WHAT'S IN A SOLAR POWER SYSTEM?

By [email protected] |

WHAT'S IN A SOLAR POWER SYSTEM?

Every solar power system or solar panel kit consists of these main components:

1. Solar panels

2. Inverters

3. Mounting system (racking)

4. Batteries

But how do these components turn sunlight into electricity you can use at your home or business? On this page, we'll go through each solar system part and clarify their functioning.

SOLAR PANELS

Solar panels are the most recognizable part of a solar power system.

They change sunlight into electricity using something called the photovoltaic effect. In this process, solar panels collect electrons from the sun's light as direct current (DC) electricity. This electricity goes through an inverter to turn into the kind we can use at home, which is called alternating current (AC) electricity.

Each panel is made up of many solar cells. These cells are like tiny silicon pieces connected together and held in place by a backsheet, a frame, and a glass cover.

A panel string is a bunch of around 4 to 10 panels connected in a row. This group then plugs into a special device called a string inverter.

Your solar array is all the panels in your system. It might have one or more panel strings connected to a string inverter or a bunch of panels each connected to a microinverter.

When you're looking at solar panels, you'll find two main types: monocrystalline or polycrystalline, and two different sizes.

Monocrystalline vs. Polycrystalline Solar Panels

Monocrystalline (mono) solar panels are made from silicon that comes from a single source and are cut into solar cells.

Polycrystalline (poly) solar panels are created by melting smaller pieces of silicon and blending them to form solar cells. The blended nature of poly cells makes them a bit less efficient than mono cells, meaning that mono panels can generate more solar power in a smaller area.

In the past, monocrystalline panels used to be more expensive due to their higher efficiency. However, this is no longer the case. As companies have focused on producing mono panels, improved manufacturing processes have brought the cost of mono and poly panels closer together. Monocrystalline cells now make up around 75% of the panels available in the market.

In terms of appearance, polycrystalline cells give solar panels a distinctive blue color, while monocrystalline panels have a sleek and modern all-black appearance.

Comparing 60/120-Cell and 72/144-Cell Solar Panels

Regular-sized solar panels are available in two standard sizes:

The 60-cell and 120-cell panels measure approximately 40 inches by 66 inches, with slight variations depending on the manufacturer. A 60-cell panel consists of 10 rows, each containing 6 cells. The 120-cell panels share the same size and layout, but the cells are halved to enhance panel efficiency.

For the 72-cell and 144-cell panels, their dimensions are around 40 inches by 78 inches, again with minor differences based on the manufacturer. A 72-cell panel is comprised of 12 rows of 6 cells each, while the 144-cell panels have the same shape but utilize half-cut cells.

The larger panels are about a foot taller and weigh an extra 8 pounds, which might make their handling a bit more challenging during installation, especially when setting up a system on your roof. However, this task can be easily managed with the help of two or more individuals.

While larger panels could offer slightly better cost-efficiency, your decision often boils down to the panel that fits best on your rooftop. If your roof is tall, you could potentially accommodate two rows of 60-cell panels. In contrast, a smaller roof might require 72-cell panels to maximize solar capacity within limited space.

These sizes are the most common within the industry, but there are also less typical sizes and shapes available. Smaller panels are more portable, making them a suitable choice for mobile applications such as on boats or RV systems.

INVERTERS

Inverters act as the intelligence behind your solar energy setup.

Inverters play a crucial role in a solar energy system. They transform the direct current (DC) electricity produced by your solar panels into alternating current (AC) electricity, which can be used to power your home devices. Additionally, they manage the flow of electricity between different parts of the system and often come with monitoring features to keep tabs on how your system is functioning.

You have several options when it comes to choosing inverters:

1. String inverters

2. String inverters with PV optimizers

3. Microinverters

4. Storage-ready inverters

String Inverters

A string inverter is like a central hub for solar panels. In this setup, the panels are connected in a chain, one after another, and the last panel in the chain is connected to the inverter.

For instance, imagine an 8 kW kit with two sets of 10 panels each, totaling 20 panels.

String inverters work well when your solar system gets direct sunlight all the time. But they face issues if some panels are shaded. When one panel in a chain is shaded, its output decreases, causing the entire chain to produce less power to match the shaded panel.

However, if your location has obstacles such as trees, chimneys, or other things blocking sunlight, using just a string inverter won't maximize your solar panel performance. In such cases, adding PV optimizers can help reduce the impact of shading and improve overall efficiency.

String inverters combined with PV optimizers provide an efficient solution. 

A PV optimizer is a small device that connects to the back of each solar panel. This device separates the output of each panel, enabling it to generate power on its own (and send performance data to your monitoring system), independently of the other panels in the array.

This setup ensures that if one panel is shaded, only that specific panel's performance is impacted. The remaining panels will maintain their optimal output.

