Commercial solar: where the business case is genuinely different

The structural advantage

Most businesses have a load profile that suits solar almost perfectly: they operate during daylight hours. Where a household exports its midday surplus at a low feed-in rate, a business is typically consuming its generation directly at full retail value - which is precisely where solar's economics are strongest.

This is why commercial systems frequently achieve shorter paybacks than residential ones despite larger capital outlay. The self-consumption rate does the work.

The 100 kW threshold

Systems up to 100 kW attract STCs - the upfront certificate discount familiar from residential solar. Above 100 kW, systems generate Large-scale Generation Certificates instead, created against metered generation over time rather than deemed upfront.

That's a genuine structural difference: an upfront discount becomes an ongoing revenue stream, with associated administration. For projects sitting close to the threshold, this is a real design decision, not a formality - and it should be modelled both ways.

Demand charges

Many commercial tariffs include a demand charge based on your peak draw in a period, not just total consumption. Solar can reduce this, but only if generation reliably coincides with your peak - which needs checking against your interval data rather than assuming.

Where a battery is involved, peak-shaving against demand charges can be a substantial part of the business case, sometimes larger than the energy savings themselves.

Beyond the energy savings

Depending on structure and eligibility, businesses may access tax treatment such as instant asset write-offs. There's also the corporate sustainability dimension - increasingly a procurement requirement rather than a nice-to-have, particularly for businesses supplying larger customers with emissions reporting obligations.

We'd caution against building a business case on the sustainability benefit alone. Build it on the energy economics; treat the reporting benefit as real but secondary.

What we need to model it properly

Interval data if you can get it - most commercial sites have smart metering and your retailer can provide it. Twelve months of bills otherwise. Roof or ground area and structural condition. Your tariff structure including any demand component. Operating hours and any planned changes to them, including electrification of vehicle fleets.