Quick answer for 400 units
Calculation: 400 ÷ 30 = 13.3 units per day; 13.3 ÷ (5.3 × 0.8256) = 3.05 kW. The 0.8256 factor combines 14% system losses with 96% inverter efficiency.
Panels needed for 400 units by panel size
| Panel | Panels | Installed array |
|---|---|---|
| 450 W | 7 | 3.15 kWp |
| 550 W | 6 | 3.3 kWp |
| 585 W | 6 | 3.51 kWp |
| 620 W | 5 | 3.1 kWp |
| 700 W | 5 | 3.5 kWp |
400 units: solar size by city
Sunnier cities need a smaller array for the same units. Peak sun hours are planning averages from the site's city dataset, not measured values.
| City | Sun hours | Array | 550 W panels |
|---|---|---|---|
| Abbottabad | 4.8 | 3.4 kW | 7 |
| Attock | 5.3 | 3 kW | 6 |
| Bahawalpur | 5.7 | 2.8 kW | 6 |
| Chakwal | 5.3 | 3 kW | 6 |
| Charsadda | 5.2 | 3.1 kW | 6 |
| Dera Ghazi Khan | 5.6 | 2.9 kW | 6 |
| Dera Ismail Khan | 5.6 | 2.9 kW | 6 |
| Faisalabad | 5.3 | 3 kW | 6 |
| Gilgit | 4.6 | 3.5 kW | 7 |
| Gujranwala | 5.1 | 3.2 kW | 6 |
| Gujrat | 5.1 | 3.2 kW | 6 |
| Gwadar | 5.6 | 2.9 kW | 6 |
| Hyderabad | 5.5 | 2.9 kW | 6 |
| Islamabad | 5.1 | 3.2 kW | 6 |
| Jhang | 5.4 | 3 kW | 6 |
| Jhelum | 5.2 | 3.1 kW | 6 |
| Karachi | 5.4 | 3 kW | 6 |
| Kasur | 5.2 | 3.1 kW | 6 |
| Khuzdar | 5.7 | 2.8 kW | 6 |
| Kohat | 5.4 | 3 kW | 6 |
| Lahore | 5.1 | 3.2 kW | 6 |
| Larkana | 5.6 | 2.9 kW | 6 |
| Mardan | 5.2 | 3.1 kW | 6 |
| Mianwali | 5.5 | 2.9 kW | 6 |
| Mirpur | 5.1 | 3.2 kW | 6 |
| Mirpurkhas | 5.5 | 2.9 kW | 6 |
| Multan | 5.6 | 2.9 kW | 6 |
| Muzaffarabad | 4.7 | 3.4 kW | 7 |
| Nawabshah | 5.7 | 2.8 kW | 6 |
| Nowshera | 5.3 | 3 kW | 6 |
| Okara | 5.3 | 3 kW | 6 |
| Peshawar | 5.3 | 3 kW | 6 |
| Quetta | 5.8 | 2.8 kW | 6 |
| Rahim Yar Khan | 5.7 | 2.8 kW | 6 |
| Rawalpindi | 5.1 | 3.2 kW | 6 |
| Sahiwal | 5.4 | 3 kW | 6 |
| Sargodha | 5.4 | 3 kW | 6 |
| Sheikhupura | 5.2 | 3.1 kW | 6 |
| Sialkot | 5 | 3.2 kW | 6 |
| Skardu | 4.6 | 3.5 kW | 7 |
| Sukkur | 5.6 | 2.9 kW | 6 |
| Swat | 4.9 | 3.3 kW | 6 |
| Turbat | 6 | 2.7 kW | 5 |
Net metering vs net billing in Pakistan
In February 2026 NEPRA replaced net metering with a net-billing model for new solar consumers. Under net billing, units you export are credited at a lower buyback rate than the price you pay for imported units, so using more of your own solar output directly (daytime loads, or a battery) is worth more than exporting it. Reports put agreements signed before 9 February 2026 outside the new rules, and sources differ on the exact new rate. Read the report.
Rules and rates have been revised more than once, so confirm the current buyback rate and eligibility with NEPRA or your distribution company before you decide on system size or a battery.
Frequently asked questions
What size solar system do I need for 400 units per month?
About 3 kW of panels at 5.3 peak sun hours. Depending on the city (4.6 to 6 sun hours in the dataset) it ranges from 2.7 kW to 3.5 kW. Installers usually round up to the next standard size.
How many solar panels are needed for 400 units?
6 panels of 550 W (3.3 kWp installed) at the national average. With 620 W panels it is 5 panels; with 450 W panels it is 7.
What inverter size suits a 400-unit solar system?
Around 3 kW, from the array size divided by a typical DC/AC ratio of 1.2. The inverter must also cover your peak simultaneous load and motor starting surge, so check your appliances with the load calculator.
How much roof space does it need?
About 18 m² (191 sq ft) for 6 panels of 550 W, including a 15% allowance for access and spacing.
How big a battery do I need for 400 units a month?
400 units a month is an average load of about 0.56 kW. Running that average load for 4 hours takes roughly 2.7 kWh of LiFePO₄ battery. Most homes back up only essential loads, which needs far less. Use the wizard to size your own backup.
Will the system cover all 400 units every month?
On average yes, because it is sized to offset 400 units. Summer months produce more than the average and winter months less, so you may export surplus in summer and import some units in winter.