Tips From Our Experts

Solar PV Inverters

Claire asks

Could you please let me know approximately how much an inverter will cost for a solar PV system and how long they last for?

Our expert’s answer

Thanks for your enquiry. Unfortunately there is no cut and dried answer to this one. It depends on the size of the PV array – the inverter is (usually) sized to match the maximum PV output. The caveat here is that sometimes people prefer a somewhat larger inverter to allow for potential PV array expansion in the future without having to replace the inverter. Larger inverters generally cost more than smaller inverters though there tends to be some benefits to be had in terms of cost per kW for the larger inverters e.g. A 4kW inverter may only be 3 times the cost of a 1kW inverter.

Inverters come with a wide variety of warranties which are a reasonable way to determine their likely longevity. Obviously, the longer the warranty, the better. If you can get a hold of a specifications sheet for them, look for a figure called MBTF which stands for Mean Time Between Failures – the bigger this number is, the better (it is usually in hours). As an indication, 4,000 hours of operation is roughly equal to 1 year’s duty so an MBTF of 40,000 hours should mean it’s good for about 10 years.

For more information about solar PV systems, see the 17 Things™.

John Knox

John Knox

The technical advice provided by the Alternative Technology Association as part of the ‘Ask an Expert’ forum/website, in relation to home and building sustainability improvements, is general in nature only. The impacts of specific energy or water saving or sustainability products will depend on how and where the are used and located, and particularly for larger investments, we would always suggest users seek a specific assessment from an appropriately qualified building designer or service / product supplier.

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