The advantages and disadvantages of using solar panels have become a topic of interest and dispute in recent decades.
The fact that the balance tends to lean towards the benefits of renewable energy resources is confirmed by global public policies to encourage people to invest in unconventional heating and electricity systems. The immediate benefits are significant, the solar energy is non-polluting, inexhaustible and, above all, free.
How Does Solar Panels Energy Produce Electricity For your home Step By Step
Under the name of solar panels are found solar thermal panels for domestic hot water and photovoltaic panels that generate electricity.
Each of these is different not only by the form of released energy (thermal versus electric) but also by the technology implemented for heating hot water, respectively the conversion of solar energy into electricity. Therefore, the operating principles between the two are different, even if they use solar radiation as a free source of fuel.
Hot water panels are solar collectors that capture heat in tubes
Then it is taken over by a thermal agent, water or antifreeze, depending on the technology used. The heating of the domestic hot water takes place by heat transfer between the heating agent and the heat exchanger existing at the boiler level. In short, the operating principle is simple, consisting of the capture of solar energy in the form of heat.
Photovoltaic panels are more complex systems, provided with solar cells in which there are layers of semiconductor material (silicon). Photons from solar radiation hit the conducting surface, release electrons, producing an electric current. These photovoltaic solar panels are based on the operation of sunlight, specifically photons, photovoltaic cells being useless in the dark.
Simplifying to the maximum, the solar thermal panels work by capturing the solar heat, the photovoltaic panels are functional by the energy of the photons (light) at the level of the semiconductor surface.
What they are and how solar thermal panels work
The principle of operation of thermal panels (hot water) consists of capturing solar energy and converting it into thermal energy.
The sun’s radiation meets the absorption surface of the collector, the caloric energy being taken over by the thermal agent that flows through the thermo-conducting pipes (of copper or aluminum).
In the case of non-pressurized panels (by gravity drop), the transfer agent may even be domestic water, the alternative being solar antifreeze for evolved pressurized panels.
For the latter, the heat exchange takes place at the boiler level through a system of double coils.
As a general principle, heat transfer takes place through different technologies, different depending on the temperature level of the liquid (water or solar-glycol antifreeze). The circulation of the thermal agent can be ensured with or without electrical equipment, depending on the type of installation (for example, pumping group versus gravitational thermosiphon)
The most common solar panels for heating are those of low and medium temperature, using solar collectors with vacuum tubes or flat solar systems.
There are also high-temperature panels that are rarely used for domestic purposes. For these, high-performance solar installations such as solar towers or Fresnel reflectors are implemented.
What is the difference between solar panels and photovoltaic panels?
Solar panels are used for the production of domestic hot water or to contribute to the heating of the building while the photovoltaic panels are used for the production of electricity.
From which elements is the installation that ensures the heating of the water with the help of solar panels
The elements used in a solar panel installation depend on the automation (or nonexistence) of the collectors, the technology used and the integration into a complex heating system.
The cheapest hot water panels are represented by the models of non-pressurized manifolds that are composed of panels provided with absorption surfaces, tubes, and reservoir, clamping supports float vessel and various silicone gaskets.
Pressurized solar panels are more complex, but also more efficient. Depending on the brand and model they can be composed of:
- Solar collectors with a variety of tubes
- Solar-glycol antifreeze (as a thermal agent)
- Thermoelectric boilers or solar boilers
- automation
- Pumping groups
- Expansion vessels
- Air vents, pressure valves
Types of solar panels for heating
The types of solar panels for heating are classified according to the mode of heating, the complexity and the technology used.
The simplest equipment for heating domestic hot water is unseen solar panels, cheap, easy to install and maintain. The operating principle is simple, the system using solar energy to heat the water and the gravitational drop for its flow, the tank is above the pipe system.
Pressurized solar panels for hot water are complex types of equipment, doubled by automation, which are part of real systems that can be used including in-home heating. They can be used as water preheating equipment before entering the circuit, reducing gas costs.
They are much more expensive than non-pressurized variants, but the price of solar panels of this type is amortized from the monthly gas bills. Besides, as mentioned earlier for these heating systems, consistent grants are granted.
They can be used in large, even industrial or residential buildings.
