Combining solar power and energy storage is part of the business of many companies like Tesla and Sunrun. By 2021, behind-the-meter storage applications will represent 50% of the U.S. storage market, according to a report from the National Renewable Energy Laboratory.
Although the use of storage applications is growing, there is no easy way for customers to evaluate their investment, unlike using the $/watt when evaluating a solar panel investment. The aim of the NREL report is to provide a useful metric that could in a long run help drive forward the solar power + energy storage combination. In which situations pairing the two technologies will make sense is yet to be determined.
One of the reasons the valuation of batteries is complicated is because they have different applications and can be paired with solar panels in not one or two varied occasions. These different uses lead to different measures when customers want to assess their investment. Having this in mind the authors of the NREL report used “total installed price of a standard solar and storage system as their primary metric”. The results of the report were presented as two cases: one for a small battery installation designed primarily for load shifting with limited back-up power, and the other for a large battery installation designed for load shifting and a greater back-up power. For now the price of adding storage is twice as high as the price of a solar installation alone, but over time, costs are expected to come down and this segment could become one of the fastest growing within the Energy Storage market.