Sizing a Rooftop Solar System

A well-sized system balances your energy needs, your roof and your budget. These steps give you a realistic starting point before a site assessment.

Step 1: Check your consumption

Collect several electricity bills and note the monthly units (kWh). Divide by the number of days to estimate daily consumption, and note seasonal changes such as air conditioning in summer.

Step 2: Decide what solar should cover

Choose whether solar should offset part of your daytime use, most of your consumption, or supply backup loads with batteries.

Step 3: Estimate system size

Divide the daily energy you want from solar by the average daily peak sun hours for your location, then allow for system losses from temperature, dust, cabling and inverter efficiency. The result is an approximate kWp size.

Step 4: Check the roof

• Available shade-free area and orientation
• Roof type: RCC slab, tin shed or other
• Structural condition and access for maintenance

Divide the kWp target by the panel wattage to estimate the number of panels, then confirm they fit the roof layout.

Step 5: Match the inverter and protection

Select an inverter whose PV input range suits the panel strings and whose output suits your loads and phase. Add DC and AC protection, cabling and mounting structures to complete the system.

Final sizing should always be confirmed on site. Send your bills and roof photos to SMART TECH for a technical review.