Solar Load Calculator — Rooftop Capacity& Inverter Sizing
Estimate your daily electricity units (kWh), recommended solar plant capacity (kW), inverter rating (kVA), number of 540W solar panels, and eligible PM Surya Ghar central government subsidy (up to ₹78,000) in seconds.
Direct Answer: How Solar Load & Inverter Sizing Is Calculated
Engineering calculation standard for residential and commercial rooftop solar in India
To calculate electrical load for solar panel installation, multiply each appliance's rated wattage by its daily run time, sum all watt-hours, and divide by 1,000 to determine daily consumption in kilowatt-hours (kWh). Next, divide your total daily kWh by your region's average peak sun hours (4.2 hours across North India and Delhi NCR) to calculate required solar plant capacity in kilowatts (kW). Inverter sizing is determined in apparent power (kVA) using the standard formula: Inverter kVA = Solar kW ÷ 0.85 Power Factor to safely absorb inductive motor surges from inverter air conditioners and water pumps. For an average home consuming 12–15 units per day, a 3 kW rooftop solar system requires a 3.5–4.0 kVA solar inverter, 6 × 540W monocrystalline panels, and 240 sq. ft. of shadow-free rooftop space, saving up to 90% on electricity bills with an approved ₹78,000 PM Surya Ghar subsidy.
Calculate Solar PV Capacity & Inverter Sizing
Estimate your solar plant kW, inverter kVA rating, 540W panel count, shadow-free roof space, and central PM Surya Ghar subsidy in real time.
Adjust the slider to match your property's typical monthly bill.
Your Sizing Results
Engineered for Delhi NCR solar conditions
Generates approx. 20.0 Units/Day (600 Units/Month)
How to Calculate Load for Solar Installation
A comprehensive step-by-step walkthrough of the electrical load calculation for solar panel setups used by professional solar EPC engineers.
1. List Appliances & Daily Wh
Multiply the rated wattage of each appliance by the hours it operates per day:
Divide total daily Wh by 1,000 to find your daily energy consumption in kWh (units).
2. Solar PV Sizing (kW)
Divide your daily kWh requirement by India's average peak sun hours (4.2 hours in Delhi NCR):
A home consuming 12 units/day needs approximately a 3 kW solar array.
3. Inverter kVA Sizing
Inverters must handle reactive power from motors and compressors. Size inverter kVA using:
For a 3 kW PV setup, choose a 3.5 to 4 kVA rated solar inverter to prevent tripping.
4. Rooftop Space Estimation
Calculate panel quantity and roof space using high-efficiency 540W monocrystalline modules:
Ensure the designated rooftop space is shadow-free between 9:00 AM and 4:00 PM.
Standard Indian Household Appliance Wattage Chart
Use this benchmark wattage reference table to calculate electrical load for solar panel sizing and battery backup requirements.
| Appliance Name | Typical Power Rating (Watts) | Average Daily Run Time | Daily Consumption (kWh) |
|---|---|---|---|
| 1.5 Ton Inverter AC (5-Star) | 1500 W | 8 Hours | 12.0 kWh |
| 1.5 Ton Split AC (3-Star) | 1800 W | 8 Hours | 14.4 kWh |
| BLDC Ceiling Fan | 32 W | 12 Hours | 0.38 kWh |
| Standard Ceiling Fan | 75 W | 12 Hours | 0.90 kWh |
| LED Bulb / Batten (10 Nos) | 150 W | 6 Hours | 0.90 kWh |
| Double Door Refrigerator (250L) | 200 W | 24 Hours | 1.80 kWh |
| Large Refrigerator (450L) | 350 W | 24 Hours | 2.80 kWh |
| 55-inch Smart LED TV | 100 W | 5 Hours | 0.50 kWh |
| Fully Automatic Washing Machine | 500 W | 1 Hours | 0.50 kWh |
| 1.0 HP Submersible Water Pump | 750 W | 1 Hours | 0.75 kWh |
| Microwave Oven | 1200 W | 0.5 Hours | 0.60 kWh |
| Storage Geyser (25L Water Heater) | 2000 W | 2 Hours | 4.00 kWh |
| Electric Vehicle (EV) Home Charger | 3300 W | 4 Hours | 13.2 kWh |
Solar Plant Capacity, Inverter kVA & Rooftop Space Matrix
Quick reference guide for common residential and commercial rooftop solar configurations in India.
