For non-technical homeowners, it can be difficult to understand how to connect a solar panel. A lot of terms, a lot of wires, and incomprehensible but expensive panels can be confusing to everyone. But in this case, it is important to have sufficient knowledge.
Indeed, the panels’ performance will directly depend on the correctness of the basic solar power system diagram. Therefore, it is very important to do everything to comply with all the rules of section 690.64 of the National Electrical Code (NEC). If doubts or questions arise during the process, it will be better to enlist the support of professionals.
Today we will analyze the basic rules to help you understand how to wire solar panels and draw a diagram.
What is a Wiring Diagram for Solar Panels?
A solar panel wiring diagram is a technical drawing according to which the entire solar panel connection process will be carried out. It must indicate all details involved in the operation of the system. The solar panel schematic must contain information about this equipment. This is a plan for solar power connections.
But for all the steps to be correct, it is necessary to correctly draw up all the drawings and consider all the details, depending on the type of system, the number of panels, and other factors. Yes, and these points will have to be taken into account.
How Do I Create a Wiring Diagram for Solar Panels?
There is the simplest solar power wiring diagram, according to which it is enough to connect the solar battery’s positive wires to the battery’s positive terminal and the negative wires to the negative terminal. But this is not always possible, and complex systems require a more complex solar schematic.
For the convenience of its implementation, you can use the free tool Canva. With it, you can quickly and accurately reflect all the features of your installation. At the same time, no technical knowledge and experience in designing solar panel wiring diagrams are required for work.
Steps to implement solar power diagrams:
- Install Canva and sign up for the tool via Facebook or any other convenient way.
- Open the app, find “Create Design” in the upper right corner and click on it.
- Specify “custom size,” “width 3508,” and “height 2480”. These dimensions correspond to the A4 format, which will simplify the task if you need to print the solar power schematic.
- Click “create a new design” to see a blank sheet. You now have a basis for illustrating solar power wiring diagrams.
The finished wiring diagram for a solar system will look something like this.
Electrical Terms Pertinent to Solar Panel Wiring
To understand how to wire solar panels to your home, you will need to study many technical terms:
- “Solar system wiring” is all solar cells connected in series, forming a driving force.
- A crimping tool is used for crimping the connection plate from the solar panel to the bare wire. The most commonly used is MS4.
- The solar connection assembly tool is a tool to tighten all MC4s with the plug/socket connection plate or unlock the connector once the connecting solar panels have been produced.
- The inverter is the main part of the solar wiring diagram, converting direct current into alternating current while providing optimal voltage.
- The string inverter is the most common type and is suitable for systems with a series or series-parallel solar power connection. If there is partial shading, they cannot be used for solar panel connections.
- The microinverter is an installation used only with a parallel type of connection, even in the case of partial shading of the solar panels. It is attached to each panel, providing maximum power.
It is also necessary to understand what wires and their types exist, what electrical current and voltage are, the principles of connection to the load side and the power line, and the differences between parallel, series, and parallel-series solar panel wiring connections. We will cover all these terms in this article. Just keep reading.
Fundamentals of solar panel wiring
When creating a solar diagram, it is required to plan the system configuration properly.
So, if the supplied voltage is too high, the system’s performance will decrease, and its service life will be reduced. If it is low, the inverter will not work because it only functions when there is an “initial voltage.” That is why the maximum and minimum DC input voltage must be taken into account.
The maximum voltage must be limited according to the NEC regulations and the available specifications of the installed inverter. It is often limited to 600 V., with the minimum voltage depending on the inverter model.
For solar panel installation diagrams, it is worth considering the input DC of the inverter, or rather its maximum value. It must be less than the current output of the system.
When it comes to the network wiring for solar panels, it is also important to choose the connection principle. There are two main options:
- “load side” – connection is made after the main switch;
- “power line” – connection is made up to the main switch.
Here is how it will look on the solar wiring diagram for the house.
How to wire a solar panel from the load side?
