[RE-wrenches] PV watts question

[Rebekah Hren]

I agree with Mike, because you can't change the inverter size in PVwatts*
directly, i*t is just a percentage of the array size based on what ratio
you choose. So if you change the ratio you aren't increasing the array
size.

So that 1 kW array in your example values is paired with an 660 watt
inverter at 1.5 ratio in the program.






On Mon, Jan 27, 2025 at 1:44 PM jay via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> HI David,
>
> My point exactly.
>
>
>
> On Jan 27, 2025, at 1:35 PM, david quattro via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> Jay you are right - that doesn’t make sense because with more PV, the
> system will reach “max AC out“ power sooner every morning and hold it
> longer into the evening
>
>
>
>
> On Mon, Jan 27, 2025 at 12:20 PM George McClellan via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Probably due to clipping.  The panels are generating more energy than the
>> power electronics can process, so that excess energy gets cut off (or
>> clipped).  It looks like a 1.2 ratio is optimal.
>>
>> George McClellan | Senior Manager, Technical Sales | REC Americas LLC
>> 735 Tank Farm Rd Ste 130 | San Luis Obispo, CA |93401
>> <https://www.google.com/maps/search/735+Tank+Farm+Rd+Ste+130+%7C+San+Luis+Obispo,+CA+%7C93401?entry=gmail&source=g>
>> Cell phone +1 805 704 3226 | Fax +1 805 357 6104
>> www.recgroup.com | george.mcclellan at recgroup.com
>>
>>
>>
>>
>> -----Original Message-----
>> From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> On Behalf
>> Of jay via RE-wrenches
>> Sent: Monday, January 27, 2025 11:56 AM
>> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
>> Cc: jay <jay.peltz at gmail.com>
>> Subject: [RE-wrenches] PV watts question
>>
>> Caution: This is an external email and may be malicious. Please take care
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>>
>> HI All
>>
>> I’m working with a customer who’s pretty savvy and is using PV watts for
>> his design.
>>
>> What I can’t figure out is the kwh/year goes down if he uses dc/ac ration
>> of 1.5 instead of 1.2 which is the default.
>>
>> Hes in Santa Fe NM.
>>
>> .8   ratio=  1663 kwh/yr
>> 1.0 ratio = 1668 kwh/yr
>> 1.2 ratio =  1671 kwh/yr
>> 1.5 ratio = 1623 kwh/yr
>>
>> I was expecting that more PV = more kWh/yr.
>>
>> What am i missing?
>>
>>
>> standard module
>> fixed roof mount
>> 14.08 loss’s
>> 10 degree tilt
>> 180 degrees
>>
>>
>>
>> jay
>>
>>
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