How to Calculate Solar System Size in Thika – 2025 Step-by-Step Guide

How to Calculate Solar System Size in Thika – 2025 Step-by-Step Guide
Published/Updated: 1 December 2025

If you live in Thika, Kamakis, Thika Road, Eastern Bypass, Ruiru or Juja and you’re tired of high KPLC bills (now averaging KSh 12,000–25,000 per month for most homes), calculating the correct solar system size is the first and most important step before buying anything.

This simple 2025 guide shows you exactly how to size your solar system using real Thika sunshine numbers and the latest prices.

Why Thika is Perfect for Solar in 2025
- Average 5.5–6 peak sun hours daily (one of the highest in Kenya)
- Zero-rated VAT on all solar products
- KPLC tariffs keep rising → payback now 3–5 years instead of 7–8 years

Step 1 – Find Your Daily kWh Usage
Check your latest KPLC bill → look for “Units Consumed” (kWh this month) → divide by 30.

Example (very common in Thika):
Monthly bill 600 kWh → Daily usage = 600 ÷ 30 = 20 kWh/day

Real Thika averages we see daily:
• 1–2 bedroom house/flat       → 6–10 kWh/day
• 3–4 bedroom bungalow         → 13–22 kWh/day
• 5+ bedroom or with AC/pump   → 25–45 kWh/day
• Small shop/factory            → 40–80 kWh/day

Step 2 – Calculate Required Solar Panel Size (kW)
Formula (works perfectly for Thika):
Solar panels needed (kW) = Daily kWh ÷ 5.5 peak sun hours

Examples:
10 kWh/day  → 10 ÷ 5.5 = 1.8 kW system
20 kWh/day  → 20 ÷ 5.5 = 3.6 kW → we round up to 5 kW inverter + panels
40 kWh/day  → 40 ÷ 5.5 = 7.3 kW → we recommend 8–12 kW system

Step 3 – Add 15–20 % for Real-World Losses
Dust, heat, inverter loss, wiring → always add 20 % extra.

Final formula we use for every Thika customer:
System size (kW) = (Daily kWh × 1.2) ÷ 5.5

Examples after losses:
20 kWh/day → (20 × 1.2) ÷ 5.5 = 4.36 kW → we install 5 kW or 8 kW system
40 kWh/day → (40 × 1.2) ÷ 5.5 = 8.7 kW → we install 12 kW system

Step 4 – Choose Real Inverter & Battery Sizes (What We Actually Stock in Thika)
Daily Usage     | Recommended Inverter | Solar Panels | Battery Bank (1-day autonomy)
10–15 kWh       | 5 kW                 | 6–8 × 550W   | 2 × 5.12 kWh lithium
16–25 kWh       | 8 kW                 | 10–12 × 550W | 3–4 × 5.12 kWh
26–40 kWh       | 12–16 kW             | 16–20 × 550W | 6–8 × 5.12 kWh
40–70 kWh       | 20–30 kW             | 25–40 × 550W | 10–16 × 5.12 kWh

Not sure of your exact kWh? Use our free solar calculator here → https://globussolar.com/solar-system-culculator/

Factors That Change System Size in Thika Area
- If you have a borehole pump → add 2–5 kW extra
- If you want 2-day backup (common in Kamakis & Eastern Bypass) → double the batteries
- Roof facing south = maximum output; east/west still works well

Ready for Your Free Quotation?
We do free site visits and exact sizing within 24 hours in Thika, Kamakis, Thika Road, Eastern Bypass, Ruiru, Juja & Gatundu.

Call/WhatsApp now: 0794 485 343
We reply in minutes! https://globussolar.com/solar-system-culculator/