Presentation on theme: "AKA Solar Thermal. Solar Thermal vs Solar Photovoltaic Solar Photovoltaic(PV for short) Converts sunlight into electricity 20% efficient 15,000 megawatts."— Presentation transcript:
Solar Thermal vs Solar Photovoltaic Solar Photovoltaic(PV for short) Converts sunlight into electricity 20% efficient 15,000 megawatts worldwide Solar Thermal Directly heats fluid by solar radiation 60% efficient 450,000 megawatts worldwide
PV Cost and power output Solar PV $6-$7 per watt currently A typical 3 KW system generates 5500 KwH per year and costs around $18,000 5500 KwH = roughly $550 dollars worth of electricity 33 year payback(without subsidies) Until recently subsidies in Austin($3.75 per watt) and the federal tax credit pushed the payback time to less than 10 years. Some were getting “Free” systems in Austin
Solar thermal cost and power output A standard electric water heater uses 400-800 KwH per year. Sometimes more. A solar water heater can offset 80% or more of that cost. Costs around $6000 Payback 6-12 years depending on Home habits(showers, laundry, etc.) Payback 2-4 years with subsidies in Austin $2000 Austin Energy rebate 30% federal tax credit
How it works There are several different types Open loop-most common, used in warm climates Drainback-used in temperate climates Glycol pressurized-used in temperate climates Passive ICS DrainbackOpen Loop
Drainback Sytems Preferred system in Texas climate Panel must be located above drainback tank Uses gravity to drain the panel during freezing spells No glycol flushing required Stores water at temperatures of 150+ degrees.
Solar thermal worldwide Worldwide, Solar thermal produces 30 times as much energy as solar PV at a fraction of the cost. Over 90% of the homes in Israel and Cyprus use solar water heating due to high energy costs China has over 27 million rooftop solar water heaters. Millions installed worldwide. Very common in Germany, Austria, the Middle East, the Bahamas, anywhere energy prices are high. In the U.S., they are most common in Florida, California, and Hawaii Solar water heating is now code required in: Spain Israel Australia Hawaii
Environmental Benefits A standard water heater uses the equivalent of 11 barrels of oil per year Equal to the fuel consumption of a small car A gas water heater uses 250 therms per year. That’s 250,000 cubic feet of natural gas. In 2005, worldwide, solar water heating offset: 70 million barrels of oil 29 million tons of carbon emissions