Renewable Energy Resilience

Nanogrids, Microgrids and Virtual Power Plants

Expert on new energy business models such as nanogrids, microgrids and virtual power plants, covering cutting edge energy and environmental issues for over 25 years.

Community Solar and the Solar Safety Net

What is “community solar?” The term means different things to different people.

One goal of a project funded by the Marin Community Foundation to be completed in June 2008 and is to provide networking services among the various West Marin communities adding solar PV systems to key high-profile community assets: community centers; schools; fire stations and water district operations. In each of the five communities targeted – Muir Beach, Stinson Beach, Bolinas, Point Reyes Station and the San Geronimo Valley – major solar PV projects moved from the planning into the development phase. In one case – Muir Beach – the solar PV system was already in place, though this was hardly common knowledge. In another case – San Geronimo Valley – this investigation salvaged a $150,000 at $2.80/watt subsidy for a 58 kW ground mounted system to serve the Lagunitas School District and the San Geronimo Valley Community Center buildings. A long delay in development of a solar PV project in Stinson Beach – (Pathfinder Communications had raised an initial $3,250 from solar vendors in February 2005) – was also spurred on by this MCF/NorCal Solar project.

When used in the context of this forthcoming report, however, “community solar” actually refers to a specific and currently unavailable solar application: the ability of multiple users – often lacking the proper on-site solar resource or fiscal capacity or building ownership rights – to purchase a portion of their electricity from a solar facility located off-site.

As explained in the ASES white paper entitled “Solar Shares Business Model” by Joseph McCabe and Jon Bertolino, this model could greatly expand emerging markets for solar energy.

The solar shares business model provides utility-scale, multi-megwatt (MW) photovoltaic (PV) systems the ability to distribute energy values across multiple utility customer classes, while capturing demand reduction at the site of the PV system, as well as valuing the Renewable Energy Credits (RECs). Net-metering in California opened up a new grid-tied market for PV in the 1990s. The potential exists to again increase the electricity market share for PV with offsite net-metering, or wheeling, of the electricity produced from PV systems.

In essence, the terms “community solar” and “solar shares” refers to the fact that multiple users can draw from a single solar photovoltaic array, or a series of arrays on different buildings, but operated as a single system, supplying clean electricity to community institutions (fire station, community centers, etc.) as well as residents that lacked good solar exposure on their own rooftops. Under this “community solar” model, participants, in essence, purchase shares of the total output from solar systems without ever having to pay the upfront costs or deal with technical installation challenges.

According to Don Smith, the most ardent supporter of “community solar” in West Marin, this “community solar” model makes inherent sense for Marin County, especially in light of ongoing deliberations about the CCA. “Placing large solar arrays at optimum locations around the County is simply much more efficient than having little ‘behind-the-meter’ arrays on individual rooftops as is required under the current net metering rules,” said Smith, who has pulled together solar development proposals for the Bolinas water and fire districts. He continued, “First, there is efficiency of scale in design, construction and monitoring costs. Second, there is increased power output per unit installed because the arrays can be placed on the sunniest sites and at the optimum geometrical orientation.”

Smith concluded his comments on the role a CCA could play in developing solar power in West Marin with this plea:

“It has been very frustrating for me as a community solar advocate to be mired in regulations that unnecessarily complicate and impede the implementation of this crucial energy source. It’s time to move forward. How can we get CCA and Solar Shares model underway in Marin?”

California’s first “community solar” program– called “SolarShare” – was launched by SMUD in September 2007. Under this program, private developers able to take advantage of the federal tax incentives will build, own and operate systems of 1 MW in size. These developers enter into 20-year fixed price contracts to sell all of the output to SMUD, which then retails this power to participating customers.

SMUD estimates that for less than $5 per month up to roughly $30 per month, most residential customers will be able to purchase between 10 and up to 50 percent of their power from these new solar facilities. SMUD, too, describes these purchases as coming from a “virtual” solar PV system. SMUD is marketing the program to customers that due to site problems, installation issues, up-front costs or status as renters, are unable to participate in the utility’s other solar programs. The end goal of SolarShare is to boost solar power production more than ten times its current level. SMUD’s existing solar capacity ranks as among the most successful in the country. The municipal utility projects to add 16 MW of solar capacity annually over the coming years.

