Every solar homeowner faces the same question: should you export excess solar to the grid (using net metering or a feed-in tariff) or store it in a battery for nighttime use? The answer depends entirely on your local export tariff, import rate, and daily usage pattern.
This guide provides a decision framework you can apply to any market, with real policy examples from the US, UK, Germany, Australia, India, and Pakistan.
Understanding the Policy Landscape
Different countries use different mechanisms for compensating solar exports:
| Policy Type | How It Works | Typical Export Rate | Example Markets |
|---|---|---|---|
| Net Metering (1:1) | Excess kWh offset against imported kWh at retail rate | Full retail rate | India (many states), Pakistan (limited), US (some states) |
| Net Billing | Excess kWh sold at a lower rate than retail import | 50-75% of retail | US (CA NEM 3.0, NY), Australia (varies by state) |
| Feed-In Tariff (FiT) | Fixed payment per kWh exported, independent of import rate | $0.03-0.12/kWh | Germany, UK (Smart Export), Japan |
| No Compensation | Excess solar energy is lost (zero export) | $0.00/kWh | Some off-grid applications, certain developing markets |
The Decision Framework
Here is a simple formula to determine whether battery storage is financially justified:
If Export Rate < Import Rate × 0.30 → Battery is clearly better
If Export Rate is between 0.30x and 0.70x of Import Rate → Mixed, depends on night usage
The 0.70 threshold accounts for the round-trip efficiency losses of a lithium battery (typically 10-15%) plus the amortized cost of the battery per kWh cycled. If the grid pays you more than 70% of what you pay to import, there is no financial reason to buy a battery.
Country-by-Country Analysis
| Market | Import Rate | Export Rate | Export/Import Ratio | Recommendation |
|---|---|---|---|---|
| California (NEM 3.0) | $0.32/kWh | $0.08/kWh (avg) | 25% | Battery strongly recommended |
| Texas (net metering) | $0.12/kWh | $0.10/kWh | 83% | Grid is best |
| UK (Octopus outgoing) | £0.28/kWh | £0.15/kWh | 54% | Mixed, evaluate night usage |
| Germany (FiT 2026) | €0.32/kWh | €0.08/kWh | 25% | Battery recommended |
| Australia (NSW FiT) | A$0.28/kWh | A$0.07/kWh | 25% | Battery recommended |
| India (Tamil Nadu net meter) | Rs. 7/kWh | Rs. 7/kWh | 100% | Grid is best |
| Pakistan (net metering) | Rs. 50/kWh | Rs. 25-30/kWh | 50-60% | Mixed, evaluate carefully |
| South Africa (no net meter) | R 2.56/kWh | R 0.00-0.80/kWh | 0-31% | Battery essential |
Calculating Monthly Savings with a Battery
Where Battery Loss kWh = Night kWh × (1 - RTE) and RTE is the round-trip efficiency (typically 0.90 for lithium).
Example (California NEM 3.0):
- Night usage: 10 kWh/day = 300 kWh/month
- Import rate: $0.32/kWh
- Battery RTE: 90% (lithium)
- Monthly loss: 300 × 0.10 = 30 kWh lost as heat
- Monthly savings = (300 × $0.32) - (30 × $0.32) = $96.00 - $9.60 = $86.40/month
Example (Germany FiT):
- Night usage: 8 kWh/day = 240 kWh/month
- Import rate: €0.32/kWh
- Export rate: €0.08/kWh (opportunity cost of not exporting)
- Net savings: 240 × (€0.32 - €0.08) = 240 × €0.24 = €57.60/month
- Plus loss: 240 × 0.10 × €0.32 = €7.68/month lost to heat
- Effective savings: €49.92/month
Battery Payback Period Analysis
| Market | Monthly Savings (Battery) | 10 kWh Battery Cost (Lithium) | Simple Payback |
|---|---|---|---|
| California (NEM 3.0) | $86.40 | $4,500-5,500 | 4.3-5.3 years |
| Germany (FiT) | €49.92 | €4,000-5,000 | 6.7-8.3 years |
| Australia (NSW FiT) | A$63.00 | A$5,000-6,000 | 6.6-7.9 years |
| UK (Octopus) | £39.00 | £3,500-4,500 | 7.5-9.6 years |
| Texas (net meter) | $5.00 | $4,500 | 75+ years (never) |
| India (net meter) | Rs. 0 | Rs. 150,000 | Never (export = import rate) |
Non-Financial Reasons for Batteries
Even in markets where batteries don't pencil out on energy savings alone, there are valid reasons to install them:
- Backup power during outages: Net metering gives you $0 when the grid is down. Batteries keep your lights on.
- Time-of-use (TOU) rate optimization: Some utilities charge peak rates 3-5x the off-peak rate. Batteries can shift solar energy to peak periods.
- Self-consumption maximization: In markets with corporate Solar REC or carbon credit programs, increasing self-consumption has additional value.
- Grid independence: Some homeowners value energy independence even at a slight financial premium.
Related Guides
- Solar Battery Size Calculator: Find Ah & kWh for Backup
- Battery Ah to kWh Conversion: Understand Your Spec Label
- Tubular vs Lithium Battery: 10-Year Cost Comparison
Compare grid export vs battery savings for your location
Open the Solar Calculator →Data sources: US EIA (2025 state-level rates), California NEM 3.0 tariff schedules (PG&E, SCE, SDG&E), UK Ofgem price cap (Apr 2026), German Bundesnetzagentur FiT rates (2026), Australian Energy Regulator (NSW, VIC, QLD), Indian state electricity board tariffs, Pakistan NEPRA (2025-26). Battery pricing based on Q2 2026 lithium LFP benchmarks. All calculations assume 90% RTE lithium battery. Payback periods exclude financing costs and degradation.
Last updated: July 2026 | Browse all guides