A commercial battery may make sense when it can store useful surplus solar and replace expensive grid electricity later, reduce suitable demand peaks, or provide backup value. I do not recommend a battery simply because the customer asks for one or an incentive exists.
Start with the problem the battery must solve
A battery stores energy; it does not create it. Before sizing storage, I want to know what energy will charge the battery and what costly electricity the battery is expected to replace.
Patterns that make me investigate a battery
- Large or consistent solar exports during the day
- Significant grid imports later in the afternoon or evening
- High peak electricity rates
- Demand charges that match a battery's ability to reduce peaks
- Low value for exported solar
- Important backup requirements
- A suitable current incentive that improves the economics
When I may not recommend one
A battery may provide weak value where the business already uses almost all solar onsite, has little later electricity demand, cannot cycle the battery enough, or would need a large battery without enough energy to charge it.
A rebate can reduce cost, but it does not turn a poor usage pattern into a good one.
Battery sizing is as important as battery selection
An oversized battery can sit partly empty or unused. An undersized battery may miss useful savings. I compare available surplus energy, later demand, usable battery capacity, charge/discharge power, efficiency, degradation, seasonality and future needs.
Demand charges need real data
For businesses with demand charges, I do not want to make a strong savings claim from a standard bill alone. Interval data can show when the peaks occur and whether the battery has enough power and energy available to reduce them consistently.
Backup and financial savings are different objectives
If the business needs backup, part of the battery may need to remain reserved for outages. That can reduce how much capacity is available for everyday bill savings. The proposal should make that trade-off clear.
Solar first, battery first, or both?
If the business still buys a lot of electricity during solar hours, additional solar may provide better value than storage. If the site already exports plenty of solar and then buys expensive power later, storage may be the logical next comparison.
Same solar system, different battery answer
Business A has 50 kW of solar, exports heavily around midday, and continues operating into the evening at a high peak rate. Storage is worth modelling.
Business B also has 50 kW of solar but uses nearly all generation onsite and closes at 4pm. A battery may have little energy to store and little later load to serve. The same equipment does not produce the same recommendation.
The decision I want to answer
What financial or practical problem will the battery solve, and is that benefit worth its cost? Until that question can be answered with reasonable evidence, I would not treat the battery as a recommendation.
Solar and battery performance and savings are estimates that depend on the individual site, electricity use, tariffs, equipment, installation and assumptions used. Current incentives and network requirements should be checked for the specific project before a proposal is finalised.
Want to look at your actual situation?
You do not need to know the system size first. Start with your electricity use, existing system and what you want to achieve.