“What’s the payback?” is the right first question about commercial solar — and the honest answer is: it depends on how your site uses power. The same array on two different roofs can pay back years apart. These are the variables that actually move the number.
Self-consumption is the engine
Every kWh your site uses at the moment it’s generated displaces a kWh you’d otherwise buy at your full retail rate. Every kWh you export instead earns a fraction of that. So the single biggest driver of payback is the match between your generation curve and your load curve — a site running machinery, refrigeration or kitchens through the day banks far more value per panel than one that’s empty at noon.
This is why Novalux sizes systems from your half-hourly consumption data rather than your roof area. The right system for payback is sometimes smaller than the roof could take — and the proposal shows why.
The battery multiplier
A battery attacks the two weaknesses of solar-only economics: it converts would-be export into displaced import, and it earns on days the sun doesn’t. It also opens grid services revenue and peak shaving that solar alone can’t reach. In most of our modelling, adding correctly-sized storage shortens payback rather than lengthening it — which is why nearly every Novalux proposal prices both options side by side.
Tax relief moves year-one cashflow
Qualifying solar and battery plant typically attracts up to 100% first-year relief through capital allowances — for most projects the £1m Annual Investment Allowance covers the full spend in year one (the 2026 rules in detail). That doesn’t change the headline payback arithmetic, but it substantially improves the year-one cash position, which is often what matters to the board.
What the 25-year picture looks like
Payback is the start of the story, not the end. Panels carry 25–30 year performance warranties; after the payback point the system generates at near-zero marginal cost for decades. That’s the sense in which energy becomes an asset rather than a cost — the cashflow turns positive early and stays positive.
Proof, not promises
Payback claims are only as good as the delivered projects behind them. Novalux publishes its completed systems — from a 1.25MWp factory rooftop to a three-farm agricultural programme — each with its case study. For a budget range built from the average pricing of those real quotes, try the cost calculator; for the exact figure, request a Quick Quote — system design, 25-year cashflow and payback within 24 hours.