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Dream team: How do inverters work with solar panels

25 Jul 2023
9 min
Beginner

Julia ZaraevaAuthor

When people look at a PV system, most praise the solar panels and completely forget about the inverter, the unsung hero bridging panels and your home. What is a solar inverter, and how does it work with solar panels? Let’s figure it out.

Master of multitasking: What does a solar inverter do

A solar system is impossible without an inverter. It has more duties than any other part of the system. Let’s look at them in detail.

Translating from DC into AC

Keeping production high

An inverter helps the whole solar system work more efficiently. It tracks the maximum power point of solar panels: a combination of voltage and current at which panels produce the most energy. Using maximum power point tracking (MPPT) technology, an inverter tweaks resistance at its input and adjusts the current and the voltage in the system.

Guarding your house

Grid-tied inverter is equipped with protection mechanisms to guard against grid disturbances. In case of a power outage, the inverter shuts down to prevent any damage to the solar system and connected equipment.

Reporting on performance

Inverter also tracks and reports real-time and historical data on energy generation and usage. This information helps to evaluate the overall health of your solar system, identify any underperformance, and do prompt troubleshooting. The inverter usually offers monitoring online or through an app, allowing you to check the performance of your solar system from anywhere with an internet connection.

Now we know what a solar inverter is and what we need it for. Let’s look at the different types of inverters with their strengths and weaknesses.

Grid-tied string inverters: Your standard choice

Grid-tied string inverters, as the name suggests, are connected to the electrical grid. String inverters are paired with chains or strings of solar panels, hence the name. This is the most widely used type.

✔ Cost-effectiveness: They are more affordable compared to other types of inverters, which makes them a popular choice for residential and commercial installations.
✔ Easy access: They are usually installed somewhere, like the side of your house or a garage, and are easy to service.
✔ Net metering: With a grid-tie inverter, you can sell excess solar energy to the grid and reduce your bills.
✔ Scalability: The system can be easily scaled up by adding more solar panels to a string.

✖ String is as strong as the weakest link: One damaged or shaded panel drags down the performance of the entire system.
✖ Grid-reliant: Grid-tied inverters shut down during grid outages as a safety precaution to prevent backfeeding

Backfeeding — the flow of electric power in the reverse direction. The inverter shuts down to prevent the energy from going from panels into the grid because the grid must be free of current in order for workers to fix it.

The way to solve the problem of the weakest link is to add power optimizers. They are installed next to the panels and make each module independent from others. Power optimizers work in conjunction with a string inverter, providing optimization benefits similar to micro inverters but at a lower price.

Micro inverters: On-site service

Microinverters are installed on each individual solar panel. They are small, the size of a book, and operate independently, converting DC to AC right on your roof. This allows each panel to work at its maximum capacity. Microinverters are useful on roofs with shading issues or if panels face different directions or are set at different angles.

✔ Enhanced efficiency: They are installed on each solar panel, allowing to minimize the impact of shading, debris, or panel faults.
✔ Reliability: The failure of one inverter does not affect the performance of the entire system. Each panel operates independently, enhancing system reliability and fault tolerance.
✔ Scalability: They can be easily scaled up by adding more solar panels with microinverters.
✔ Easy monitoring: They provide real-time data on the performance of each solar panel, which is great for easy detection of faults or underperforming panels.
✔ Stronger warranty: They usually have a warranty of about 25 years.

✖ Higher cost: They are the most expensive of the available inverter types.
✖ Not so easy access: They are connected to each panel, and servicing them requires getting up on the roof.

Micro inverters are commonly used in grid-tie systems. They usually don’t support batteries and don’t work during outages — unless you have Enphase IQ8.

Off-grid battery inverters: Choice of independence

Off-grid inverters are used for solar systems that operate independently of the electrical grid. These systems are found in remote areas or locations where grid connection is not available or feasible. Off-grid systems require batteries to store solar power for use during times of low or no solar generation. DC power from your solar panels goes to the batteries, and then your inverter converts it into AC power for your house.

✔ Off-grid: They make you independent of the electrical grid, not a bad choice for remote areas or locations without grid access.
✔ Cost-effective: They are simple and budget-friendly, a nice option for powering a boat or an RV.

✖ Limited power: Limited access to backup power beyond the capacity of your batteries. If the power in your batteries runs out, you can’t draw it from the grid.
✖ No net metering: You can’t sell excess solar energy to your utility which increases the payback time of your solar system.

Hybrid inverters: Taking the best of two

A hybrid inverter combines a grid-tied inverter and a battery inverter in itself. It is connected to both the utility grid and an energy storage system, such as batteries.

Houston, we have a problem: Solar inverter issues and troubleshooting

The inverter is a critical and the most vulnerable part of the whole system. Problems can occur due to component failure, overheating, moisture, dust, manufacturing defects, and many other factors. If your inverter fails to produce AC power, here are some troubleshooting steps you can take:

Any error messages or fault codes?
Solar inverters often display error messages or fault codes when something’s gone wrong. Consult the inverter’s user manual, contact the manufacturer’s technical support, or just google to interpret the specific error code and fix the problem. Don’t forget about safety when dealing with solar inverter issues. In some cases, you may need a professional to inspect and repair the inverter.

Any tripped circuit breakers?
Check your switchboard and make sure your solar system’s circuit breakers are on. Then check your inverter’s switches. If anything has tripped, flick them back on.

Any power in the grid?
If you have a grid-tied system, find out if there is a problem with the grid. Grid-tied inverters shut down during grid disturbances or power outages for safety reasons. This feature ensures that electricity is not fed back into the grid, which could potentially harm utility workers who are fixing the power lines.

Any problem with the software?
Like any electronic device, solar inverters rely on software. Sometimes, these software components may encounter errors and freeze. Restarting the inverter allows the software to initialize properly and potentially resolve temporary glitches or errors that may be causing the problem.