Powerwall frequency below 60 Hz Off Grid

[jfb130]

I’ve recently been testing my power walls to see how they would work in an off grid situation. The power walls start off at 65Hz to 97% then to 60 Hz which lasts for about 40% of the battery life. when it gets to below 60% it drops down to 59.5 Hz 59.6 Hz etc., the problem is it 59.5 or 59.6 Hertz my enphase inverters shut off and stop producing. I know they do it at 65 Hz to not overload the battery when fully charged. The problem with the Enphase inverters is that it’s recognizing below 60Hz frequency as out of the ordinary and shutting down . Any ideas on why my power walls are producing less than 60 Hz for frequency during an off grid event?

 

[power.saver]

I’ve recently been testing my power walls to see how they would work in an off grid situation. The power walls start off at 65Hz to 97% then to 60 Hz which lasts for about 40% of the battery life. when it gets to below 60% it drops down to 59.5 Hz 59.6 Hz etc., the problem is it 59.5 or 59.6 Hertz my enphase inverters shut off and stop producing. I know they do it at 65 Hz to not overload the battery when fully charged. The problem with the Enphase inverters is that it’s recognizing below 60Hz frequency as out of the ordinary and shutting down . Any ideas on why my power walls are producing less than 60 Hz for frequency during an off grid event?

Below 60Hz is used to stop EV charging. There is a setting in the App for this, if you increase the Share with Vehicle % then the PW will go lower before reducing the frequency. But that means you could drain most of your PW into your EV (if you have one).

 

[wwhitney]

the problem is it 59.5 or 59.6 Hertz my enphase inverters shut off and stop producing.

What inverter model and how old are they?

UL 1741 Supplement A requires PV inverters to support (among other things) a "low frequency ride through" setting. For example in California the Public Utilities Commission requires that they be configured to produce normally between 58.5 Hz and 60.5 Hz. Not sure if Florida has any such rules, but the inverters are certainly capable of being configured to keep producing down to 58.5 Hz.

So I suggest you contact your solar installer or Enphase about getting the inverters reconfigured. Even older models like the M215 support UL 1741 SA, I believe. It should just take an inverter firmware update and/or grid profile adjustment to enable the desired behavior.

Cheers, Wayne

 

[cali8484]

Enphase M series (e.g. M215, M250) support frequency range adjustments through grid profile changes but they don't support UL1741SA which requires frequency-watt and other proportional power curtailment features. The M series will only turn full on or off.

It's interesting that Tesla is using under-frequency for EV charging control rather than out-of-band comms similar to Tesla PV inverter power curtailment control.

 

[wwhitney]

Enphase M series (e.g. M215, M250) support frequency range adjustments through grid profile changes but they don't support UL1741SA which requires frequency-watt and other proportional power curtailment features. The M series will only turn full on or off.

Thanks for the correction! Does CA Rule 21 require any power curtailment features, or just ride through? I.e. is M215 compliant with CA Rule 21 (at least prior to the new requirement of UL 1741 SB compliance as of 4/1/2023)?

Cheers, Wayne

 

[cali8484]

Thanks for the correction! Does CA Rule 21 require any power curtailment features, or just ride through? I.e. is M215 compliant with CA Rule 21 (at least prior to the new requirement of UL 1741 SB compliance as of 4/1/2023)?

Cheers, Wayne

The M series is not compliant with the current version of CA Rule 21 but they are only required to be compliant with the CA Rule 21 version at the time they were made (and they are). The current version of CA Rule 21 (UL1741SB based) requires many things including voltage and frequency ride through and in-band power controls (curtailment, reactive power, etc.) and newly required out-of-band (SunSpec) power controls.