Solar Power Requirement Calculator

Calculator Engine

Monthly Electricity Bill (NPR)

Avg Sunlight Hours/Day

Desired Backup (Hours)

System Voltage (Battery Bank)

Recommended for modern hybrid/lithium setups (High Efficiency).

Did you know? Nepal receives an average of 4.5 to 5 peak sun hours per day, making it an excellent location for solar energy harvesting.

Result Summary

Recommended System Size

2.31 kW

Panels (Approx)

6 x 400W

Storage Needed

29 Ah @ 48V

Estimated Annual Impact

Total Generation~3042 kWh

Potential Bill SavingsNPR 30,000

Note: Estimates are based on 80% system efficiency and standard 400W panels. Actual generation varies based on roof tilt, shading, and local weather patterns.

Nepal's Solar Resource & System Sizing Methodology

Nepal is exceptionally well-positioned for solar energy. With an average of 4.5–5.0 peak sun hours per day across most of the country (6+ in high-altitude Mustang and Humla), the country receives a solar irradiance of approximately 3.6–6.2 kWh/m²/day. Our solar calculator converts your monthly electricity bill into a precise system specification using the standard photovoltaic sizing methodology.

The calculation chain: Bill → kWh/month → kWh/day → System kW (adjusting for peak sun hours and 80% real-world efficiency) → Panel count (based on 400W panels, current market standard) → Battery capacity (Ah) for the desired backup duration.

Battery Voltage Selection Guide for Nepal

12V Systems: Small off-grid setups under 500W. Simple, low-cost. Common for basic lighting and phone charging in remote areas. Not suitable for modern inverters or whole-home backup.
24V Systems: Medium setups 1–3kW. Handles most appliances. Standard for many residential solar installations in Nepal with lead-acid batteries.
48V Systems (Recommended): Modern standard for whole-home solar (3kW+). Thinner wiring, higher efficiency, compatible with lithium iron phosphate (LiFePO4) batteries. Best option for new installations in 2025+.

How to use

Enter your average monthly electricity bill in Nepalese Rupees (NPR).
Adjust the average sunlight hours for your specific location (4.5 to 5 is typical for Nepal).
Specify how many hours of battery backup you need during load shedding or nighttime.
Select your preferred battery bank voltage (48V is recommended for modern systems).
The calculator will instantly provide your required system size (kW), the number of panels needed, and the required battery capacity (Ah).

Core Mathematical Logic

Our tool uses standard industry formulas adapted for maximum precision.

Result = f(Inputs)

Inputs = Your provided data

Result = The computed answer

Solar Requirement Calculator Guide

The Solar Requirement Calculator helps Nepali households and businesses determine the exact solar panel capacity, battery storage, and inverter rating needed to power their electrical loads. With Nepal's abundant sunshine (averaging 6.8 hours of peak sunlight daily) and the ongoing push to reduce dependence on the national grid and diesel generators, solar power is increasingly a practical and economical choice. You can gain deeper insights by using the matrix algebra console.

1. Nepal Solar Energy Quick Facts

Parameter	Nepal Value
Average Peak Sun Hours	5.0–6.8 hours/day (varies by region)
Best Solar Region	Mustang, Manang, Karnali (high altitude, minimal clouds)
Grid Solar Tariff (NEA)	Net metering available; Rs. 5.97/kWh buyback rate
Tax Exemption	Solar panels & equipment VAT exempted in Nepal
Typical Home System	1–5 kW for residential, 10–100 kW for commercial
Average System Cost (Nepal)	Rs. 1,20,000–1,50,000 per kW installed (2024)

2. Step-by-Step Solar Sizing Calculation

Formula: Solar Panel Wattage Required

Panel Capacity (W) = Daily Energy Need (Wh) ÷ Peak Sun Hours ÷ System Efficiency Additionally, the ideal weight calculator is highly recommended for related estimations.

Step 1: Calculate Daily Load Many users also utilize Probability Calculator alongside this analysis.

List all appliances × wattage × hours used. E.g.: 5 LED bulbs (10W × 5h) + fridge (150W × 24h) = 4,100 Wh/day

Step 2: Apply System Losses For a broader understanding, you may also want to explore this auto estimator.

Divide by efficiency (typically 0.75–0.80 for inverter + wiring losses): 4,100 ÷ 0.80 = 5,125 Wh needed from panels

Step 3: Divide by Sun Hours

5,125 Wh ÷ 5.5 peak hours = 932W ≈ 1 kW solar array needed If you find this useful, checking out the length converter can provide further context.

3. Battery Storage Sizing

Battery capacity ensures you have power at night or during cloudy days (common during Nepal's monsoon season June–September). Key formula:

Battery Capacity (Ah) = (Daily Wh × Backup Days) ÷ Battery Voltage ÷ Depth of Discharge (DoD)

Example: 4,100 Wh/day, 1 backup day, 48V system, 80% DoD (lithium): 4,100 × 1 ÷ 48 ÷ 0.80 = 107 Ah → use a 120 Ah 48V battery bank.

4. Off-Grid vs. Grid-Tied vs. Hybrid Systems in Nepal

System Type	Best For	Nepal Suitability
Off-Grid	Remote villages with no NEA connection	High – Rural hills and mountains
Grid-Tied	Urban areas with net metering benefit	Moderate – Available in Kathmandu, Pokhara
Hybrid	Both grid backup and battery storage	Best for Nepal – handles load shedding

NEA Bill Calculator Word Counter VAT Calculator

Frequently Asked Questions

Solar systems lose energy through: inverter conversion (DC to AC, ~5–10% loss), cable/wiring resistance (~2–3% loss), temperature derating (panels produce less at high temperatures), and dust accumulation. Cumulatively, 80% is the standard industry real-world efficiency factor used for sizing calculations.

For small setups (under 1kW), 12V is acceptable. For medium systems (1–3kW), 24V is standard. For whole-home setups (3kW+), 48V is strongly recommended, it allows thinner wiring, handles more power safely, and is compatible with all modern hybrid/lithium inverters available in Nepal.

Nepal averages 4.5–5.0 peak sun hours per day in the Terai and hilly regions. High-altitude districts like Mustang, Humla, and Dolpa receive 6+ hours, making them ideal for solar. Coastal/valley locations like Kathmandu average about 4.5 hours due to monsoon cloud cover (June–September).

As of 2025, a complete 3kW grid-tie solar system in Nepal costs approximately NPR 4–6 lakh, depending on panel brand, inverter type, and installation complexity. A 5kW system with lithium battery backup costs NPR 8–12 lakh. Payback period is typically 5–8 years given rising NEA tariffs.

For grid-tie systems (systems connected to the NEA grid) above 5kW, approval from the Nepal Electricity Authority (NEA) and your local distribution center is required. Off-grid systems and small on-grid systems under 5kW can typically be installed without prior government approval, though local bylaws may vary.

On-grid (grid-tie) systems feed surplus power back to the NEA grid and draw from it at night. They do not require batteries but provide no backup during outages. Off-grid systems use battery banks for 24/7 independent power. Hybrid systems combine both, grid-connected with battery backup for outages, which is the most popular option in Nepal today.