Thinking About a Solar Battery? Bigger Might Be Smarter
With the federal battery rebate officially launching in July 2025, many households are now asking: What size battery should I get? While your first instinct might be to go small and save money, here’s the surprising truth — bigger batteries often cost less per kWh once the rebate is applied.
In this blog, we’ll break down how the rebate works, why larger batteries offer better value, and what size might be right for your home.
How the Federal Battery Rebate Works
The federal battery rebate launching in July 2025 is designed to lower the upfront cost of home battery systems. But instead of offering a flat percentage discount, the rebate is calculated based on the usable capacity of the battery in kilowatt-hours (kWh). This means the larger the battery (in kWh), the bigger the total rebate you receive.
For example:
| Battery Size | System Cost (Before Rebate) | Rebate (est. $400/kWh) | Net Cost (After Rebate) | Cost per kWh (After Rebate) |
|---|---|---|---|---|
| 5 kWh | $6,000 | $2,000 | $4,000 | $800/kWh |
| 10 kWh | $10,000 | $4,000 | $6,000 | $600/kWh |
| 15 kWh | $13,500 | $6,000 | $7,500 | $500/kWh |
You can calculate battery rebate for different system size with our Federal battery rebate calculator.
Larger Batteries = Lower Installation Costs Per kWh
When you install a bigger battery, your inverter, wiring, and installation costs don’t scale up at the same rate. In fact, many of these costs are fixed or only slightly increase with a larger system. And with modern stackable battery designs, like those offered by Redx like RX-7000Plus , you can add capacity in modular blocks. This makes it even easier and cheaper to install more storage, without needing additional cabling, control systems, or labour.
So not only are you getting more rebate dollars, you’re also getting more value per dollar spent—which makes larger batteries a smarter financial choice.
Why Bigger Batteries Make Sense for Many Homes
1. More Value for the Rebate
Since the rebate scales with battery size, you’re getting more government support when you install a larger system. It’s like getting a bulk discount — with help from the government.
2. Better Coverage for Your Energy Needs
A 5 kWh battery might only cover 3–4 hours of evening usage. A 10–15 kWh battery can power your home longer, especially if you have high evening loads or use heating/cooling at night.
3. More Room to Grow
If you plan to get an EV in the next few years or expand your solar system, a bigger battery gives you flexibility. It’s harder (and sometimes more expensive) to upgrade later.
4. Improved Backup Capability
During blackouts, a small battery might run out quickly. A larger battery offers more peace of mind — keeping lights, fridges, or medical devices running longer.
What Battery Size Is Right for You?
It depends on your household’s daily usage, roof size, and solar system. But here’s a simple guideline:
5–10 kWh: Small homes, light evening use
15 kWh: Medium-sized homes with average usage
20+ kWh: Large homes, heavy loads, or EV charging
If budget allows, going bigger often gives better long-term returns — and with the rebate in place, now’s the time to go bold.
FAQ: Bigger Solar Batteries and the Federal Battery Rebate
Is there a minimum battery size to qualify for the rebate?
Yes. Your battery must have at least 5 kWh of usable capacity to be eligible.
Can I combine the federal rebate with a state incentive?
In many cases, yes. Check your state’s rules — some allow “stacking” of rebates, which can reduce your cost even further.
Is it better to get two small batteries or one large one?
One large battery is usually more efficient, cheaper to install, and takes up less space than two smaller ones.
Does a larger battery take longer to charge?
Yes, but with enough solar generation, most larger batteries can still be fully charged during daylight hours.
Will a bigger battery pay off faster?
In many cases, yes. The lower cost per kWh and improved energy coverage can speed up your return on investment.
