What Are The Different Types Of Solar Inverters
Inverters are an important part of any solar installation; they are the brains of the system. Solar inverters often come in 5 different types. They mostly differ in their principal application as defined by their power capacity. When checking feedbacks and reviews, such as a Growatt inverter review, you should also know the kind of solar inverter that you’re buying.
Although the inverter’s main job is to convert DC power produced by the solar array into usable AC power, its role is only expanding. Inverters enable monitoring so installers and owners can see how a system is performing. Inverters can also provide diagnostic information to help O&M crews identify and fix system issues. These important components are increasingly taking on decision-making and control functions to help improve grid stability and efficiency. With the growth of solar+storage, inverters are also taking on responsibility for battery management. Here is a look at some different types of solar inverters.
- String Inverters
These devices are the most common type of solar inverter. It got its name from the strings of solar panels that are connected to the device. This type of inverter is what we often see in many residential homes. One device is enough to convert the DC power generated by the solar system of the house into appliance-friendly AC power. One drawback of this design is that its AC power generating capabilities are only as good as the least productive solar panel in the string.
- Central Inverters
This type of solar inverter is almost like a string inverter. However, it has a larger power capacity. It is best used in commercial establishments or households with a massive power requirement. Another difference is that central inverters have a combiner box that ‘gathers’ the DC power coming from the solar panels and directs the power to the central inverter. The central inverter then converts the DC power to AC power.
Microinverters are small, often no bigger than a paperback book. This type of solar inverter gets connected straight onto each solar panel. If you have 20 solar panels, then you also have 20 solar microinverters. The main advantage of this device is that it can optimize the performance of each solar panel. Even if one solar panel is under the shade, it will not have a substantial effect on the overall power produced by the solar grid.
Microinverters are also becoming a popular choice for residential and commercial installations. Like power optimizers, microinverters are module-level electronics so one is installed on each panel. However, unlike power optimizers which do no conversion, microinverters convert DC power to AC right at the panel and so don’t require a string inverter. Also, because of the panel-level conversion, if one or more panels are shaded or are performing on a lower level than the others, the performance of the remaining panels won’t be jeopardized. Microinverters also monitor the performance of each individual panel, while string inverters show the performance of each string. This makes microinverters good for installations with shading issues or with panels on multiple planes facing various directions. Systems with microinverters can be more efficient, but these often cost more than string inverters.
Microinverters can also be sold through panel manufacturers already integrated into the panel, similar to Smart Modules but instead known as an AC Module. This makes installation easier and cheaper.
- Hybrid Inverters
Solar energy enthusiasts call these hybrid inverters as multi-mode solar inverters. It connects to a battery via a DC coupling technique, while also staying connected to the solar panels. The hybrid inverters are with sensitive electronics that manage the charge and discharge cycles of the battery. The inverter allows for the charging of the battery using energy from the solar panels or power from the electrical grid. In a way, hybrid inverters are a combination of a battery inverter and a string solar inverter.
- Battery Inverter/charger
These inverters are perfect for motor homes that require a steady supply of electricity in their vehicles. The inverter converts battery DC power into usable AC electricity. It then moves this electricity to a switchboard to help power the different electrical appliances in the vehicle. This inverter is also useful for people living off the grid.
With the growth of solar+storage, battery-based inverter/chargers are becoming increasingly important. Battery based inverter/chargers are bi-directional in nature, including both a battery charger and an inverter. They require a battery to operate. Battery-based inverter/chargers may be grid-interactive, standalone grid-tied or off-grid, depending on their UL rating and design. The primary benefit of inverter/chargers is that they provide for continuous operation of critical loads irrespective of the presence or condition of the grid. UL1741 requires the grid-tied generation source to stop generating power in the event of a grid outage. This de-powering is known as anti-islanding, as opposed to ‘islanding’ which is defined as generating power to power a location in the event of a grid outage. Therefore, UL1741 grid-tie inverters will not generate power in the event of a grid outage, so a user will experience an outage irrespective of the availability solar harvest. Battery-based inverter/chargers will power the critical loads in the event of a grid outage, but will do so in a manner to not create the islanding condition. Further, UL1741 inverter/chargers may be rated as either interactive or standalone. The former export excess power to the grid, while the latter do not–by rating and by definition. In all instances, the battery based inverter/charger manages energy between the array and the grid while keeping the batteries charged. They monitor battery status and regulate how the batteries are charged.