PGE hourly zero summing and billing....

[sorka]

So I've noticed now that if I use say 1 kWH of energy from the grid and than dump 1 kWH of energy back to the grid within the same hour(i.e. from 8 to 9...not that last 60 minutes) that PG&E will show it as 0 kWH.

I haven't yet received my first bill with NEM (should be on the 1st). Will this block of zero sum usage be counted towards NBCs? i.e. will I get 1 kWH worth of NBC charges even though it doesn't show usage on their graph or green button download data?

Are they actually tracking minute by minute usage and just not showing it on an account level?

BTW, I've noticed that tesla is smart about zero summing usage in self powered mode. While PG&E shows zero usage or production for hours of self powered, the reality is the TEG is pushing and pulling from the grid constantly. Sometimes it's a few KW for 10 or 20 seconds and sometimes it's from the grid. The TEG seems to keep track of this and makes sure to average out the consumption/production so that it zero sums in each hour block.

 

[wwhitney]

So I've noticed now that if I use say 1 kWH of energy from the grid and than dump 1 kWH of energy back to the grid within the same hour(i.e. from 8 to 9...not that last 60 minutes) that PG&E will show it as 0 kWH.

I haven't yet received my first bill with NEM (should be on the 1st). Will this block of zero sum usage be counted towards NBCs? i.e. will I get 1 kWH worth of NBC charges even though it doesn't show usage on their graph or green button download data?

No, NBCs are charged per billing interval, which is 1 hour for residential accounts. So you get full NEM during the hour. If you use 1 kWh (net) in a given hour, and export 1 kWh in the second hour, then you trigger 1 kWh of NBCs.

Cheers, Wayne

 

[Ampster]

I've noticed now that if I use say 1 kWH of energy from the grid and than dump 1 kWH of energy back to the grid within the same hour(i.e. from 8 to 9...not that last 60 minutes) that PG&E will show it as 0 kWH.

Yes if PG&E billing increments every hour. However, my understanding is that they use 15 minute increments. Also PG&E only sees what goes through their meter so what you generate, serves your loads first and only excess goes to grid. Therefore no NBCs.

If it is 15 increments and during first half hour you generate .5 kWh but use 1 kWh then next half hour you generate .5kW and use nothing then you would get NBCs on .5kWh but no other charge because net for an hour is zero.
I am not disagreeing with the comment from @wwhitney about billing increments because I don't know. Just trying to illustrate the concept of Net Metering. In summary, it is only what PG&E sees flowing to (generation) or from (usage) the grid for that increment that gets counted. Behind the meter usage and generation only matter when they net and create flow through meter.

 

[getakey]

Residential is 1 hour increments. Commercial is 15 minute

 

[sorka]

Yes if PG&E billing increments every hour. However, my understanding is that they use 15 minute increments. Also PG&E only sees what goes through their meter so what you generate, serves your loads first and only excess goes to grid. Therefore no NBCs.

If it is 15 increments and during first half hour you generate .5 kWh but use 1 kWh then next half hour you generate .5kW and use nothing then you would get NBCs on .5kWh but no other charge because net for an hour is zero.

If this is how it works then it introduces a transparency issue because we only have access to hour interval data from PGE so if they decide to say you put in x kwh from 8:00 to 8:30 and took out the same x kwh from 8:30 to 8:59, they could charge you NBCs for x but not have to prove to you that you really pulled x from the grid.

For anyone who's getting bills with NBCs now, are your NBCs matching your net usage on an hourly basis as measured by PG&E or do the NBCs show higher kwh usage than PG&E hourly net consumption?

 

[getakey]

as I posted above, it is hourly for residential
we covered this in another thread before and I posted a link. Let me see if I can find that

 

[Ampster]

For anyone who's getting bills with NBCs now, are your NBCs matching your net usage on an hourly basis as measured by PG&E or do the NBCs show higher kwh usage than PG&E hourly net consumption?

I would change my example but it has been clarified that it is hourly. The only way you would see the detail is to download Green Button data.
It only amounts to $10 per month for me and it correlates to the fact that most of it comes when I charge my cars at off peak. Did that address your concern?

 

[wwhitney]

If this is how it works then it introduces a transparency issue because we only have access to hour interval data from PGE so if they decide to say you put in x kwh from 8:00 to 8:30 and took out the same x kwh from 8:30 to 8:59, they could charge you NBCs for x but not have to prove to you that you really pulled x from the grid.

That the interval data available to us is 1 hour data is further evidence that the residential billing interval is 1 hour, not 15 minutes. Because as you say, it would be a transparency issue, and if PG&E's billing computers had the 15 minute data, there'd be no reason for them to aggregate it before exporting it to us.

Cheers, Wayne

 

[Ampster]

PG&E's billing computers had the 15 minute data, there'd be no reason for them to aggregate it before exporting it to us.

I thought the GreenButton data was in 15 minute intervals? That may have also been the source of my initial erroneous assumption.
We will never know the state of the data at our beloved IOUs. There a was a time several years ago when Green Button data as not available from SCE for people on NEM, because their computer programming was so archaic that it could not handle negative integers.

 

[h2ofun]

I thought the GreenButton data was in 15 minute intervals? That may have also been the source of my initial erroneous assumption.
We will never know the state of the data at our beloved IOUs. There a was a time several years ago when Green Button data as not available from SCE for people on NEM, because their computer programming was so archaic that it could not handle negative integers.

I just downloaded my green button data. I hour numbers

 

[wwu123]

I looked at some of my previous Green Button downloads. Some of the files are in 1 hour increments; others in 15 min increments. I'm not sure what was the criteria, possibly shorter requested intervals generate the more fine-grained 15 min increments.

 

[miimura]

When I had solar before I got Powerwalls, my PG&E meter was set for 15 minute intervals. When I got my Powerwall PTO, my Service IDs were changed and my meter started reporting on 1 hour intervals.

However, the meter reports in "Channels". In my Paired Storage detailed bill, I can see that there are 6 lines of metering reported. One for each TOU period and one for each direction, import or export. The Channel IDs ending in A are reporting the amount imported during the given Off-Peak / Part-Peak / Peak TOU period and the one ending in C is for export. In theory, they could still charge you NBC based on your consumption during the TOU period based on the A Channel value, even if the net usage was zero. However, I have not compared my Green Button data to see how this Channel data aligns with the reported interval data. It could be simply sorting the positive and negative values from the 1 hour intervals into Channels. Alternatively, the meter could be accumulating Channel data within the 1 hour intervals. I have not seen any specific language in the Tariffs that say either way. In the end, I am on NEM 1 and don't pay NBCs, so it doesn't matter to me.