Up on the housetop: home solar energy going utility-scale

houses with home solar panelsEveryone knows the utilities hate home solar power. Not everything everyone knows is necessarily true.

It’s true that power companies feel threatened by rooftop solar. They’ll cooperate with it where they must. They’ll oppose it where they can.

Duke Energy, for example, resists solar installations for its North Carolina customers. North Carolina law does not favor home solar.

In neighboring South Carolina, Gov. Nikki Haley signed the Distributed Energy Resource Program Act in 2014. Duke Energy promptly announced a solar rebate program.  It helps its South Carolina customers offset the high upfront costs of installing home solar. [The link to the press release no longer works as of January 2017.]

The state of New York has likewise inspired a major utility to cooperate with distributed energy. Its experiment has nationwide implications.

New York City’s virtual power plant

home solar panels on rooftopIn New York State, Gov. Andrew Cuomo has laid out Reforming the Energy Vision to promote renewable energy.

The plan calls for deeper penetration of solar and other renewable technologies. Meeting that goal depends on wider use of “distributed energy.”

As a result, ConEd has announced a partnership with two solar companies, SunPower and Sunverge, to create what it calls a “virtual power plant.”

The three companies are launching a pilot program that will involve more than 300 homeowners in Brooklyn and Queens. These customers have already leased solar panels from SunPower. They will receive and lease a battery backup system.

Usually, rooftop solar systems operate independently of each other. The three companies will integrate all these rooftops into a single grid-tied system.

In other words, the project does not involve 300 separate solar installations. It amounts to a utility-scale solar installation on 300 rooftops. The companies will control the resulting two-way flow of electricity with cloud-based technology.

The panels will have a total generating capacity of 1.8 MW. The batteries will combine for an aggregate energy output of 4 MWh.

Peak demand for air conditioners occurs during the day when the sun is shining. Peak demand for lighting and all the gadgets people use at home occurs in the evening.

Utilities can already use solar power for the daytime peak.  The evening peak requires them to start and stop expensive peaking plants. This type of plant runs on fossil fuels much less efficiently than baseline plants. Therefore it costs more to operate and maintain it.

The combination of all those batteries will provide ConEd with stored solar power. It will reduce the need for the fossil fuel peaking plants. The pilot program itself won’t be big enough to shut down the peaking plants. A permanent city-wide program should eliminate the need for them entirely.

In addition, the battery storage can power at least some of the homes’ appliances if the power fails. Customers will have to pay a premium fee for the right to use the electricity stored in their batteries, though. Not every homeowner, therefore, will find it financially worthwhile to participate in the pilot.

Nationwide implications

If the pilot succeeds, it will have obvious benefits for home solar power in states with laws favorable to distributed energy. Utilities will be able to stop fighting it. So more states will embrace it. Society will gain the advantages of renewable energy without threatening utilities’ profitability.

This news coincides with rapidly falling prices for solar power. Academic and corporate researchers are improving technologies both for solar panels and storage batteries. Therefore when the regulatory climate also improves, more homes will be able to take advantage of solar power.

Nation’s largest residential solar storage project to launch this summer / Lorraine Chow. EcoWatch. June 17, 2016.
Battery storage for solar systems offered to hundreds; do you qualify? / Tracey Porpora. SILive, June 13, 2016.
REV demonstration project outline: clean virtual power plant / conEdison, July 1, 2015.

Photo credits:
Houses with solar panels. © Copyright Christine Westerback and licensed for reuse under this Creative Commons License.
Single house with solar panels. Pubic domain from Wikimedia Commons.

Leave a Reply

Your email address will not be published.