However, there are limitations in the number of tubes in a system to avoid overheating and positioning them about geographical coordinates.
Depending on the technology used there are pressurized solar panels with a tank above the tubes and solar panels provided with a boiler in the house.
From the used absorption surface and the structure, there are two types of pressurized panels:
- Flat solar panels
- Vacuum solar panels – this category also includes the best solar panels on the market, heat pipe technology.
Flat systems of solar panels
Flat solar panel systems are the first non-conventional pressurized equipment on the market to be manufactured since the 1970s. At these, the housing is made of black galvanized metal that has the role of absorbing solar energy.
The annual solar energy absorption capacity for this type of system is lower than for vacuum tube panels. There are disputes that the flat panels would be more weather resistant than the vacuum collectors, but there are no differences, both being covered with glass. Moreover, repairs can be cheaper in the case of drain tubes, which are replaced individually.
Panel systems with vacuum tubes
Vacuum tube panel systems are complex technologies in which solar energy collectors are designed with borosilicate (very resistant) glass tube systems, placed in parallel and having an absorbent role. The outer tubes contain the second row of tubes, between the two being empty, hence the name. The vacuum has the role of eliminating the losses of convective heat. The inner tube is wrapped in absorbent material and surrounded by pipes through which thermal agent circulates (solar-glycol antifreeze).
These are very efficient solar systems that can cover up to 100% of the hot water requirement in summer and up to 80% in winter, depending on the weather conditions. A great advantage of this type of panel is that it works at lower efficiency including in winter or on cloudy days.
Under what conditions are recommended solar panels
To be functional, but especially efficient, solar panels must be located with maximum exposure to the sun. From here the positioning, based on the geographical coordinates and the inclination level of the panels, must be considered.
How to Get The Maximum Exposure to the sun?
For maximum sun exposure, solar heating panels should be located south. This is because the sun rises to the east and sets to the west, the highest radiation intensity being covered when the sun crosses the horizon line to the south.
Also for maximum exposure to the sun, the solar collectors with vacuum tubes should be mounted at an angle between 20-35 degrees.
Mounting possibilities
The solar panels can be mounted:
- On the ground – with supporting structures and implementation of complementary pipes up to the boiler
- On the roof-by mounting and mounting systems
In both cases, the geographical coordinates (facing south) must be taken into account. There must be no obstacles that prevent the absorption of solar energy (trees, fences, etc.).
The existence of a boiler compatible with solar panels
Pressurized solar panels can be used by connecting to compatible boilers, provided with special valves. If there is no possibility of connection to the equipment already installed, a second, compatible boiler can be installed, which can economically heat the water before entering the circuit.
At the moment on the market, complete packages consisting of pressurized solar collectors, boilers compatible with solar systems and the whole set of automation are sold.
Verification and maintenance of a solar panel installation
Maintaining an unconventional heating system is relatively simple, and the procedures and verifications of a solar panel installation are always carried out by specialized companies.
During the verification, the specialists aim first and foremost to inspect certain components such as location, ACM flow rate, antifreeze concentration, the pressure of the expansion vessel and the degree of valve wear, the valve that makes the connection to the boiler, the functionality of the anti-freeze protection.
The advantages of using solar panels
The benefits of using solar panels have made them increasingly popular with consumers. Ecology and environmental impact mitigation is the most widely publicized benefit. The list is much longer and involves sustainability and long-term savings
Solar energy brings advantages and disadvantages, the benefits tend to outweigh any less convenient aspects. The sun as an inexhaustible source of energy, the free use of solar energy and the reduction of heating costs through the use of an ecological source, the low maintenance costs are the most important arguments.
Using an ecological source and reducing the CO2 footprint
From the governmental level, NGOs, companies, up to the individual consciousness, there is a concern for replacing polluting energy sources with ecological sources to reduce the negative impact on the environment. It is a sign of responsibility and respect for our children and for all generations to come.
Heating systems using conventional fossil fuel eliminate a large volume of combustion gases in the atmosphere, which contributes to the deterioration of the greenhouse effect, implicitly to global warming.
The solar panels, thermal and electrical-photovoltaic, use solar energy as an inexhaustible and renewable resource, the emission of gas being 0 during the exploitation. A single panel used to power a boiler annually reduces carbon dioxide emissions by about 700 kg.
