How to finance solar in Perth: cash, loan, HEEL, or PPA?
Most Perth households pay for solar upfront or via a personal loan. Here's how the main financing options compare (including Synergy's HEEL loan) and which approach suits different situations.
For most Perth households, a 6.6kW solar system costs roughly $5,000–$10,000 installed after the STC rebate, depending on component tier (current Perth pricing), a significant upfront expense that determines how you finance it. The financing method affects your net savings and the payback period.
Here are the main options, with honest numbers for each.
Option 1: Upfront cash
How it works: Pay the full installation cost at commissioning (typically invoiced on completion of installation, before the meter upgrade).
Cost: Full system price, nothing else.
Why it's the simplest: No interest, no ongoing payments, no third-party arrangement. Your electricity savings start from day one and go entirely to you. Payback period is purely a function of system cost and electricity savings.
Worked example:
- System cost after STCs: $6,500
- Annual electricity savings: $1,500
- Payback: 4.3 years
- Net benefit over 25 years: $1,500/yr × 25 years, less the $6,500 system cost, ≈ $31,000 before panel degradation and tariff changes
When it makes sense: If you have the capital available and no better use for it earning above 8%+ after tax. Paying off a mortgage early typically beats the savings rate; investing in equities has uncertain return. For many Perth households, solar cash ROI (8–20%+ annualised before degradation) is among the best risk-adjusted uses of savings.
Option 2: Personal loan (unsecured)
How it works: Borrow the system cost from a bank or credit union at a fixed interest rate, repay over 3–7 years.
Current rates (2026): Variable, but personal loan rates in Australia typically range from 6.5%–12.5% for creditworthy borrowers. Compare rates before choosing.
Effect on payback:
- System cost: $6,500 at 8% over 5 years
- Monthly repayment: approximately $131
- Total interest: approximately $1,370
- Total cost: approximately $7,870
If the system saves $1,500/year, you're marginally cash-flow negative during the loan term (monthly saving of $125 against a $131 repayment ≈ net -$6/month), close to break-even but not positive until the loan is repaid. After that, the full $1,500/year is savings. Effective payback from original cost: approximately 5.2 years including interest.
When it makes sense: When you don't have upfront capital but your monthly electricity saving covers most or all of the loan repayment. Check that the monthly electricity saving (divide annual saving by 12) roughly matches the monthly repayment. If the electricity saving significantly exceeds the repayment, you're cash-flow positive from the start.
Green loans: Some lenders offer lower-rate "green" personal loans specifically for solar and energy efficiency purchases. Check your bank and credit union for current green loan rates.
Option 3: Home equity / mortgage offset
How it works: Redraw from your mortgage or use a home equity loan at mortgage interest rates (currently 6%–7.5% variable in Australia).
Effect on payback: Lower interest rate than a personal loan. If your mortgage rate is 6.5% and you redraw $6,500:
- Extra interest cost over 5 years (assuming you repay over 5 years): approximately $1,100
- Effective cost: approximately $7,600
Slightly cheaper than a personal loan, and the repayment flexibility of a mortgage redraw may suit some households better.
When it makes sense: If you have available equity and a mortgage redraw facility. Be aware that redrawing extends your mortgage balance: factor this into the comparison with upfront cash.
Option 4: Synergy HEEL loan (Home Energy Efficiency Loan)
How it works: Synergy offers an interest-free or low-interest loan for eligible energy efficiency upgrades, repaid through your electricity bill (as an additional bill charge).
Current terms (verify with Synergy directly): Synergy's HEEL program has evolved. As of 2026, the program provides loans for eligible upgrades including solar, batteries, heat pump hot water systems, and insulation. Repayment is typically added to your electricity bill over 36–60 months.
Why it can work well: If interest-free, it's effectively the same as cash from a total-cost perspective. Repayment via electricity bill is administratively simple.
What to check with Synergy before relying on it:
- Maximum loan amount (has varied; check current limit)
- Eligible equipment list (not all solar brands or battery types qualify)
- Whether the loan can cover a battery as well as solar panels
- Current interest rate (zero, subsidised, or variable?)
- Income eligibility criteria (some HEEL variants are means-tested)
How to apply: Through Synergy's website or by calling Synergy directly. The loan application precedes the installation, so factor approval time into your timeline.
Option 5: Solar PPA (Power Purchase Agreement)
How it works: A third-party company installs solar on your roof at no upfront cost. You agree to buy the electricity generated by "your" panels from the PPA provider at a discounted rate (typically below grid tariff). The PPA provider owns the panels and system.
Perth availability: PPAs are more common in commercial solar than residential in WA. Residential PPA providers operating in Perth are limited compared to the eastern states.
The appeal: Zero upfront cost, discounted electricity from day one.
The catch:
- You don't own the system: you can't claim the STC rebate (the PPA provider claims it)
- Contract terms of 10–25 years can complicate selling your home
- After the PPA term, you may have the option to buy the system at residual value, renegotiate, or have it removed
- The discounted electricity rate may rise over time (check whether the PPA has rate escalation clauses)
- Net present value (NPV) of a PPA is typically lower than outright ownership for creditworthy buyers who can access a personal loan
When a PPA might suit: If you have poor credit, can't access finance, and a PPA provider offers terms competitive with your current electricity bill, it may be the only viable path to some savings. Otherwise, ownership almost always comes out ahead financially.
Which approach is right for you?
| Situation | Recommended approach |
|---|---|
| Have savings and no better high-return use | Cash upfront |
| Have a mortgage with equity and redraw | Mortgage redraw |
| No upfront capital, good credit | Personal loan (compare rates) |
| Synergy customer, eligible for current HEEL terms | HEEL if interest-free |
| No capital, poor credit access | PPA as a last resort (check terms carefully) |
Whichever route you take, the rebates come off first: the complete Perth solar rebates guide covers what a compliant quote already nets out. When you're ready to compare offers, get quotes from vetted Perth installers.
Personal loan rates, Synergy HEEL program terms, and PPA availability change frequently. Verify current rates and eligibility with your lender and Synergy before making a financing decision. This guide is not financial advice.