Micro-inverters are all the buzz in residential solar right now. This post will help you understand the pros and cons of traditional inverters vs. micro-inverters.
As mentioned on our Solar 101 Technology page, solar panels produce a direct current (DC) which needs to be inverted into an alternating current (AC) before it is able to be used by household appliances. That’s the job of the inverter. Traditionally there is one inverter that is mounted low on the side of a house next to the power meter. That one box does all of the inverting. Because it handles fairly high voltage coming from the solar panels, it is the one part that may need to be replaced over the life of a solar energy system. Solar panels have 20+ year warranties, whereas inverters typically have 10-15 year warranties.
Micro-inverters have recently started appearing in the news, and here’s why: Instead of having one inverter for the entire array, a micro-inverter could be installed on each panel, or every few panels. The micro-inverters would convert the DC to AC right at the source, then AC wires would run down to the circuit breaker and power meter. Each micro-inverter would be handling lower voltage and therefore may not wear out as quickly.
But more importantly, micro-inverters allow the system to be more efficient and therefore produce more energy. When set up in the traditional method, a solar array is only as efficient as the least efficient panel. ie. the weakest link. If you have 5x 200 watt panels, but one of them is shaded or dirty such that it’s only producing at 50% efficiency, then the entire system will only work at 50% efficiency. That means that instead of producing 1,000 watts, the system would only produce 500 watts. However, if each panel had a micro inverter on it, only the one panel that is dirty or shaded would be effected. So in this scenario one panel would be at 50% and therefore producing only 100 watts, but the other 4 would still be at 100% producing 200 watts for a total of 900 watts. With micro-inverts – 900 watts, without – 500 watts. Granted, that’s a fairly extreme example, but it gets the point across.
Additonally, Inverters are currently sized according to the number and type of solar panels on the roof, and if a home owner wanted to add more panels in the future that may require a different inverter with a larger capacity. Whereas now that micro-inverters are being used, in theory, additional panels with their own micro-inverter could be added to an existing array without needing to replace anything.
Micro-inverters also make it one step easier for home owners who want to take the do-it-yourself approach. That said, solar installations using traditional inverters or micro-inverters will both still require an electrician to do the final wiring of the system.
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