Cost of Implementing a Solar System
The average lowest retail cost of a large photovoltaic array is approximately $4 a watt (down from $7.50 in 1990). The most common size module used is about 4′ 5″ x 2′ 2″ and produces 120 Watts. To power a small, occasionally used island cabin (approx. 400 sq. feet) a simple system can cost under $1000. For this price the system would include a 120W PV module and module mount, 2 deep-cycle batteries, a charge controller, a 400W inverter, fuses, and wiring. This type of system could run lights, radio, small TV, etc. but not a typical refrigerator. The module would produce about 0.5 kWh/day (under good solar conditions) and the batteries would store a useful 2 kWh.
If you were staying in the cabin full-time you would need to run appliances full time. This means that you would need more batteries, more PV modules and a bigger and better inverter. This would bring the cost of the system to between $3000 and $4000 excluding appliances.
If you wanted to have say, a 2,000 sq ft home on an island your system would need to be even larger. If you use 2000 kWh/month in the summer in the Phoenix area. That implies a fixed PV array of about 13,000 to 16,000 Watts! A system like that would cover about 1400 ft2 and typically cost between $70,000 and $90,000. However, most remote homes use propane for cooking and heating and propane or solar thermal for hot water. Taking this into consideration in combination with designing the house well, and using energy-efficient lights and appliances, one can often bring the cost of a solar electric system down to $25,000 to $30,000. Finally, your net cost could be reduced further with many jurisdictions now giving tax and rebate incentives. Some estimates are that solar electric power can now pay for itself in five to ten years in many places
