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Updated July 2026

Solar System Sizing & Design Calculators

Design your solar system correctly before you buy: the right kW capacity, panel count, roof space, tilt angle, load calculation and even the cable sizes.

Solar System Size Calculator The solar kW capacity your home needs, from monthly units or bill amount. How Many Solar Panels Calculator Calculate solar panels needed with 540W to 620W modules, from bill or system size. Solar Roof Area Calculator Shadow-free roof area needed per kW, or the system size that fits your roof. Solar Panel Tilt Angle Calculator Optimum tilt angle, direction and azimuth for your city, with seasonal settings. Solar Load Calculator Home load calculation appliance by appliance: connected watts and daily kWh. Solar Wire Size Calculator DC cable size in sq. mm with voltage drop checked against the 3% limit.

The Right Order to Design a Solar System

  1. Know your load: the solar load calculator converts your appliances into connected watts and daily units.
  2. Size the array: the system size calculator turns consumption into kW using your city's peak sun hours.
  3. Count the panels: the panel calculator translates kW into modules at your chosen wattage.
  4. Check the roof: the roof area calculator verifies the space, and the tilt angle calculator sets the mounting angle.
  5. Wire it safely: the wire size calculator keeps DC voltage drop under 3%.

Once the design is settled, move to the cost and finance calculators for pricing, subsidy and payback.

The Two Numbers Every Solar Design Starts With

All six tools here ultimately serve two figures, and confusing them causes most design errors. kWh (units) per day is energy: it sizes the panel array, because panels earn their keep over the whole day. Watts running simultaneously is power: it sizes the inverter and any battery, because those must survive the worst single moment. A home can use just 8 units a day yet need a 3.5 kVA inverter for one AC evening; another can use 15 units with a 2.5 kVA peak. Measure both honestly (the load calculator produces each) and every downstream decision, from panel count to cable size, falls into place.

Solar Sizing Calculators: Frequently Asked Questions

How do I size a solar system for my home?+
Divide your monthly units by (peak sun hours × 30 × 0.8) to get kW, then convert kW to panels and roof area. The calculators in this category do each step with real city data for 90+ Indian locations.
What is the most common mistake in solar system design?+
Sizing from a single winter bill. Indian consumption swings heavily with AC use, so a system sized on a mild-month bill undersizes badly. Use an annual average or the load calculator for an honest picture.
Do I need the wire size and tilt calculators as a homeowner?+
Your installer handles both, but checking their numbers takes a minute and catches corner-cutting: undersized DC cable and flat panel mounting are two of the most common quality shortcuts.
Are these design tools India-specific?+
Yes. Sun hours, latitudes, module wattages, roof norms and voltage conventions all reflect Indian residential practice in 2026, not US or European defaults.
What information should I gather before designing a system?+
Three things: twelve months of electricity bills (or the units line from each), a measured shadow-free roof area, and an honest appliance list with daily hours. With those, the six calculators here take you from consumption to a complete, quote-ready design.

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