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What is the difference between solar and photovoltaic panels?

Faced with rising energy prices (gas, electricity and fuel), renewable energies are gaining ground and represent a sustainable and increasingly reliable alternative. Among the natural resources used by individuals to produce energy, the sun is the most solicited via solar thermic or photovoltaic panels. But then, what is the difference between these two technologies?
The sun: a resource with great potential

First of all, it should be remembered that to produce energy, it is the sunshine that counts, not the heat. Thus, even in winter, when temperatures are low, the sun can produce energy to preheat water and air or produce electricity. Solar energy has two major advantages compared to hydro and wind energy: it is a clean and accessible resource. Clean on the one hand, because it is a resource that does not alter the environment and does not induce pollution at the time of transformation. Note that a large majority of the components of the panels are recyclable. Accessible on the other hand, since the installation of panels is relatively affordable, with few constraints and easy maintenance. 

The difference between a solar thermal and photovoltaic panel

There are two categories of solar panels: solar thermal panels and solar photovoltaic panels. A solar thermal panel captures the sun’s rays and transforms them into heat, which is then reused for domestic hot water or heating. A solar photovoltaic panel transforms the sun’s rays into electricity to run the various electrical appliances in the home. The electricity from photovoltaic panels can be used continuously, stored in batteries or sold to the grid in case of excess production.

There are also hybrid solar panels on the market, i.e. panels with mixed sensors that produce electricity and heat. Big advantage of this technology, photovoltaic panels when they reach a certain temperature lose efficiency, in a hybrid panel we have water circulating that will cool the panel and allow to maintain efficiency. This technology is necessarily more expensive to purchase.

In Portugal, the government requires “the installation of solar thermal systems to heat domestic water in new buildings (…) when the solar exposure is sufficient”. To do this, it is necessary to call on experts who will determine the energy needs of the home, the appropriate technology, the suitable location and will proceed to an optimal installation. The ADENE (Agency for Energy) website lists qualified Portuguese companies (brands and installers) in the field. 

An ideal Portuguese context, and yet…

With an average of 300 days of sunshine per year, Portugal is the perfect environment for the development of solar energy. However, the Portuguese newspaper Jornal de Negocios points out that “Germany, which does not enjoy this advantage, at least not like Portugal (…) is the largest market for solar energy in Europe”. A Portuguese gap explained in part by the late creation of photovoltaic power stations. Pedro Amaral Jorge, CEO of APREN (Renewable energy portuguese association), recalls that “when, finally, [solar] technology began to show promise, Portugal entered an economic and financial crisis, which led to a near stagnation of the sector.” But the government is aware of the accumulated delay with, as proof, the inauguration in October 2021 in the Algarve, of the largest photovoltaic power station in the country, with more than 661,500 panels.

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