Yes or no: Should 1,500 volt solar inverters be installed on rooftops?

As part of our 2020 Solar PV Inverter Buyer’s Guide, we asked manufacturers “Should 1,500 volt solar inverters be installed on rooftops?” Here is what they had to say.

KACO inverter

KACO 1500 volt inverter project in Norway.

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Should 1,500 volt solar inverters be installed on rooftops?

Matt Marx, Strategic Marketing Manager at SMA: “No, because current code requirements prohibit the use of 1,500 V inverters on anything classified as a “building,” which can often include carports depending on individual AHJs (authorities having jurisdiction). However, if advancements in the electrical code and inverter technology allow for deployment of 1,500 V inverters in the future, installers would recognize the same benefits as in ground-mount projects including a significant reduction in balance-of-system costs.”

Terence Parker, senior applications engineer, Ginlong Solis: “Internationally, we see 1500 V rooftop PV systems. The U.S. NEC addresses large scale PV electric supply stations in Article 691 and allows the use of “engineering best practice”. We think that the U.S. should completely adopt 1500 V systems for rooftop, but time will tell. With advanced Arc Fault Detection and module level rapid shutdown capability, we think that the 1500V system is perfectly safe for commercial rooftops. On the other hand, 1500V is the development trend of large industrial and commercial roof projects, which can reduce LCOE, and recover costs faster.”

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Enphase spokesperson: “No. Go with low-voltage AC by using microinverters for safety and to ensure you can manage performance guarantees by avoiding the risk of a single inverter taking an entire system down.”

Kai Block, KACO new energy: Yes, they should. We’ve got two examples where our partners say that the option of longer strings results in less module rows. This saves component costs and expenses for cables and wiring work will go down, too. Here is Norway’s first commercial solar roof with 1500 V technology.

Lior Handelsman, VP of Marketing & Product Strategy and Founder of SolarEdge: “1500 volt inverters are meant to increase string length; however, they do have a number of limitations, such a safety concerns, electrical codes, costs, and unknown effects on modules and PID. However, because our inverters work on a fixed string voltage, string lengths are based on power, not voltage, and can enable strings of up to 15,300 watts in commercial systems. That is about 2.5 times longer than strings enabled by 1000V systems.”

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