First of all, this is the most common option for connecting solar panels. It implies that the panels will be connected after the circuit breaker. The latter will have two poles and two sections, but it must be located far from the main switch. Further, in the solar panel battery wiring diagram, it should be reflected that the wires from the panels will be connected to the circuit breaker. This is convenient since most inverters already have an automatic shutdown in case of power surges and other problems. But even if it is not there, you can purchase an external shutdown system for a small amount. The latter and the connection from the load side will completely protect your battery from possible downside risks by simply turning it off.
There are various National Electrical Code (NEC) rules that govern the process of solar system wiring diagrams. Learn and apply them when wiring a solar system.
How to connect solar panels on the power side?
In this principle, the panels and the switch are connected to a junction box. But it is seldom used, as it requires additional permission or is prohibited in some states.
Required Information for Determining How to String Solar Panels
Before proceeding with how to wire solar panels to your home – analyze the following data about your solar system and inverter:
- Study the characteristics of the inverter. Pay attention to the minimum voltage that is needed for its operation and the maximum allowable to receive.
- Find out how many MPPT trackers you need to run the inverter.
- Specify how much power the inverter can supply before shutting down.
- Study the information about solar panels, namely, how much maximum voltage the panel can give at idle – Voc.
- Assess there is no discrepancy between the minimum and maximum voltage of the panels with the range of the inverter.
- Determine if there are different conditions between the “rows of solar panels.” If there is, buy additional MPPTs and connect strings with different conditions.
Then you need to make calculations according to all the individual characteristics of the solar panels and the inverter, correct the solar panel schematics and proceed to solar panels wiring. But first, let’s look at how to wire solar panels in series and parallel.
Series vs. parallel stringing
Perhaps the most important approaches to wiring a solar panel are series and parallel wire connections. There is a huge difference between them, though. They have a completely different effect on the voltage and current distribution through the circuit.
Connecting solar panels in series
Here is a simple solar panel diagram by series connection.
The positive terminal on one battery will then be connected to the negative terminal on the other, and so on. Once connected, each panel will increase the total voltage while the current in the entire circuit will remain at the same level.
The main disadvantage is that if the current in one of the panels is lower than in the others, all panels will reduce it to the lowest output level.
Connecting Solar Panels in Parallel
As you can see in the solar panel layout diagram below, they are all connected in parallel.
This type of connection is more complex. The positive terminals of all panels are connected to one wire, and the negative terminals to the other. And each subsequent battery in the solar power wiring increases the current in the common circuit, but the voltage, in this case, remains unchanged. This is the advantage of the parallel type of connection; if one panel is darkened or its current is lower than in the others, the other batteries will work at full capacity.
Guidelines for Stringing Solar Panels
The solar panel circuit diagram is ready; all the main points have been studied, so it’s time to start installing.
How to Connect to Solar Panels’ Wires and Connectors?
Most often, solar panels have MC4 connectors. To connect them, you will also need an MC4 and an extension cable to connect them. Considering a possible size difference, you need to make measurements so that it is enough both for the panels and for bringing them to the inverter.
To connect all panels and the inverter when installing according to the solar electric system diagram, you will need:
- Strip wires.
- Connect them with the connecting plate using a crimping tool.
- Install the lower parts – compression sleeve, strain relief, and terminal cover into the connector.
- Install the upper parts into the connector – the connector housing, the film, and the seal.
- Combine all the details and press them with your hands.
- Fix and install the rotating element of the MC4 connector using a suitable tool.
Here are the first steps in implementing the solar combiner box wiring diagram:
How to Wire a Solar Panel System in Series?
How to wire up solar panels when using a series connection? Everything is simple. It is enough to connect the MC4 plug of the negative terminal of one battery to the MC4 plug of the positive terminal. Repeat these steps for all series solar wiring panels. Then, connect the MC4 plug connector of the first module and the MC4 female connector of the last module to the inverter in the appropriate connectors.
How to Wire a Solar System of a Parallel Type?
