Community Solar Savings Calculator
Calculate your savings from a community solar subscription. Compare your utility rate to the community solar rate and estimate annual bill reductions.
Solar + Battery Savings Calculator
Estimate additional savings from pairing solar panels with battery storage. Calculate self-consumption gains and peak rate arbitrage value.
kWh/day
kWh/day
$/kWh
$/kWh
$/kWh
$
kWh
%/yr
Self-Consumption Savings⧉
$584.00
Annual from stored solar
Peak Arbitrage Savings⧉
$730.00
TOU rate shifting gains
Total Annual Savings⧉
$1,314.00
$110.00/month · $3.60/day
Payback Period⧉
9.1 years
Within typical warranty
Cycles per Day⧉
1.33
Heavy cycling — check warranty
15-Year ROI⧉
43.1%
10-yr net: $18.00
Annual Savings with Degradation
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Year-by-Year Breakdown
| Year | Annual Savings | Effective Capacity | Cumulative Net |
|---|---|---|---|
| 1 | $1,314.00 | 13.5 kWh | -$10,686.00 |
| 2 | $1,288.00 | 13.2 kWh | -$9,398.00 |
| 3 | $1,262.00 | 13.0 kWh | -$8,136.00 |
| 4 | $1,237.00 | 12.7 kWh | -$6,900.00 |
| 5 | $1,212.00 | 12.5 kWh | -$5,688.00 |
| 6 | $1,188.00 | 12.2 kWh | -$4,500.00 |
| 7 | $1,164.00 | 12.0 kWh | -$3,336.00 |
| 8 | $1,141.00 | 11.7 kWh | -$2,195.00 |
| 9 | $1,118.00 | 11.5 kWh | -$1,077.00 |
| 10 | $1,096.00 | 11.3 kWh | $18.00 |
| 11 | $1,074.00 | 11.0 kWh | $1,092.00 |
| 12 | $1,052.00 | 10.8 kWh | $2,144.00 |
| 13 | $1,031.00 | 10.6 kWh | $3,175.00 |
| 14 | $1,010.00 | 10.4 kWh | $4,186.00 |
| 15 | $990.00 | 10.2 kWh | $5,176.00 |
Popular Battery Comparison
| Battery | Capacity | Power | Warranty | Est. Cost |
|---|---|---|---|---|
| Tesla Powerwall 3 | 13.5 kWh | 11.5 kW | 10 yr | $9,200–$12,500 |
| Enphase IQ 10T | 10.08 kWh | 5.0 kW | 15 yr | $8,000–$11,000 |
| Franklin WH | 13.6 kWh | 10.0 kW | 12 yr | $9,500–$13,000 |
| LG RESU Prime | 9.6 kWh | 5.0 kW | 10 yr | $7,000–$9,500 |
Planning notes, formulas, and examples
About the Solar + Battery Savings Calculator
Adding battery storage to a solar system unlocks additional savings in two key ways: increased self-consumption and peak rate arbitrage. Without a battery, excess daytime solar goes to the grid at potentially low credit rates. With a battery, you store that energy and use it at night when rates may be higher.
Self-consumption savings come from using your own stored solar instead of buying grid power at retail rates. Peak rate arbitrage (also called peak shaving) works when your utility has time-of-use pricing — you charge the battery during cheap off-peak hours or with solar, then discharge during expensive peak hours.
This calculator estimates both savings streams: the value of self-consuming solar that would otherwise be exported at a lower rate, and the value of shifting energy from peak to off-peak rates. Together, these determine whether adding a battery is financially worth the additional cost.
By calculating this metric accurately, energy analysts gain actionable insights that inform equipment selection, system design, and operational strategies for maximum efficiency and savings.
When This Page Helps
Batteries add $8,000–$15,000 to your solar system cost. This calculator helps you determine whether the additional savings justify that expense, and how long it takes for the battery to pay for itself.
How to Use the Inputs
- Enter daily kWh of solar energy you can self-consume from battery instead of exporting.
- Enter your retail electricity rate.
- Enter the daily kWh you can shift from peak to off-peak hours.
- Enter peak and off-peak electricity rates.
- Review your combined annual savings from self-consumption and peak arbitrage.
Formula used
Self-Consumption Savings = kWh Self-Consumed × Retail Rate × 365
Peak Arbitrage Savings = kWh Shifted × (Peak Rate − Off-Peak Rate) × 365
Total Annual Savings = Self-Consumption + Peak ArbitrageExample Calculation
Result: $803/year
Self-consuming 8 kWh/day at $0.15 saves $438/year. Shifting 5 kWh from peak ($0.30) to off-peak ($0.10) saves $365/year. Total battery savings: $803/year. Against a $10,000 battery cost, payback is about 12.5 years.
Tips & Best Practices
- Battery savings are highest with time-of-use rates where peak/off-peak spreads exceed $0.15/kWh.
- In areas with flat rates and full retail net metering, battery savings are minimal.
- The federal ITC applies to batteries installed with solar, reducing effective cost by 30%.
- Battery capacity degrades over time; most lose 20–30% capacity over 10 years.
- Consider backup power value — batteries protect against outages, which has non-financial value.
- Size your battery to capture the most excess solar; a 10–13.5 kWh battery covers most households.
When Batteries Make Financial Sense
Batteries are most valuable when: (1) your utility has time-of-use rates with a large peak/off-peak spread, (2) net metering credits are well below retail rate, or (3) demand charges apply. In these scenarios, batteries can save $500–$1,500/year, achieving payback within the warranty period.
Beyond Dollar Savings
Backup power during outages has real value that's hard to quantify. A battery can keep critical loads running for 4–12 hours during a grid outage. For homeowners in areas with frequent outages, this resilience may be worth the investment even if pure financial returns are marginal.
The California Effect
California's NEM 3.0 made batteries nearly essential for new solar installations. With export credits as low as $0.04–$0.08/kWh versus retail rates of $0.30–$0.50/kWh, each self-consumed kWh saved with a battery is worth 4–8 times more than exporting it.
Sources & Methodology
Last updated:
Frequently Asked Questions
Annual battery savings range from $200 to $1,500 depending on your rate structure and self-consumption patterns. Homes with time-of-use rates and large peak/off-peak spreads save the most. Homes with flat rates and full net metering save the least.
Financially, batteries are worth it if annual savings exceed $700–$1,000 (for a $10,000 battery with 10+ year warranty). In California under NEM 3.0 or areas with TOU rates, they often pencil out. In flat-rate states with net metering, usually not.
Peak rate arbitrage means charging your battery when electricity is cheap (off-peak hours or from solar) and discharging during expensive peak hours. The savings equal the kWh shifted multiplied by the rate difference between peak and off-peak periods.
Without a battery, excess solar goes to the grid, often at a reduced credit rate. With a battery, you store that excess and use it at night at full retail value. The savings equal the difference between retail rate and export credit rate for each kWh stored.
Most home batteries are warranted for 10–15 years or a certain number of cycles. Tesla Powerwall and Enphase batteries typically retain 70–80% capacity at the end of warranty. Real-world longevity may exceed the warranty period.
Yes, batteries installed as part of a solar system or charged primarily from solar qualify for the 30% federal ITC. This reduces a $10,000 battery to $7,000 effective cost, significantly improving the payback calculation.
More in this topic
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Calculate how solar panel output declines over time due to degradation. Estimate year-by-year production and total lifetime energy output.