Why Correct Sizing Matters
One of the most common mistakes Zimbabwean solar buyers make is choosing a system that is too small — and then blaming solar energy when it fails to meet their needs. An undersized system means battery depletion, load-shedding of your own appliances, and reduced lifespan for your batteries. An oversized system wastes capital you could spend on something else.
Getting the sizing right starts with understanding your daily energy consumption — which appliances you run, their power ratings, and how long you use them each day.
Step 1: List All Your Appliances
Write down every electrical appliance you want your solar system to power. For each one, note:
- Power rating (Watts) — usually on a label on the device or in its manual
- Quantity — how many of that appliance you have
- Hours per day — average daily runtime
| Appliance | Typical Wattage | Daily Hours |
|---|---|---|
| LED Bulb (9W) | 9 W | 5–8 h |
| TV (42" LED) | 80–120 W | 4–6 h |
| Fridge (200L) | 100–180 W | 8–12 h (compressor cycles) |
| Laptop | 45–90 W | 4–8 h |
| Phone Charger | 5–25 W | 2–4 h |
| Fan (standing) | 45–75 W | 4–8 h |
| DSTV Decoder | 25–40 W | 5–8 h |
| Router / Modem | 10–20 W | 24 h |
| Electric Kettle | 1,500–2,200 W | 0.25–0.5 h |
| Microwave | 800–1,200 W | 0.25–0.5 h |
| Iron | 1,000–2,200 W | 0.5–1 h |
| Geyser (electric) | 2,000–4,000 W | 1–3 h |
Tip: Avoid electric geysers, irons, and kettles on solar where possible — they are extremely power-hungry. A solar geyser or gas alternative is far more economical.
Step 2: Calculate Your Daily Load (Wh/day)
For each appliance, multiply: Qty × Watts × Hours/Day to get Watt-hours per day (Wh/day). Sum all appliances.
Rather than doing this manually, use our Solar System Sizing Calculator — enter your appliances and instantly get panel, battery, and inverter recommendations.
Step 3: Size Your Solar Panels
Zimbabwe receives an average of 5.5–6 peak sun hours per day — excellent for solar. To account for system inefficiency (about 20% loss from panels to battery to load), apply a correction factor:
Round up to the nearest standard panel size. A common configuration would be 4 × 200W panels = 800W to comfortably cover this load.
Step 4: Size Your Battery Bank
Your battery bank must store enough energy to power your home for 2 days of autonomy (in case of extended cloudy periods), at a maximum 50% depth of discharge (DoD) to protect battery life.
Common system voltages are 12V, 24V, or 48V. Larger systems should use 48V for efficiency. Lead-acid batteries are cheaper upfront; LiFePO₄ lithium batteries last 3–5× longer and are better value long-term.
Step 5: Choose Your Inverter
Your inverter must handle the peak simultaneous load — what runs all at once at the worst moment. Add 25% headroom:
Motor-driven appliances (fridges, pumps, air conditioners) draw 3–7× their rated wattage at startup. Always factor this in when sizing your inverter, or use a soft-start inverter.
Summary: Quick Reference Formula
| Component | Formula |
|---|---|
| Daily Load | Σ (Qty × W × Hours) |
| Solar Panels | Daily Load ÷ 0.8 ÷ Peak Sun Hours |
| Battery (Ah) | (Load × Days) ÷ (Volts × DoD) |
| Inverter (VA) | Peak Load × 1.25 |
Get a Professional Load Assessment
While this guide gives you a solid starting point, every home is different. Bluedrop offers free professional load assessments where our engineers visit your property, measure your actual consumption, and design a system tailored precisely to your needs — with a formal written quotation.
Contact us or use our Solar Calculator to start your sizing online.