Solar Inverters 101: Which Type Should I Buy?

Tori Barrington

Key Points (TL;DR)
  • The three types of solar inverters are string inverters, string inverters with power optimizers, and micro-inverters.
  • String inverters are the cheapest and most common type of inverter.
  • Micro-inverters and power optimizers are attached to each panel, allowing the homeowner to monitor efficiency of each individual panel.
  • String inverters and power optimizers convert the direct current into usable electricity at a centralized inverter.
  • Micro-inverters convert the solar power into usable electricity right at the solar panel.
  • String inverters are highly affected by shade, while power optimizers and micro-inverters are not as affected.
  • Q&A
    What size solar inverter should I buy? Your solar inverter should be about the same size as your solar panel system. If your solar panel system is 5kW, your inverter will need to be able to convert that energy, so the inverter should be 5,000W.

    Due to factors like temperature and shade, solar panel systems don’t always produce as much energy as advertised. Because of this, your inverter can be a slightly smaller size if need be.

    Why is a solar inverter necessary? Solar panels convert sunlight into a form of electricity called direct current (DC). Your home is powered by alternating current (AC), so a solar inverter is necessary to convert the DC into AC, which your home can actually use.
    What type of inverter is best? The type of inverter that is best for you will depend on your unique home.

    The string inverter is the most common and most affordable. It has also been around the longest, so its reliability has been proven. However, production decreases in several solar panels if there is any amount of shade on even one solar panel.

    If your roof is shaded during the day, power optimizers or micro-inverters may be the better choice for you. They are more expensive, but efficiency only decreases in the shaded solar panel rather affecting productivity of multiple solar panels.

    Which type of solar inverter is cheapest? The string inverter is the most affordable type of solar inverter.

    The technology is located on ground-level, so installation is less complicated, and therefore less expensive, than other inverters.

    Its one centralized inverter converts the electricity from multiple solar panels, so you don’t have to purchase equipment for each panel like you do for power optimizers or micro-inverters.

    3 Types of Solar Inverters

    Installing solar panels on your roof is a sustainable way to save some money, but in order to generate enough electricity to make a difference in your monthly utility bill, your system needs to be as efficient as possible.

    Solar inverters are an essential part of your solar panel system, and they contribute to the overall efficiency.

    Photovoltaic cells on each panel convert sunlight into electricity in the form of direct current (DC), but the appliances in your home are powered by alternating current (AC) electricity. Solar inverters convert DC into AC that your home can actually use.

    There are three types of solar inverters: string inverters, power optimizers, and micro-inverters.

    The type of inverter(s) that you purchase for your solar project will be dependent on your unique situation. After learning about the pros and cons of each type of inverter, you should have a better idea of which inverter would be the most efficient for your home.

    Cost Panel Monitoring Shade Maintenance
    String Inverters Cheapest No Affects many panels All equipment on ground-level
    Power Optimizers Less expensive Yes Affects individual panel Equipment on roof and ground-level
    Micro-Inverters Most expensive Yes Affects individual panel All equipment on roof

    String Inverters

    String inverters are the most common type of inverter and have been around the longest.

    A string inverter groups panels together into “strings” and connects them to a central inverter, where the DC is converted into AC.

    The central inverter is located at ground-level, so it must be installed somewhere in or on your house. Depending on how large your solar panel system is, you may need multiple inverters, which may not be very aesthetically pleasing.

    However, having an inverter at ground-level has its advantages. First of all, string inverters are more affordable because the installation is not as intensive, and therefore labor costs less. Also, if something were to break, a maintenance team would not need to climb on your roof and take the solar panels apart to figure out the issue; the central inverter is very accessible.

    While string inverters are the most affordable type of solar inverter, it’s important to take other factors into consideration.

    Electricity is collected from each string of solar panels, so if one panel in the string is partially shaded, the efficiency of every panel in that string will be affected. Because of this, string inverters are recommended for homes with no shading on their roof during the day.

    The string setup of this type of inverter allows for string-level monitoring, meaning the efficiency and production of each group of panels can be monitored. However, this type of inverter does not allow for individual panel monitoring.

    Power Optimizers

    Power optimizers can be added to string inverters to improve performance and eliminate some of the disadvantages that come with a regular string inverter.

    In this system, there are components that are attached to each individual solar panel. As each panel generates DC power, it is sent through the string inverter to the central inverter to be converted into usable electricity.

    String inverters with power optimizers still require a central inverter in or on your house at ground-level, but the power optimizer components are attached to each panel on the roof. If something stops working with the inverter, a maintenance team has easy access to fix it. If the power optimizers break, it will be slightly more labor intensive. The maintenance team will have to climb on the roof and move the solar panels around to get to the components.

    Power optimizer systems are slightly more expensive than a regular string inverter, because it includes the cost of the string inverter plus the additional optimization components.

    Because the power optimizers are attached to each individual panel, the shading problem that occurs with a regular string inverter is solved. If part of a solar panel is shaded during the day, it will only decrease the efficiency of that particular panel, not the rest of the panels in the string.

    The arrangement of the power optimizers also allows for panels to be monitored at an individual level.

    Micro-Inverters

    String inverters with power optimizers are individualistic while operating at a system level, but micro-inverters operate at a completely individual level.

    Micro-inverters are relatively small devices that are attached underneath each solar panel. Instead of transferring the current to a centralized inverter, micro-inverters convert the DC power to AC power at the individual solar panel.

    This system does not require a central inverter, which may be considered more aesthetically pleasing. However, this can prove more difficult for maintenance. If a micro-inverter break, the team will have to climb onto your roof and detach the micro-inverter from the solar panel to inspect the problem.

    Micro-inverters are the most expensive type of solar inverter, because you need one for each of your solar panels. Depending on how large your solar panel system is, that could get very expensive very quickly. Installation is also more labor intensive, which raises the cost as well.

    Micro-inverters do not have issues with shading like string inverters do. If a solar panel receives some shade during the day, that one solar panel’s efficiency will decrease, but it will not affect any of the other solar panels.

    Because an inverter is attached to each panel, homeowners can monitor the efficiency of each solar panel separately.

    Recommended Reading:

    Which type of solar inverter is best for my home?

    When choosing which type of solar inverter is ideal for your home, consider your budget, the size of your solar panel system, and the amount of shade it receives.

    String Inverters

    If your solar panel system is large and your budget is tight, a string inverter is probably the best choice. With a large system, the cost of micro-inverters or power optimizers can be expensive.

    If your roof is always sunny and never shaded during the day, a string inverter is definitely the best bet.

    If your solar panels receive some shade during the day, the increased cost of a different inverter may not be worth the slight decrease in productivity during shaded hours. However, if you can afford it, it might be worth looking into a different solar inverter.

    Power Optimizers

    If your solar panel system is getting some shade during the day and you have some extra money to put towards a better inverter, a string inverter with power optimizers is a good choice.

    Even though it is more expensive, this system will operate better in some shade and will pay off in the long run with decreased utility bills.

    Micro-Inverters

    This option is ideal if your roof receives some or a lot of shade during the day. It is the most expensive option, but the micro-inverters are attached to each solar panel, so it functions better in the shade.

    Ready to find a solar company near you?