UK Study Debunks Efficiency of Rooftop Solar Battery Backup Power

Published July 11, 2018

A new study from Great Britain refutes claims backup battery storage systems can cost-effectively offset the intermittency of residential rooftop solar power.

In assessing the cost-effectiveness of backup battery systems for rooftop solar panel arrays, the study concludes “such an installation is unlikely to provide any financial benefit.”

“Battery Wastage: Why Battery Storage for Rooftop Solar Doesn’t Pay,” was written by Capell Aris, a fellow at the Institute for Engineering and Technology in the UK, and published by the London-based Global Warming Policy Foundation.

The research is specific to conditions prevailing in Britain, though its conclusions have implications for rooftop panel arrays in other locations around the world.

Location, Climate Limiting Factors

Aris analyzed three types of electricity and battery scenarios to determine the benefits of battery storage: a household drawing all of its electricity from the grid; a household with a rooftop panel array, sourcing electrical energy from both the grid and solar panels; and a household with a rooftop panel array with a battery packet or system as a backup.

The study found most of the UK is too far north for the nation’s 32 million households to replace their current sources of electricity with solar power, regardless of storage possibilities. This is particularly true for winter, when there is little sunlight and heavy cloud cover. Nor could large solar installations with battery storage provide significant electric power to the grid, for the same reason, the study found.

“The low level of winter solar generation means there is little possibility that a battery store of realistic size can affect grid energy import in this period [winter],” writes Aris.

Battery Storage Costs

Even for homeowners who install solar panels, using a battery pack to provide power at night or when the sunlight isn’t sufficient to power one’s home is much more expensive than simply using electricity from the existing power grid.

“Given the high costs of these [battery] stores, the stored energy cost exceeds present retail electricity costs,” writes Aris.

These costs are even higher when one considers even with a warranty, which typically lasts five or ten years, the productive life of a battery storage system is less than for the solar array it is backing up, and far less than the commercial life of the power sources providing electricity for the electric power grid, meaning the expensive battery system will have to be replaced, adding to the overall costs of the electric power to the homeowner.

Inherent Inefficiencies

Jay Lehr, science director at The Heartland Institute, which publishes Environment & Climate News, says the fact that solar power has limited usefulness in any society with a modern, interconnected electric grid will not stop those benefitting from government support from touting it.

“People in the United States and in other industrialized countries do not need solar energy except in the rare instance where a person lives off the grid, which few of us do,” said Lehr. “However, as long as the public is charged with supporting rooftop solar with mandates and subsidies, the producers of this so-called renewable energy will try to show it can be effective through some kind of add-on like battery storage.

“Once it is recognized lithium ion batteries are not an economic answer or panacea solution to the problem of solar unreliability, other ‘miracle’ backup gimmicks will follow,” Lehr said.

‘Intermittent Power Production’

James Taylor, president of the Spark of Freedom Foundation, says the inherently intermittent nature of solar power means battery technology will have to improve substantially before solar can replace traditional electric power sources.

“Unless there are breakthroughs in battery storage technology, solar power will always be hampered by intermittent power production,” said Taylor. “Without efficient, reliable battery storage, solar power will never be able to replace conventional power production, and will merely supplement it.

“At the utility scale, the intermittency and unpredictability of wind and solar power require producers to keep backup conventional power plants cycling even when conventional power is not needed, adding unnecessary extra costs to the system,” Taylor said. “Storage inefficiencies will continue to present a serious problem for large, utility-scale solar and wind power.”

Bonner R. Cohen, Ph.D. ([email protected]) is a senior fellow at the National Center for Public Policy Research.


Capell Aris, “Battery Wastage: Why Battery Storage for Rooftop Solar Doesn’t Pay,” The Global Warming Policy Foundation, April 30, 2018: