Many people think that the installation of a solar system is complicated, expensive and of limited efficiency and therefore they do not yet have one. There are of course cases when the placement of photovoltaic devices is necessary and then even skeptics install them. Only then they realize that: first – there is lots of information on the subject; Second – it is not difficult at all and third, but not least important – the benefits are numerous and sustainable. Let’s just simply analyze what we need to get free electricity from the sun, in other words, what does a solar system mean? What does it consist of?
Each photovoltaic current source must have: a solar panel (a photovoltaic cell) a battery, specific connecting wires having a particular section , consumers designed to aborb power from the conversion of sunlight into electricity, a voltage inverter, if consumers are of 220 volts and a device to control the processes, which is called solar panels controller.
In order to select the proper power of the solar panel, the battery and the inverter, we recommend the convenient and easy to use calculator of the power of solar panels.
The solar controller monitors the state of the battery’s charge, it manages the charging processes, and it can switch on and off the consumer. Thus, the battery is used in an optimal way and its durability considerably increases. Moreover, the controller protects the system from overcharging, from deep discharge of the battery, as well as from reverse current to the solar panel. Usually the controller has six terminals grouped in pairs with the corresponding indications.
The batteryhas to be connected to one of the pairs, and it is obligatory that we start connecting namely the battery. We have to connect the solar panel to the second pair of terminals, and to the third pair we need to connect the consumer, if it is on 12 volts or the inverter, if we want to power consumers to 220 VAC. There is a clear correspondence between the power of the solar panel, the power of the battery, the size of the current that can flow through the controller, the total power of the consumers that are connected simultaneously to the photovoltaic system, as well as the section of the cables that connect all components. If you do not observe the power correspondence and the specified successiveness in connecting the devices to the controller – the system will burn. It is good to know that given a cable length of 10 meters, with a nominal charging current of the controller of 10A, the cross section of the connecting wire has to be 6mm2 or more.
When the size of the charging current of the controller is 8 A – the cross section must be 5 mm2, when the current is 6 A – 3mm2 and respectively at charging current of 5 A, the cross-section of the connecting wires can’t be less than 3mm2. The cables for solar panels are special. As they work outdoors in extreme temperature fluctuations, prolonged exposure to strong sunlight, rain, snow and other weather conditions, they have extremely stable insulation specially protected against prolonged exposure to UV-rays. Their price is relatively higher than that of conventional power cables, but experts recommend using this particular type of wires because of their qualities. When connecting the photovoltaic panel to the system, it is very important that it is covered with an opaque material in order to prevent the generation of electricity in the course of the connection process. Always connect the positive terminal first, then the negative, and it applies not only to the solar panel, but also to the battery and the consumer.
Most solar panel controllers have different light indications in order to keep the user of the controller informed at any time about the amount of electricity available. Some consumers, for ex. emergency lighting, security- signaling systems and others are not supposed to be disconnected from the controller. They can be connected directly to the battery, but it should be borne in mind that in this case the controller will not be able to prevent the battery from deep discharging and therefore it needs to be further secured.
Solar panel controllers, among other things, have special requirements regarding their location. For example, the controller must not be installed outdoors or in damp areas. It must not be placed in direct exposure to sunlight. The controller must be mounted on a wall or a flat surface with a distance of at least 10 cm to the nearest object to provide natural air convection. It is recommended that the controller is mounted near the battery, but at a distance not less than 30 cm.
Controllers do not require special service, i.e. they are maintenance-free, although preventive maintenance of the entire system is recommended once a year so that dirt and dust can be removed and the connecting screws – tightened.
Different controllers work with different voltages: 12 VDC, 24 VDC, 48 VDC. Another parameter that is crucial in the selection of a controller is its own consumption. Quality controllers are characterized by very low own consumption of about 4 mA. More expensive models can be programmed, controlled remotely, etc. Of course, you can connect more than one solar panel to the controller, taking into account the total power of the controller and the way the panels are connected (series, parallel or mixed connection).
Choosing a reliable and quality controller is one of the most important preconditions for long and efficient operation of the entire solar system. It is important to verify whether the selected device corresponds to DIN EN ISO 900-2000 or a similar standard, whether it is purchased from a reputable company with traditions in the sale of PV systems, such as Vikiwat Ltd. and whether it is consistent with the power capacity of the solar system. As you can see there is nothing complicated about installing a solar system, and the best comes next as the produced current is completely free. As prices of electric energy constantly increase, the popularity of systems producing energy from the sun, wind and other renewable sources will increase.