Choose solar equipment by the service it must deliver: electricity while the grid is available, specified loads during outages, or water for irrigation. These services require different measurements, controls and acceptance checks, even when the panels look similar.
For a home, collect recent electricity bills and an appliance schedule. For a farm, collect water demand, source details and pumping records. Add the site location, photographs and information about shade, access and the existing electrical connection.
Write the service requirement first
On a narrow screen, scroll the table sideways. Keyboard users can focus the table region and use the arrow keys.
| Use | Starting information | Ask the supplier to demonstrate |
|---|---|---|
| Grid-connected rooftop electricity | Bills, daytime use, roof survey and distribution company (DISCOM) | Expected generation, self-use/export assumptions and connection process. |
| Essential loads during outages | Load watts, simultaneous demand, hours required and outage timing | Which circuits operate, usable stored energy, power limits and transition behavior. |
| Agricultural pumping | Water volume by season, water levels, pumping head and delivery schedule | Water delivered at the required head under the stated seasonal conditions. |
State success in the appropriate unit: kWh for electricity over time, kW for instantaneous electrical capacity, and litres or cubic metres per day at a stated head for pumping. Panel capacity in kWp describes a rated generating capacity; it needs a site and operating model to become a service estimate.
Specify backup as a complete function
Ordinary grid-connected solar can stop supplying a building when the grid fails. Outage service requires a system designed for the necessary separation, controls and supported loads. The U.S. Department of Energy’s 2020 explanation of rooftop-solar resilience describes this technical distinction; Indian connection requirements must be confirmed with the local DISCOM and installer.
Ask the installer to identify the backup circuits on the drawing, the inverter’s continuous and starting capability, battery operating limits and the conditions under which backup ends. Agree on an acceptance demonstration under the approved installation procedure.
Fictional essential-load calculation
Three selected loads total 200 W and must operate for five hours: 200 × 5 = 1,000 Wh, or 1 kWh delivered to the loads. If an illustrative combined usable-energy and conversion factor is 0.80, nominal storage is 1 ÷ 0.80 = 1.25 kWh.
This is an energy illustration only. Actual selection also needs power and starting ratings, temperature and aging allowances, recharge conditions and the manufacturer’s operating limits. The 0.80 factor is an invented assumption to replace with the proposed system’s evidence.
Evaluate water delivery separately
For irrigation, record the required water volume through the crop season and the hours or days when it must arrive. Ask for a pump selection at the total head, including water-level variation, elevation and pipe losses. Have the supplier explain its seasonal solar assumption and how shortages are handled.
A water tank may shift the time of delivery, while electrical storage shifts electricity use. Compare those options against the actual irrigation schedule, land and water constraints. Ask who will measure delivered water and how the acceptance record will identify the head, weather and operating period.
The official PM-KUSUM portal distinguishes decentralized generation, standalone agricultural pumps and solarization of grid-connected pumps/feeders. Check the relevant component and state implementing agency for current notices, vendor information, service arrangements and application windows.
Compare complete offers and current terms
For residential rooftop applications, begin with the official PM Surya Ghar portal, also linked by MNRE’s programme notice. The latter is an April 2024 notice; use current programme and DISCOM documents for an application. Record the date and authority behind each eligibility, subsidy, metering or export-credit statement.
Request itemized equipment, mounting work, electrical protection, connection work, monitoring, maintenance, warranties and exclusions. Have the site survey address roof condition, shading, access and environmental exposure. Compare generation estimates using the same assumptions, with losses and downtime visible.
Keep bill savings separate from generation. Ask how much electricity is assumed to be used on site, how exports are treated and which bill charges remain. Before accepting an offer, identify the party responsible for commissioning, documentation and service, then list the evidence that will establish the promised electricity or water service.
Use the solar-cost guide to examine generation and cost assumptions.
India solar service brief
India solar service brief — plain-text download. Save a copy and fill it in with your own information. The file includes instructions, assumptions and references so it can be used independently.