Op-ed: ‘Virtual net metering’ is key to ‘shared solar on homes’

Regarding Mirror story, “Could the ‘Shared Solar’ movement work in shady Connecticut?” April 14, 2014:

Eugene DeJoannis

Eugene DeJoannis

I hope any law that does pass [about shared solar energy] includes direction to PURA [Public Utilities Regulatory Authority] to do a study of what the true value of solar power is to society, so we can set this matter to rest. Other states have done this and valued it near or above retail power rates.

I don’t agree with Paul Spencer [president of solar developer Clean Energy Collective] that the economics of shared-solar-on-homes do not work with neighbors sharing the output from a single PV array on one of their roofs. If the economics work for a single user on an individual home (and clearly 5,000 CT homeowners think they do work), the economics would be even better if the PV array covered the entire roof instead of just enough for a single homeowner. It’s a matter of the economy of scale: An installer can install a single larger system much more quickly than two smaller systems, and not much longer than for a single smaller system on a roof with good solar access.

I can imagine a financing system developed by CEFIA, the state agency that disperses the Clean Energy Fund’s incentive payments for solar systems, where they own the system on a single home, but sell shares of the output to the homeowner to meet their needs and also to a neighbor who doesn’t have a sunny roof. CEFIA could leverage their incentive funding to install larger systems on every home they pay an incentive to, and the homeowners who buy shares provide most of the financing. A big advantage to this model is that as the needs of homeowners change, they could buy or sell some capacity from CEFIA’s bank of excess capacity.

To do this we need a utility accounting system called “virtual net metering” so that the neighbor who owns a share of the host home’s solar power is credited with their share on their monthly bill. No new equipment is needed; the utility already measures how much power is being imported or exported by the solar system to their grid. They just need an accounting system to assign a percentage of the output to the neighbor who invested in the system. The host homeowner gets the advantage of full roof coverage, which not only looks more uniform, but keeps the entire roof cooler and extends its life.

The system would allow investors to vary the size of their virtual systems as their family needs change, children move out or go away to college, etc. The CT solar industry would be more efficient by installing full-roof solar arrays on every job, and consumers would benefit from lower prices (typically buyers pay a premium for systems smaller than 3 kW, because the setup for the roof work is just as costly for the installer as for a large system). So larger systems on every home would increase the economy of scale, and maximize the solar capacity on the 20 percent of CT homes that have suitable roofs for solar.

We should stop wasting the scarce and valuable roof-space resource by installing full capacity systems on every good roof and sharing the cost and the output with those who are not able to have solar where they live. This seems to me to be much simpler than the large community solar model that requires a developer to find a large site for the solar array, get rights to build on it, and then find 30 or 40 investors to buy shares of the output.

Shared-solar-on-homes is simpler and involves fewer parties than large community solar, and would be more efficient for all parties involved. All we need is a “virtual net metering” law like Massachusetts has.

Eugene DeJoannis, as reported in an April 14 Mirror story, is unable to install solar panels on the roof of his Manchester home because a neighbor’s trees block the sun.