6.7.7 Describe the general principles of solar photovoltaic energy

• Photons of light excite electrons into a higher state of energy, allowing them to act as charge carriers for an electric current
• Multiple cells are combined into arrays to provide adequate voltage and power
• DC is converted to AC through an inverter
• PV: 12-50% direct conversion. Most are in the range 12-20%. Efficiency declines with age; systems last 10-30 years. Electricity is only generated when the sun shines: at maximum 50% of the time.