Exploring New Solar Models in Marin County

By Peter Asmus

Marin County, as well as other communities in the San Francisco Bay Area, the Central Valley and in the Los Angeles Area, are currently investigating “Community Choice Aggregation” (CCA), a legal term that refers to a new way for cities and counties to purchase electricity. Created by the passage of AB 117 by the California Legislature in 2002, local governments can now represent constituents-at-large by choosing their power supply portfolio.

Before this law was passed, the only way for a California local government to have a say in where its power (and those of the residents and businesses residing within its boundaries) came from was to become a municipal utility. The CCA process provides an easier way to change the content of the power supply – by a vote of each local government – without taking on the burden of managing the power lines, collecting bills, and the divisive politics involved with the typically highly contested (and expensive) municipalization process.  Interestingly enough, Massachusetts, Ohio, New Jersey and Rhode Island also allow some form of local government power purchase aggregation.

Under the proposed business plan for Marin County’s CCA, the goal is to obtain 100 percent of the supply from renewable energy sources. That equates to roughly 240 Megawatts (MW) of electricity load, largely residential in composition. Votes by each of the 11 cities residing within Marin County – and the County Board of Supervisors themselves – will occur sometime this fall. While a diverse portfolio of renewable energy supply is incorporated into the business plan for “Marin Clean Energy” – as the CCA program is now being called – studies show that the majority of this supply could be supplied by solar photovoltaics (PV) placed on existing rooftops. Due to the high cost of solar PV, Marin Clean Energy projects the majority of power will come from a 100 MW wind farm, most likely to be constructed in the Montezuma Hills region of Solano County. Less than 20 MW of solar PV is in the current planned portfolio, largely due to the high cost of solar PV.

One way to further lower the costs of solar PV – which adds reliability and national security benefits to the local power grid – is to design community-based programs that achieve economy of scale and reach markets that have yet to tap solar energy in a big way.

The Marin Community Foundation (MCF) provided a grant to investigate new models of solar development that might be made more possible under a CCA. This project opens an investigation into two new models of solar energy development: “Community Solar” and a “Solar Safety Net.” The resulting white paper to be published in June 2008 is designed to explore new models of solar energy development particularly suited to West Marin, a sparsely populated rural region isolated by topography. This effort is designed to fill gaps in the planning, structuring and financing of new models of solar energy development that are gaining community support throughout West Marin, but which are frustrated by existing state regulations that fail to account for recent advances in grid inter-tie technology.

A top priority of this project is to bring greater social equity to the solar market, while providing a forum and platform for activists, businesses, government and community organizers to address the obstacles and opportunities for community cooperation in development of new renewable resources under the proposed CCA for Marin County. In the event that the CCA does not move forward in 2008, this project will still provide useful information about how “Community Solar” and a “Solar Safety Net” might be structured under the status quo relationship with Pacific Gas & Electric (PG&E), the host investor-owned utility.

Community Solar

What is “community solar?” The term means different things to different people. One goal of the MCF project was 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 networking effort salvaged a $150,000 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 was also spurred on by this MCF project with a vote in March 2008.

When used in the context of this 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 from 10 to 50% 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 expects to add 16 MW of solar capacity annually over the coming years.

Solar Safety Net

Another goal of this MCF 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” would look like. Interestingly enough, the mere concept of a Solar Safety Net brought forth by this investigation has led to the development of the nation’s first prototype system to be installed this May at the Dance Palace in Point Reyes Station.

Key Advances Necessary for a Widely Dispersed Solar Safety Net

Advanced Inverters: SMA, a German company, has recently brought to market a new 5000 watt inverter called the “Sunny Island” that is capable of “AC coupling,” a service equivalent to “islanding.” This inverter is capable of safely switching from grid-connected to battery charged service because it can send an artificial signal that simulates an active grid, which is then detected by standard solar inverters, allowing them to operate during blackout conditions. This is an important advance. Typical “grid-tied” solar arrays are designed to automatically shut off during blackouts in order to avoid back-feeding power to the grid. These battery-chargers/islanding inverters can be chained together and then engage in intelligent communication between each other as well as solar inverters. When integrated to the computer-linked Sunny Web Box, these processes can be managed completely on-site without the need for action by the host utility or the California Independent System Operator.

Better Batteries: The Sunny Island inverter can charge current technology such as deep cycle lead batteries. If money is no object, these batteries can be scaled up into larger and larger stacks. A very promising technology for the near future appears to be lithium ion batteries. They are about one-tenth the weight of current battery technology and are far less toxic, but cost four to five times as much as a traditional battery. The technology needs to scale up, and the Chinese are leaders in this R&D, developing batteries capable of backing up 1 MW of electricity load. In contrast, the Tesla car that is being developed as a potential plug-in hybrid currently relies on 2,200 lithium laptop batteries.

Battery Isolation Technologies: The last piece of the puzzle when it comes to developing mass-scale Solar Safety Net systems relying upon “green” batteries is figuring out how to isolate each lithium ion battery cell. In current rigging arrangements, when one battery dies, it creates a “hot spot” in the battery array, causing it to fail. If the Solar Safety Net is to achieve its reliability goals with lithium ion batteries during emergency power outages, this dilemma – which appears to be the largest current technical obstacle – needs to be resolved. That said, current battery systems are a completely functional cost-effective solution that can be employed to implement first generation Solar Safety Net systems today.

The research outlined in this article is ongoing and comments, suggestions are welcomed for the final stage of analysis, which must be completed by June 1, 2008. This analysis and documentation of early-adopters is hoped to spur creative thinking in other regions of the state and country, where unique circumstances and different regulatory structures may foster diverging models. Please send your ideas about technical and regulatory issues pertaining to “Community Solar” and the “Solar Safety Net” to pthfind 'AT' earthlink.net.

Peter Asmus is President of Pathfinder Communications and has served as a consultant to the Local Government Commission, County of Marin, California Energy Commission and the California Air Resources Board. His forthcoming book on energy with the University of California Press is entitled Introduction to Energy in California. www.peterasmus.com.

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