Solar panel wiring is also termed stringing. The technique of how to string solar panels together is a major concern for any solar installer. The major to consider is the fact to understand how different stringing configurations impact the voltage, current, and power of a solar array. On the basis of this, one can select an appropriate inverter for the array and make sure that the system will function effectively.
The stakes are high. If the maximum voltage of your array of the inverter exceeds the limit, then the production will be affected and can ever fluctuate as per the expected range of the production. If the voltage of the specified array is too low for the inverter you’ve chosen, then the system will reduce production accordingly. This is all because the inverter will not operate until it reaches the “start production” limit.
Modern solar panel design software like thesolarlabs is capable enough to manage this complexity for the operator.
Basic concepts of solar panel wiring:-
All you need to do is wire the panel together to attain a functional solar PV system. This creates an electrical circuit through which current will flow. The procedure includes the connectivity of the wires that will ultimately convert the DC power to AC power, whose power can be utilized in your homes and sent to the grid. This technology is typically referred to as “stringing” in the solar industry, and each series of panels are connected together, which is determined as a string.
Series v/s. parallel stringing:-
There are a variety of ways to understand or approach solar panel wiring. The major differentiation is to understand the concept of stringing solar panels in series versus stringing solar panels simultaneously. These unique stringing configurations have different effects on the electrical current and voltage in the circuit.
Connecting solar panels in Series:-
Stringing solar panels in series is basically connecting the wires next to each other.
You must be familiar with a typical battery. There are two types of terminals in solar panels which are positive and negative terminals. When stringing in series, the wire from the positive terminal of one solar panel is connected to the negative terminal of the next panel, and it runs further in the same way.
When stringing panels are in series, each additional panel is involved in the total voltage, which is symbolized as (V) of the string, but the current (I) in the string remains constant.
Connecting solar panels in parallel:-
Stringing solar panels in parallel is a bit complicated. Rather than connecting the positive terminal to the negative terminal in the next series, when stringing in parallel, the positive terminals of all the panels on the string are connected to a single wire, and the negative terminals are connected to another wire.
When stringing panels are in a parallel stage, each additional panel increases the current (amperage) of the circuit. However, the voltage of the circuit remains constant (equivalent to the voltage of each panel). As an effect of this, we get an advantage that if one panel is heavily shaded, the rest of the panels can operate in a normal way, and the current of the overall string will not be decreased.
Rules to consider regarding how to string solar panels:-
1. Ensure the minimum and maximum voltage range of the inverter
The strings that are connected to the inverters must be under the range limit of the inverter voltage. It must not exceed the maximum input voltage or maximum current or fall below its minimum/start voltage.
2. Make sure that the strings have similar conditions
Once you’ve determined that your strings are within the acceptable length for the inverter specifications, another essential key to consider is that the strings must have similar conditions (for instance, same azimuth/orientation, same tilt, and same irradiance) at which they are connected to the same inverter MPPT.
3. Advanced considerations to optimize your design
We have already discussed the stringing configuration that will comply with the specifications of your inverter and the energy production of the system.
How to estimate the size of the String:-
The size of the string is dependent upon the specific voltage of your panels and inverter, along with outside factors like temperature.
Each panel has an output voltage. These voltages of the panels are transmitted to the inverter. Here we have mentioned some of the sizes to choose from:
Open Circuit Voltage (Voc): In Voc, the voltage is supplied when the circuit is in the open stage. In simple words, when current isn’t passing through the circuit, this state occurs when the inverter isn’t switched on.
Max Power Voltage (Vmp): In Vmp, the voltage is supplied when the circuit is turned on and is operating normally under load (current flows through the circuit).
These numbers can be seen on the panel spec sheet as the numbers are unique for each and every panel.
While going through the inverter spec sheet, have a look at the rated MPP voltage range. This is the exact spot for ideal operations.
Also, keep track of the maximum DC input voltage. In case you exceed the maximum operating voltage, the inverter would get overloaded and potentially burn the equipment. Going over the max operating voltage will void the warranty on your inverter.
The same goes for a minimum DC voltage. Typically this won’t create any issue.
How can we boost the efficiency of the Solar Panel?
In every condition, the workability of the solar panel varies. Some of the factors that affect the functioning of the panels are the installation spot and angle and the type or model of panels.
Go with the Right Solar Panels
There are countless varieties of solar panels. However, regardless of its size, every solar panel may vary in terms of efficiency.
Usually, the most efficient solar panels belong to the mono-crystalline panels, which are famous for their circular edges and even color. Unfortunately, they tend to be very expensive.
Regularity in Cleaning the Solar Panels
A solar panel doesn’t have migrating parts. It simply states that it requires no maintenance. However, you should install it with proper care.
If you want to enhance the efficiency of your solar panels, all you need to do is to clean the panels on a regular basis, as dirt particles may accumulate on their surface. How frequently you should clean your solar panels totally depends upon the cost consumed to clean them. Also, how often does it rain in your region?