| Solar Size (kW) | Inverter (kVA) | Daily Generation | 540W Panels | Roof Area | PM Surya Ghar Subsidy | Approx. Net Cost | Est. Annual Savings |
|---|---|---|---|---|---|---|---|
| 1 kW Solar System | 1.2 – 1.5 kVA | 4 – 5 Units/day | 2 Panels | ~80 Sq. Ft. | ₹30,000 | ₹30,000 – ₹35,000 | ₹11,500 / yr |
| 2 kW Solar System | 2.5 kVA | 8 – 10 Units/day | 4 Panels | ~160 Sq. Ft. | ₹60,000 | ₹60,000 – ₹65,000 | ₹23,000 / yr |
| 3 kW Solar System | 3.5 – 4.0 kVA | 12 – 15 Units/day | 6 Panels | ~240 Sq. Ft. | ₹78,000 (Max) | ₹1,02,000 – ₹1,12,000 | ₹36,000 / yr |
| 4 kW Solar System | 4.5 – 5.0 kVA | 16 – 20 Units/day | 8 Panels | ~320 Sq. Ft. | ₹78,000 | ₹1,55,000 – ₹1,68,000 | ₹48,000 / yr |
| 5 kW Solar System | 5.5 – 6.0 kVA | 20 – 25 Units/day | 10 Panels | ~400 Sq. Ft. | ₹78,000 | ₹2,10,000 – ₹2,30,000 | ₹60,000 / yr |
| 7.5 kW Solar System | 8.5 – 10.0 kVA | 30 – 35 Units/day | 14 Panels | ~600 Sq. Ft. | ₹78,000 | ₹3,40,000 – ₹3,70,000 | ₹92,000 / yr |
| 10 kW Solar System | 12.0 – 12.5 kVA | 40 – 50 Units/day | 19 Panels | ~800 Sq. Ft. | Commercial Tax Benefits | ₹5,20,000 – ₹5,80,000 | ₹1,30,000 / yr |
| 15 kW Solar System | 17.5 – 20.0 kVA | 60 – 75 Units/day | 28 Panels | ~1,200 Sq. Ft. | Commercial Tax Benefits | ₹7,50,000 – ₹8,40,000 | ₹2,00,000 / yr |
Solar Inverter Sizing: Real Power (kW) vs. Apparent Power (kVA)
Why an inverter rating in kVA must exceed the DC peak wattage of your solar PV array, and how power factor impacts real-world performance.
Power Factor (cos θ)
Real power (kW) performs actual mechanical or thermal work, while apparent power (kVA) represents the total power flowing through alternating current (AC) circuits. The ratio is the Power Factor (PF):
Residential homes operate at an average 0.80 to 0.88 power factor due to inductive motors.
Inrush & Motor Surge Headroom
Inductive loads such as 1.5-ton inverter air conditioners, water pumps, and refrigerator compressors draw 2.5× to 3× their rated current for 2–5 seconds during startup:
Sizing your solar inverter with a 15–20% buffer prevents nuisance tripping when compressors engage.
Hybrid Battery Sizing Formula
For hybrid or off-grid solar systems with energy storage, battery bank capacity is calculated using depth of discharge (DoD):
Lithium iron phosphate (LiFePO4) batteries allow 90% DoD, compared to 50% for tubular lead-acid batteries.
Why Property Owners Trust Brightleaf Energy for Rooftop Solar
From engineering load assessments to hassle-free PM Surya Ghar subsidy disbursement, Brightleaf Energy delivers turnkey rooftop solar installations backed by 25-year performance warranties.
Tier-1 Hardware & 25-Yr Warranty
We only install MNRE-approved Tier-1 TOPCon and Mono PERC solar panels with 25-year linear performance warranties and top-tier European/Indian inverters.
100% Subsidy Assistance
Our operations team manages your complete PM Surya Ghar Muft Bijli Yojana documentation, portal submission, and direct bank subsidy disbursement of up to ₹78,000.
Expert Inverter & Load Sizing
We perform an on-site electrical load calculation for solar panel readiness, ensuring your solar inverter rating matches heavy inductive loads like inverter ACs and EV chargers.
Fast DISCOM Net Metering
End-to-end liaisoning with BSES Yamuna, BSES Rajdhani, TPDDL, DHBVN, PVVNL, and NPCL for bidirectional net meter installation and grid integration.
3D Drone Shadow Analysis
Our rooftop solar calculations are verified on-site with drone surveys and 3D shadow simulation tools to optimize tilt angle and eliminate seasonal generation losses.
500+ Commissioned Plants
Trusted by hundreds of villas, independent builder floors, residential societies, and industrial plants across Delhi, Gurugram, Noida, Ghaziabad, and Faridabad.
3 Simple Steps to Your Custom Solar Sizing Estimate
Select Appliances & Daily Usage
Choose the appliances in your property — ACs, fans, lights, fridge, TV, washing machine, water pump — and set daily operating hours.
Review Plant Capacity & Inverter Sizing
Our tool instantly computes your daily energy consumption (kWh), recommended system size in kW, and optimal inverter rating.
Download Your Personalized Report
Get an engineering solar assessment with subsidy breakdown, net cost, payback period, and CO₂ offset sent to your email or WhatsApp.
Why Homeowners & Businesses Use This Tool
Instant Electrical Load Sizing
Execute complete electrical load calculation for solar panel setups in seconds without tedious manual formulas.
Dual kW & kVA Sizing
Get matching plant capacity and inverter ratings for surge-safe performance.
Accurate Rooftop Solar Space
Calculates realistic shadow-free rooftop space (approx 80 sq. ft. per kW) for high-efficiency 540W modules.
PM Surya Ghar Subsidy
Automatically factors up to ₹78,000 residential central government subsidy to reflect true net cost.
Downloadable PDF Report
Receive an engineering report detailing payback period, monthly unit output, and 25-year return on investment.
Free Site Assessment
Backed by Brightleaf Energy — Delhi NCR's trusted turnkey rooftop solar EPC company.
Frequently Asked Questions About Solar Sizing
How to calculate electrical load for solar panel installation?+
What is the difference between kW and kVA in solar inverter sizing?+
What is the standard formula for solar load calculation?+
How much rooftop area is required for 1kW, 3kW, and 5kW solar systems?+
How much government subsidy can I get under PM Surya Ghar Muft Bijli Yojana?+
How many units of electricity does a 1kW, 3kW, and 5kW solar system generate daily?+
Can this solar load calculator be used for commercial and industrial buildings?+
How long does it take to recover the cost of rooftop solar installation?+
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