Leo Daniel , I would recommend specifying your system first. Your panels are rated for a power output, then the question becomes are you going to use it, or use it and store it, or use it - store it - release it, or a combination of the three? Also, the amount of water that you would like to desalinate will be a design factor too. Consider this article as a starting point for some background reading: https://news.dualsun.com/co-en/12/2014/what-is-the-optimal-orientation-and-tilt-angle-for-solar-panels/.

The solar panel angle of your solar system is different depending on which part of the world you are.

Solar panels give the highest energy output when they are directly facing the sun.

The sun moves across the sky and will be low or high depending on the time of the day and the season. For that reason the ideal angle is never fixed.

To get the most sun reaching the panel throughout the day, you need to determine what direction the panels should face and calculate an optimal tilt angle. This will depend on:

Where you live

What time of the year you need the most solar energy

solar panel angle

Calculating the Optimal solar panel Angle

As a rule of thumb, solar panels should be more vertical during winter to gain most of the low winter sun, and more tilted during summer to maximize the output.

Here two simple methods for calculating approximate solar panel angle according to your latitude.

Calculation method one

The optimum tilt angle is calculated by adding 15 degrees to your latitude during winter, and subtracting 15 degrees from your latitude during summer.

For instance, if your latitude is 34°, the optimum tilt angle for your solar panels during winter will be 34 + 15 = 49°.

The summer optimum tilt angle on the other hand will be 34 – 15 = 19°.

Calculation method two

This is an improvement of the general method that gives better results. In this method, the optimum tilt angle for solar panels during winter is calculated by multiplying the latitude by 0.9 and then adding 29°. In the above case example of a latitude of 34°, the tilt angle will be (34 * 0.9) + 29 = 59.6°.

This angle is 10° steeper than in the general method but very effective at tapping the midday sun which is the hottest in the short winter days.

For summer, the tilt angle is calculated by multiplying the latitude by 0.9 and subtracting 23.5°. In the above case example, this angle would be (34 * 0.9) – 23.5 = 7.1°.

For optimum tilt angles during spring and fall, 2.5° is subtracted from the latitude.

Good question

Do you have local data on solar irradiance as a function of azimut and height angle (see for example a map valid for France)? If yes, the optimum angle can be easily deduced: it is the direction at maximum global irradiance. In most location, this direction is facing the equator (e.g. south in the northern hemisphere) and the height is close to the local latitude. However, if your solar still uses a concentrator (lens or mirror) the optimum angle is that of the sun.