Solar Thermal
Heating water with the sun is as old as man. However, the technologies developed in solar thermal panels in the past few decades have brought the possibity of using the renewable resource of the sun for heating either water or air as a viable option almost anywhere you live.
We typically use an active indirect closed loop system: An active system means that a pump is used to actively circulate the water/glycol solution through the system; an indirect system heats the gylcol solution through the panels and sends it to a heat exchange unit where it heats the water; and a closed-loop system continually recirculates the same glycol solution through the entire system.
Heated water from a solar thermal system can then be stored in a solar thermal tank to be used as needed. Another popular option is to use the preheated water from the solar tank to supply a Tankless Water Heater. The tankless on-demand system gives the residential user the comfort of a back-up system, yet allows for decreased energy costs since the preheated water allows for a lower consumption of energy by the tankless water heater.
Solar Thermal Panels
Solar thermal panels come in 2 basic designs: Flat Panel and Evacuated Tubes.
Flat Panel is the most common. They can be used to heat either water or air. It is essentially a blackened matrix radiator with darkly coated copper tubes wound back and forth throughout the panel. It can then be covered with a glazing material to protect the system and control the temperature of the system.
Evacuated Tubes are based on the same design of your thermos: create a vacuum space between 2 other layers to act as an insulator to decrease energy loss. Although evacuated tube solar panels come with a higher initial price tag, they also perform better on overcast days since they have the ability to absorb infared energy. This feature makes evacuated tubes more attractive in cooler climates.
Photovoltaics
Photovoltaic panels differ from solar thermal in that they produce DC electricity directly from the sun. PV panels vary in cost and efficiency depending on the material used in the manufacture. Listed in increasing order of efficiency and cost, PV panels are made of one of the following: amorphous silicon, string ribbon, polycrystalline silicon, monocrystalline silicon, and Group III–V Techonologies such as gallium arsenide or copper indium diselenide (CIS).
Depending on your location in the United States, a site's photovolatic economics and paybacks can vary. Obviously the greater the sun potential of your site, the shorter the payback period. Insolation is a measure of the available energy from the sun. It is expressed as “full sun hours of irradiance level of 1000 watts per square meter”. It can be measured directly at your site with solar monitors, or you can consult a solar insolation map of the United States such as the one found at the NREL website
Hybrid Systems
Although off-grid systems with batteries are available, typically the Solar PV system is grid-tied to the utility through your electrical panel after converting the DC power into useable AC power with an inverter. In conjunction with net-metering, the ability of the utility to buy back the power you generate, Federal and State Incentives, decreasing costs of solar PV systems in conjunction with increased efficiencies, the economic viablilty becomes increasingly more attractive.
Hybrid Systems, a combination of solar and wind (either Horizontal Wind or Vertical Wind ), can make the economics even better. In many parts of the country, the greatest sun resource is in the summer months, and the greatest wind resource is during the cooler months. A hybrid system would enable year round energy production from renewable energy sources.
Links
Bright Idea Energy Solutions is a registered dealer for the following solar manufacturers and/or wholesalers:
Next Generation Energy has developed many of their own solar products and also distributes solar products from many of the major manufacturers. Next Generation Energy prides itself in its engineering and sales support for turnkey installations. Next Generation has developed a state of the art racking system called Zilla™ that is "So Simple It's Scary™."
AEE Solar has been in the renewable energy business since 1979, and is a wholesale distributor for most of the major solar manufacturers in the industry. They have a complete online catalog that is viewable in pdf form, and have one of the most extensive inventories in the industry. They pride themselves on "being more than a business. It is a way of life."