By using the sun’s radiation as a contribution to heating or supplying electricity, the carbon footprint of a physical or legal entity is significantly reduced.
The carbon footprint (CO2) represents the total volume of greenhouse gases emitted by an organization, community or company in the course of its activity. Reducing the carbon footprint is one of the most important concerns in the segment of organizational, community and international social responsibility.
Using an endless source of energy
The fossil fuel, located in the basement, has formed throughout the existence of the Earth, and through the continuous extraction of coal and oil these resources have diminished considerably.
Solar energy is an inexhaustible source, cyclically constant. By using a solar panel to heat the hot water, approximately one tonne of oil is consumed in less than one year.
Reducing costs for obtaining hot water
Solar panels can provide up to 80% of the annual domestic hot water requirement of a home, representing a consistent economy for each family.
Working year-round, the vacuum solar panels can manage the entire volume of DHW during the hot season, with the yield decreasing in winter.
Also, home heating can be cheaper using solar panels to preheat the water in the circuit.
Solar panels are reliable and have low maintenance costs.
With no moving components, the risk of failure is low. However, the clean maintenance of the panels is one of the maintenance operations, the dirt affecting the absorption power of solar energy.
In case one of the tubes break, the system also works in its absence. Changing the glass tube is important to ensure the heating efficiency.
The hot water solar panels require periodic checks in which specialized teams inspect the functionality of the system, like any other technical heating equipment, in the case of pressurized models being a mandatory safety measure.
The disadvantages of using solar panels
The long list of advantages of solar panels is supplemented by several disadvantages. There is no perfect system, but objectively the benefits of solar installations are much greater.
One of the strongest opinions against solar panels, regardless of their type, is brought by the fact that it does not 100% provide the necessary water and hot water. This is a consequence of the fact that solar energy is available in limited time intervals (day-night cycles, summer-winter cycles).
Insufficient supply of 100% of the hot water requirement using solar panels
Solar panels contribute significantly to the volume of hot water consumed annually in a home (up to 80%), but cannot cover the need individually. A building must be provided with a boiler or boiler for the tenants to enjoy the hot water permanently.
An additional installation that carries leakage risks
Solar panels are part of complex heating systems that are part of water circuits. Pipeline wear, extreme temperatures, and faulty mounting can cause pipe breakage and flooding in the home.
Pressurized panels are provided with valves that decongest the pressure in the system. If the equipment is not checked periodically, overpressure is another risk attracted to solar-powered technologies. From this point of view, the non-pressurized panels are safer, operating under gravitational fall. Each of the solar systems has its advantages and disadvantages.
Risk of solar panels deterioration due to inclement weather
The solar installations for the hot water have in their composition glass, in an area that depends on the type of panel. Although borosilicate from which the heating system is produced is very resistant, hail can break the glass.
In vacuum tube installations, the problem is solved relatively simply, each tube being individually changeable. More expensive are flat panel solar repairs.
The need to conserve the installation in winter
Not all types of solar panels operate at negative temperatures. Some models require preservation over the winter, as the water (used as heat) freezes to 0 degrees. The way the panels are kept is by removing the water from the circuit.
On the other hand, there are high-pressure pressurized solar installations (for example, heat pipe technology) that also work during the winter, indeed at lower efficiency due to shorter days and cloudy days. Depending on the type of installation and the glycol concentration, they can withstand temperatures up to -25 degrees Celsius.
Making it difficult to sell a building with solar panels
The houses provided with solar panel systems have higher prices in the real estate market, and their sale is much more difficult for two reasons. On the one hand, buyers allocate a certain budget for the purchase of a home and cannot cover amounts up to 20% higher, as is the case with buildings with alternative energy systems.
On the other hand, buyers cannot size the savings brought about by green equipment and see the unjustified price difference.
More about off the grid living here
Ressources:
https://en.wikipedia.org/wiki/Solar_panel
https://en.wikipedia.org/wiki/Photovoltaic_system
https://en.wikipedia.org/wiki/Balance_of_system
https://web.archive.org/web/20140421050855/http://science-edu.larc.nasa.gov/energy_budget/
