Solar HeatingEvery school-age child knows that solar energy is the power provided by the sun. The sun is earth's main source of heat and light since the beginning of time. Due to the fast depleting natural resources and the alarming rate of pollution due to carbon emission and greenhouse effect, there is a growing thrust to revert (at least in part) to solar energy.
At present China is the top country that has maximized the full potential of solar energy by harnessing the sun's renewable energy for solar heating. Although solar heating panels have been introduced back in the 1970s to the 1980s in the United States, the technology did not really catch on as most of the companies went bankrupt. However, as new solar heating panels are now in the market, it can be safely said that solar heating panels are now very efficient.
Active and Passive Solar Heating
There are two kinds of solar heating: active and passive. Active solar heating requires a form of solar collector to harness the sun's power and store it. The system has a control unit for the pumps and fans that draw and process the collected energy from the storage as needed. Active solar heating uses the sun's energy to heat space or water either directly or indirectly with the use of solar collectors.
Passive solar heating does not use any mechanical means to harness the sun's energy. This system is dependent on the general architectural design of the house, the materials used and the absorptive components of a building. The orientation of the house plays an important role in this case as its windows should generally face south. The house itself is the solar collector and the storage device. Adobe stone is an example of a great natural material that collects heat from the sun during the day, stores it then releases it gradually during the night.
Photovoltaic Panel and Thermal Panel Solar
Solar panels are convenient in a way as they have no mechanical parts that need to be maintained or replaced. You basically just have to mount them on your roof or at your backyard out in the sun, hook the necessary wires and the panels will do their work. Solar panels that came out in the 1980s are still in working condition today.
There has been a lot of confusion between photovoltaic solar panels and solar thermal panels. The two systems are both alternative active solar heating (both are solar panels) but their systems are different.
In a nutshell photovoltaic panels will convert the sun's energy that it has collected into solar electricity. If you have sufficient panels to supply the electric wattage necessary to run your whole house, then it could be said that you do not need to subscribe from the local electrical power supply because your photovoltaic panels are sufficient. You are therefore living "off-grid". Photovoltaic solar panels may also be installed only for powering the boiler for the hot water supply. If this is the case, then the required panels would definitely be a lot less than when harnessing the sun's radiation for the whole house.
Solar thermal panels are mostly used for heating the water supply. However, it also has the capacity to collect enough heat to distribute throughout your home. Solar water heaters were first used in the 1940s and then a boom in the late 70s to early 80s during a worldwide energy crisis. A drop in solar water heaters interest came when energy crisis was averted but in today's current energy and pollution scenario, solar water heaters have comeback. Not only can they be used for heating the house's water supply for they can also be used for heating up swimming pools and spaces.
Solar Thermal Panels and Photovoltaic Panels Compared
Solar thermal panels can collect up to 70% of the sun's radiation while a solar PV only converts 12% its harnessed sun's radiation into solar electricity. If this is the case then you would only need about 42 square meters of collectors to produce enough energy to power up a typical gas furnace. This would translate to less area and less panels of solar collectors therefore less expenditure for the panels. Note that PV panels are five times more expensive than thermal panels whereas thermal panels are six times more efficient than PV panels.
The downside is, PV panels are efficient all year round while solar thermal panels are only at its peak during the summer and at its lowest when they are most needed during the cool seasons. Solar thermal heat is not easy to store especially when your house has not been fitted with an efficient thermal mass walls or floors. However, solar-heated water is almost always routed to through a conventional water heater where it gets a temperature boost before being distributed to its point of use. Solar-heated water using the passive system is highly recommended in warm climates. Another method is the passive thermosiphons where water collector goes to the rooftop tank where it displaces the cold water that is returned to the bottom of the collector for heating. Countries in the tropical zone can store heated water in their storage tanks for as longs as 3 to 4 days.
In the UK, solar thermal water heating is the general choice for heating water supply because of a shorter payback range of 7 to 15 years as compared to photovoltaic 20 to 30 years payback. Also, there are more qualified contractors of solar water heaters in the UK as the installation of such system requires expertise. There is a need for computation of panels needed, the plumbing requirement and other necessary installation for the solar heating to function effectively.
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