The panels, inverters and cabling behind a residential and a commercial solar system are drawn from the same technology. What differs, often substantially, is how the system is assessed, sized and installed, because homes and businesses use electricity, use their roofs and are occupied in different ways.
Load profile
Residential demand tends to concentrate in the morning and evening, around occupancy, cooking and, in this region, air conditioning through the summer. Commercial demand more often concentrates during opening or operating hours, which for many businesses overlaps closely with generation.
This single difference is usually what decides whether storage is worth discussing, more than any other factor.
Roof and structure
A residential roof is typically pitched, single-occupant, and free of plant. A commercial roof is more often flat, shared with air conditioning units, ducting and maintenance access, and subject to safety zones around its edges. The usable surface on a commercial roof is frequently smaller than the total area suggests.
Decision-making and documentation
A residential project usually has one or two decision-makers who will also live with the result day to day. A commercial project often involves a building owner, an operator, and sometimes a separate facilities contractor, each of whom needs different information: financial justification, operational impact, and technical detail respectively.
Documentation matters more, not less, in a commercial setting, because the people managing the system in five years may not be the people who commissioned it.
Installation constraints
A residential installation is scheduled around a household's daily routine and, usually, a short supply interruption. A commercial installation is scheduled around trading hours, and the disruptive parts of the work, particularly the electrical connection, are planned into a single agreed window so the business does not close.
Where they are more alike than different
Underneath these differences, both cases follow the same design order: assess the building, understand the load, then select components. Neither should start from a preferred system size.
Related: Solar Solutions
This article is general, technical background written for the Solara Energy demonstration website. It is not project-specific advice.
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