hen people think of harnessing the energy of the sun, the first thing that comes to mind is photovoltaic systems. However, there is another option that is often overlooked - solar energy collectors. In this article, we are going to look at solar collectors more closely, go through their types and discuss what benefits they can bring.
What are solar collectors?
Solar power collectors use older technology than photovoltaic systems and a much simpler one. While PV cells convert sunlight into electricity through the photovoltaic effect, solar collectors gather direct radiation energy and transfer it into usable heat.
Solar energy collectors are mainly used for hot water generation and are suitable for both domestic and large-scale applications such as thermal energy plants.
How is the sun's energy converted into heat energy?
For household purposes, non-concentrating solar thermal collectors are used – systems that work by absorbing direct radiation. These solar collectors are installed in a fixed position and do not track the sun's movement, therefore, their number of working hours per day is quite limited. And yet, such solar collectors can help homeowners cut energy costs and offer a viable alternative to conventional domestic water heaters.
Large facilities employ concentrating solar collectors that use reflectors or lenses to redirect and concentrate the sun's radiation onto an energy receiver. These solar collectors are more powerful and collect energy throughout the day.
Solar energy in Boston is gaining popularity due to incentives, rebates, and favorable solar policies. Residents are increasingly adopting solar panels to harness renewable energy.
Types of solar collectors to utilize the sun's energy
Flat-plate energy collectors
Flat-plate systems are the most well-established technology for solar thermal collectors. You can recognize a flat-plate collector by its large absorption plate, typically a sheet of aluminum painted black for better radiant energy absorption.
The plate has a series of vertical copper tubes or pipes attached to it. As sunlight heats up its surface, it transfers the heat to the pipes. After that, the water pumped from the storage tank travels up the hot pipes.
The plate and the pipes are placed within an insulated metal casing with a tempered glass cover on top, which does not absorb heat and ensures the durability of solar heating collectors.
Evacuated tube energy collectors
Evacuated tube collectors (ETC) are solar collectors comprised of several parallel twin glass tubes: a thin inner tube and a thicker outer tube forming a vacuum between them. Each inner tube contains a copper pipe connected to an absorber fin.
The vacuum between the glass tubes serves as an insulation layer and minimizes heat loss making these solar energy collectors way more efficient than flat-plate options. In addition to this, the cylindrical shape of the tubes enables passive sollar tracking, which allows these solar collectors to perform well at different radiation angles.
Bowl energy collectors
Bowl solar energy collectors have a similar working principle to parabolic dish energy collectors, but with the difference that they have a fixed mirror instead of a tracking one. The rest is the same: the mirror collects the incoming sun's energy and focuses it on a receiver, and the tubes attached to the receiver heat the water.
What is the price of solar collectors?
Now you probably want to know how much solar heating collectors cost. Well, there's a whole host of factors at play here, including your hot water usage, sunlight and temperature levels in your region, and local incentives available. On average, the whole system costs around $3,500. Apart from an energy collector itself, this price includes all of the other elements such as a hot water tank, control panel, and plumbing.
The final cost largely depends on what type of collector you decide on. For example, evacuated tube collectors are usually more expensive than flat-plate solar collectors.
Sun energy collectors vs solar PV energy
Even though solar heating collectors can’t become a full-fledged alternative to PV energy installations in most cases, they nevertheless offer a couple of distinct advantages. The first one is unsophisticated design, and therefore minimal maintenance. Solar power collectors take up less space, generally more than twice less than photovoltaic energy systems. Another strong point is high efficiency: they turn up to 90% of radiation into heat while PV system efficiency ranges from 15% to 20%. And lastly, solar collectors are cheaper.
But the drawbacks may well outweigh. The most obvious one is a much more limited utility than of PV panels. Not only can’t collectors generate electric energy, but they are not typically suited for central heating. In addition to this, solar heating collectors can’t offer stable performance, as they produce much less heat in the winter months than in summer.