# 3kW vs 5kW vs 10kW Solar System — Which is Right for Your Indian Home? **Last Updated:** February 1, 2026 One of the most common questions from people going solar in India is: **How big a solar system do I need?** Get this wrong and you'll either overspend (buying more than you need) or undersell (your solar barely makes a dent in your bill). This guide helps you find the perfect size. --- ## The Basic Rule: Match Your Average Monthly Consumption The easiest way to size your solar system: **System size (kW) = Monthly units consumed ÷ 120** *(120 is an approximate multiplier for most Indian cities with 5 peak sun hours)* ### Quick Sizing Table: | Monthly Bill | Monthly Units | Recommended Size | Expected Generation | |-------------|---------------|-----------------|-------------------| | ₹500–₹1,500 | 100–200 units | 1–2 kW | 130–260 units/month | | ₹1,500–₹3,000 | 200–350 units | 2–3 kW | 260–390 units/month | | ₹3,000–₹5,000 | 350–500 units | 3–5 kW | 390–650 units/month | | ₹5,000–₹8,000 | 500–750 units | 5–7 kW | 650–910 units/month | | ₹8,000–₹15,000 | 750–1,200 units | 7–10 kW | 910–1,300 units/month | --- ## 1 kW Solar System **Monthly Generation:** 110–140 units (India average) **Cost (2025):** ₹55,000–₹75,000 (before subsidy) **After Subsidy:** ₹25,000–₹45,000 **Roof Area Needed:** 80–100 sq ft **Ideal for:** - Small 1 BHK apartments - Homes with bills under ₹1,000/month - Rural homes with minimal appliances - Backup for essential loads (lights, fans, small TV) **Typical Appliances Covered:** 6 LED lights, 3 fans, 1 TV, occasional mobile charging --- ## 2 kW Solar System **Monthly Generation:** 220–280 units **Cost (2025):** ₹1,10,000–₹1,50,000 (before subsidy) **After Subsidy:** ₹62,000–₹1,02,000 (max subsidy ₹48,000) **Roof Area Needed:** 160–200 sq ft **Ideal for:** - 2 BHK apartments - Homes with bills of ₹1,500–₹2,500/month - One small air conditioner (if used selectively) **Typical Appliances Covered:** All lights and fans, refrigerator, TV, 1 AC (2–4 hours/day) --- ## 3 kW Solar System — Most Popular Choice **Monthly Generation:** 330–420 units **Cost (2025):** ₹1,50,000–₹2,00,000 (before subsidy) **After Subsidy:** ₹72,000–₹1,22,000 (max subsidy ₹78,000) **Roof Area Needed:** 240–300 sq ft **Ideal for:** - 3 BHK homes — the most common choice - Monthly bills of ₹2,500–₹4,000 - 1–2 air conditioners - Middle-class families **Typical Appliances Covered:** All standard home appliances + 1–2 ACs (4–6 hours/day) **Why it's popular:** Gets maximum PM Surya Ghar subsidy (₹78,000), fits most rooftops, and eliminates 80–100% of typical household electricity bills. --- ## 5 kW Solar System **Monthly Generation:** 550–700 units **Cost (2025):** ₹2,50,000–₹3,25,000 (before subsidy) **After Subsidy:** ₹1,72,000–₹2,47,000 (subsidy capped at ₹78,000) **Roof Area Needed:** 400–500 sq ft **Ideal for:** - Large 3–4 BHK homes or villas - Monthly bills of ₹5,000–₹8,000 - Multiple ACs or heavy appliances - Small home-based businesses (salon, small shop) **Typical Appliances Covered:** Full home load including 2–3 ACs, washing machine, water heater (geyser), computers --- ## 10 kW Solar System **Monthly Generation:** 1,100–1,400 units **Cost (2025):** ₹5,00,000–₹6,50,000 (before subsidy) **After Subsidy:** ₹4,22,000–₹5,72,000 **Roof Area Needed:** 800–1,000 sq ft **Ideal for:** - Large bungalows or farmhouses - Monthly bills of ₹8,000–₹15,000 - Home with EV charging or large pool pump - Small commercial establishments --- ## Roof Space: Do You Have Enough? Approximate roof area per kW of solar: | Panel Type | Area per kW | |------------|-------------| | Standard Mono PERC | 80–100 sq ft | | High-efficiency TOPCon | 65–80 sq ft | | Bifacial panels | 75–90 sq ft | **Important:** Not all of your roof is usable. Deduct area for water tank, staircase room, shading from walls, and maintain spacing for maintenance access. Typically usable area = 50–70% of total terrace area. --- ## On-Grid vs Off-Grid: Which System Type? ### On-Grid (Most Common, Recommended): - Connected to DISCOM grid - Works with net metering - No battery required (most affordable) - Eligible for PM Surya Ghar subsidy - Powers home during day, draws from grid at night ### Off-Grid (With Batteries): - Works independently from grid - Needs battery bank (adds ₹60,000–₹2,50,000 to cost) - Ideal for areas with frequent power cuts - Not eligible for PM Surya Ghar subsidy - Higher maintenance ### Hybrid (Best of Both): - On-grid with battery backup - Stores excess solar in battery, uses when grid fails - Most expensive upfront - Growing in popularity in metros with occasional cuts --- ## How to Calculate Your Payback Period **Payback Period (years) = Net System Cost ÷ Annual Savings** **Example for 3 kW in Pune:** - System cost: ₹1,75,000 - Subsidy: ₹78,000 - Net cost: ₹97,000 - Monthly savings: ~₹3,500 (350 units × ₹10/unit) - Annual savings: ₹42,000 - **Payback: 97,000 ÷ 42,000 = 2.3 years** After payback, you generate free electricity for another 22+ years. --- ## Get a Free Quote for the Right System Size The best way to know what size you need is a site visit from a professional installer who will assess your roof, consumption, and give you an accurate system design. 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