The Angle Matters
If you want your solar panels to absorb more sun rays, all you need to do is to install them in a south-facing location with an appropriate angle. Paying attention to this part is crucial as the slope can also affect the neatness of the panels.
Reduce the number Of Devices
Here we have mentioned another trick to maximize the efficiency of the solar panel. The technique says to lessen the number of devices you’re using. If possible, try to utilize a single device at a time.
The usability limit is dependent upon your solar panel’s output and the amount of energy your devices use. For instance, stop using the dishwasher while using a washing machine.
Differentiation between String and Array in solar panel:-
After making an estimation of how many solar panels you require, you can call a solar power provider to install a system for your home. If you want to opt for the DIY approach, you have to know the different parts and terms used in the respective field, including cells, modules, strings, and arrays, and their connectivity.
A solar panel, or we can say a PV module, is made up of several cells, where multiple solar panels are wired in a series or parallel. The design is known as a solar array. A string consists of solar panels that are wired in a series set to one input on a solar string inverter.
In case two or more solar panels are wired together, that is a solar / PV array. String sizing depicts how many solar panels can be wired to an inverter to obtain the best results. The best output depends on several factors, including the inverter voltage capacity.
What is the Difference Between Solar Cell, Panel, Array, and Module?
A solar panel is another name for a PV (photovoltaic) module. Generally, a solar panel is made up of several semiconductors called cells. There are 36 cells in a typical solar panel, for example- the Sonali 190W 12V. In the situation when the sun strikes the cells, the energy is converted into DC electricity. DC electricity can be utilized directly by DC-powered devices. AC electronics, however, require an inverter to convert DC energy into AC energy.
One can take the solar panel or module as the housing for the cells. So, a 12V solar panel/module has 36 or 72 cells that are connected in parallel or series. For increasing power generation, several solar panels or modules may be wired together to create a solar or PV array.
Here, the question arises, what makes solar arrays effective in their modularity? The answer for the same is that you can use more than a single panel to increase power or change the wiring to suit your requirements. The cells are shielded by a hard plastic/glass sheet. These are heavy-duty materials made to protect the cells from the elements, though solar panel covers are also available.
The terminology solar array is also used for solar farms, but generally, it refers to a group of solar panels that are wired together for residential use. They are also used on RVs or ground-mounted systems with multiple solar panel installations.
How Many Solar Panels Should Be Included In an Array?
The number of arrays is defined by the requirement of the solar panel. The location, electricity usage, and available space on your roof (or ground) of the user will determine how many panels create your array.
Let’s go through it with the help of an example.
The house consumes 1000 kWh per month. Among the combinations and solar panel sizes, you can buy.
• 5 x 250W = 1250W
• 4 x 315W = 1260W
• 3 x 375W = 1125W
Due to various reasons, solar panel output is often lower than its rating; in such a situation, we suggest having more than 1000W total in case of cloudy or rainy days. If your system produces more power than the requirement, you can store it in a battery bank or export it to the power grid and receive credit. When solar production reduces, you can use that credit.
Series V/s. Parallel Solar Panel Wiring:-
Once you get your solar panels, you can install them in an array. The array may be installed either in series, parallel, or both depending on your system.
In a series, the voltage is included, but the amperage remains the same. In a series connection, the positive terminal of the solar panel is connected to the negative terminal of the next panel.
While, in a parallel configuration, the amperage increases, but the voltage remains constant. In a parallel configuration, the positive terminals of all the panels are connected in a single wire, and every negative terminal is connected to another wiring.
The current is denoted by the number of parallel cells, while the number of series refers to the voltage. Series connections have a bypass diode that protects the cells. Only one bypass diode is evitable for every 15 to 20 cells. The diode helps the current transmit through the solar panel.
Here, the decision needs to be taken regarding which one is better, either series or parallel?
Here, your solar installer will give you the answer about which is best for your home. The reason behind this is it depends on your electricity usage. If you need higher voltage, a series connection is an ideal choice for you. But, if more requirement of amperage arises, then parallel is the better wiring configuration.
After the configuration of the solar array, it has to be connected to an inverter to access AC-powered appliances on solar. This is a situation where the sizing of the string came into existence.
How Many Solar Panels are there In a String?
A string panel can be wired up to 8 solar panels into a single inverter input. Most inverters have three string inputs, which means it contains 24 solar panels. The inverter's operational range affects the number of solar panels.
Inverters operate within a particular voltage range, and the voltage is generated inside the solar modules under that range. If the modules produce too much power, there is a possibility of damage to the inverter. On the contrary, if the power is too low, the inverter will not run. So, it must produce the right level.
One can visualize the voltage range on the inverter itself or the product operating manual. However, there are various factors that affect the stringing of solar panels.