Array Oversizing

[nwdiver]

LOL !
Looks to be about two Molly's

(apologies if I mangled her name.)

Miley. My sister named her after the singer.

Yeah... looking forward to getting this all installed. Need larger 'AC disconnect' labels... the ones we have are meant for tiny 60A disconnects.

But I generally agree with your assessment that upgrading from 3.8kW up to 7.6kW to keep your oversize ratio < 1.2 is generally worth it. It's at the 32A (7.6kW) and 48A (11.4kW) thresholds where oversize ratios of up to 1.5 start to make sense. Going >48A is increasingly problematic so I think even up to ~1.7 might actually make sense on a case-by-case basis. But once you commit to a larger interconnect... might as well stack inverters and use it

 

[SageBrush]

Miley. My sister named her after the singer.

Yeah... looking forward to getting this all installed. Need larger 'AC disconnect' labels... the ones we have are meant for tiny 60A disconnects.

But I generally agree with your assessment that upgrading from 3.8kW up to 7.6kW to keep your oversize ratio < 1.2 is generally worth it. It's at the 32A (7.6kW) and 48A (11.4kW) thresholds where oversize ratios of up to 1.5 start to make sense. Going >48A is increasingly problematic so I think even up to ~1.7 might actually make sense on a case-by-case basis. But once you commit to a larger interconnect... might as well stack inverters and use it

This all makes good sense to me.

Tell Miley I will make amends

 

[nwdiver]

So here's the first full years production after we expanded this array. We added (4) 310w panels to the existing (15) 295s. The MPP current of the 310s and 295s is nearly identical so worked fine to mix panels. All clipping occurs on String A. String B never clips so this is a good real world example of how much production is lost.

Didn't initially plan on this array being oversized by ~50%... but annual losses for 2020 due to inverter saturation are still only ~4%. I estimate on average < 45kWh per panel? So ~400kWh lost and ~10121kWh produced.

If I were designing this system from scratch I would 100% use a 5kW instead of a 4kW inverter since the additional cost is ~$100. When it was just 4.4kW I think I saw clipping maybe twice for about an hour over a year.

 

[mspohr]

It’s time to start wasting solar energy

 

[nwdiver]

It’s time to start wasting solar energy

Jinx!

It’s time to start wasting solar energy