Calculate the solar system size you need, installation cost, government subsidies, annual savings, payback period and 25-year ROI. Includes India PM Surya Ghar subsidy and net metering info.
☀️ Solar System Calculator
Region
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Recommended System Size
📊 Cost & ROI Breakdown
📈 25-Year Financial Projection
🏛️ Government Solar Subsidies
🇮🇳
PM Surya Ghar: Muft Bijli Yojana (2024)
India — Central Government Scheme
Subsidy slabs:
• Up to 1 kW: ₹30,000 subsidy
• 1–2 kW: ₹30,000 + ₹18,000 per additional kW
• 2–3 kW: ₹78,000 + ₹9,000 per additional kW (max ₹78,000 for residential)
• Above 3 kW: Fixed ₹78,000 subsidy
Eligibility: All residential consumers with grid-connected homes. Must use empanelled vendors via the National Portal.
How to apply: Visit pmsuryagarh.gov.in → Register → Apply for subsidy → Get empanelled vendor → Install → Claim subsidy.
Benefit: Also get 300 units free electricity per month for eligible beneficiaries.
🇺🇸
US Federal Solar Tax Credit (ITC)
30% of total system cost
The Inflation Reduction Act extended the Investment Tax Credit (ITC) at 30% through 2032. For a $20,000 system, you get $6,000 back as a federal tax credit. Many states offer additional incentives (net metering, state tax credits). Check dsireusa.org for state-specific incentives.
🇬🇧
UK — Smart Export Guarantee (SEG)
Export payments for excess generation
The UK discontinued the Feed-in Tariff in 2019. The Smart Export Guarantee (SEG) requires energy suppliers to pay for exported electricity. Typical SEG rates: 3-15p/kWh exported. No upfront subsidy, but 0% VAT on residential solar installations applies. Home Upgrade Grant may apply for low-income households.
📐 Solar System Sizing & ROI
System Size Calculation
Daily kWh needed = Monthly kWh / 30
System Size (kW) = Daily kWh needed
/ (Sun hours × (1 - System Loss%))
Example: 300 kWh/month, 5.5 sun-hrs, 20% loss
Daily kWh = 300 / 30 = 10 kWh
System kW = 10 / (5.5 × 0.80) = 2.27 kW
→ Recommend 2.5 kW (round up to nearest 0.5)
Net System Cost = Gross Cost - Subsidy
Simple Payback = Net Cost / Annual Savings
25-Year ROI = (Total Savings over 25 yrs - Net Cost)
/ Net Cost × 100%
Note: Savings increase each year as electricity
prices rise. Panel output decreases ~0.5%/year
due to degradation (most panels have 25-yr warranty).
Net Metering
When your solar system generates MORE than you use:
Excess units fed back to the grid
Credited at a buy-back rate (usually 2-4 ₹/unit)
When you use MORE than your system generates:
Draw from the grid at normal tariff rates
Net bill = Units consumed from grid × tariff
- Units exported × buy-back rate
With net metering, systems can reduce bills to near
zero for many households.
❓ Frequently Asked Questions
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