Moreover, PV optimizers enable monitoring at the individual panel level. You can easily track the performance of each panel through your monitoring portal. If a panel is not performing well, it might indicate a need for cleaning or replacement. (In systems using only string inverters, monitoring provides performance data for the entire system, requiring individual testing to pinpoint issues.)

Microinverters

Similar to PV optimizers, microinverters are installed on the back of each solar panel. They optimize the system's performance and allow for monitoring of each individual panel.

Unlike optimizers, microinverters don't require a central string inverter unit to connect the system. Instead, the microinverter unit itself handles the inversion process.

This means that each combination of a microinverter and a panel functions as a small, self-contained solar power system. You don't need to worry about matching panel strings to the power limitations of a string inverter.

As a result, the design of a system using microinverters is much more flexible, modular, and expandable compared to systems using string inverters:

You can start with a small setup and expand it later without needing to retrofit or reinstall anything.

On roofs with unconventional shapes, you can place panels facing different directions without having to connect panels in a string.

You can replace or repair individual panels or microinverter units without disrupting the entire system.

Although microinverters have a higher initial cost, they come with a longer warranty period, making them a more valuable choice over the system's lifetime. String inverters usually have warranties of 5-15 years and often require replacement midway through the system's lifespan.

Inverters Ready for Storage

By default, grid-tie inverters do not have the ability to charge batteries. If you plan to add energy storage to your setup, make sure to seek out an inverter that can handle battery charging. These are often called "storage-ready" or "hybrid" inverters.

For those looking to incorporate storage into a microinverter system, the Enphase Ensemble package is a great option. It combines Enphase's microinverters, batteries, and monitoring into a unified system.

MOUNTING SYSTEMS

A solar panel mounting system creates a solid base for your solar panels.

Mounting systems are the foundational framework that secures your solar panels firmly. They include rails and flashing to attach the rails to your roof or ground setup.

Most residential solar setups fall into these two categories:

1. Roof-mounted systems

2. Ground-mounted systems

We will also discuss some unique mounting solutions with specialized uses, like pole mounts and ballasted mounts.

Roof-Mounted Systems

Roof mounts utilize your house's rafters to support the solar panel weight.

For roof setups, you need to locate and mark your roof's rafters. This way, you can drill holes into them and secure the flashing. If the rafters are not visible along the roof's edge, you can use a stud finder or measure from inside the attic.

Roof mounts are the typical choice for homes due to convenience and cost-effectiveness. Placing panels on the roof saves space, which is crucial for limited yard space.

If your roof faces South, West, or East and has enough room, a roof mount is usually the most cost-effective choice.

Ground-Mounted Systems

Ground mounts are standalone structures made of metal pipes set in concrete footings. They take more effort and money to install since you're building a new structure.

Ground mounts offer flexibility in panel orientation. You can point panels directly at the Equator and tilt them for maximum output. Roof mounts have fixed angles and facing.

Ground mounts are also easier to clean and maintain. You don't need to climb onto the roof.

Ground mounts suit commercial and rural areas with ample space to maximize panel capacity.

Pole Mounts

Pole mounts lift panels high on a tall pole. They're useful for:

1. Snowy regions

Pole mounts tilt panels to shed snow. They can lift panels higher to clear winter snowbanks.

2. Hillside setups

Pole mounts require only one anchor point, making installation on steep slopes easier.

Ballasted Mounting

Ballasted systems have a frame filled with heavy material like dirt to hold panels in place. They don't need concrete anchors, making them quicker and more affordable to install.

SOLAR POWER BATTERIES

Solar batteries store energy from the sun and give you independence from the main power grid.

In systems that are not connected to the main power grid or have backup power, having a local battery bank is essential to store usable energy on-site. This is useful in situations where the main power supply fails, during severe weather, or other disruptions.

There are three types of batteries you can use with your solar power setup:

1. Flooded Lead-Acid Batteries

   These are sometimes called "wet cell" batteries because they contain liquid electrolyte that can be accessed by removing the battery caps.

   Charging these batteries causes the liquid in the electrolyte to evaporate, so they need regular refilling with distilled water. Maintenance checks are needed monthly.

   These batteries are more likely to fail if not properly maintained and may not be suitable for those who can't commit to monthly maintenance.

2. Sealed Lead-Acid Batteries

   These batteries are sealed to prevent leaks and harmful fumes.

   They require minimal maintenance and can be installed in any position without needing ventilation.

   There are two types: absorbent glass mat (AGM) and gel batteries. AGM batteries are cheaper and better in cold temperatures, while gel batteries are more expensive and perform better in hot climates.

3. Lithium Batteries

   Lithium batteries cost about three times more than sealed lead-acid batteries, but they last about three times longer.

   They offer faster charging and discharging, are lighter, and require no maintenance.

   You can start with a small lithium battery setup and expand it as needed.

While lithium batteries have a higher upfront cost, their longer lifespan makes them more cost-effective over time compared to lead-acid batteries.