Commercial rooftop solar for business premises

The value of commercial solar comes mainly from electricity used on site, because it replaces electricity bought at your contract rate. A food retailer running refrigeration all day, a workshop with machinery, or an office with cooling can use most of what the panels generate. A site that is closed at weekends or busy only in the evening exports more and earns less per unit.

Half-hourly consumption data from your supplier or meter operator is the best starting point. With it, the installer can size the array to your daytime base load, show how much would be exported, and test whether a battery or a charge point for company vehicles would change the picture.

A structural check comes first. Lightweight industrial roofs were not always designed for extra load, and the fixings for panels on metal sheeting differ from those on tiles or membranes. Many older industrial and farm buildings have asbestos cement roof sheets; the dutyholder for the premises has to manage asbestos, and it must be identified before anyone drills or walks on the roof.

If you lease the building, you usually need the landlord's written consent, and it is worth agreeing who owns the panels at the end of the lease and who pays for removing and refitting them when the roof is repaired. Tell your buildings insurer early; some insurers set conditions on rooftop solar, inverter location and fire detection.

In England, solar on non-domestic buildings has its own permitted development right, Class J of Part 14 of the General Permitted Development Order. Among its conditions: panels on a pitched roof may not protrude more than 0.2 metres from the roof slope, panels on a flat roof may not be more than 1 metre above its highest part, and no equipment may sit within 1 metre of the roof edge. Listed buildings and scheduled monuments are excluded. For larger solar PV that falls outside the microgeneration definition, you must first ask the council whether it wants to approve the design and appearance, including glare for neighbours.

Wales, Scotland and Northern Ireland have their own systems. Electrical and structural work also has to meet the Building Regulations, and as the client you have duties under the Construction (Design and Management) Regulations 2015, such as allowing enough time and making sure the contractor has the information it needs about the building.

Source: legislation.gov.uk

Commercial systems are usually too large for the connect-and-notify route. The installer applies to the network operator under G99 before installation, and the operator may take weeks to respond. On constrained networks the offer may include an export limit or reinforcement costs, so this answer can decide the size of the system.

The Smart Export Guarantee covers solar installations up to 5MW in Great Britain. Above 50kW, you need to show that the installation is suitably certified, but the installer itself does not need MCS certification for the SEG. Many businesses instead sell surplus through their supply contract or a power purchase agreement; your energy broker or supplier can compare the options.

Source: ofgem.gov.uk

The zero rate for energy-saving materials covers installations in residential accommodation and buildings used solely for relevant charitable purposes. Installations on offices, shops, warehouses, hotels and similar premises are charged at the standard rate, which a VAT-registered business can normally reclaim.

• array size, panel and inverter models, and the yield estimate with shading
• the share of generation expected to be used on site, based on your data
• structural assessment, roof fixing method and any asbestos survey
• G99 application, timescale and any export limit or network cost
• planning route, including any prior approval application
• fire safety measures, isolation points and access for firefighters
• operation and maintenance terms, monitoring and response times for faults

Describe the site, roof type and annual consumption, and confirm your phone number and email. Commercial solar installers in the region see an anonymised version, and one company can buy it; after that nobody else is offered it. The installer pays Offrano for the request, and we email you its name, address and phone number before your details are released.

There is no guarantee of a buyer; unsold requests are withdrawn after 21 days, and you can run your own tender at any time. Offrano confirms that buyers are registered businesses but does not assess their technical ability, so ask for references for comparable roofs and check certification and insurance yourself.