The National Renewable Energy Laboratory (NREL) ]released its annual cost breakdown of installed solar photovoltaic and battery storage systems.

U.S. Solar Photovoltaic System and Energy Storage Cost Benchmark: Q1 2021 details installed costs for PV systems as of the first quarter of 2021. The link above will download the full report as a .pdf.

The report said that costs continue to fall for residential, commercial rooftop, and utility-scale PV systems by 3%, 11%, and 12%, respectively, compared to last year.

Some typical content:

As demonstrated in Figure 13, the kit for a 5-kW/12.5-kWh storage system costs approximately
$6,406–$6,662 with a total installed cost of $15,852 (DC-coupled) to $16,715 (AC-coupled).12
Also, Figure 14 (page 24) shows the cost of residential storage systems for different system

NREL 1Q 2021 residential example

Worth downloading this report if you are interested in costs.