How do you design a PV installation?
How do you design a PV installation? Every solar energy system is unique. That’s why choosing the right inverter for the right solar panels can be tricky. We’ll give you the tools to make the right decision easier.
What you need to design a PV installation:
- Inverter datasheet
- Solar panel datasheet
To determine the ideal setup for a specific location, start by calculating the annual energy consumption. Then decide which inverter and solar panels fit best. Consider the following:
- Shading;
- Tilt angle and orientation of the panels;
- Correct string configuration.
Tilt angle and orientation
All solar panels in the same string must have the same tilt angle and orientation. That’s because the voltage and current output must match across the entire string. Why is this important for the inverter? If the panel outputs differ too much, the inverter won’t be able to find the Maximum Power Point (MPP), resulting in a lower yield.
In the Netherlands, it’s generally most effective to oversize the inverter by 10% to 20%, depending on the tilt and orientation. Under ideal conditions, the system might clip slightly, but overall performance will be much better in less-than-ideal conditions — which are common in the Netherlands.
Shading on solar panels
Check if the panels may be affected by shading, caused by trees, chimneys, dormers, nearby buildings, or even other panels (especially on flat roofs). If one panel is shaded, the entire string can be affected. Minimize shading as much as possible. If unavoidable, SolarEdge is a strong solution.
String configuration
Example: A household consumes 4,500 kWh per year. You could choose a system with 4,500 Wp, which yields approximately 4,100 kWh annually. Let’s say you use JA Solar Monocrystalline Percium 300Wp panels with a Solis 4k single-phase inverter. Overloading With 15 x JA Solar 300Wp panels, you get 4,500Wp — matching the household’s usage. Next, determine how many strings to use. A key factor here is voltage: too much voltage can damage the inverter, and this isn’t covered under warranty if it’s not installed according to specifications. The Solis 4k supports a max DC voltage of 600V. Each JA Solar 300Wp panel has an open-circuit voltage of 39.85V. Multiply: 15 x 39.85 = 597.75V. So, it seems like all 15 panels can go in one string. But you must also consider temperature coefficients. The rule of thumb is to add 15%: 597.75 x 1.15 = 687.41V — well over spec. So, this installation needs to be split into two strings: ideally 8 and 7 panels. Startup voltage An inverter requires minimum voltage to start. The Solis 4k needs 120V to boot. It starts based on open-circuit voltage but runs using the MPP voltage. With 7 panels in the shortest string, that’s 7 x 32.26V = 225.82V. Now apply a temperature coefficient: 225.82 x 0.85 = 191.95V — still more than enough to start the Solis 4k.
Extra tip
The inverter is the most vulnerable part of the system. So be careful where you source it from. Many manufacturers are outside Europe, and if issues arise, support may be slow. At Libra Energy, we’re certified to handle aftersales for all inverters we sell. That means fast and reliable support.