Solar EPC — residential, commercial, industrial

What the work involves

A solar installation is an electrical project before it is a product purchase. The array is the visible part; the parts that determine whether it performs are the load assessment, the protection design, the earthing and the quality of the terminations.

1. Load assessment

We start from what the site actually consumes — meter readings or billing history, connection phase, and the daily shape of the load. A site with a strong daytime load suits grid-tied solar closely. A site whose consumption is mostly after sunset needs a different conversation, and possibly a different system type.

2. Site survey

Roof structure and orientation, available area, shading through the day, cable routes, and the condition of the existing distribution board. Where the existing electrical installation needs remedial work before solar can be added safely, we say so.

3. Design

Array layout, string configuration, inverter selection, DC and AC protection, earthing and lightning considerations, and a single-line diagram. The design is documented so any competent engineer can inspect or extend it later.

4. Installation and commissioning

Mounting structure, module installation, cabling and terminations, protection devices, earthing, then testing and commissioning. Handover includes as-built documentation and a walkthrough of the system, its protection devices and what to do if something trips.

How the three sectors differ

The technology is the same. Almost nothing else is.

Homes

Single-phase supply, a load that peaks in the evening and through summer afternoons, and a roof that was designed for weather rather than for an array. The decisive questions are how much of the consumption happens while the sun is up, whether the house needs to keep running during an outage, and whether the existing distribution board can accept generation without remedial work. Most domestic sites land between 3 kW and 10 kW.

Commercial premises

Offices, retail, clinics, schools and warehouses have the load profile solar suits best: consumption that happens in daylight, on weekdays, in the same hours generation is available. That makes self-consumption high and the payback arithmetic simpler. The complications are usually structural — roof condition, plant already occupying the roof, and cable routes through an occupied building that cannot simply be shut down for a day.

Industrial sites

Three-phase supply, motor loads with high starting currents, tariff structures that penalise poor power factor, and an existing LT installation that is often the real project. Here the array is frequently the smaller half of the scope: boards, protection coordination, earthing and power-factor correction have to be right before generation is worth adding. This is where our electrical engineering work matters most, and where a solar-only contractor is out of their depth.

What goes into a system

We specify equipment against the site rather than against a price list, and the selection criteria are the same every time.

• Modules. Selected for the area available, the structure’s tolerance, and manufacturer warranty terms that are actually honoured in this market. Where roof area is tight, higher-efficiency modules buy back capacity; where it is plentiful, they usually are not worth the premium.
• Inverter. Sized to the array and to the connection phase, with headroom for how the site loads it. A hybrid inverter is specified only when there is a backup requirement that justifies it — see hybrid and off-grid.
• Mounting structure. Chosen for the roof: ballasted or anchored frames on flat RCC, rail systems on sloped sheets, and elevated structures where the roof is in use. Wind loading is a design input, not a formality.
• DC and AC cabling, isolation and protection. Correctly sized conductors, UV-rated DC cable, isolators at both ends, surge protection where exposure justifies it, and terminations made to a torque figure rather than by feel.
• Earthing and bonding. Array frames bonded, electrode arrangement checked, and continuity tested rather than assumed.
• Monitoring. So output can be compared against what the design predicted, which is the only way an underperforming system announces itself.

How long an installation takes

We do not publish a fixed duration, because the honest answer is a range set by things we can name:

• System size and structure. A domestic rooftop array is a different job from an elevated commercial structure requiring fabrication.
• Roof access and site conditions. Occupied premises, height, and whether work can proceed during business hours.
• Remedial electrical work. If the board, earthing or protection needs correcting first, that work has its own schedule.
• Utility processes. Where net metering is involved, the application, inspection and meter change are on the distribution company’s timeline, not ours.

What we commit to is a schedule stated before work starts, and being told about slippage by us rather than noticing it yourself.

What usually goes wrong, and how it is avoided

Systems rarely fail dramatically. They underperform quietly, for a short list of reasons:

• Shading that was never measured. A single shaded module can drag a whole string. It is resolved by re-arranging the array, changing string layout, or using module-level electronics — decided at survey, not after commissioning.
• Undersized or poorly routed DC cable. Voltage drop is invisible on a sunny day and expensive over twenty years.
• Terminations tightened by feel. The most common cause of heating, arcing and eventual failure at a connection.
• Structures never checked for wind loading. Failures here are not gradual.
• Generation added to a board that could not take it. The array works; the installation it feeds becomes less safe.

Warranties, in plain terms

There are three distinct things people call “the warranty”, and they are worth separating before signing anything:

1. Manufacturer product warranty on modules, inverter and battery, covering defects. Registered in your name, with the paperwork handed to you.
2. Manufacturer performance warranty on modules, covering output degradation over time — a different document with different terms.
3. Workmanship, which covers the installation itself and is the installer’s own commitment. Its scope and duration are stated in your quotation, so that it is a written term rather than a verbal assurance.

Ask any installer which of the three they are quoting. The answer is informative.

What we do not do

We do not quote a system size over the phone, and we do not price a system before seeing the site. An indicative figure from the sizing estimator is a starting point for a conversation, not a proposal.

We also do not lead with a price per watt. It is the number easiest to compete on and the one that says least: it can be reduced by thinner cable, a lighter structure, a cheaper inverter, or by leaving the existing board’s condition out of the scope entirely. The price guide explains what a quotation should itemise so that two of them can be compared honestly.