A solar panel is an assembly of solar cells that can convert light directly into electricity. By combining the capacity of several solar panels, part of a family’s electricity needs can be covered.
At the moment, depending on the type of panel, 5 to 19 % of the light energy can be converted into electricity. This is known as the “output” of the panel. As the technology is constantly being improved, the output should increase further.
Using solar panels you can convert sunlight, which is free and inexhaustible, into electricity. This conversion is achieved thanks to the so-called “semiconductor” material from which each solar cell is made.
The material most often used for solar cells is silicon. This material can occur in three forms:
These various forms produce different types of solar panels with differing prices, useful lives and output:
A solar panel generates direct current. To be able to use this current in the home or place the surplus on the grid, it has to be converted to alternating current of 230 V. This is done by the converter, which is integrated into the electrical circuit close to the solar panels.
The capacity of a solar installation is expressed in watt peak (Wp). This is the maximum electrical capacity that a solar cell can yield under ideal circumstances: solar collector directed towards the sun in a cloudless sky.
The ideal orientation for solar panels is indeed south-facing. If the panels are installed between the south-east and the south-west, the loss of output amounts to 5 %. If the panels are installed outside these limits, the loss increases rapidly. In Belgium the ideal angle is 35°.
Here an installation of 1,000 Wp facing due south at an angle of 35° and without any shade generates approximately 850 kWh/year.
For a Brussels family, in practical terms that means:
In the city it is often difficult to use more room for solar panels. But as the output of the panels is increasing all the time, it will be possible to cover an ever bigger proportion of the needs with the same surface area!
At the start of 2009 I had photovoltaic panels fitted on my roof. Thanks to the grants and the green power certificates, I have already recouped the investment!Read the testimonial
Pascale has had solar panels since 2009. An investment that has proved highly cost-efficient for her.
“I live in a fairly traditional Brussels town house with very high ceilings. It’s magnificent, but difficult to heat! So my heating and power costs were high. Every time I put a little bit by, I invested in energy-saving measures. For instance, I replaced all the bulbs with low-energy versions and had double glazing fitted. But I dreamed of providing my own energy as much as possible. So I thought it would be a good idea to have photovoltaic panels fitted. That was in 2008. Because energy grants were being heavily promoted, I decided: ‘I’ll go for it!’
I contacted a Brussels firm that dealt with it very well. They did a few simulations for various different panel models and surfaces. Eventually I opted for a version where I could recoup the cost price in eighteen months. And that’s the way it was: thanks to energy savings made by having a few minor jobs done, the energy grants and the green power certificates, my investment started earning money after just over a year and a half!
To obtain green power certificates I read my special meter once a year. I send the meter reading to Brugel by e-mail. They let me know how many power certificates I’m entitled to. After that, on the basis of a list of potential buyers I send out an e-mail asking them to make me an offer and I sell to the highest bidder! In my case that’s my own energy supplier: they offer their customers a very advantageous price. And it’s all very quick: I sign a document for the buyer and send the information to Brugel, which transfers the green power certificates to the buyer, and I receive the amount of the sale in my bank account.
My twelve panels, covering a total surface area of around 16 m², now supply between 80 and 90% of the power I use. But I have to admit I’m lucky: my roof is a bit higher than the neighbours so a shadow never falls on the panels, plus the roof is perfectly oriented. And that’s not all: thanks to the grants, I was able to replace my central heating boiler for a new model that is far more efficient!”
Editor. A great deal has changed since 2009: the conditions for obtaining energy grants are more stringent, the federal tax deductibility has been abolished, etc. But the cost of solar panels has fallen sharply in the meantime.
With the current energy grant system, the Brussels government guarantees that the cost of a photovoltaic installation can be recouped in seven years.
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