NREL Releases Landmark Residential Solar + Energy Storage Cost Breakdown

Originally published on CleanTechnica.

The US National Renewable Energy Laboratory has published a landmark report extensively detailing component and system-level cost breakdowns for residential PV solar systems equipped with energy storage.

The decreasing cost of solar systems has been well documented over the last several years, with increased innovation and decreasing manufacturing costs combining to make solar PV a competitive and economic choice for residents and utilities across the United States, and in fact the world. As such, the costs attributed to the development of residential and utility-scale solar projects has been well defined for some time — even though that figure keeps decreasing.

However, in the same way that technological innovation and manufacturing has helped to lower the costs of solar PV projects, the same catalysts have acted on energy storage technology. As a result, the attractiveness and economic viability of energy storage systems has increased dramatically over the last year or two, to the point where energy storage options are more and more frequently being considered to run in tandem with solar systems.

Researchers from the US Department of Energy (DOE) National Renewable Energy Laboratory (NREL) have therefore published what is currently the most detailed component- and system-level cost breakdowns for residential solar PV equipped with energy storage. The report, Installed Cost Benchmarks and Deployment Barriers for Residential Solar Photovoltaics with Energy Storage: Q1 2016, also serves to quantify the previously unknown or uncertain soft costs for combined solar PV and energy storage.

“There is rapidly growing interest in pairing distributed PV with storage, but there’s a lack of publicly available cost data and analysis,” said Kristen Ardani, lead author of the report and a solar technology markets and policy analyst at NREL. “By expanding NREL’s well-established component- and system-level cost modeling methodology for solar PV technologies to PV-plus-storage systems, this report is the first in a series of benchmark reports that will document progress in cost reductions for the emerging PV-plus-storage market over time.”

Putting aside for a moment the cost factors involved with energy storage options, their use with residential solar PV systems are invaluable, as they increase the viability and function of a solar system which is otherwise restricted to use only when the sun is shining. Energy storage allows for excess generated electricity to be stored onsite for use when the clouds come in, or the moon comes up.

Not only has energy storage become more appealing, but the falling costs of solar have opened the door for people to begin affording energy storage options with their solar PV systems. However, according to NREL, “gaps remain in developing an in-depth understanding of the costs of combined PV and battery systems and in effectively communicating their value proposition.”

This is where the new report steps in, by extensively detailing the costs and any barriers to adoption currently in play in the market. As can be seen below, the authors of the report separated installation costs into 13 categories that cover both hard and soft costs. The report’s findings are centered around two grid-tied system applications — a “small-battery case” and a “large-battery case.” Of particular interest is the small-battery case, which is made up of a 5.6 kW solar PV array combined with a 3-kW/6-kilowatt-hour (kWh) battery. Unsurprisingly, as the image shows below, the benchmarked price for the small-battery case is approximately twice as expensive as a standalone 5.6 kW PV system.

Modeled total installed cost and price components for residential PV-plus-storage systems, small-battery case (2016 U.S. dollars)

As can be seen, there are variances depending on whether the PV and battery system are installed at the same time, or added to an existing array, and whether you choose DC or AC — which itself has its own pros and cons.

The large-battery case is made up of a 5.6 kW solar PV array combined with a 5-kW/20-kWh lithium-ion battery system, and is much more expensive — though its intended use is to meet greater backup power and energy requirements in the event of a grid outage.

Modeled total installed cost and price components for residential PV-plus-storage systems, small-battery case (2016 U.S. dollars)

Reprinted with permission.

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  • EEF

    The graph at the end intended to show the large-battery case repeats the graph from the small-battery case.