What does a 5 kW solar system mean?
“5 kW” is a convenient size description, but a proposal should state both the module array rating in kWp (DC) and the inverter rating in kW (AC). These can differ in an engineered design. The number on the proposal is not a promise that the system will produce that power all day.
For a home in Kolkata or elsewhere in West Bengal, review consumption, roof space and connection requirements before choosing a size. A high bill alone does not prove that 5 kW is the correct capacity, particularly where usage changes between summer and winter.
How many panels would be needed?
Panel count depends on module wattage and the proposed array rating. The examples below are arithmetic illustrations, not approved equipment combinations.
| Module rating | Quantity | Total DC rating |
|---|---|---|
| 500 W | 10 | 5.00 kWp |
| 540 W | 10 | 5.40 kWp |
| 600 W | 8 | 4.80 kWp |
| 600 W | 9 | 5.40 kWp |
A designer must also check module dimensions, string voltage, current, inverter compatibility and connection limits. Choosing higher-wattage panels does not remove the need for these checks.
How much electricity can it generate?
Generation changes with sunlight, temperature, shading, orientation, equipment and losses. To understand the calculation, consider a purely illustrative net daily yield of 3.5–4.5 kWh per kWp. This range is an assumption for the worked example, not a measured or guaranteed West Bengal yield.
For a 5 kWp array, that assumption gives 17.5–22.5 kWh per day. Multiplying by 30 gives 525–675 kWh in an illustrative 30-day month. Real monthly output varies; a monsoon month and a clear-weather month should not be assumed identical.
The word “net” here means system losses are already represented in the assumed yield. Do not apply another loss factor to the same number. A project estimate should instead use local weather inputs, the actual layout and documented losses.
Generation is not the same as rupee savings
If 600 kWh were generated in a month, the bill benefit would depend on when the household uses electricity and how exported energy is treated. Multiplying all 600 units by an average bill rate may overstate savings when that rate includes fixed charges or when exports have a different value.
Separate energy consumed directly, exported energy and any remaining imports. Ask the proposal to explain its tariff assumptions and metering treatment. Do not assume the bill reaches zero or that the same saving continues unchanged for decades.
Roof area and backup are separate design questions
Panel surface area is only part of the roof requirement. A layout must also allow for shading, obstructions, row spacing, access, drainage and maintenance. Read our roof-area planning guide before treating a generic square-foot estimate as a final design.
An ordinary on-grid inverter does not provide power-cut backup. If you want essential appliances to run during outages, the battery, inverter and safe isolation arrangement must be designed for their power and energy requirements. A “5 kW solar” label does not establish how many hours of backup are available.
What should you do next?
Collect several recent bills and note daytime usage, supply phase, sanctioned load and any expected increase in consumption. Share safely obtained roof details and a separate list of essential backup loads. The applicable DISCOM and any scheme conditions need checking for your connection.
Compare proposals using the solar cost checklist, try our calculator, and request a site-specific assessment. Final panel count, price and generation estimates should follow the survey and agreed equipment selection.