Community & shared solar
Check your target subscription against typical percentage-of-usage caps and flat kWh ceilings before you try to enroll above the limit.
How it works
Step 1
Most percentage-based caps use your trailing 12-month usage, so pull this from your utility account rather than estimating. If you haven't sized your subscription yet, start with the subscription size calculator.
Step 2
Programs often apply a percentage cap and a flat kWh ceiling at the same time, and whichever is more restrictive is the one that applies. This tool checks both automatically and shows which one binds. If your household is on the larger side, compare against the project size vs subscriber count tool too.
A percentage-of-usage cap ties your subscription size to your actual usage, preventing over-subscription relative to what you consume. A flat kWh ceiling exists separately to prevent any single account, even a very high-usage one, from claiming a disproportionate share of a limited shared array. Most standard residential programs apply whichever limit is more restrictive. If you want the source document behind this, the DSIRE database has it.
If your target subscription size comes back above the applicable maximum, you'll need to reduce your subscription to fit within the limit, which means accepting a smaller offset percentage than originally planned. Run the subscription size calculator again with a lower offset target, then check your savings with a smaller offset using the 50% offset calculator if a partial subscription still makes sense. A rooftop system faces its own physical ceiling too, covered by the maximum roof capacity calculator.
If you're planning a usage increase from an EV or heat pump, keep in mind that most caps are based on your current historical usage rather than a future projection. You may need to wait until the new equipment is installed and usage has increased before subscribing at the higher level, or ask your provider whether they make an exception for documented planned growth. The Department of Energy's community solar basics guide notes this kind of cap policy varies significantly by program, so it's worth asking directly rather than assuming a standard rule applies.
Small business and commercial programs typically allow a higher percentage cap, often around 200% of usage, and a much higher flat ceiling, reflecting the more variable and generally larger usage patterns of business accounts. If you're subscribing on behalf of a business, use the small business program type for a more accurate check, or see the project size vs subscriber count tool for how larger accounts fit into a shared array's total capacity. A grid interconnection limit can also cap what a large array can support, covered by the grid export cap calculator. Check the DSIRE database for your state's specific cap rules, since some states set these limits by statute rather than leaving them to individual providers.
Questions
Most states cap standard residential subscriptions at around 100% to 120% of a subscriber's historical annual usage, to prevent one household from claiming an outsized share of a shared array. Programs often set a flat kWh ceiling as well, commonly around 25,000 kWh a year for residential accounts.
Regulators cap subscription size relative to usage so that community solar credits function as a bill offset rather than a way to profit from reselling excess credits. This keeps the program focused on its purpose of helping subscribers reduce their own electric costs.
Some providers allow subscribing slightly above current usage in anticipation of a known future increase, though this is subject to the same percentage cap. Ask your provider directly whether they accommodate planned usage growth, or plan to increase your subscription size once the new equipment is installed.
Yes, small business and commercial programs typically allow a higher percentage cap and a much higher flat ceiling than residential programs, reflecting the larger and more variable usage patterns of business accounts. Check with your provider for the exact commercial program limits.