When implementing the solar panel schematic diagram by parallel connection, it is necessary to connect the positive MC4 plugs of all panels in one connector and the negative ones in the other. For simplicity, use large connectors.
Frequently Asked Questions
What is voltage?
Voltage is the pressure from power sources in an electronic circuit and provides the current moving through a conductive circuit, which provides this or that work. It is measured in volts (V), a unit of measurement that characterizes the difference in electric charges at two different points in a circuit. Due to this difference, current flows in the circuit. Voltage reflects the amount of potential energy in the solar power diagram that can be conducted.
In a solar battery, this pressure is affected by sunlight or its amount. The more active the sun, the more voltage will be in the network. But the higher temperature, the lower pressure, and vice versa.
What is the current of electricity?
Electric current is the directed movement of charged particles along the solar panel wiring diagram schematic, carried out under an electronic field’s influence. It is measured in amperes and is designated I. There are direct, alternating, periodic, and other types of current.
But the solar panel produces direct current, and most electrical appliances consume alternating current. Therefore, a converter is required to enable the device to operate, acting as an inverter.
What is an MPPT?
MPPT is the maximum power tacker in solar panel wiring diagrams. It provides constant voltage and current control.
Inverters not only convert DC to AC but also maximize output power. The latter is constantly changing under the influence of environmental factors. Inverters act as regulators of this difficulty.
MPPT requires more or less stable operating conditions for the panels to work effectively. With differences in the orientation of the systems or differences in the dimming level, the tracker’s performance may also decrease. But if this problem is unavoidable, you should install several MPPTs, and connect unstable chains to a separate taker. All this should be reflected in the KEY.
What kind of wiring is necessary for solar panels?
The correct wires are needed to ensure a stable and normal flow of current in the circuit from point A to point B. Before creating a solar setup diagram, consult with professionals or evaluate the National Electrical Code (NEC) standards. For example, according to the latter, conventional wires during the operation of solar panels are prohibited.
Wiring solar panels will require special wires that last about 25-30 years and are resistant to UV rays, fire, high temperatures, moisture, and temperature extremes.
Single-core wire, with a single wire.
Stranded wire, with several wires and a much larger surface.
The multi-core solar panel connecting wires are more durable, flexible, stable, and reliable.
Special wires are also available for rooftop installations – TUV PV Wire or EN 50618 PV cable. And for above-ground facilities where it is necessary to run the wire underground, a USE-2 cable is used.
Is it better to wire solar panels in series or parallel?
The main difference between the principles is that with series, the voltage increases, and with parallel, the current strength. Therefore, the choice is based on the individual features of the house, roof, and other indicators. Before how to wire up solar panels, you can consult with professionals.
Sometimes it is better to use a parallel connection because if one panel fails, the others work properly. But sometimes this option is not suitable.
The best option is to combine both types of connection. This will increase both the current and voltage, so after the implementation of the diagram of solar panel installation, the system will work with maximum efficiency.
What is the maximum number of solar panels I can connect to my inverter?
It all depends on the characteristics of the inverter and solar panels you plan to buy. If the inverter has a power of 5000 W, and one panel is 300 W, then about 17 panels can be connected in the solar panel system diagram.
Can I directly connect solar panels to a battery?
The panel produces energy at different intensities in practice. During the day, unstable energy will flow directly into the battery, causing damage to the battery. The charge controller is necessary to ensure stability and eliminate system wear.
Can solar panels and an inverter function independently of a battery?
Due to the development of technology and the emergence of new models, batteries are no longer a mandatory attribute. But only if you do not plan to store excess energy at home but want to send it to the general utility network.
How to select the appropriate size solar power inverter
It all depends on the needs of your home. As we wrote above, a 5000 W inverter accounts for about 17 panels of 300 W each. If you don’t need that many panels in solar panels schematics, then the inverter can be much less powerful. In addition, when using micro-inverters on each panel, you can increase the load on your inverter. But you only need to do this gradually, connecting one additional panel at a time.