Using Home Equity for Solar: How Much You Can Really Borrow

Using home equity, most Australians can borrow for solar panels and batteries up to around 70–80% of their property value (sometimes higher with LMI), minus their existing home loan, provided they pass serviceability tests and keep a cash buffer. The safe borrowing number is usually lower than the bank’s maximum once you factor in rising rates, living costs and realistic solar savings.

Here’s how to work out a decision‑ready figure this week.

Work out your safe borrowing limit for solar before signing any contracts.

1. Quick answer: a simple way to estimate your solar borrowing limit

Step 1 – Estimate usable equity
Property value × safe LVR (often 70–80%) − current home loan.

Step 2 – Check repayments pass your own stress test
Model loan repayments at an interest rate 3% higher than today and assume solar savings are 20% lower than quoted (ATO / RBA style prudence, aligned to APRA’s buffer and our guidance in /insights/solar-rebates-stcs-feed-in-tariffs-finance-plan).

Step 3 – Keep a buffer
Aim to retain at least 3–6 months of all living costs and loan repayments in cash or true offset after the top‑up, not zero out the offset (see the broader rule of thumb in /insights/how-much-equity-safely-release-home-australia).

If the repayments still fit and the buffer remains intact, you’re in the right ballpark. If not, your safe borrowing limit is lower than the bank’s number.

2. How lenders actually calculate how much you can borrow for solar

2.1 The LVR limits: how equity caps your borrowing

Lenders look first at loan‑to‑value ratio (LVR):

• 80% LVR: standard cap with no LMI for most owner‑occupiers.
• 90–95% LVR: sometimes possible, but with lenders mortgage insurance (LMI) and stricter assessment.
• 70–75% LVR: common self‑imposed cap for investors and risk‑aware borrowers.

Equity available for solar = (Property value × target LVR) − existing loans secured by that property.

If your equity is tight, read /insights/using-home-equity-pay-for-solar-safe-lvr-buffers before you push to higher LVRs.

2.2 Serviceability: the income and expenses test

Even if the equity is there, banks must apply:

• APRA 3% buffer: they test your loans at 3 percentage points above the actual rate.
• Minimum living expenses (HEM): they use a benchmark if your declared spending looks low.
• All debts included: credit cards (limit, not balance), car loans, HELP debt, BNPL, personal loans.

This means your solar borrowing power via equity can be lower than your pure equity suggests, especially if your income has dropped or living costs have risen.

2.3 Term length: 5–10 years vs 25–30 years

For solar, the real question is not just “how much can I borrow?” but “over how long?”

• Shorter term (5–10 years): higher monthly repayment, far less total interest.
• Long home‑loan term (25–30 years): lower monthly repayment, but often 2–3× the total interest for the same system price (see Fact 5 in the knowledge list).

We unpack these trade‑offs more deeply in /insights/green-loan-vs-home-loan-top-up-solar.