1. What is solar thermal?
Solar thermal is the specialist term for heat produced using solar energy. Thermal collectors convert sunlight into heat which is used for hot water, for back up heating or for heating a swimming pool. It may also be used to heat air directly using hot air collectors.
2. What is Photovoltaic solar energy?
The word Photovoltaic (PV) is composed of two terms: Photo - Photon which means "light" and Voltaic from "Volt" which is the unit used to measure electric potential at a given point.
Photovoltaic systems use cells to convert sunlight into electricity. PV cells can be made from different so-called semiconductor materials. Today, silicon is the most widely used material, but other, usually compound (made from two or more elements) semiconductors is also used. They are silent and non-polluting, utilise a source of energy that renews itself, and require no special training.
3. What difference is there between thermal solar energy and Photovoltaic solar energy?
The photovoltaic solar energy system converts sunlight directly into electric power to run lighting or electric appliances. A photovoltaic system requires only daylight (non direct sunlight) to generate electricity.
The solar thermal energy system generates and produces heat. This energy can be used to heat water or air in buildings or in many other applications.
Both use the irradiance of the sun even if the technology is quite different.
4. Can solar collectors be mounted on the flat surface?
Yes they can be mounted on a flat roof, or on the ground by using the Flat Roof Frame. The collector should be installed at a minimum of 20 degrees angle to ensure optimal heat pipe operation.
5. Can solar collectors be used in the cold conditions?
Yes. Solar collectors can be used in temperatures as low as -35。C, although performance is reduced in such extreme conditions. We have exported to Russia, Finland and other cold areas.
6. How do solar systems benefit the environment?
A three-person household would use a solar tank with a volume of 300 litres and a collector surface area of 6 m². In 25 years, this solar system will have provided 60,000 kWh of energy for hot water production. This will save one ton of CO2 emissions each year - in a single household.
7. Do the solar systems still operate when it's cloudy?
On cloudy days in the summer, the solar system still uses up to 80% of the solar radiation, and in the winter it uses 25% of the radiation of a solar day. In these cases the solar system uses the diffuse radiation reflected by the clouds.
8. Is the collector protected from hail and lightning?
All high quality solar collectors are equipped with certified heavy duty solar glass and can withstand hail. To protect the system from lightning strikes, it is recommended that a lighting rod be affixed to the house.
9. How long will it take to recoup my investment？
SolarMaster solar collectors are much more affordable than many other solar hot water heaters. For a household of 4, the price of a full system may be similar to that of a new electric or gas system. Depending on your location (solar levels) and current hot water usage, the annual electricity or gas saving will differ. However in a normal household that spends 25% of its electricity bill on hot water heating, the full cost of the purchase may be recouped as quickly as 4-5 years in reduced bills. You will definitely make considerable savings during the life of the solar hot water heater.
10. What is the lifetime of a Photovoltaic system?
The estimated lifetime of a PV module is 30 years. Furthermore, the modules' performance is very high providing over 80% of the initial power after 25 years which makes photovoltaic a very reliable technology in the long term.But this doesn't mean that PV systems don't produce energy after 25 years. Most PV systems installed more than 25 years ago, still produce energy today!
11. Does a PV system require any maintenance?
A PV system requires very little maintenance as the glass is self cleaning with aid of sun and rain, however a 5 year inspection would be wise.
12. What is a Photovoltaic system composed of?
Elements of a grid-connected PV system are: PV modules - converting sunlight into electric power, an inverter to convert direct current into alternating current, sub-construction consisting out of the mounting system, cabling and components used for electrical protection, and a meter to record the quantity of electric power fed into the grid.
Off-grid (stand-alone) systems use charge controllers instead of inverters and have a storage battery for supplying the electric energy when there is no sunlight e.g. during night hours.
13. What can solar thermal technology be used for?
There is a wide variety of applications for solar thermal technology. The most common application is the heating of pool water, the heating of domestic hot water and space heating. Not very wide spread yet are solar cooling systems, because of the complexity of the technology and the high initial investment costs. Also, process heat applications such as in breweries or car washes, as well as in the food and textile industries, are still in their infancy.
14. What is the difference between vacuum tube collectors and flat plate collectors?
With flat plate glazed collectors the absorbers are fitted in a box closed by a pane of glass (90 % market share in 2009 in Europe). Vacuum tube collectors – which are the dominating technology in China (96 % market share in 2008) – have the absorber coating on the outside of the inner tube in placed within an evacuated glass tube. Generally speaking, the advantage of vacuum tubes is a higher efficiency (less space required for the collector on the roof) and higher temperatures (necessary for process heat and some solar cooling technologies).
15. Is solar thermal technology still a niche market?
There are a number of mature markets like Israel, Austria, Barbados, China or Cyprus where solar thermal is used by a wide majority of people for heating the domestic hot water and sometimes for room heating.
One factor that shows the market penetration of this technology in a certain country is the total capacity installed per capita. In Cyprus there were 0.65 kWth in operation per capita at the end of 2007 followed by Israel (0.5 kWth/head), Austria (0.23 kWth/head) and Barbados (0.2 kWth/head). You find niche markets when looking at market penetrations such as in the United States with only 0.006 kWth per capita or in sunny South Africa with so far not more than 0.0036 kWth per capita. Also, there is still quite a large untouched potential worldwide in using solar thermal technology for cooling and for supplying process heat.