SolarCity, Sungevity, Sunrun, Verengo and other leading US rooftop solar companies have joined forces to defend distributed generation incentives, it was announced on Friday.

The Alliance for Solar Choice (TASC) represents the majority of the US rooftop solar market and will focus initially on ensuring the continuation of net energy metering (NEM). NEM returns credit to solar customers for the energy they put back on the grid and is currently in place in 43 states.

Utilities are attempting to curb NEM as the costs of solar declines, making it increasingly competitive with retail rates in some states. California's NEM programme is capped at 5% aggregate consumer peak demand for systems up to 1MW in size. The state is at around 3% of this cap already, but utilities are concerned that demand will only increase as solar becomes cheaper to install. In 2011, the CPUC rejected a general rate case brought by San Diego Gas & Electric General, which sought to limit this "silent subsidy" which utilities say shift costs to their non-solar customers.

Sunrun co-Founder Edward Fenster, said: “Americans are choosing solar in record numbers to save money on electric bills. While this benefits the American consumer and the economy, monopoly utilities want to stop this progress to protect their own interests.”

SolarCity CEO, Lyndon Rive, said: “Without consumer choice and empowerment, the utilities will continue to increase their rates and profits. If Americans are denied the right to choose how they produce and consume electricity, monopoly utilities will continue to choose their profits over the interests of consumers.”

TASC members point to studies conducted in Arizona, California, Hawaii, Idaho, and Vermont that have found solar provides a net benefit to ratepayers and to state economies.

A study published this year by Crossborder Energy showed solar customers with net metering will deliver a financial benefit of more than $92 million annually to all California ratepayers. Over the next 30 years, California schools and public agencies are projected to save more than $2.5 billion on energy bills through net-metered solar systems, said the report.

Utility trade association Edison Electric Institute (EEI) recently reported that utilities view rooftop solar as a threat to their monopoly business model, which guarantees utilities high profits from large infrastructure projects funded by ratepayers.

TASC executive director Anne Smart will manage the organisation’s policy and public outreach efforts. Prior to TASC, Smart was the director of energy for the Silicon Valley Leadership Group, a public policy business trade organization.

The California Public Utilities Commission has contracted Energy and Environmental Economics (E3) to provide a cost-benefit analysis of NEM by October this year.