Inverter Clipping Anxiety

[RoBoRaT]

I recently signed a change order for 10.72 kW solar PV system with 2 Powerwalls.

My installer insist that it is ok to have:

16 LG 335 on SE3800H inverter
16 LG 335 on SE3800H inverter

This setup results in DC/AC ratio of 1.41. Each SE3800H is rated to handle up to 1.55 ratio.

Per PVWatts, my annual production is estimated to be 17000 kWh from 10.72 kW system on 1.41 DC/AC ratio.

Reducing the ratio to 1.21 by using SE3800 and SE5000 goes up to 17350 kWh annual production.

My installer says though that changing one of the inverter to SE5000 is not possible since its over the allowed PV/PW total output considering 120% rule.

Is it worth changing the plan/order to chase down 350 kWh clipping per year? Or is it ok since the DC system output is expected to degrade overtime anyway?

Thanks for your insight.

 

[cwied]

350 kWh at $.40/kWh is $140/yr. This would probably be the most you could recoup from avoiding clipping. In fact, given that the clipping would probably not happen during peak rates, it would probably be a little less. It sounds like to avoid the clipping, you'd have to at least get a third Powerwall and pay the difference in inverter costs. It's hard to imagine that it would make financial sense to do so.

 

[RoBoRaT]

350 kWh at $.40/kWh is $140/yr. This would probably be the most you could recoup from avoiding clipping. In fact, given that the clipping would probably not happen during peak rates, it would probably be a little less. It sounds like to avoid the clipping, you'd have to at least get a third Powerwall and pay the difference in inverter costs. It's hard to imagine that it would make financial sense to do so.

Putting it in $ vs kWh clearly shows the clipping's worth.

My installer threw in "bird abatement" screen at no cost ($500) since they had to change to 2 SE3800. I guess it is a good deal then.

Thanks again, cwied!

 

[NuShrike]

How much is it to make panel/inverter adjustments so you won't go over the 120% rule? Subtract 30% and then divide it by 25 /warranty years to see if the amortization is worth it. Adjust your electricity probable losses at maximum TOU rates.