Install solar panels? We sort out the concepts!

Are you thinking aboutå to install solar panels onå your boat, caravan, mobile home, summer cottage, villa or property? Have you already installed and feel unsure about; if everything really went right? This blog post explains the concepts and gives you concrete tips for your installation.

Right now the interest in installing solar panels is huge, but there is a certain complexity, or at least some concepts, calculations, dimensions, etc. in a solar system that you need to adhere to for the solution to be both safe and effective.

Solar energy throughout the year
Before we go into; the solar system itself, we thought we would start by doing; through the basic requirements to be able to produce solar energy on our part of the earth and how they differ over the year.

The example below refers to Stockholm, where we can see that the production is at its highest in mid-April there ; the sun is efficient and it is still relatively cool, which increases the efficiency of the solar panels. In general, it can be said that the production is relatively good during the period April to August, but during March and October they only provide 50% and during November to February no more around 25% of the summer months. In other words, you need to include this in the dimensioning from the outside when on; When you need the energy and where you are.

Battery bank
Another important parameter in the solar system is the type and voltage of the battery bank and if if you generalize the whole thing, you can say that the voltage from the solar panels needs to exceed the battery's voltage by +5V so that a charging must be able to be started. This is not a big problem in a 12V bank, but can be a challenge in a 48V bank where; you have to dimension the panels for a higher system volt to handle charging the part of the year you want to consume the energy.

It is also much more efficient to charge a Lithium bank versus a lead bank (AGM, GEL etc.) and if you want to know more about this, you can read our blog post "Energy-optimizing the property with Victron ESS system" there we do a little deeper into the battery issue.

Solar cell regulator
The regulator is like a "Battery charger" that uses the energy from the solar panels to charge the battery the bank. The regulator has twoå main parameters and there is a lot of V and A respectively they can handle and it is important to dimension the regulator for maximum power from the solar panels.

Victron Energy has produced an MPPT calculator which takes care of the dimensioning based on given measurements from the solar panels and it is also good to add panel properties other than the predefined Victron panels. The calculator also takes into account the battery bank's voltage and you can work with different cable lengths, dimensions and where the installation is to bring. back så accurate information as possible.

You can find the MPPT calculator hear and think about; that Victron's controllers called "Smart Solar" have BT capability and those called "Blue Solar" lack this feature.

In larger systems or in systems with very partial shading parts you often set up the solar system in smaller groups and have more regulators that work together for maximum effect.

The solar panel
There are a number of different panel types and models from a upsjö of manufacturers and our experience is that over time it usually pays to buy well-reputed panels locally in Sweden because they are inconvenient to ship in case of possible warranty exchanges etc. while the well-reputed manufacturers often have a higher efficiency on their panels.

One of the most important values ​​to keep track of; What is the maximum system voltage a panel can cope with? above all, the "flat" ones that are suitable for gluing and similar assembly can have a low maximum system with the result that they could not be connected in series. Victron Energy's frame tensioned panels have a maximum system voltage of; 1000V. If you want to do the installation yourself without a qualified electrician, it is important that the maximum system voltage is below 100V.

Parallel connection
A parallel connection of två or more panels means that you get the same system volts but a higher total power because each connected panel adds additional power. Parallel connection is preferable if you have several panels in a group that have different shading, but it can also be be idé to have several smaller regulators that are connected to each panel instead of one larger regulator for several panels.

The recommendation is to always stick to the same model of panel when connecting in parallel and think about that the öked effect alsoå requires thicker cables between panels and regulator so as not to lose power.

Series connection
In solar systems, a higher system volt is needed (usually for 24V or 48V battery banks) series connection of solar panels is used, however it is important that the maximum voltage does not exceed the maximum system of the panels voltage.

Another parameter with series connection is that depending on panel, a bypass diode is needed "over" the panels and it is therefore important to check if the panels you have chosen have a built-in bypass diode or if you have to add an external diode. Solar panels from Victron Energy have a built-in bypass diode.

The recommendation is to always stick to the same model of panel when connected in series and think about; that the öked effect alsoå requires thicker cables between panels and regulator so as not to lose power.

Combined systems
In larger solar systems, you need to combine serial and parallel connections to find tubes A combination of tension and large amounts of panels. The maximum number of panels in series varies depending onå model and the number of parallel groups are limited by the regulator's specification and the same conditions as for ordinary parallel and serial configurations naturally apply on both sides.

Särings & Cabling
Solar panels are a constant source of energy which also causes the circuit to flow smoothly; as soon as there is enough sun and it is therefore extra important to carry safe rain but still be able to make the system as efficient as possible with the help of a main switch or similar. Normally, you secure between panel and regulator and between regulator and battery. As you can see in the example above ärå each series-connected group is protected separately.

In smaller solutions, automatic fuses with built-in switches are a good alternative. they both function as fuses but also; as a switch to be able to make the system more current. From the solar panels you normally secure 1.5x maximum current and from the regulator you secure according to what is stated in the regulator's manual.

Under this link you will find some suggestions for external automatic circuit breakers.

Many panels use MC4 connectors and there are also; ready-made MC4 cables in varying lengths and dimensions from most manufacturers. MC4 connectors and cables allow connection and ensure watertight assembly. For the slightly larger regulators, it is often possible to choose a model that has ready-made MC4 inputs, but the usual are screw terminals and there; you just cut off the connector at the end to be connected to the regulator.

In the Victron Energy MPPT calculator, you can enter cable length and dimension to see what power loss a certain cable dimension entails , it also happens good to use the app Victron toolkit which has a good cable calculator. See även blog the entry "Which cable dimension should you use for which user?".