How Does a Home Solar System Work?

While the roots of solar energy go back to the 1700’s, the photovoltaic technology we still use today came from Bell Labs in 1954. In a relatively short time, solar panels have evolved rapidly and now offer increased efficiency at lower costs.¹ Solar energy now powers commercial developments, homes, and even the International Space Station!²

While solar panels may be the most visible part of a home solar system, there are several important components between the solar panels and a lightbulb or appliance in your home.

What Makes Up a Home Solar System?

A typical home solar system contains the following components:

• Solar panels and racking
• Inverter
• Utility and Solar Meters

In addition, home solar + battery storage systems may include a critical loads panel, which is separate from your main breaker box.

Solar Panels

Also known as photovoltaic (PV) panels or modules, solar panels absorb the sun’s rays to power your home.

Solar panels are made of silicon cells covered in glass. There are two main types, and the difference between them comes down to how the silicon is manufactured to form the cells within each panel.

• With monocrystalline panels, solar cells are made using silicon that is formed into long cylinders and then cut into wafers. The name “monocrystalline” comes from the fact that single-crystal silicon is used in this type of panel construction. At Sunnova, we use monocrystalline panels.
• With polycrystalline panels, rather than use a single crystal of silicon, multiple fragments of silicon are melted together and then sawed into pieces to form the wafers of the panel. Hence, the prefix “poly” – although polycrystalline panels are also sometimes referred to as “multicrystalline.”

Monocrystalline and polycrystalline solar panels both serve the same purpose: converting the sun’s power into energy. However, monocrystalline panels tend to be more efficient than polycrystalline panels because electrons will not encounter as many boundaries.

Solar Panel Racking

Although the solar panels are arguably the MVP (most valuable part) of any home solar system, the mounting system (also known as racking) is what attaches your panels to your roof. There are primarily two configurations, and the one your installer uses will depend on the type of roof you have.

If you’re a Sunnova customer, your home solar system includes a 10-year roof penetration warranty related to the installation of your home solar system for extra piece of mind. Refer to the Warranty Agreement in your agreement for complete warranty terms and limitations.

Roof-penetrating solar racking has been used since the inception of solar. This type of mounting requires installers to drill holes in your roof to secure the racking system in place.

• Roof-penetrating solar racking is better suited to traditional or composite asphalt rooftops.
• Reputable installers will take great care in sealing the area around your racking equipment to prevent leaks; they should also provide you with a warranty that covers leakage.
• Some installers may offer mounting options that attach directly to your roof, which are usually faster to install and more aesthetic.

Inverters

The inverter converts the direct current (DC) electricity from your panels into alternating current (AC) electricity that your home’s appliances can use. There are three main types of inverters available, and the best one for your home depends on how your solar array is configured:

• String inverters have been around the longest and are usually the most inexpensive option. This type of inverter is installed at ground level. With a string inverter, solar panels are wired in series, meaning all the solar panels are connected to the inverter and to each other. If a single solar panel fails, then it will likely cause the other connected solar panels to underperform.
• Microinverters offer the latest technology and are ideal for complex solar installations, such as solar panels that face in different directions. Microinverters are installed behind each solar panel or integrated into the solar panel directly. With microinverters, each solar panel will operate independently.
• String inverters with DC optimizers are a hybrid between microinverters and string inverters. Each panel is connected to a DC optimizer that runs to a string inverter at ground level, allowing each panel to operate independently.

Your installer will help you choose the right type of inverter and install it properly according to local building and electrical codes.

Utility and Solar Meters

You’re probably familiar with a traditional electricity meter, which is what your utility company uses to measure your energy usage each month. But when you go solar, you will either need to replace your traditional meter or add a second one to measure how much solar energy you produce and send back to the utility.

Sunnova home solar system customers will have two meters:

• Your Sunnova meter will measure your home solar production.
• Your utility meter will measure how much utility electricity you use and how much solar energy you send back to your utility. If you have an older meter, you will need to get a dual direction meter from your utility.

Battery Storage

For greater energy independence by storing solar production and the added security of a backup power source for essential appliances during grid outages³, consider adding a battery to your home solar system. The way your battery is linked, or “coupled,” to your solar system will depend on the type of battery you use.

• DC coupling: A battery-ready inverter is also known as a hybrid inverter. What makes it a hybrid is that it’s shared by both your solar panels and your battery. Since both components operate in DC power (your panels produce it and your battery stores it as such), there is no need for a second inverter specifically for the battery.
• AC coupling: AC coupled systems have two inverters: one for the solar panels and one for the battery. This simply means your solar panels and your battery are both connected to their own inverters to produce usable AC power.

Critical Loads Panel

If you’re a Sunnova customer with a home solar + battery storage system, we may install a critical loads panel as part of your home solar system. The critical loads panel contains circuits from your main breaker box that are essential to power during a power outage, such as specific outlets and your fridge.

For most homeowners in the United States, electricity from a single battery will not power an entire home. Your battery is connected to your critical loads so that large or non-essential loads do not drain your battery.

Your battery is connected to your critical load panel.

• While the sun is out, your home solar system provides power to your home, and excess solar production can charge your battery or export to your utility for net metering.⁴
• At night, energy from the battery may power your home, depending on your battery configuration.
• If your battery is in backup only mode, you will only be able to use your battery during a power outage.
• During a power outage, your battery will only power your critical loads.3 If there is sun, your solar panels will continue to charge your battery during a power outage.

Learn more about our home solar and solar + storage offerings. Going solar has never been easier!