Battery Value When Paired With Solar
Solar without storage exports excess daytime production to the grid, often at a lower credit rate than what you pay to buy power back at night. A battery captures that excess for your own use instead, and this tool evaluates whether the battery's cost is worth that captured value.
At your inputs, the battery, added to your solar system has an NPV of -$6,911 over 10 years, with a discounted payback of no discounted payback within this horizon.
| Net cost after confirmed incentives | $10,000 |
|---|---|
| Annual savings | $400 |
| Net present value | -$6,911 |
Breakeven: No discounted payback occurs within the selected horizon.
- This uses planning estimates you entered, not a contractor quote or guaranteed savings.
- A positive NPV does not guarantee the actual outcome; it reflects your entered assumptions discounted at your chosen rate.
What this also tells you: A positive NPV means the option is worth more than its cost even after discounting future savings back to today; a negative NPV means the upfront cost outweighs what the savings are worth today.
This is a planning estimate based on your entries. It does not size equipment, determine electrical or building-code compliance, verify incentive eligibility, or replace a contractor quote or professional energy audit.
Why this decision comes up
A solar owner deciding whether to add a battery needs to know whether the captured value of otherwise-exported production is worth the battery's cost, a genuinely different economic case than a standalone battery purchase.
How this is calculated
This discounts the annual value difference (solar-plus-battery versus solar-alone) back to today's dollars over your ownership horizon, netted against the battery's cost, to produce an NPV and discounted payback.
A worked example
With the defaults ($10,000 battery net cost, $900/year with solar alone dropping to $500/year with battery added, 10-year horizon, 5% discount rate), the annual savings is $400 and the NPV comes out negative at about $6,911, meaning at these defaults the captured export value alone does not clear the battery's cost. A lower export compensation rate or a confirmed incentive would improve this materially.
Common mistakes
A common mistake is assuming a battery's value with solar is automatically strong just because it "uses" otherwise-wasted production. If your export compensation is already close to retail rate, there may be little captured value left for a battery to add.
Limitations
This does not include outage protection value, which a battery paired with solar can also provide. See the outage cost avoided tool to add that separately.
Common questions
Why does export compensation matter here?
If your utility credits exported solar generously (close to your retail rate), a battery has less to gain from storing it instead. If export compensation is low, a battery captures much more relative value. See the solar-cluster export-credit tool for that specific comparison.
Does this assume net metering or a different compensation structure?
This tool uses your own entered annual cost figures, so it works regardless of your specific compensation structure, as long as your inputs reflect it accurately.
How does this compare to the standalone battery value tool?
That tool evaluates a battery without solar, relying only on rate arbitrage from the grid. This one assumes you already have or are installing solar, which usually improves a battery's economics.
Does this work if I'm installing solar and battery at the same time?
Yes, enter the annual cost difference between a solar-only and solar-plus-battery scenario regardless of whether you are installing both together or adding the battery afterward.
Does a confirmed incentive apply the same way here as in the standalone tool?
Yes, subtract any confirmed incentive from the battery's net cost before entering it, the same rule used throughout this cluster.