Solar Photovoltaics

1. Solar Photovoltaics

2. Solar Photovoltaics(PVs) • Make electricity directly from sunlight without pollution, moving parts, or on site noise • Sun covers the Earth with over 5,000 times as much energy as is used by all of humanity • PV panels have limited efficiency and buildings have limited area for them • Generally expensive • Use passive designs before using solar electricity generation

3. PV Power Production • Depends on 5 main factors • Site conditions: latitude, longitude, and local weather • Orientation and exposure of the panels to the sun • Efficiency of the panels • Available area for the panels • Power conversion electronics

4. Site conditions • How much sunlight hits the site? • Known as “solar potential”, “incident solar radiation”, or “insolation” • Wh/m2 x day • kWh/m2 x year • Look at various maps available • Determine how man kilowatts of energy strike the site per square meter per year to help calculate the size and efficiency of the PV you will need

6. Orientation • More directly the sun shines on it the more energy generated • Use the same angle as the latitude (in degrees) • To max for winter add 15 degrees, for summer subtract 15 degrees • Some are mounted on poles and follow the suns path

7. Efficiency (5-20%) • Crystalline Silico – higher efficiency, lost performance in overcast skies • Thin Film • Concentrating – require full direct sun

8. Area • Depends on the efficiency of the panels and amount of sunlight • Less expensive panels require more area • Typically on roofs, but over parking areas provides shade • Building integrated photovoltaics are built into building products