Would you like to reduce your electricity consumption? A photovoltaic installation is the ideal solution, provided you meet these 4 criteria.
Are you tired of depending on your electricity and gas supplier?
Do you want to take control of your destiny and make your home as self-sufficient and independent as possible with sustainable energy for the future?
A photovoltaic installation is the first step to ensure you have a constant and free electricity supply.
Unfortunately, this is not always possible, as sometimes local conditions make it impractical to install a photovoltaic system for electricity production.
That’s why we have created a list of five points to help you determine if your home meets the essential conditions for installing a production system, without falling into the traps of unscrupulous and improvised salespeople who, in order to make an additional sale, would install panels in your basement.
Be careful, it is important to know these 4 points before installing your home solar system, as it would be of little use afterward!
Consumption
The first consideration to make before signing a contract for the installation of a solar system is quite simple: does your electricity consumption justify an investment in sustainable energy for the future? To be very clear, there are many situations where a building consumes so little that any consideration of the profitability of a photovoltaic installation becomes pointless.
If you live alone, work far from home, and don’t even come back for lunch, your consumption will certainly be very low, both in terms of kilowatt-hours and euros. In this case, photovoltaics are certainly not among your priorities, and a genuine professional should not advise you to pursue it.
An investment in photovoltaics starts to make sense beyond 2,300 kWh per year. If your consumption is below this theoretical threshold, the installation suited to your needs would be very small and therefore more expensive in relative terms (the fixed installation and design costs are almost identical to those of a larger installation).
The distribution of consumption throughout the day is also very important: the more concentrated your consumption is during the day, the more an investment in photovoltaics becomes profitable.
Available roof space
A photovoltaic installation occupies a variable surface area depending on the total power and efficiency of the individual panels.
Assuming you need a 4 kW installation (the most common size) and imagining that you use the most efficient panels on the market, the required space is about 15 m², reaching about 20 m² in the case of very low-efficiency panels.
To give you an idea, there should be a free rectangle on the roof of about 15 tiles vertically and 30 tiles horizontally (these are indicative measurements; if you want to dive deeper, it is necessary to consult a technician).
Shading
Common question: do solar panels work in full sun or even with diffuse light?
Short answer: they always work, both in full sun and cloudy weather, but production in direct sunlight is much higher, up to ten times more! (even though some will try to tell you that their panel is amorphous, polycrystalline, monocrystalline, etc., and therefore works well even in the shade).
Avoidable shadows must be avoided at all costs. If you can avoid placing a panel directly behind a chimney, there is no reason not to do so.
Even though there are many ways to reduce the effects of local shadows (for example, power optimizers), when possible, panels should be placed away from vents, chimneys, or any other elements that might cast shadows during the day.
There are two types of shading: shading due to the horizon and local shading.
The first can be assessed using specific calculation programs or directly on site during an inspection (in all cases, the help of a technician is necessary).
Regarding local shading, the calculation of a technician is also essential.
However, common sense allows anyone to understand that a 10-meter-high tree located directly in front of the installation is not favorable.
Possible causes of local shading may include: trees and plants, chimneys and vents of any kind, parts of the roof or house at different heights, other taller buildings nearby.
Of course, a detailed analysis of local shading can only be carried out by qualified personnel with the appropriate equipment. Not considering shading or considering it incorrectly is the primary cause of low production from photovoltaic installations.
Over the years, I have seen installations of all kinds: panels behind chimneys, under other sections of the roof, in shaded positions during half of the year by other buildings, etc.
Roof orientation
It may seem obvious, but it still needs to be stated to avoid any misunderstanding: solar panels perform better when oriented towards the SOUTH. This is fundamental for having high-performing sustainable energy for the future for as long as possible.
They have a still very interesting yield in all intermediate orientations between WEST and EAST, and can still reach about 90% of their yield when oriented directly WEST.
On the other hand, any orientation towards the NORTH, even by just a few degrees, should be avoided, as the drop in yield, all other conditions being equal, is very rapid.
In terms of orientation as well, we have seen really strange installations, systems that could not reach the expected yield even if there were two summers a year! In this case, it’s hard to talk about sustainable energy for the future, isn’t it?
The most outrageous thing is that sometimes you can see houses where part of the roof oriented southeast is completely free and another part oriented northwest is covered with photovoltaic panels (if you want to have some fun, go to Google Maps and check for yourself!)
Bonus tip: Altitude above sea level
No one ever takes into account the altitude of the installation site when evaluating the installation of a photovoltaic system (certainly not your electrician or the salesperson who doesn’t even go onto the roof!).
Why is altitude important? What can happen?
The answer is surprising, a very technical consideration that only a few experts can understand: in the mountains, it can snow.
Here’s what can happen if the correct snow load is not considered.
The supports that hold the installation did not withstand the snow load and completely destroyed all the tiles located underneath, causing not only water infiltration but also the breakage of a panel’s glass.
The repair of the tiles and the replacement of the supports and the damaged panel cost the client much more than if they had immediately chosen an appropriate fastening system.
The fault obviously does not lie with the client but with the installer who carried out the installation and who did not properly advise the client on the suitable installation system for the area in question.
Solutions vary according to the expected snow load and can be multiple: adding an additional profile, choosing reinforced supports, increasing the number of supports, and combinations of these three options.
You now have the minimum essential knowledge to roughly assess the profitability of a photovoltaic installation (if you have read the entire article, you know more than most electricians and salespeople who sell photovoltaic installations, congratulations!)
