facility to exploit 310 days a year with sunlight, and allowed residents to purchase it to supplement conventional energy. The program required no set-up or maintenance for the participant.
Participation is sold in whole and half units of 1 kilowatt (“kW”). A 1 kW “unit” on the SunSmart grid cost $6,000. One unit equals approximately 15% of the average home’s monthly power (or about 140 kWh). A one-time tax credit of 25% of the purchase price, up to a maximum of $2,000, was available from the state of Utah. Purchasers received a monthly energy credit for the energy produced that month by the “unit” of panels.
Community solar in the United Kingdom
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