Stand-alone components

What are the components that make up an off-grid solar kit? In this article we are going to talk about the different elements that make up an off-grid solar kit, that is, a solar kit that is not connected to the grid and that will be the only source of energy for our house, devices... The basic elements of an off-grid solar kit are:

Solar panels
Solar panels convert solar radiation into direct current. Obviously, the higher the irradiation, the more energy the solar panels will produce at the same power output. However, it must be taken into account that two identical panels will have a different yield depending on the radiation, which changes according to the geographical area, or also due to the inclination and orientation, among other causes.

We can categorise the typology of solar panels in different ways; the most common is to differentiate panels according to whether they are polycrystalline or monocrystalline.

Differences between monocrystalline and polycrystalline silicon

There are solar panels which, due to their operating voltage, were created specifically for off-grid solar kits, although this is becoming less and less important due to the work carried out by the charge regulator.

Charge regulator
It acts by cutting and regulating the passage of energy between the panels and the battery, depending on the battery's state of charge. For it to work correctly, its power must be sized correctly and the right type must be chosen to obtain the best performance from our panels.

Charge controllers can be of 2 types:

PWM controllers : Is more economical and is recommended for small, low-cost solar systems. It can only be used if the nominal voltage of the solar panels and batteries is the same, e.g. with 12V solar panels and 12V batteries.

MPPT controller : They are much more efficient as they adjust the incoming panel voltage to the voltage required by the battery according to its stage of charge, so they can produce around 30% more energy than a PWM. The only requirement is a nominal panel voltage higher than the working battery voltage and they are the only possible option when using panels with a non-standard voltage.

Solar inverters
Solar inverters need to be connected to batteries and are responsible for converting the direct current that can be extracted from them into alternating current suitable for normal household consumption. Isolated inverters, in general, can be of 12V, 24V or 48V: 12V, 24V or 48V and it is very important that they generate a pure sine wave to avoid faults in the electrical devices connected to them.

We can choose several power options depending on the simultaneous consumption we need to connect. Although there are exceptions, the logical and usual are powers of up to 1500W at 12V, around 3000W at 24V and from 4000 or 5000W at 48V.

It is very common to integrate the charge regulator within the inverter itself and also the functionality of a battery charger from an external source. This is very useful because in off-grid installations it is common to have a petrol or diesel generator that can cover emergency consumption in low production conditions.

Solar batteries
Solar batteries are responsible for storing the energy that is captured and not used during the hours of sunshine. This way we will have that energy available at night or at times of lower production. They account for almost half of the budget for an off-grid solar system and it is therefore very important that they meet our needs.

There are small, inexpensive batteries for more discreet uses and large accumulators for larger requirements. There are also different types of technologies such as lead acid batteries, AGM batteries, GEL batteries, stationary batteries or lithium batteries.

The batteries are grouped together to obtain the working voltage required by the inverter and their capacity must also be in accordance with the power of the inverter and the use we are going to give to the system. Also make sure that the charge regulator is set up to operate at the voltage of the battery bank so that everything works.

All the elements mentioned above need to be connected to each other. For this purpose, it is necessary to respect the cross-sections, as current flows at very different intensities between the above-mentioned elements. The recommended distances should not be exceeded, since, when working at low voltages, voltage drops can cause the whole system to malfunction.

Initially it may seem an unimportant complement; however, it is responsible for firmly attaching the solar panels to the surface on which we are going to place them. The importance of a correct inclination and orientation should not be overlooked in order to achieve the best possible performance from a solar system.

In addition, it is common to have a fuel-powered generator for emergency recharging of the solar system's batteries. Normally, if the solar system is well dimensioned to what is needed, the generator is used very few days during the year.

For more information about AutoSolar's off-grid solar kits, do not hesitate to contact our technical professionals, they will advise you without obligation on the products that best suit the desired installation and can make a system to your needs.

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