Solar panels with a battery: when does it really pay off?

The biggest economic call in the solar transition: battery or no battery? Here's a data-based, no-marketing decision sheet.

When a battery IS worth it

• You have frequent blackouts (>5/year) and can't have the fridge/router down
• Your consumption is mostly nighttime (>60%) — shift work, night AC, etc.
• Your utility's export rate is tiny (<5¢/kWh)
• You live in a remote or weak-grid area (storms, wind cuts)
• You have an EV usable as V2H backup

When a battery is NOT worth it

• You have 1:1 or near-parity net metering (still strong in NJ, MA, CA NEM 2.0 holdouts)
• Your consumption is 70%+ daytime (home office, pool, day AC)
• Stable grid, no blackouts
• Tight budget: the battery nearly doubles the kit price
• You want payback under 6 years (battery stretches it to 9-10 years)

The simple math

Subtract: peak rate - off-peak rate - export credit received = extra savings per kWh stored. Multiply by yearly stored kWh (1,500-3,000 typical residential). Compare to amortised battery cost (10-12% of cost per year). If savings > cost, it pays.

The most common trap

Salespeople promising 'full independence' with tiny 5-7 kWh batteries. For real autonomy you need 15-25 kWh, adding $9,000-17,000 to the kit. Net metering is the best 'battery' while favourable regulation lasts.

Also read solar without a battery and what to do with surplus solar. If you decide for storage, size it in what battery do I need.