Design your complete solar system — calculate electrical load, solar panel sizing, battery backup, inverter capacity, and cable size. Built for homeowners, engineers, and solar installers.
This comprehensive calculator helps you plan every aspect of your electrical and solar energy system — from calculating your daily electrical load to sizing solar panels, batteries, inverters, and cables. Whether you're designing a home backup system, an off-grid cabin, or a commercial solar installation, this guide and calculator give you the knowledge and tools you need.
Electrical load is the total amount of power consumed by all your electrical appliances and devices, measured in watts (W) or kilowatts (kW). Understanding your load is the foundation of any solar system design because it determines how much energy you need to generate, store, and distribute.
Connected Load is the sum of all appliance wattages if everything runs at once. Actual Consumption is what you really use based on hours of operation. The difference is significant — most homes only use 30–50% of their connected load at any time.
Daily energy consumption = Sum of (Quantity × Wattage × Hours per day) for all appliances.
Example:
Total = 7,450Wh = 7.45 kWh per day
Solar panels convert sunlight into DC electricity. To size your array:
Required Solar Capacity (kW) = Daily Consumption (kWh) ÷ (Peak Sun Hours × System Efficiency)
Peak sun hours vary by location — typically 4–6 hours in Pakistan, India, and the Middle East. System efficiency (75–85%) accounts for losses from wiring, inverters, temperature, and panel degradation.
Example: 7.45 kWh ÷ (5 × 0.8) = 1.86 kW. With 550W panels: 1860 ÷ 550 = 4 panels.
Batteries store solar energy for use at night or during outages. Sizing depends on backup hours, voltage, capacity, and depth of discharge (DoD).
Battery Energy (Wh) = (Connected Load × Backup Hours) ÷ (DoD × Efficiency)
The inverter converts DC to AC. It must handle your maximum load plus surge for motors and compressors.
Inverter Size = Maximum Load × (1 + Surge%) × (1 + Safety Margin%)
Example: 3000W × 1.25 × 1.20 = 4,500W ≈ 5 kVA inverter.
Proper cable sizing prevents overheating, voltage drop, and fire risk. Cable area depends on current, voltage, length, conductor material (copper vs aluminum), and allowable voltage drop (2–3% typical).
Q: Can I run my entire house on solar?
A: Yes, if your solar capacity and battery storage match your daily consumption and backup needs.
Q: How many solar panels do I need for a home?
A: An average home using 10 kWh/day needs 8–12 panels of 550W each.
Q: What battery type is best?
A: Lithium-ion — higher efficiency, longer life, and deeper discharge. Lead acid is cheaper but requires more maintenance.
Q: Does this calculator work for three-phase systems?
A: Yes, it supports single-phase and three-phase cable sizing.
Q: Is solar power worth it in Pakistan?
A: Yes, Pakistan receives 5–6 peak sun hours daily, making solar highly viable with payback periods of 3–5 years.
Q: How long do solar panels last?
A: Most panels come with 25-year performance warranties, with 80% output guaranteed after 25 years.
Q: What maintenance does a solar system need?
A: Periodic panel cleaning, checking connections, and monitoring battery health.
Q: Can I expand my solar system later?
A: Yes, if your inverter and charge controller have spare capacity.
This tool brings together five essential calculations in one place — load analysis, solar sizing, battery backup, inverter capacity, and cable estimation. It saves you time, prevents costly mistakes, and gives you a complete picture of your energy needs. Whether you're planning a home solar system or a commercial installation, this calculator makes the process simple and understandable.
Disclaimer: Results are estimates for preliminary planning only. Final system design must be verified by a qualified electrical engineer and comply with local electrical codes and installation conditions.