How to choose a commercial solar provider: accreditations, questions and red flags

For commercial solar, look for recognised accreditations rather than claims alone. MCS certification covers the quality of design and installation and is often needed for some incentives; NICEIC or NAPIT registration shows the electrical work is independently assessed. Membership of a trade body such as RECC adds a consumer-standards layer.

Ask to see the certificates and check they are current and cover commercial-scale work, not only domestic. An installer comfortable evidencing their credentials is a good early sign. Confirm which accreditations are relevant to your project with the provider, as requirements differ by scheme and system size.

Useful questions go beyond price. Ask how they sized the system, and whether it was based on your actual half-hourly consumption or a rough estimate. Ask who manages the DNO connection application (G99 or G98), what monitoring you will get, and how aftercare and maintenance are handled once the system is live.

On the commercial terms, read the warranties carefully. Panels, inverters and workmanship usually carry different lengths of cover, and a performance warranty should state what output is guaranteed and what remedy applies if it is not met. If a funded route is offered, get the per-kWh rate, term and end-of-term position in writing.

Some patterns should give pause. Pressure to sign quickly, reluctance to provide references or certificates, quotes with no clear system size or yield assumptions, and headline savings figures with no workings behind them all warrant more questions. Deposits that feel disproportionate, or a company with no traceable trading history, are worth checking too.

Ask for two or three recent commercial references and, if you can, speak to those sites about how the install went and whether output matched the projection. A credible provider expects this level of due diligence and will not rush you into a decision.