When you weigh up solar, it’s natural to frame it as “spend $14,000” versus “spend nothing”. But that framing is wrong, and it quietly stacks the deck against solar. Staying on the grid isn’t the zero-cost option — it’s a recurring bill you pay forever, one that has trended upward for years and shows no sign of stopping. The real choice isn’t “solar versus nothing”. It’s “a one-off cost that ends versus a monthly cost that never does”. Seeing it that way changes the maths.
“Doing nothing” is really a decision to keep paying
Every month you stay grid-only, you hand your retailer the full retail price for every unit you use — around 39 cents per kWh in New Zealand, on top of fixed daily charges. That isn’t a sunk fact of life; it’s an ongoing choice with a price tag attached. Over the 25-year life of a solar system, a typical household’s grid bills add up to a very large number — comfortably into the tens of thousands of dollars — and that’s before you account for prices rising.
The point isn’t that grid power is bad. It’s that “not deciding” is itself a decision: you’re choosing to keep paying that bill in full, indefinitely. Solar doesn’t bolt a new cost onto a free situation. It swaps one cost structure for another.
The two cost shapes, side by side
Picture it as two different shapes of spending.
Grid-only: nothing up front, then a bill every month, forever, that tends to rise. Comfortable in the short term, open-ended in the long term. You never “finish paying”.
Solar: a larger up-front cost — $12,000–$16,000 for a typical system, or a low-interest loan in its place — then sharply reduced bills, and once it’s paid off in roughly six to nine years, close to free power for the system’s remaining 15-plus years. You finish paying, and then it starts paying you.
The crossover point is the whole game. Before payback, grid-only looks cheaper month to month. After payback, solar pulls ahead and keeps pulling ahead for more than a decade. The longer you’ll be in the house, the more decisively it wins.
Rising prices tilt the field
Here’s the part the “doing nothing is free” framing misses entirely: the grid bill isn’t static. New Zealand retail electricity prices have climbed steadily over the years. If they keep rising — and little suggests they won’t — then every year your grid-only bill gets bigger, while the power your panels make costs you the same: nothing. Solar is therefore partly a hedge. You’re locking in a chunk of your electricity at today’s cost, insulated from future increases. Doing nothing leaves you fully exposed to whatever prices do next.
Where doing nothing genuinely is the better call
To be fair to the grid, there are homes where staying put is the smart move, at least for now:
- You use very little power. A small bill means small savings, so the up-front cost takes a long time to repay. The rising bill still rises — just off a low base.
- The house is empty all day and you won’t add a battery. Most of your solar would export at the low rate while you buy expensive power back at night, which pushes the crossover point out.
- You’re moving soon. If you’ll sell before payback, you may not bank enough savings to come out ahead — though an owned system can lift the sale price somewhat.
In these cases, doing nothing isn’t free either — but it’s the cheaper of two imperfect options, and waiting for a battery, an EV, or the 2026 export reforms is reasonable.
The honest comparison
For most owner-occupied New Zealand homes with daytime usage, the comparison comes down to this: keep paying a rising bill forever, or invest once, finish paying in well under a decade, and run on near-free power after that. Framed as “solar versus nothing”, solar looks expensive. Framed honestly — as “a cost that ends versus a cost that doesn’t” — the picture flips for a great many households.
The mistake to avoid is treating inaction as the safe, free default. It isn’t. It’s a choice to keep your money flowing out the door at retail rates, month after month, for as long as you own the home.
Want to see where your own crossover point lands — the moment solar would stop costing you and start paying you, against your real bill? Our free assessment maps both cost shapes over time for your specific home, so you can compare doing something with doing nothing honestly.
Sources: Retail price and payback ranges per MBIE and EECA; long-run electricity price trends per MBIE energy statistics; 2026 export reforms per the Electricity Authority. Figures are indicative and vary by home and retailer.