As solar energy continues to become more affordable, many families are expressing interest in this local, clean power source, but are unable to install a solar system at their homes for various reasons. In fact, due to structural constraints, shading from trees, and other issues, about 75% of residential rooftop area in America is not suitable for hosting a solar system. This prevents a large segment of the population from taking advantage of solar energy. The solution to this problem is Community Solar. Community Solar (aka Shared Solar) takes place through the development of solar energy projects that provide power to multiple community members. Community Solar systems are typically sited close to the community they will serve. These programs leverage economies of scale to reduce the price of solar for individual customers. This model allows Southerners to access the benefits of solar energy even if they would be unable to install solar panels on their own homes or businesses. Community Solar can be utility-sponsored (either a utility developing its own program or working with a solar company to offer a program), or it can be third party-sponsored in states that allow for competition. By offering well-designed Community Solar projects, utilities can give their customers meaningful access to affordable, local solar power and tangible control of their energy choices. By providing families more options to lower their energy costs and take advantage of the South’s vast solar resource, Community Solar can create healthier, cleaner, and stronger communities across the region. Community Solar programs also provide benefits for utilities by increasing customer satisfaction, bolstering clean energy investment, and contributing to local economic development. Utilities can take advantage of economies of scale by choosing the optimal system size and number of participants. They can also decide which location will offer the most value to the grid. Community Solar can be a win-win by providing tangible benefits to participating customers, strengthening local communities, and delivering valuable clean energy to the grid. We encourage utilities to adopt the following best practices when developing Community Solar programs to ensure that all customers receive meaningful access to solar power through this innovative program.

The concept of energy sovereignty redefines the priorities for decision making regarding energy systems while encouraging increased reliance on renewable energy technologies like solar. Energy sovereignty involves centering the inherent right of humans and communities to make decisions about the energy systems they use, including decisions about the sources, scales, and forms of ownership that structure energy access. Current U.S energy policy does not center concerns of energy sovereignty, and in many cases may work against it. Policies to enhance energy sovereignty can accelerate electricity decarbonization while also empowering community scale decision making and offering communities control to reduce the myriad externalities associated with the fossil-fuel energy system. Energy policy designed based on the concept of energy sovereignty would prioritize community voices in energy system decision making, ensuring that communities are given an opportunity to express their right to self-determined sovereignty in energy systems transitions and energy system use. Energy sovereignty is an inherently place-based practice, and policy tools that center energy sovereignty would enhance community capacity to plan for transitions while embracing considerations of the health and wellbeing of communities, both human and non-human, now and in the future. The policy tools most effective for enhancing energy sovereignty may not yet exist, but they are essential for promoting a just energy transition that benefits all communities based on their own understanding of energy transition priorities and values.

Driven by climate change and economics, energy generation is undergoing a necessary and rapid transformation towards non-emitting renewable energy, especially solar and wind. As the world decarbonizes, the energy grid will become distributed, characterized by increased local control and decreased transmission losses. The future grid also provides extensive energy security, local employment, and local risk reduction, if coupled with battery storage. Photovoltaics (PV), the direct production of electrical energy by photovoltaic cells, stand out as a key component in the required transition for social and economic reasons: scalability, safety, rapid deployment, longevity, reliability, resilience, and minimal emissions. In the last decade, the cost of solar has decreased precipitously and reached grid parity (costing the same or less than electricity from conventional sources) for most of the world in 2015. In 2019, unsubsidized residential solar was less expensive than most rates charged by utilities, while industrial solar-plus-storage produced electricity at rates that outcompeted all other means of electricity generation. Both residential and industrial solar have a miniscule carbon footprint, as compared with fossil fuels. Since globally 64% of electricity is generated through the combustion of fossil fuels, the potential to decarbonize through solar and wind is not only enormous, but is a societal imperative. Decarbonization of electrical generation becomes even more essential considering the adoption of heat pumps, electric vehicles, and other electrification initiatives. As shown by Jacobson et al. (2019), using just wind, water, and solar, almost complete decarbonization of energy is achievable before 2050. In this period of multiple crises, the UN’s Sustainable Development Goals (SDGs) offer a framework to understand and address global issues concurrently. The framework also ensures that tackling one goal does not incidentally hinder or reverse achievement of the others. Community owned solar, especially with added storage, contributes to climate change action, pollution reduction, and energy security, while reducing the relatively high energy burden for low income households. Before addressing avenues to and challenges of community solar, it is necessary to briefly summarize the many benefits of PV, separating societal benefits from benefits to an existing electrical grid. Given the stark reality of less than 10 years remaining to achieve the SDGs (United Nations 2015), community solar provides a readily available and economically viable solution to multiple SDGs. It targets the elusive middle ground in scale between residential and industrial solar and can deliver electricity competitively and at scale without requiring massive investment in supporting infrastructure. Most importantly, community solar provides more than just affordable and clean energy by democratizing the renewable energy transition. By giving power to the people, communities can utilize community solar programs in providing decent work, reducing inequalities, and increasing local resilience – while making a positive climate impact.

