Inverters are crucial to solar systems, transforming DC electricity into AC that can power your home. They can also disconnect your solar array from the grid in case of a power outage.
Choosing the right inverter depends on your specific system design and needs. EnergySage Marketplace can help you compare solar quotes from installers with a variety of inverter options.
Efficiency
Since all electricity your installation produces flows through the inverter, efficiency is a key metric. A good inverter reaches high levels of efficiency but it is possible to get even better.
Efficiency is a function of DC output power and the inverter temperature. Sandia National Laboratories developed a test that takes these factors into account and provides an accurate rating called CEC efficiency. This weighted efficiency rating is available for thousands of inverters through the CEC Solar Equipment List program.
Ideally, the inverter should have a clean sine wave output with total harmonic distortion (THD) below 6 percent. It's also a good idea to look for inverters that can handle most of the maximum power your panels produce. This reduces clipping, which means the top of the output voltage is "thrown away" and wasted energy.
The inverter's ability to harvest energy efficiently is also affected by shading. This is why string inverters are often paired with power optimizers, which install at the panel level and mitigate the effects of shade by delivering a high amount of energy before it gets to the inverter.
Convenience
The electricity that comes out of your solar panels is initially direct current (DC). Inverters convert this power to alternating current, which is the kind of energy that powers your table lamp.
Older inverter types – known as string inverters – do all this DC to AC conversion at one, centralized location. This makes them inexpensive, durable and easy to maintain.
However, this approach doesn’t make it as simple to monitor the performance of individual solar panels or mitigate shading. If one panel is shaded, for example, it will affect the performance of all of the panels in that string.
Newer microinverters solve this problem by putting a small inverter next to, or built into, each individual solar panel on your roof. This system transforms DC to AC electricity right where the panel is, so panels that may be in partial shade can still produce a significant amount of energy. These inverters can also be paired with DC power optimizers, which are installed at the module level and relay each panel’s performance characteristics to facilitate monitoring and maintenance.
Connectivity
The Solar Inverter System is the brains behind your solar energy system. It takes the DC electricity produced by your solar panels and turns it into AC electricity that can power your home or business.
A central inverter, also known as a string inverter, accepts the DC electricity from multiple solar panels through a combiner box and transforms it into AC. It's a larger device than microinverters and is typically mounted on the ground or roof.
Microinverters are installed at the panel level and convert energy into AC on a per-panel basis. This reduces maintenance costs and allows shade or sun-blocking on one panel to not affect the efficiency of others.
A hybrid inverter works with battery storage to enable you to take advantage of solar incentives like NET metering or a feed-in tariff. It connects to the batteries through a DC charger and integrates with the solar panel array through a process called 'DC coupling'.
Warranty
Depending on the manufacturer, solar inverters come with some kind of warranty. This is an essential protection that helps ensure the quality of your equipment. However, it is important to understand what the warranty covers and what it doesn’t. For example, most warranties don’t cover labour costs for installing new components or replacing inverters. Many manufacturers also charge for shipping, handling, and customs charges if they need to ship in replacement parts.
Additionally, warranties can vary in length from 10-25 years. The longer warranties usually offer better coverage, but they can also be more expensive. It is also important to note that most warranties are transferable if you decide to sell your home. This allows potential buyers to know that your system is under warranty and will continue to function well in their home. This is a great way to add value to your home and increase its curb appeal. Some installers include several inspections as part of their installation warranty, which is a nice feature for homeowners.
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