Planning an On Grid system

In the case of PV On-Grid systems, the system sizing depends on profitability, the energy price or feed-in tariff, available mounting area and approved or connectable PV power.

Factors affecting design

• The most important requirement is the roof orientation

• Optimal inclination angle between 30 – 45°
• Transmission possibility of a PV system to the local electricity network/provider (connecting approval)
• Restrictive avoidance of shadowing of the PV system (chimneys, trees, constructions etc.) Shadowing affects the output of the system majorly.
• Additional ventilation shaft for PV cables
• Space for inverter in a cool and easily accessible location (inside or outside if IP65)
• Grounding and lightning protection on roof, overvoltage protection DC/AC site.
• Calculate additional roof specifics:
  • For inclined roofs approx 25kg/m² (range 15-30kg/m²) or ca 180kg per 1kWp installed PV power.
    The needed mounting area for a 1kWp PV system in crystalline technology will be around 7m².
  • For flat roofs approx 50kg/m² (range 7-70kG/m²) or ca 360kg per 1kWp installed PV power.
    The area-use ratio is about 30%, ie. from 100m² flat roof or land area, can be approx 30m² PV surface area mounted and a 4kWp PV system in crystalline technology.
  • For thin-film PV technology, the applicable PV power will be around half less, or the needed mounting area (PV surface) and system weight twice big.