Solar Wiring in Series or Parallel for Optimal Energy Output

Once you have the basic knowledge of how solar works, it is time to dive deeper into the specifics – solar wiring and why it matters. While your solar panel installation company will handle the wiring for you, if you decide to go that route, there are two main types of inverter systems: microinverters and string inverters. Both types of inverters serve the same fundamental purpose—converting Direct Current (DC) power generated by solar panels into usable Alternating Current (AC) power. However, they differ in design, circuit configuration, and overall performance, which makes each better suited to different environmental and installation conditions. Microinverters and string inverters can be compared by system performance in terms of sunlight availability, shading tolerance, voltage drop and power loss, and wiring complexity. The performance is largely due to how the solar system is wired, whether in parallel or series.

Microinverter systems are installed with each solar panel having its own inverter. Each microinverter is connected to the others in a parallel circuit. In this configuration, each panel and microinverter pair operates independently.

String inverter systems, on the other hand, connect multiple solar panels in series to a single, central inverter, forming a series circuit. A circuit of series-connected panels is called a “string”. In this configuration the panels in each string are dependent on each other in the power-generating process. In this article we will compare the two, and decide which wiring is best for every situation.

What is Wiring in a Series?

Wiring solar panels in a series means connecting the positive terminal of one solar panel to the negative terminal of the next, creating a chain-like circuit. This configuration increases the voltage of the rooftop solar panel system while keeping the current the same as a single solar panel. For example, if you have four solar panels, each with a voltage of 12 volts and a current of 5 amps, wiring them in a series would result in a total voltage of 48 volts (12V x 4), while the current remains at 5 amps. Here are some advantages and disadvantages of this type of solar panel wiring:

Advantages of Series Solar Wiring

1. Higher Voltage Output: String Inverters transmit high-voltage direct current power (up to 600V DC) from the solar panels to the inverter. The advantage is with higher voltage, the current can be lower for the same power output, resulting in lower loss over long distances. This high-voltage configuration makes string inverters relatively efficient in rooftop installations where solar panel output is consistent across the array and where long wiring distances are needed.
2. Reduced Line Loss: Ohm’s Power Law describes the relationship between power (P), voltage (V), and current (I). It’s expressed with the formula:

P=V×I 

In a series solar circuit, power is transmitted at a higher voltage. In a parallel solar circuit, power is transmitted at a higher current. When power travels through a wire, some of it is lost as heat due to the resistance of the wire. This power loss due to resistance can be calculated using: 

P(loss)=I^2×R 

String inverter systems with series wiring benefit from this principle by using higher-voltage direct current, which reduces power loss over longer distances. In contrast, microinverters operate at lower voltages since they convert DC to AC at each panel, so they don’t rely on high-voltage transmission for efficiency. 

Disadvantages of Series Solar Wiring

1. Shading Sensitivity: Shading is a bigger concern in string inverter systems. Shading on one panel can reduce the performance of the entire string, as the current flow is constrained by the panel with the least sunlight. This “Christmas light effect” limits the efficiency of string inverters in areas where partial shading is inevitable. Modern solar panels have bypass diodes, a protective component that helps the energy current bypass faulty or shaded cells, and many string inverter systems have optimizers, components that help improve performance, which help mitigate shading issues.
2. Not Ideal for Low Sunlight Conditions: In a string inverter system, all solar panels in a series string are interdependent. If one panel’s sunlight exposure decreases, it can reduce the overall output of the entire string. For example, if a single panel in a string is partially shaded or has an issue, it will limit the electricity flowing through the other solar panels, as they operate at the same current. Because of this, string inverters are best suited for installations with uniform sunlight exposure across all solar panels.

What Does Wiring Solar Panels in Parallel Mean?

Wiring solar panels in a parallel configuration involves connecting all of the positive terminals together and all of the negative terminals together, creating multiple paths for the electricity currents to flow. This configuration increases the current of the solar panel system while keeping the voltage the same as a single solar panel. Using the same four 12-volt, 5-amp solar panels, wiring them in this configuration would result in a total current of 20 amps (5A x 4), while the voltage remains at 12 volts. Outlined below are some advantages and disadvantages of this wiring type:

Advantages of Parallel Solar Wiring

1. Greater Current Flow: Parallel wiring is ideal for increasing the overall current of a solar panel system, which can be useful for rooftop systems paired with batteries and requiring a higher current to operate effectively.
2. Improved Shading Tolerance: Because each solar panel operates independently in a microinverter setup, they do not rely on the performance of other panels. If one solar panel receives less sunlight (for example, due to orientation or dirt), it will not affect the output of the rest of the system. This makes microinverters highly effective in rooftop installations where sunlight conditions vary across the solar panel array, such as on roofs with multiple orientations or irregular shading.

Disadvantages of Parallel Solar Wiring

1. Higher Line Losses: Microinverters convert direct current to alternating current at the panel level, so the power transmitted through the wiring from each solar panel to the utility grid or home system is already in AC. Microinverters operate at a lower voltage than string inverters, typically around 240V AC. While this means the system doesn’t gain the power-saving benefits of high-voltage transmission, its efficiency comes from a different advantage. Each solar panel operates independently, allowing the system to minimize energy loss caused by shading or partial panel failure, rather than relying on reduced voltage drop during transmission.
2. Current Imbalance: In parallel circuits, slight variations in the current output of solar panels, caused by manufacturing differences or degradation, can result in the panel with the highest current output restricting the overall current of the circuit. This may lead to less efficient power generation.

Solar in Series or Parallel: Which Should You Choose?

The decision between wiring your rooftop solar panel system in a series or parallel largely depends on your specific energy needs, the design of your solar panel system, and the characteristics of your home. Often, your solar installer will decide for you which wiring system is the best fit. Here’s a closer look at specific scenarios where one option may be more suitable than another:

How Blue Raven Solar Optimizes Your Wiring Configuration

When considering the benefits of solar in string (series) or microinverter (parallel) configurations, it’s important to work with an experienced provider like Blue Raven Solar to ensure your customized solar panel system is designed for maximum efficiency. Blue Raven Solar’s expertise ensures that your system is tailored to your home’s specific energy needs, roof design, and sunlight exposure. 

Blue Raven often recommends microinverter (parallel) configurations for homeowners who have complex roof designs, partial shading, or unique energy requirements, as this setup allows each panel to operate independently. This results in optimized energy output even when one panel is shaded or soiled. Additionally, microinverters can enhance system monitoring and longevity, providing peace of mind and better performance. 

For homes with simpler layouts and no shading issues, a string (series) configuration may be more suitable and cost-effective, as it centralizes the power conversion. Regardless of the setup, Blue Raven Solar works closely with homeowners to assess their property and electricity usage, selecting the configuration that maximizes performance and savings. 

By choosing Blue Raven Solar, you gain a partner dedicated to providing reliable, clean energy for years to come, backed by superior customer service and professional installation.