With myriads of solar energy options available in recent times, it can be quite tricky to choose the one that best suits your needs. The technical details can be confusing, and having come across the various processes involved in wiring solar panels in series or parallel, it is common to begin to question the necessity of wiring your solar panels together at all.
Unbeknownst to many, investing time in creating such a system provides many benefits. Apart from giving you optimum and uninterrupted performance, a well-wired solar panel system will also give you a greater return on investment.
If you have difficulty knowing how solar panels can be wired, either in series or parallel, you have come to the right place. This comprehensive guide will expose you to the various details and steps involved in wiring solar panels in series or parallel. The piece has been designed to start from the basics to make your understanding of the subject easier and more relatable. Without delay, let’s get to it.
How to Wire Solar Panels in Series
Series wiring can be carried out in two ways. It is essential that you know this to avoid making a mistake. First off, you can have a series wiring of two or more solar panels with similar technical features (identical solar panels). You can also have a series connection of two or more panels with different technical features (non-identical solar panels).
In order to have an in-depth understanding of how to wire solar panels in series, some essential components need to be considered. In making solar panels, several solar cells connected in series are used. Some solar panels (for instance, the 230Wp 32V model) can contain as many as 60 solar cells wired in series.
These solar cells help convert the sun’s rays into electrical energy. This process is generally referred to as the photovoltaic effect. Most solar cells available in the market are designed with silicon (a semi-crystalline material), blue or black.
How to Wire Two Identical Solar Panels in Series
When searching for the best alternative to increase the voltage of two or more solar panels having equal power and current, series wiring can be extremely useful.
By wiring solar panels in series, the devices’ voltage automatically increases. In every solar panel system, an increase in voltage will decrease the rate of energy loss along the cables. To discover the highest system voltage value, read the label attached to the panel.
Wiring in series is quite simple. The positive pole of one solar panel should be connected to the negative pole of the other. This will lead to a double voltage at the output. For instance, if you wire two 5A 12V solar panels in series, a double value of 24V will be produced while the current remains at 5A.
Evidence of Shading In Series Connection and How to Solve it
Instances of shading, particularly when wiring two or more identical solar panels in series, cannot be completely ruled out. You might be wondering what the exact causes of shading are. Its causes include poles, trees, and other protrusions. To enjoy a seamless performance from your solar panel system, you must ensure the panels don’t shade each other and they must be carefully positioned away from the objects that cause shading.
Climatic conditions can also induce shading. In that case, you need to understand how to solve the problem to avoid decreasing the rate at which electricity is produced.
As you already know, a solar panel contains several solar cells wired in series. Perhaps a section of the panel is shaded; the result is a low current circulation due to high resistance. To make things worse, the shaded sections absorb electrical energy, thus, contributing to the load. As a result of the impact of joule, the current that moves through these shaded parts causes an increase in temperature, which triggers fires and dissolves welds.
With technological advancements and improvements, solar panel manufacturers have been able to design tools that reduce and completely erase instances of shading. Having divided the device into several sections, each section containing a good number of solar cells, the manufacturers insert a bypass diode in each section. With the aid of this bypass diode, shaded sections are excluded so that they do not have adverse effects on the entire solar panel.
Therefore, solar panels with bypass diodes are the best choice for solar power systems. The sections the panel is divided into largely depend on the number of bypass diodes it has. Suppose all the sections of a solar panel are covered in shadow while the other panels are open to the sun’s rays. In this case, a bypass diode should be inserted into each panel in parallel. This will exclude the shaded panel from the others and prevent it from adversely affecting the production of electrical energy in the other solar panels wired in series.
In a grid-wired solar panel system, the grid-tie inverter plays the crucial role of keeping a tab on the maximum power point (MPP). On the other hand, in an off-grid PV system, the MPPT solar charge controller plays the role.
Selecting The Right Diode For The Work
Selecting the right diode for wiring can be more of a challenge than fun because there are many diode options available in the market. Since your task is wiring solar panels in series or parallel, the best one to choose is the Schottky diode. This diode reduces the rate at which power spreads out and disappears. Beyond that, it comes with a relatively low threshold vintage of about 0.35V. This is in contrast to the 0.6V that comes with most diodes.
Another factor you should consider when choosing a diode is the section and length of the electrical wire. This is because an increase in the number of available solar panels will result in a corresponding increase in current, ultimately resulting in the rapid dissipation of electrical energy. Perhaps the current is relatively high; you can settle for a cable with an appropriate section.
How to Wire Two Non-identical Solar Panels in Series
Wiring two or more solar panels with different currents but equal voltage in series is impossible. This does not rule out the fact that they can’t be wired via other means. A parallel connection is ideal if you find yourself in such situations where the panel voltage is equal while the current is different.
