Question about size of the inverter

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sergeykoren

Registered:1513885013
Posts: 7

Posted 1513885213	Reply with quote #1

Solar company size my system to 24x315Wh panels, which is 7.5kWh, and 5kW inverter They mentioned to me that this is correct design. But it looks little bit strange to me. Is it ok to have inverter less than solar panels can produce or i have to return design back?

stmbtwle

Registered:1388591029
Posts: 2,925

Posted 1513900958	Reply with quote #2

Solar panels rarely produce what they're rated at, especially considering latitude and orientation, so I can understand their thinking. However it still seems strange to me. Where are you, and what is the panel orientation? __________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay

sergeykoren

Registered:1513885013
Posts: 7

Posted 1513948430	Reply with quote #3

I am located in Massachusetts They did design of the base that system is at a 1.5 watts of DC to 1 watt of AC ratio.

Rick H Parker

Registered:1489180564
Posts: 808

Posted 1513961313 · Edited	Reply with quote #4

Is it ok to have inverter less than solar panels can produce or i have to return design back? Nothing wrong with the panels having a higher transfer capacity then your inverter. __________________ Rick H Parker Kansas, USA Electronics Engineering Technologist

stmbtwle

Registered:1388591029
Posts: 2,925

Posted 1513963135 · Edited	Reply with quote #5

Seems that it's often done... PROBABLY what will happen is that your inverter will only output the 5 kw it's rated for, and excess from the panels (if any) will be wasted as heat, It's not likely that your panels will ever put out 7.5 kw, but I honestly don't know how to calculate what to expect. This might be of help: http://solarprofessional.com/articles/design-installation/optimal-pv-to-inverter-sizing-ratio#.Wj1BclWnFxA __________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay

colinmcc

Registered:1371329966
Posts: 174

Posted 1514353712	Reply with quote #6

This isn't an unusual ratio, it means that your inverter will reach maximum output earlier in the day and maintain it later in the day, and for that matter earlier/later in the year. If the inverter and PV had the same output rating you'd only get that out of the inverter on a good, cold day with loads of incident sun, Which would be rare, if ever at all. If that was the AC you needed it would be almost never satisfied. As long as 5kw is enough to supply your needs then go with it. You'll get your needed 5kw for longer each day!

bhavin66

Registered:1364325381
Posts: 19

Posted 1514421768 · Edited	Reply with quote #7

Not unusual but I would rather have the inverter sized close to the theoretical panel output. I have panel sized at 7.665kw and inverter 7.6kw. That way I feel I did not compromise anywhere. Incremental cost would not be more than a few hundred dollars.

colinmcc

Registered:1371329966
Posts: 174

Posted 1514422192 · Edited	Reply with quote #8

bhavin66 Most of the year your inverter would only put out it's max a few hours a day, if that. If 5kw was your max requirement then fair enough.

bhavin66

Registered:1364325381
Posts: 19

Posted 1514425340 · Edited	Reply with quote #9

Quote: Originally Posted by colinmcc bhavin66 Most of the year your inverter would only put out it's max a few hours a day, if that. If 5kw was your max requirement then fair enough. My usage is about 9.25kw but with the roof space I have utilized to max capacity I could install only 7.6kw (21x365w)

stmbtwle

Registered:1388591029
Posts: 2,925

Posted 1514463706	Reply with quote #10

It's YOUR installation, get a larger inverter if you like. I can understand the smaller inverter, but you could also be limiting your output. The trick is finding the sweet spot. What do other installers/designers in your area use for a ratio? __________________ Solar is like the wind. It may be free, but putting it to work isn't! Willie, Tampa Bay

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