Commercial solar for offices, retail and cold storage

Commercial solar covers a wider range of buildings than industrial does — an office in Gulberg, a showroom on Main Boulevard, a cold store on the outskirts of DG Khan — and the technical work varies less between them than the commercial questions do.

So I start with two questions that have nothing to do with panels: do you own the building, and if not, how long is left on the lease? A commercial system pays back over years. If your tenure is shorter than the payback, the engineering is irrelevant. I would rather establish that in the first phone call than after a design.

Cooling load is the best-matched commercial load there is

Air conditioning and refrigeration demand rises with ambient temperature, which rises with the same sunlight the array is converting. The hotter the afternoon, the more your chillers draw and the more your array produces. Very little is exported, so the buyback rate barely touches you.

Cold storage is the strongest version of this. The DG Khan cold storage plant is a 143 kW system for exactly this reason, and the client has since come back for further work. Warehousing with no cooling load is the weakest — a shed with lights draws very little, and the roof area tempts an oversized system that exports most of what it makes.

If you currently run a generator, the arithmetic is different

Most commercial payback calculations compare a solar unit against a grid unit. If you are running a diesel generator through load shedding, some of what you displace is priced against diesel instead — a considerably more expensive unit. That shortens payback, and it is also the one commercial case where storage frequently does justify itself, because the alternative it displaces is fuel rather than a slightly cheaper tariff.

I will ask what your generator actually costs you per month to run. Most owners know this number precisely, and it is usually the most useful figure in the whole conversation.

If you do not own the building

A short lease does not always end the conversation, but it changes who the conversation is with. Three arrangements come up in practice, and it is worth knowing which one you are proposing before you approach a landlord.

• The owner pays and raises the rent, or takes the saving directly. Simplest, and the easiest to agree where the building owner is also a business owner who understands the arithmetic.
• You pay and negotiate a rent adjustment or a lease extension against it. This needs the payback period and the remaining term written into the same document, or you are relying on goodwill you may not have in year four.
• You pay and the system is removable. Honest, and worth less than people hope — the array can be unbolted, but the structure penetrations, the cabling and the metering work stay behind, and remounting on a different roof costs a meaningful fraction of a new installation.

What does not work is installing on a rented roof without written agreement and hoping it goes unnoticed. It is discovered at the point of the DISCO application, because the connection agreement carries the owner name — which is also the moment it becomes an expensive problem rather than a cheap one.

Installing without closing the business

A factory can often take a shutdown window. A showroom cannot. Commercial installation is therefore scheduled around trading hours, with the noisy and disruptive work — drilling, structure anchoring — done outside them, and the single unavoidable outage for the AC changeover and metering work agreed with you in advance rather than sprung on you.