Are you thinking of buying a solar kit and have doubts? Do you have a solar kit and your inverter has broken and you don’t know which one to choose? In this article, we will dispel some general doubts about the different inverters that exist. First of all, you should know that the inverter is the most important element of the kit since it is in charge of converting the energy generated by the solar panels (direct current, DC) into the energy that your home needs (alternating current, AC).
Well, first of all, What does an inverter do? The inverter is in charge of marking the ranges at which the different elements of your solar kit must work. On the one hand, the inverter limits the total power at which the set of installed solar panels can work. If our inverter works between 3-5 kW, the total sum of energy generated by our plates has to oscillate between those amounts. If this is not the case, we are using the inverter inappropriately and we will have many operating problems both with the inverter and with the rest of the elements of the solar kit.
On the other hand, the power of our inverter will be linked to the power of the batteries that we have chosen. In the technical sheet of each inverter we can check the ranges in which to work. That is to say, the choice of the inverter for our solar kit is of vital importance, therefore, we will talk about the different types of inverters. We will choose our inverter according to the needs of our home. Next, the suitable inverters are detailed according to whether the house has a connection to the electricity grid or not.
Isolated inverters can only be used in those homes where there is no power outlet, so the only source of energy supply will be the one provided by the solar kit and/or a diesel, gasoline or similar generator.
Batteries, therefore, are essential to achieve the energy autonomy of the home also at night and on stormy days or when consumption exceeds the photovoltaic production of the panels. Hence, for the correct operation of our isolated solar kit, it is necessary, apart from an inverter, a charge regulator and a battery charger so that the batteries work properly. We can find isolated inverters of 12, 24 and 48V and we will choose the power according to the voltage of the batteries.
On the other hand, you can also buy an inverter charger. The only difference between these and isolated inverters is that charger inverters have a built-in charger that will charge the batteries. The charger inverters also work at 12, 24 and 48V.
Within the family of isolated inverters, you can opt for an inverter-charger-regulator (also known as 3-in-1 inverters). Now, try to guess the difference between common isolated inverters and this guy. Exactly! The difference is that these inverters have both a regulator and a charger integrated inside them. The 3-in-1 inverters also work at 12, 24 and 48V, depending on the battery voltage, and offer within the same device the functions of transforming the energy received by the solar panels so that it is compatible with the current of the house and charging and regulate the charging of the batteries whenever the photovoltaic production is higher than the consumption of the home at that time. 12v inverter applications are very common in life.
On the other hand, for those homes that are connected to the electricity grid and wish to install a solar kit so that daytime consumption takes as an energy source the one provided by the solar panels, a grid connection inverter or hybrid inverter should be used. .
Regarding grid connection inverters, they are prepared to work connected to the grid. We will have to take into account the energy generated by our plates, which has to oscillate within the capacities of the grid connection inverter.
Generic or pure grid connection inverters do not work with batteries, so the energy produced but not consumed will be fed into the grid if the installation has been legalized and the wattmeter has been correctly configured or this excess energy will be lost. Of the common grid connection inverters we find two variations:
On the one hand, you can opt for a hybrid inverter, which stands out because it can work both with and without batteries. On the other hand, if your energy needs are not very large, you can bet on a microinverter. Microinverters are within the family of grid connection inverters but the power at which they work is lower (less than 600W) and it is not possible to connect a wattmeter so that they can only be used when there is constant consumption in the grid. living place.
How to choose the right inverter
First of all, it is important to know how to differentiate between power and energy, so we will start with these concepts.
- The power term refers to the demand of the electrical device at that same moment. The power of the electrical device is the product of the current times its voltage and is measured in watts (W).
- The term energy refers to the time that electrical device is in operation with its respective power.
Example: An 80W laptop is running 4 hours a day. The power consumed by the laptop is 80W per 4h = 320 Wh/day.
Secondly, it is necessary to know that in the characteristics of the inverter it indicates the maximum power that it admits. This power is what limits the installation and must not be exceeded.
Example: if we buy a 3000 watt power inverter, it will limit us to this power and we will not be able to connect any device that exceeds 3000W or we will not be able to connect a set of devices that exceeds that power simultaneously.
If the power of the inverter is exceeded, the inverter will cut off the supply to protect itself and not damage any internal components. The inverters are prepared to be able to withstand twice their nominal power for a few seconds in order to withstand the peaks in starting power of motors or pumps that have a higher consumption.
Finally, you have to know that the inverters are responsible for transforming the charging voltage of the battery from direct current to alternating current 230V.
Depending on the power of the inverter, a battery voltage is used so that the installation works correctly. It’s recommended that:
– For 12v systems, inverters of up to 1000W of power are installed.
– For 24V systems, install inverters between 1000W and 3000W of power.
– For 48V systems, inverters greater than 3000W of power are installed.
In short, we must avoid installing powerful inverters in installations where the battery voltage is very low. Since that would cause the battery bank to discharge more quickly to the point of reaching the maximum current limit of the battery and deteriorating it.