Rooftop solar isn't only for big factories. For shops, offices, clinics, schools, small workshops and homes, a 5–50 kW system can cut a large slice off the electricity bill. Here's how to size one and choose the right type.
Start with your bill
Your electricity bill tells you most of what you need. Take the average monthly units (kWh) over the last 12 months and divide by 30 to get your daily use.
In Bangladesh, a well-installed system produces roughly 3.5–4 units per kWp per day averaged over the year. So:
| Average monthly use | Daily use | System to cover it |
|---|---|---|
| 600 units | 20 units | about 5–6 kWp |
| 1,500 units | 50 units | about 13–14 kWp |
| 4,500 units | 150 units | about 40 kWp |
That is the size that would match your total use over a year. If most of your use is in the evening, a smaller system — or one with a battery — may make more sense. We'll check this against how your load actually runs through the day.
How much roof you need
Allow roughly 6–7 m² (65–75 sq ft) of shade-free roof per kWp. A 10 kWp system needs around 60–70 m²; a 40 kWp system around 240–280 m². Flat concrete roofs, tin sheds and carports can all work — shade from water tanks, neighbouring buildings and trees matters more than roof type.
On-grid, hybrid or off-grid?
- On-grid — the simplest and lowest-cost option. Solar supplies your daytime use and the grid covers the rest. It switches off during load shedding for safety.
- Hybrid — on-grid plus a battery. Keeps lights, fans, computers, refrigeration or medical equipment running during outages, and can store midday solar for the evening.
- Off-grid — for sites with a weak or no grid connection, with batteries sized to carry the load on their own.
Net metering for small systems
If your system sometimes produces more than you use — on weekly holidays, for example — net metering lets the surplus offset units you buy later. Under the Net Metering Guideline 2025, the system's inverter capacity must stay within your sanctioned load, and you'll need SREDA-cleared equipment and a net meter. We handle the application for you. Read more in our net metering guide.
Looking after it
Small systems need little care: regular cleaning of the panels (more often in the dry, dusty months), a yearly check of connections and the inverter, and a look at the monitoring app if you have one. We offer maintenance plans for small systems too.
Buy it or pay per unit?
Most small systems are bought outright (CapEx) — they are affordable and the savings stay with you. For larger small-business sites, zero-investment models such as OpEx can also work. Tell us about your site and we'll suggest the simplest option.
Sizing figures are rules of thumb for early planning. Actual output depends on orientation, tilt, shading, equipment and weather; every quote we give is based on a site visit.