Understand daily energy use
Before you size your solar array, start with your actual electricity consumption. Pull the last 12 months of utility bills or meter readings and calculate your average monthly kWh usage. Divide that by 30 to get a rough daily figure. Whether you run a household, small farm, clinic or school, knowing your baseline prevents under- or overbuilding your system.
Gauge sun exposure
Your solar yield hinges on how much sun hits your roof. Uganda enjoys roughly 4 to 5 peak sun hours per day, but shade from trees or neighboring buildings can cut that drastically. Use tools like NREL’s PVWatts to model your exact address and estimate daily production. (Energy.gov) Armed with that data, you’ll match panel capacity to real-world output.
Determine system size
Once you know your daily kWh need and sun hours, calculate your bare-bones array size. For example, a household using 30 kWh per day divided by 5 sun hours requires about a 6 kW system. Then add 20 percent to cover real-world losses and panel degradation, bringing it to 7.2 kW. (GoGreenSolar) This cushion ensures you still meet your needs on cloudy days or as panels age.
Choose panel wattage
Solar panels today range from 350 to 480 watts, with 400W modules as the common baseline. Higher-wattage panels mean fewer units but may cost more upfront. Your choice should balance budget, space and performance goals. Learn more about different solar panels in our overview.
| Panel wattage | Area per panel (sq ft) | Panels for 1 kW |
|---|---|---|
| 300W | ~15 | 4 |
| 350W | ~17 | 3 |
| 400W | ~17.5 | 3 |
Table: Panel wattage versus physical footprint and count for every kilowatt
Evaluate roof requirements
Next, confirm you have enough square footage and structural support. A standard 60-cell residential panel measures about 65 inches by 39 inches (roughly 17.5 sq ft). (Aurora Solar) Multiply that by your panel count to check if your roof can host the array. If space is tight, you might opt for higher-wattage or half-cut modules that squeeze more power into the same footprint.
Include system losses
Real-world systems never hit their nameplate capacity. Plan for losses from inverter conversion (around 5–10 percent), soiling, wiring resistance, shading and panel aging. Over 25 years, panels degrade roughly 0.8 percent annually, meaning a 400W module may produce only 320W by year 25. (GoGreenSolar) Building in a performance buffer keeps your system reliable through its lifetime.
Optimize panel orientation
Orientation and tilt directly impact your output. In Uganda’s equatorial region, a tilt matching your latitude (around 1° S) maximizes year-round yield but a fixed 10°–15° angle will do. South-facing roofs are ideal, but if your utility uses time-of-use rates, west-facing arrays can offset higher evening costs. (GoGreenSolar) Discuss roof slope and orientation with your installer to ensure full exposure.
Conclusion
Sizing your solar system confidently means you meet your energy needs today and for decades to come. You’ve learned to track daily kWh use, factor in Ugandan sun hours, calculate array capacity, choose panel wattage, confirm roof space, account for losses and fine-tune orientation. Next, request quotes from qualified installers, review component warranties and secure any available incentives. With the right planning, your solar investment will deliver reliable, cost-saving power for years.
