Guide · Installation
Orientation, tilt and shading
Before even talking about brands or power, three physical parameters decide a good part of what your roof will produce over twenty-five years: the direction the panels face, the angle they're mounted at, and the shade that passes over them through the day. Well adjusted, these three levers cost almost nothing and pay back years of production. Let's look at them one by one, in the order they matter.
Orientation: due south, and nothing else?
In Morocco, the sun traces its arc to the south. Panels facing due south collect the maximum radiation over the whole day: it's the reference configuration, the one that gives the highest production for a given surface and power.
An east or west orientation isn't a deal-breaker. The loss is estimated at about 10 to 15 % compared to due south, which remains entirely profitable if your roof leaves no other choice. An east orientation may even suit a morning consumption profile better; a west one, a household that comes home in the late afternoon. What matters is not ending up with your back to the sun: a north-facing wall is to be ruled out.
Tilt: neither flat, nor too steep
The ideal tilt angle for a panel roughly matches the site's latitude, then is lowered slightly to favour annual production. Our own irradiation data (PVGIS, optimised for annual production) gives a remarkably stable optimum from one city to the next, despite latitudes ranging from roughly 28° to 36° north: Agadir, Marrakech, Casablanca, Rabat and Tangier all point to about 30°.
These values come from satellite irradiation data (PVGIS / Global Solar Atlas) and are optimised for total annual production, not a single month. In practice, your roof's slope is often dictated by the existing architecture, and a few degrees' gap from the optimum has a modest effect on annual production — much less than shading, as we'll see next.
A completely flat installation (0°) isn't ideal: production drops, and standing water dirties panels faster. A slope between 15° and 35°, however, remains in a very acceptable range across the whole country.
Shading: the parameter that penalises most
This is the most underrated factor, and often the costliest. A standard installation wires its panels in series: current passes from one to the next like links in a chain. If a single link is shaded, the whole chain is penalised. Production doesn't drop by 10 % because one panel is half-shaded; it can collapse much more, because it's the weakest panel that sets the pace for the others.
Shade sources to watch out for have often been there all along, but you only really spot them by checking the hours of the day and the seasons:
- A chimney or ventilation duct casting a moving shadow as the sun moves
- A shared wall or parapet that cuts off the sun early in the morning or late in the afternoon
- A palm tree, tree or antenna that may not be a problem now but will become one in a few years
- Rows of panels shading each other if the row spacing is poorly calculated
Before any project, an on-site shading analysis — ideally at different hours and accounting for the winter solstice, when the sun is lowest — is essential. That's when you spot the obstacles that only look harmless in summer.
When shade is unavoidable: the solutions
If your roof has partial, unavoidable shaded zones, two technologies can limit the impact:
Power optimisers are installed panel by panel and let each one operate at its own maximum power point, independently of its neighbours. A shaded panel no longer drags the others down; it simply gives what it can.
Micro-inverters go even further: each panel has its own micro-inverter that converts DC to AC right at the panel level. Again, each panel is completely independent. This type of installation is more expensive but also brings very fine, panel-by-panel real-time production monitoring, useful for spotting a problem quickly.
These two solutions are relevant as soon as shading is regular and affects a significant part of the installation. If your roof is perfectly clear and shade is anecdotal, a classic inverter with bypass diodes is enough: no need to overpay.
What to check on your roof
For orientation, aim for due south when possible; an east or west face costs about 10 to 15 % of production and remains profitable, a north face is to be avoided. For tilt, an angle around 30° works regardless of your city, and most Moroccan roofs already fall into an acceptable range, so there's no need to dwell on it. The real subject, the one worth climbing onto the roof at several times of day for, is shade: a poorly placed chimney, wall or tree penalises a whole chain of panels, far more than a slightly off orientation. A serious on-site study always starts there.