The Complete Guide To Stringing Solar Panels

by Jul 20, 2021Solar Energy

The Complete Guide To Stringing Solar Panels

The Complete Guide To Stringing Solar Panels

Every solar installer should take a moment to understand how to string solar panels together correctly. It’s a simple process, but one that every professional solar need to know, especially if you’re planning on selling solar installations. So on this page, we’ll cover everything you need to know about the basics.

When you string multiple solar panels together in series, the resulting voltage will be lower than any individual panels. While it can be tempting to connect as many solar panels as possible for maximum power, choosing the correct.

Key Electrical Terms to Understand for Solar Panel Wiring

Several critical electrical terms are associated with solar panel wiring but are not necessarily widely known or used.

What Is Voltage?

Voltage is the potential for an electric current to flow between two points. Voltage is a measure of electrical pressure, used in conjunction with other measurements to specify the amount or intensity of an electric charge that flows through a conductor such as a wire. The SI unit for voltage is named “volt” after Alessandro Volta (Volta’s Law), who invented the voltaic pile, which produced a steady voltage output. Standard voltages in household circuits include 110-120 V, 220-240 V, and 400-440 V. Aside from these, typical voltages found in everyday appliances are high voltages.

What Is Current?

Electric current is the flow of electrons through a conductor (wire) from one end to the other. For example, when an electric charge flows through a metal wire, there are free electrons in that piece of metal that move with the flow of control. The motion of these free electrons is called current and can be measured using an ammeter (a unique instrument designed to measure electric current).

Current can also be defined as how much electrical charge moves past a point per unit time. This definition links to Ohm’s law, which states V = I R, where V is voltage, current, and R is resistance.

What is Electric Power?

Power (P) = voltage (V) x current (I) = V*I.

To put it another way; Power in watts equals volts times amps, and we can write that as P=VI. The above equation shows how a given amount of power, measured in watts, can be achieved with different voltage and current combinations. It says that if the voltage is twice, then-current must be half what it was before to deliver the same amount of power (or vice versa). Similarly, if you halve the voltage across an electrical device, you will need four times as much current to deliver the same amount of power.

Basic Guide To Stringing Solar

One of the essential parts of a solar power system is how current will flow from the photovoltaic cells into your home. Wiring panels together requires experience and knowledge; if you don’t know what you’re doing, you could accidentally create a hazardous situation resulting in injury or death. If you don’t feel qualified to wire panels yourself, hire an expert certified by an accredited organization such as the North American Board of Certified Energy Practitioners (NABCEP). Here are some basic concepts to know:

Guide To Stringing Solar Series vs Parallel Stringing

Whether to string solar panels in series or parallel depends on the output voltage and current requirements. Solar panel strings are most commonly strung in parallel instead of sequence because the combined voltage is twice, but power output remains the same for a given circuit.

Connecting Solar Panels in Series

Stringing solar panels in series involves connecting each panel to the next in a line (as illustrated on the left side of the diagram above). Like a typical battery you may be familiar with, solar panels have positive and negative terminals. However, this series results in a continuous voltage source – meaning that there are no seams in the head, unlike stringing panels in parallel.

When stringing panels in series, each panel additional adds to the total voltage (V) of the string, but the current (I) in the line remains the same. When connected in series, however, there is only one seam (at either end), so if one or more panels fail for any reason, their power will go from your system instead of just being isolated as it would be with parallel strings. Since two identical sets of 20 panels produce much higher output voltage than a single set of 40 panels, stringing in series is very common when using large arrays.

Connecting Solar Panels in Parallel

In general, when connecting two solar panels, it’s easiest to connect both positive leads of each solar panel and then connect the negative wires. But, unfortunately, there’s no way for the current to flow from one panel into the other when you do this.

When connecting more than two panels, though, things are trickier as we need to add another meeting without interrupting the circuit. Unfortunately, this means that we can’t have any “bridges” between panels where current could flow through at one point along our course – it’d be pretty bad if we connected panels like this:

This solar would be a short-circuit, and the panels would blow up! So we need to arrange our solar panels so that every pair of positive terminals is connected directly by a wire (or some other conducting path), but only indirectly via another panel’s negative terminal. Here’s one way to do it:

We can make two improvements to this design; however, if you look closely, you’ll see that all the negative connections are still shared – i.e., each panel connects to two others on the same point. We can remedy that by moving those connections around into something like this:

Now there’s no shared connection between any pairs of panels, which means that we won’t have a short circuit if anything goes wrong! As you can see from the first picture above, though, if done correctly with enough panels, this makes for a very high probability of working correctly. One more thing to note about these diagrams is that every positive terminal connects directly to another panel’s negative terminal (i.e., no shared connections on the negative side).

Guide To Stringing Solar When Determining How to String Solar Panels

This article will discuss those critical components and give the information you need to make good decisions on how to string your system.

First, we should size batteries not to reach 100% state-of-charge (SOC) during daylight hours when generation is high. As a rule, do not allow the bank voltage to rise above 13.2 volts or fall below 11.0 volts for 24 consecutive hours at any time off-grid (or while connected to only one PV array). The best way to ensure this if batteries have been oversized is to alternate controllers between banks; thus, if one bank is at full charge, the other will be at 50% SOC. Solar panels also allow you to use all of your batteries daily. On cloudy days or during long winter nights when there is little power production from solar, batteries that would otherwise reach full charge in an hour are only partially charged. 

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