Paying cash shortens the path to bill savings; financing spreads cost but adds interest and contract risk. Australian households should compare the two with the same generation and tariff assumptions — not with a salesperson’s preferred product.
Cash buys simplicity
Upfront payment maximises the value of STC discounts and avoids finance fees. Payback calculations stay clean: net capital versus annual bill reduction. The trade-off is opportunity cost — money that could stay in an offset account or emergency fund.
| Path | Strength | Watch-out |
|---|---|---|
| Cash / redraw | Lowest total cost if rate is zero | Liquidity hit |
| Secured loan / mortgage top-up | Often lower rates | Debt on the home; advice needed |
| Unsecured green loan | Keeps mortgage untouched | Higher rate; fees |
| Installer finance | Convenient at point of sale | Compare APR, balloon, and ownership terms |
- Convert every offer to total dollars paid over the term
- Confirm who owns the system if payments stop
- Check whether warranties transfer with finance structures
- Model a FIT drop and a mild shade year under both paths
Cheap monthly payments can still be expensive electricity.
“Interest-free” is not assumption-free
Deferred payment plans may embed higher hardware pricing. Compare the financed system’s net equipment value against a cash quote for identical panels and inverter.
When finance is rational
If cash would stress emergency reserves, a modest loan that still leaves monthly bills lower can be sensible — provided the APR and term are transparent. Do not finance a battery you do not need just to bulk a package.
Tax and investment properties
Landlords face different deduction and depreciation questions than owner-occupiers. That is accountant territory; do not take sales-floor tax claims at face value.
Decision rule
Choose the path that keeps you in the system for the long haul without fragile cashflow. A slightly slower payback with sleep-at-night financing beats a cash strain that forces a distressed sale of the asset.