Understanding battery-based demand charge reduction
How battery peak shaving compares to solar alone
More reliably, since a battery can discharge at exactly the moment of the peak regardless of the time of day. A business with a 220 kW peak and a $18.50/kW demand rate paying $4,070 a month could use a 100 kW battery to shave the peak down to 120 kW, cutting the charge to $2,220 a month, a 45.5% reduction and about $22,200 in annual savings. That's a notably better result than the demand charge reduction estimator shows for solar alone on the same peak, because timing risk is removed entirely, a comparison also worth running through the solar savings calculator by utility rate for the usage-charge side of the same bill. Once you have a size in mind, the quick financing comparison tool in our Financing section can help you compare loan, lease, and cash purchase options for the system you just sized.
Why battery shaving is more predictable
A battery's discharge power rating sets a hard, predictable ceiling on how much it can shave off any single peak event, independent of weather or time of day. Solar's demand offset varies month to month depending on whether the peak happens to align with sun hours, while a well-controlled battery system delivers close to the same reduction every billing cycle. That consistency is often worth more to a facilities manager than a slightly higher but variable solar-only offset, and it's part of why the time-of-use savings calculator treats battery dispatch separately from solar production timing. Sandia National Laboratories hosts the DOE's peer-reviewed Energy Storage Handbook, which covers the discharge power rating and duty-cycle concepts behind that predictability in more technical detail.
Sizing a battery to fully eliminate the charge
In theory, a battery with a discharge power rating equal to or greater than your peak demand could flatten it to near zero, though that's rarely cost-effective given battery pricing. Most commercial battery systems are sized to shave 30% to 60% of peak demand, which captures the bulk of the savings without paying for capacity that only helps during the single highest peak of the month. Run a few different battery sizes through the battery demand charge payback calculator to find the size where the marginal cost stops being worth the marginal savings, and the battery storage size calculator in our battery storage section for the underlying capacity math from a residential and small-scale angle.
Does the battery need solar to work
No, a standalone battery system can perform peak shaving on its own by charging during low-demand periods and discharging during the peak. Pairing it with solar adds usage-charge savings on top of the demand-charge savings, which is why solar-plus-storage is common, but the demand-shaving function works independently of whether solar is present. Check the commercial demand charge calculator to see how much of your bill is demand versus usage before deciding which combination makes sense. The Department of Energy's end-use load profile data is a useful reference if you want to sanity-check typical commercial load patterns against your own utility bills either way.