Solar Safety Net

Another goal of this project is to specify the size, technology and policy impediments to developing solar-based emergency power systems, with particular emphasis on advances in inverters and battery systems. This preliminary analysis will review how a “Solar Safety Net” might work at the individual residence level, the neighborhood level (individual transformer islanding), and at the level of a community center or fire station or other centrally located facility where citizens gather during power outage or other disasters. By calculating the necessary capacity and technical requirements of an adequate back-up system for each of the three proposed Solar Safety Net applications, it is hoped that standard packages could be developed and then deployed throughout the nation as part of a nationwide nimble emergency response system.

The white paper will include schemata of what a “Solar Safety Net” what look like. Interestingly enough, the mere concept of a Solar Safety Net brought forth by this investigation has led to the development of the nations first prototype system to be installed this May at the Dance Palace in Point Reyes Station.

At present, grid-connected solar arrays like those scattered throughout downtown point Reyes Station go down too when the grid crashes, an occurrence that is likely to be more frequent as climate change and security threats grow over time. Given recent power outages, there is growing interest in the concept of a “Solar Safety Net,” a concept that is being developed by the Solar Economy Institute of Mill Valley and has become a class project for students of the Presidio School of Management.

“Solar has always made sense to me,” proclaims Jerry Lunsford, the community center’s technical director, and a long-time environmentalist who lives in a solar-powered off-the-grid home just outside Point Reyes Station. “Self reliance should be the goal here and being responsible for our own electrical generation is a large part of the puzzle when it comes to responding to pollution and global climate change,” he said.

“We are very vulnerable in the rural areas of West Marin,” said Lunsford. “Our electrical infrastructure is vulnerable to many possible failures. In the event of a catastrophic winter storm or earthquake, the Dance Palace could be without the basic needs of power, light and heat for many hours or days. Since this is a disaster relief site, this is far from the ideal situation. Having a small battery based backup system will allow us to meet the basic survival needs of our neighbors and the community for an extended period of time,” he said.

Lunsford ‘s approach to developing what is apparently the nation’s prototype “Solar Safety Net” is to divide the 10 kW system into a hybrid system featuring one 6 kW array connected to a grid-tied inverter (which converts the Direct Current electricity from the solar PV panel into the Alternating Current needed to feed into the grid) and a second 4 kW solar PV array that is tied to a second separate inverter that is then backed up by batteries. The design allows the back-up batteries to power just the most essential services – such as refrigeration and key lights -- at the community center for up to perhaps one week if the power is out.

Lunsford has been boosting the reducing energy consumption at the Dance Palace for years, and part of the current overhaul of the Dance Palace’s energy supply infrastructure includes new electric on-demand hot water systems. “The Dance Palace is trying to lead the way, showing our West Marin that energy self reliance is possible at the community and individual level. I foresee a day when all community organizations generate enough electricity locally to sustain local operations. It's all part of a more holistic picture, a community that acknowledges its ecological footprint,” he added.

The installation of the entire system is scheduled for the weekend of May 16th, 17th and 18th. A public workshop, to be presented by the Solar Living Institute of Hopland, California, is currently seeking twenty residents of West Marin to participate and learn some solar basics. If the workshop is not filled with locals by April 14th, the workshop will be opened up to residents outside this region. Please contact or call (415) 663-1075 for more information.

This solar project benefited from a $25,000 grant from the County of Marin. County Supervisor Steve Kinsey announced the grant in the spring of 2007 (and implied similar grants may be forthcoming for other community center solar projects throughout Marin County). The Dance Palace also benefited from another unsolicited matching grant from Stinson Beach philanthropist Marion Weber of $10,000. Thanks to the California Solar Initiative, which is investing $3 billion of ratepayer funds over a decade to add 3,000 Megawatts (MW) of solar PV to the state’s power grid, an expected rebate from the state will help cover perhaps 30 percent of the equipment capital costs. Solar Depot, a large solar panel distributor with roots in West Marin, has also offered discounted equipment prices. Most of the labor will be provided by volunteers.

Please send your ideas about technical and regulatory issues pertaining to “Community Solar” and the “Solar Safety Net” to


©2016 Peter Asmus. Photo credit: David Clites. Website by: