1,000VDC Systems

3 replies [Last post]
meby's picture
Joined: 2012-04-17

I see more PV equipment being offered at the 1,000VDC rating. Does anyone have any compelling arguments to make as to the advantages/disadvantages of installing a 1,000VDC system over a 600VDC system?

helpfulguy2's picture
Joined: 2014-03-13

I can think of a few items in favor of a 1,000VDC system.
1. conductor size can be smaller
2. easier to get higher AC voltage out of inverter.
3. on a same sized system, fewer strings
4. on a equal sized array, fewer combiner boxes.

AnthonyBasden's picture
Joined: 2015-07-20

1,000V systems are generally accepted as having a lower first cost versus 600V systems. With all things, trade offs are present.

The 1,000V system will have a lower energy yield over its lifetime than a 600V system due to shading with all design parameters being equal. If you have a 600V system with 14 panels/string, and shading removes power production from that string, you're out around 3kW to 4kW for as long as the shading lasts. If you have a 1,000V system, you might have 23 panels per string. If shading takes out that string, you're out 5kW to 7kW for as long as the shading lasts.

If you're looking to maximize the number of panels installed to the site area, a lower voltage system may be appropriate. It's easier to fit multiples of 14 in project area than it is to fit multiples of 23. Granted that on large arrays, this difference is negligible.

If you're looking at residential systems, NEC 690.7(C) states that you're limited to 600VDC - you don't have a choice.

Kramirez's picture
Joined: 2015-12-01

In addition to the reasons stated above, a lot of inverters now do not even have a voltage window which would allow 600V nominal strings, or work so poorly at this voltage you would never want to do it.

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