How to Wire Solar Panels in Parallel
Wiring solar panels in parallel also come in two forms. When wiring in parallel, the connection can be made between two or more solar panels with similar technical features (identical solar panels). If it doesn’t take that form, the wiring can also be made between two or more panels having different technical features (non-identical solar panels).
How to Wire Two Identical Solar Panels in Parallel
To have easy and simple wiring between two or more solar panels with similar technical features, the solar panels must have the same power and voltage. For example, the 12V/10A measurement of one must correspond with the 12V/10A measurement of the other.
This will make it possible for you to connect the negative pole of one solar panel to the negative pole of the other and the positive pole of one solar panel to the positive pole of the other. Simple as that may sound, it requires some technical skills. To make this identical connection possible and timely, an MC4 Y-branch solar connector can be used.
Effective wiring of identical solar panels in parallel is possible only when some conditions are met and a step-by-step approach is properly followed. Below are the steps to follow when bridging the gap.
- Start by placing the solar panels side by side.
- Make sure that both panels are set or directed towards the sun at the same angle.
- Ensure that there’s no instance of shading between the panels. Do a quick check to ascertain that.
- Place the panels at a distance from potential causes of shading.
- Check the distance of the solar panels and select the right section of the electrical cable that goes hand-in-hand with it.
- Wire the terminals of the solar panels together using junction boxes.
What To Do if Shading Occurs in a Parallel Connection
While wiring solar panels in parallel, there can also be cases of shading.
As it stands, you should know that the voltage indicated at the ends of a solar panel that has experienced shading is not based on its irradiation condition. Instead, it largely depends on the conditions of load to which it is subjected. Without mincing words, a shaded solar panel still has the potential to collect a great share of solar energy.
This means that it can still offer a positive working voltage, just like when it is completely irradiated. Thus, decreasing the current proportional to the solar radiation.
When using a grid-connected PV system, you should know that you can’t do without a solar inverter that is up to the task. This will fetch or provide the panel string maximum power point (MPP) in shading and full irradiation conditions.
On the other hand, the MPPT solar charge controller is your best bet when using an off-grid solar energy system. This is where the blocking diode comes into the picture. If you are looking for the perfect device to protect the whole panel strings from potential reverse currents, you can depend on the blocking diode to serve that purpose and even more. It is suitable for large solar power systems.
Concerning reverse currents in solar panels, several studies and research initiated and conducted by the Fraunhofer Institute for Solar Energy Systems ISE in recent times have indicated that, compared to short circuit current, solar panels are more capable of withstanding reverse currents up to 7 times. The research also showed that solar panels do not suffer damage from this condition.
It is often recommended that, when choosing a solar panel, you should go for the one that is equipped with three or more bypass diodes on the inside in order to prevent energy loss during shading.
How to Wire Two Non-identical Solar Panels in Parallel
Non-identical solar panels have varying characteristics. While the voltage is similar (as the case may be), the wattage is different. Thus, wiring two non-identical solar panels in parallel is possible.
However, when both the wattage and voltage are different, wiring solar panels in parallel is entirely impossible. This is because the voltage won’t match, making the panel with a lower voltage act as a load. Instead of producing current, this panel absorbs it.
For instance, if you have two 6V solar panels and a 12V panel, the former can be wired in series while the latter is connected to the initial 6V solar panels in parallel. The only setback here is that the efficiency of this wiring is relatively at a lower ebb. Thus, before making a connection in parallel, it is vital that you check the solar panels’ voltages.
How to Wire Solar Panels in Parallel and Series
Solar panel wiring is possible using both parallel and series connections simultaneously. However, before you set out to wire your solar panels this way, you need to pay premium attention to the current. This method is suitable for multiple solar panels ranging from three to six and even more.
A solar power system can get damaged and suffer current-related problems if the output value reaches 70V. To avoid this, it is advisable that you wire solar panels in series and parallel. This will increase their current and voltage at the same time.
Let’s take a practical approach to understand this method further. If, for instance, you are wiring six 10A solar panels in parallel, the outcome will be a relatively high current of about 60A. You can connect two panels in series to obtain a double voltage to generate a more effective energy performance and optimize the energy production process. The two solar panels wired in series can then be wired in parallel with others to triple the current and double the voltage.
This method of connection is the most suitable for wattage systems. The choice of the battery bank voltage and the total wattage must be determined at the design phase when using an off-grid PV system.
It is important to know that you can either wire solar panels in series or parallel. A combination of the two methods is also possible (and necessary) in certain situations. If you want to enjoy continuous operation even when one of the panels is not working properly, you can opt for the parallel connection. When wired in series, your solar panels’ voltage increases significantly. A combination of the two methods will give you increased current and voltage at the same time.