What an 800 kW Solar Plant Costs and Needs: Roof, Connection, Approvals

An 800 kW rooftop plant indicatively costs about ₹1.92 to ₹2.08 crore excluding GST, at ₹24,000 to ₹26,000 per kW. It needs about 80,000 sq.ft of shadow-free roof, generates about 96,000 units a month in northern India, and usually connects at 11 kV. At this size you are above the 500 kW net-metering limit, so the metering route needs deciding before the design.

What does an 800 kW plant cost?

Secured Engineers publishes a C&I solar band of ₹24,000 to ₹32,000 per kW excluding GST on its solar EPC page, with larger plants at the lower end. We publish cost pages for 100 kW, 250 kW, 500 kW and 1 MW, but not for 800 kW, so the figure here is scaled between the 500 kW and 1 MW pages and is indicative only.

The scope behind the figure is a rooftop plant with modules, inverters, mounting structure, DC and AC cabling, earthing and lightning protection, protection and metering, installation, testing and commissioning, and DISCOM liaison. It excludes HT-side works such as a bay or transformer addition, roof strengthening, batteries, ground-mount land and statutory fees. At 800 kW the HT scope is the swing item, so check that every quotation states whether it is inside the price. Run your own bill through the solar calculator, then the solar payback calculator, which shows payback as scenarios by the share of output you use on site.

How much roof and how much generation?

Plan on about 100 sq.ft of shadow-free roof per kW, so about 80,000 sq.ft. That is rarely one roof. Expect several sheds with different heights, orientations and skylights, and let a shadow study replace the planning figure. Generation of about 120 units per kW per month is our planning figure for the northern belt, which gives about 96,000 units a month. It is higher in Rajasthan and Gujarat and lower in the east, and your location sets the real number.

If the roof is short, the usual alternatives are a carport, a ground-mount on spare industrial land, or a smaller roof plant plus open access for the balance. See our guide to open access solar for that route.

Why do buyers stop at 800 kW, and when is 1 MW better?

Buyers stop below 1 MW for reasons that have little to do with the price per kW, which our band puts at much the same for 800 kW and 1 MW. The usual reasons are:

• The roof. The usable area runs out near 80,000 sq.ft before it reaches 1,00,000.
• The sanction. The contract demand or sanctioned load does not support more, and the DISCOM caps the plant against it.
• The daytime load. Sunday and holiday output is exported, and the export rules in most states pay less than self-use.
• The transformer. Reverse flow at peak generation minus minimum load must fit the existing transformer.

1 MW is the better size when the roof, sanction and daytime load all support it. The extra 200 kW costs about ₹48 to 52 lakh on our band, and it spreads the fixed items, such as the HT bay, the protection scheme, the metering and the approvals, over more kilowatts. The reverse also holds: if the load is a single shift and the roof is tight, 800 kW may already produce more than you can use. Test both sizes in the payback calculator before you decide.

Which connection voltage and inverter architecture?

At this size the connection is usually on the HT side, at 11 kV, through your existing transformer bay or a dedicated one. Protection for reverse power, over and under voltage and frequency must coordinate with the existing scheme. Some sites with several LT supply points can stay on the LT side. The DISCOM and the electrical inspector decide. Our guides on 11 kV connection and transformer headroom cover the works.

Ask whether 800 kW means module capacity (DC) or inverter capacity (AC), because regulations and DISCOMs can apply their limits to either. On inverters, a string architecture of roughly ten to sixteen units in the 50 to 100 kW class is typical at this size, and a smaller number of larger central units is the alternative. We usually favour strings because a failed unit costs a small share of the output and is replaced from stock, whereas a failed central inverter can idle a large block. The guide to string versus central inverters sets out the trade-off.

What do the rules allow above 500 kW?

The Ministry of Power's annual report for 2021-22 records that an amendment to the Rights of Consumers Rules raised the net-metering limit from 10 kW to 500 kW. An 800 kW plant therefore exceeds it, and the state commission's regulation decides what happens next. The options are to size to the net-metering limit and add the balance later; to use net billing or gross metering where the state offers them; to run behind the meter with the plant sized to the daytime load, with export control if the DISCOM requires; or to use open access for part of the output. Banking and settlement of surplus energy differ by state, so check them before fixing the capacity.

The module rules matter too. MNRE's O.M. of 4 August 2026 says net-metering and open-access projects, defined to include gross metering and net billing, must use ALMM List-I modules, and are exempt from List-II (cells) only if commissioned by 31 December 2026. It says neither list applies to behind-the-meter plants used solely for captive consumption by a private consumer, other than government entities and public sector enterprises. Your contractor should state which applies to your metering.

What is the approval sequence, and what does a timeline depend on?

1. Check the sanctioned load and transformer headroom, then freeze the capacity.
2. Prepare the design and the single-line diagram.
3. File the DISCOM application. Under the central rules as amended in February 2024, the feasibility study for systems above 10 kW is to be completed in 15 days, with deemed approval if it is not.
4. Electrical inspector. Under the CEA safety regulations, 2023, an installation above the voltage notified by the state is inspected and approved by the Electrical Inspector before supply, and the capacity above which generating units, including solar, need inspection before commissioning is also fixed by the state. Check both for your state.
5. Install and test, then arrange DISCOM inspection, metering and synchronisation. The same 2024 amendment gave the licensee 15 days to commission a rooftop system.

There is no honest single timeline at this size. The two statutory legs above are 15 days each on paper. What dominates is the module and inverter lead time, the HT works and the inspector's visit, plus the roof readiness. Ask any bidder for a dated programme that separates those items.

How Secured Engineers helps

Secured Engineers designs the plant in-house and files the DISCOM net-metering application, the electrical inspector filing and related approvals in-house. Solar can sit under one MEPF contract with your electrical, fire and HVAC work, so the HT side of an 800 kW plant is part of one scope. We work from offices in Noida (Delhi NCR) and Ludhiana, across 535+ projects in 18+ states, with 89.77% repeat clients.

Send us your last twelve electricity bills and the sanctioned load, and we will tell you what size the roof, the connection and the rules support before you buy. Message us on WhatsApp, call +91 70099 85817, or ask for a free proposal.