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sergeykoren

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Posts: 7
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

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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?

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
sergeykoren

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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

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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.



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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
stmbtwle

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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

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Solar is like the wind. It may be free, but putting it to work isn't!
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colinmcc

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Posts: 153
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

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Posts: 19
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

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Posts: 153
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

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Posts: 19
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

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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?


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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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