Community shared solar is a new and growing model for broadening local solar markets and extending the benefits of solar energy to new customers. By expanding access to solar energy, community shared solar can be a useful tool for San Francisco and other jurisdictions that seek to expand use of distributed, local solar power. To help educate stakeholders, including other Rooftop Solar Challenge partners and other cities, this paper discusses: (1) the basics of community shared solar; (2) the benefits of community shared solar; (3) variations in design of community shared solar programs; (4) examples of community shared solar program; (5) California’s regulatory context; and (6) community shared solar’s potential to expand San Francisco’s solar market. Community shared solar could also improve San Francisco’s solar market by enabling more San Francisco residents and businesses to invest in solar energy. The majority of San Francisco residents live in multi-family buildings, rent, or both: two-thirds of residential units are in multi-family buildings and 60% of San Francisco households rent. Community shared solar would allow renters and others who cannot install solar onsite to purchase solar energy for their home or business.

Worldwide, water is becoming scarcer and more expensive due to the effects of climate change. Significant adaptation will be necessary to ensure adequate supply and efficient use of a diminishing resource. This reduction in the supply of water will affect agriculture and will require a change in focus from increasing productivity of land to increasing productivity per unit of water consumed.

Community-based Stormwater Strategies and Vegetation Management for Sustainable Solar PV Development

Solar photovoltaic (PV) technology is being deployed at an unprecedented rate. To this end, we investigated critical soil physical and chemical parameters at a revegetated photovoltaic array and an adjacent reference grassland in Colorado, United States.

This study, performed by a research group that includes AgriSolar Clearinghouse partners Greg-Barron Gafford and Jordan Macknick, describes an integrative approach for the investigation of the co-location of solar photovoltaics and crops, and the potential for co-located agrivoltaic crops in drylands as a solution for the food-energy-water nexus impacts from climate change. 

The research focused on three common agricultural species that represent different adaptive niches for dryland environments: chiltepin pepper, jalapeño, and cherry tomato. The researchers created an agrivoltaic system by planting these species under a PV array—3.3m off the ground at the lowest end and at a tilt of 32°—to capture the physical and biological impacts of this approach. Throughout the average three-month summer growing season, researchers monitored incoming light levels, air temperature and relative humidity continuously using sensors mounted 2.5m above the soil surface, and soil surface temperature and moisture at 5-cm depth. Both the traditional planting area (control) and agrivoltaic system received equal irrigation rates, with two irrigation scenarios—daily irrigation and irrigation every 2ays.

The researchers found that shading from the PV panels can provide multiple additive and synergistic benefits, including reduced plant drought stress, greater food production and reduced PV panel heat stress. The agrivoltaic system conditions impacted every aspect of plant activity, though results and significance varied by species. The total fruit production was twice as great under the PV panels of the agrivoltaic system than in the traditional growing environment

Cumulative CO2 uptake was 65% greater in the agrivoltaic installation than in the traditional growing area. Water use efficiency was also 65% greater, indicating that water loss to transpiration was equal between the treatment areas. The increased productivity in the agrivoltaic system is probably due to an alleviation of multiple stress interactions from heat and atmospheric drought.

Because PV panels are sensitive to temperature, the cooling of panels below daytime temperatures of 30 °C positively impacts their efficiency. In this study, researchers found that the PV panels in a traditional ground-mounted array were significantly warmer during the day and experienced greater within-day variation than those over an agrivoltaic understory. Researchers attribute these lower daytime temperatures in the PV panels in the agrivoltaic system to a greater balance of latent heat energy exchange from plant transpiration relative to sensible heat exchange from radiation from bare soil. Across the core growing season, PV panels in an agrivoltaic system were ~8.9+0.2 °C cooler in daylight hours. This reduction in temperature can lead to an increase in PV system performance. Using the system advisor model (SAM) for a traditional and a colocation PV system in Tucson, AZ, researchers calculated that impact from temperature reductions from the agrivoltaic system would lead to a 3% increase in generation over summer months and a 1% increase in generation annually.

These results show the additive benefits of agrivoltaics, to both crop production and energy production, as well as the impacts to ecosystem services such as local climate regulation, water conservation, and drought resiliency.

This guide provides information that can assist both lenders and consumers in financing solar energy systems, which include both solar electric (photovoltaic) and solar thermal systems. It also includes information about other ways to make solar energy systems more affordable, as well as descriptions of special mortgage programs for energy-efficient homes.

The program provides guaranteed loan financing and grant funding to agricultural producers and rural small businesses for renewable energy systems or to make energy efficiency improvements. Agricultural producers may also apply for new energy efficient equipment and new system loans for agricultural production and processing.