25 kW solar system — size, output and cost

What this size typically covers

A 25 kW array suits a site consuming in the region of 3000 units a month. That figure comes from a planning assumption of roughly four peak-sun-hours a day in Punjab, derated for temperature, soiling and inverter losses — about 120 units per kW per month.

It is a planning figure, not a guarantee. Real output varies with orientation, tilt, shading, module and inverter selection, ambient temperature, and how well the system is maintained.

Roof area

Approximately 2500 square feet of usable, unshaded area. Assess area honestly: parapet shadows, water tanks, stairwell blocks, and buildings to the south all reduce what is genuinely usable, and a layout that ignores them underperforms from day one.

How many modules is that

Roughly forty-five modules at around 500-550 W each — an array occupying most of a substantial rooftop, or a purpose-built structure over a yard or car park.

At this scale the structure is an engineering deliverable in its own right: loading on the building, wind uplift, access for maintenance, and drainage that still works once a large part of the roof is covered.

What a 25 kW system typically runs

Industrial and larger commercial sites: production areas, cold storage, workshops with motor loads, larger office and retail buildings, and institutions.

Systems of this size are rarely intended to cover the whole load. They are sized against the daytime base load — the consumption that is present whenever the site is working — because that is the part solar offsets most reliably. Peaks driven by machinery starting and stopping are a supply and protection question, not a generation one.

Supply and phase

Three-phase, with the electrical scope frequently larger than the solar scope. Expect the project to involve the LT panel, protection coordination, earthing, cable containment, and often a power-factor measurement — because at this size the tariff penalties for poor power factor are real money, and correcting them can be worth more than a few extra kilowatts of array.

That work is electrical engineering with solar attached, which is the way we would rather scope it than the other way round.

With or without a battery

Most installations at this size are grid-tied, exporting surplus under net metering where the connection permits it.

Storage at 25 kW is a specific decision with a specific justification — a process that cannot be interrupted, a cold chain, or equipment that is damaged by an abrupt stop. It is designed around that process rather than around a number of backup hours, and generator integration is often part of the same conversation. See hybrid and off-grid.

Summer, winter and the shape of the year

Output is not constant across the year, and neither is consumption. Generation is highest in the long, clear days before and after the monsoon, and lowest in the short days of winter and under the dust and cloud of the wettest weeks. In this region the summer months combine the highest consumption with strong generation — which is why solar addresses a summer bill more directly than a winter one.

Two consequences worth planning around: a system sized against a summer bill alone will be larger than the year needs, and one sized against a winter bill will disappoint in June. We size against twelve months where the data exists, and say which way we are erring where it does not.

What determines the cost

We do not publish a price for this size, because a credible number depends on things that are only known after a site visit:

• Roof type and the mounting structure it requires
• Distance and route from array to inverter to distribution board
• Condition of the existing electrical installation
• Module and inverter selection
• Whether net metering is included
• Whether battery backup is part of the scope

Market-indicative ranges circulate widely online. They are not our prices, and repeating them here would imply a quotation we cannot stand behind.

If this size is not right

• Around 1,800 units a month: 15 kW.
• Above 3,000 units a month, or across multiple buildings and connections: the sizing is a site-specific exercise rather than a standard size, and it starts with twelve months of consumption data and a survey. Contact us with the bills.
• The sizing estimator still gives a useful starting figure, and rounds up rather than down.

Next step

Use the sizing estimator to get an indicative size from your own bill or consumption. An engineer verifies the load and the site before any proposal.