Solar Panels – get free energy from the sun

Solar Panels – get free energy from the sun

A solar panel is made up of many smaller solar cells that capture energy from the sun and turn it into usable energy that can be stored in a battery. With the battery, we can then use that energy for different devices, such as a 12 V refrigerator in a boat.

Choose the right type of solar panels depending on the conditions and purpose

Monocrystalline solar panel

Monocrystalline solar panels are usually mounted on a thin plate made of plastic or aluminium. The advantage of these is that you can mount the panels directly onto a surface using either screws or adhesive. These panels are often flexible. Monocrystalline solar panels are a bit more efficient than polycrystalline panels, and therefore cost slightly more.


Polycrystalline solar panel

Polycrystalline solar panels are usually mounted on an aluminium frame. They are not flexible and need to be mounted with separate brackets. To achieve maximum efficiency, the panels should be mounted on an angled bracket (e.g. 25-5095). If you instead want to mount the panels in a fixed position, you can use 25-5091.


What is a solar charge controller?

The voltage supplied from the solar panels is too high to be stored directly in the battery, and a regulator is therefore needed between the panel and the battery. The controller regulates the voltage from the solar panel and also detects the receptiveness of the battery to charging and regulates it according to the battery level.

Different types of regulators – MPPT and PWM

  • MPPT controller

    The MPPT controller is the most efficient controller for solar panels. It makes use of the entire voltage range and compresses it into usable energy. The MPPT controller is up to 30% more efficient than a PWM controller. Biltema’s range includes two different models: the 25-5099 for up to 10 A, and the 25-5077 for up to a full 20 A.

  • PWM controller

    The PWM controller is a simpler variant of the controller and lacks the output-boosting properties of the MPPT controller, which means that excess energy is lost. This controller is a great option for smaller PV systems where you don’t necessarily need to use the maximum capacity.


The solar panel should be mounted south facing and placed so that it is not unnecessarily covered by shadows from trees and other objects, which reduce the radiation reaching the panel. The panel should be optimally angled at a 30-degree inclination during the summer, and at 70 to 90 degrees during the winter. 45 degrees is recommended to maximise charging throughout the year.

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