FAQ's
A1b For PV power, there are many sizes of panels; to power the average house (for most of the time) at least 3kW of power is needed and can require at least 15 kWh insolation of the PV arrays. The required total area is about 200 sqft.
A2a Solar thermal collectors as flat plates cost from about $2,000 to $4,000 installed for residential systems (for 40 to 80 gallons per day usage) [flasolar.com]
A2b Evacuated tube collectors cost more, ($3,000 - $6,000 installed).
A2c PV power typically cost from $2.50 - $4.00 per Watt.
A3a Two flat-plate collectors will yield about 250,000 BTU.
A3b Evacuated tubes usually come in 1 square meter; they are more efficient than flat-plate collectors and yield 30% more heat.
A4a Solar thermal collectors provide very cheap heat to warm water or space. These work well with good insulation and radiant floors. FSEC† found that solar water heaters offer potential savings, compared to electric water heating, of as much as 50% to 85% in the water heating portion of the utility bill.
A4b Solar PV collectors are effectively used for water pumping, transferring or circulating air, and battery charging. PV power can provide emergency power for safety lighting, medical equipment, fireplace fans, and well pumps.
† FSEC Florida Solar Energy Center