How to size a solar system for a Ugandan home
A step-by-step guide to calculating the panel, battery and inverter capacity you need based on your actual loads — written for Uganda's climate and grid situation.
Why sizing matters
Buying a solar kit that is too small means your battery drains by 10 pm and your appliances cut out overnight. Buying too large means you waste money on panels and batteries you will never use. Getting the sizing right is the single most important decision in a solar installation.
Uganda receives an average of 5.2 peak sun hours per day — higher in the drier months (December–February, June–August) and slightly lower during the long and short rains. This is a key number in every calculation below.
Step 1 – List your loads
Write down every appliance you want to run on solar and for how many hours per day:
| Appliance | Watts | Hours/day | Wh/day |
|---|---|---|---|
| 4 LED lights (10 W each) | 40 W | 6 h | 240 Wh |
| 43-inch LED TV | 80 W | 4 h | 320 Wh |
| Phone and laptop chargers | 60 W | 3 h | 180 Wh |
| Refrigerator (energy-saving) | 80 W | 24 h (cycles ~50%) | 960 Wh |
| Fan | 50 W | 8 h | 400 Wh |
| Total | 2,100 Wh/day |
This typical three-bedroom Kampala home needs about 2.1 kWh per day.
Step 2 – Choose your autonomy days
Autonomy days are how many days of cloudy weather your battery bank can survive without the sun. For Uganda, 1.5–2 days is the standard recommendation. During a rainy spell you rarely go more than two days without enough sunshine to at least partially recharge.
Required battery capacity = Daily Wh × Autonomy days ÷ Depth of Discharge (DoD)
For a lithium (LiFePO4) battery with 80% DoD: 2,100 × 2 ÷ 0.8 = 5,250 Wh ≈ 5.3 kWh
That is roughly a 100 Ah / 48 V lithium battery pack, or 200 Ah / 24 V.
Step 3 – Size the solar panels
Panels must replace the daily consumption plus charge losses (inverter and wiring losses add ~20%):
Required panel wattage = (Daily Wh × 1.2) ÷ Peak sun hours = (2,100 × 1.2) ÷ 5.2 = 484 W of panels
Round up to the next standard size. A 3 × 200 W = 600 W array gives you comfortable headroom for cloudy days and future load growth.
Step 4 – Choose the inverter/charge controller
For a home system you have two common paths:
- Hybrid inverter (MPPT built-in): easiest to wire, single unit. Look for a unit rated at least 20% above your peak simultaneous load. For the example above, peak load ≈ 310 W, so a 1.5 kVA or 2 kVA hybrid is correct.
- Separate MPPT charge controller + pure sine inverter: more flexible, cheaper to repair. Size the MPPT for your array voltage and current (e.g., a 60 A / 48 V MPPT for a 600 W array at 48 V).
Uganda-specific tips
Dust: Red murram dust settles on panels quickly in the dry season. Budget for cleaning every 2–3 weeks or install tilted panels (≥15°) so rain does the job.
Grid as backup vs. off-grid: If you are in a Kampala suburb with intermittent Umeme supply, a hybrid with grid-tie capability lets the grid top up the battery during rolling outages without running a generator.
Buy certified panels: Counterfeit panels are common in Owino market. Always ask for the IEC 61215 certificate and check the QR code on the panel frame links to the manufacturer site.
Quick rule of thumb
For every 1 kWh of daily consumption you need roughly:
- 250 W of solar panels
- 2 kWh of battery storage (lithium) or 3 kWh (lead-acid)
- 1 kVA of inverter capacity (minimum)
Next steps
Once you have your numbers, compare full kits against buying components separately. For loads under 3 kWh/day, an all-in-one kit is usually cheaper installed. For larger sites, separate components give you more flexibility. Talk to our technical team — we size systems for free and carry all major brands in stock.