PGE Billing vs Tesla Data Explanation

[SolarBob]

What am I missing?

For 29 Billing Days I was billed by PG&E 127 kWh that shows on the Tesla download data.

I am having trouble understanding how I can generate 1678.7 kWh of Solar Energy with 973.2 kWh of Home Usage and have a from Grid of 127 kWh.

Obviously I am not understanding the Tesla data spread sheet.

It seems to me I should have banked 705.5 kWh into the PG&E grid.

Can someone help me understand how this spreadsheet balances.

 

[getakey]

It shows you banked 785 kWh to the grid. Are you saying it should have only been 705?

Easier to see this if you look at the graphs in the Tesla app

 

[SolarBob]

I banked 785 kWh. How can I be charged anything. What is PG&E doing with my banked power. With banked power I had thought that would pay for power when charged from the grid. Everyday I am generating more solar than house use. Where is my banked solar going? I don't understand how this works. I had thought the meter goes in both directions.

Comments?

 

[jjrandorin]

I banked 785 kWh. How can I be charged anything. What is PG&E doing with my banked power. With banked power I had thought that would pay for power when charged from the grid. Everyday I am generating more solar than house use. Where is my banked solar going? I don't understand how this works. I had thought the meter goes in both directions.

Comments?

Maybe read through teslas information on this. Since you say you dont understand, start there:

Your Utility Bill After Solar | Tesla Support

Learn more about how your utility bill can change after installing Tesla solar.

www.tesla.com

TL ; DR. You will still receive a monthly bill, every month. Your banked energy is calculated and withdrawn from when you use less than you generate, which will, in general, happen from November - February, and may happen in the summer if you run your AC all day.

Start with reading teslas information in the link above.

 

[Redhill_qik]

I banked 785 kWh. How can I be charged anything. What is PG&E doing with my banked power. With banked power I had thought that would pay for power when charged from the grid. Everyday I am generating more solar than house use. Where is my banked solar going? I don't understand how this works. I had thought the meter goes in both directions.

Comments?

With PG&E, you don't bank kWh directly instead you bank the cost of the kWh at the TOU rate that you exported and that offsets the TOU cost of kWh that you import. You are exporting more right now, but when summer comes around and you are running your A/C that may change.

You also have a Minimum Daily Charge (MDC) of $0.32854/day so for a 30 month period that is $9.86. The electricity that you import has a small Non-Bypassable Charges (NBCs) that vary a little and are currently $0.02252/kWh if you imported 127 kWh then that would be $2.86. If you are a net generator with your export credits higher than your import costs then you won't owe anything if your annual NBC total is less than your annual MDC charges that were already paid and you will get a small amount of credit for the excess generation at $0.02-0.03/kWh.

 

[aesculus]

It seems to me I should have banked 705.5 kWh into the PG&E grid.

I don't think it's as easy as this because when you use PW data for your home, you have the two way losses. Yes when you consume or send solar power directly there are no losses. So more data would be needed to fully understand this.

I suppose you could try to assume that any power coming from the PW must have 20% losses (10% each way). I did not do that math. (example 319 * 1.2 = 382.8).

Also did you use any Storm Watch power? That could skew it a bit, but probably not much.

 

[getakey]

You are using from the grid when the solar charges the PW. You are also using from the grid when the sun goes down and you switch to Off Peak rates depending on your PW settings

 

[miimura]

Since you have Powerwalls, you need to look at the detailed billing when it is available. The header should look like this:

 

[SolarBob]

The problem is for some reason I was not on that plan therefore I was not getting the proper credits for banked Grid power. PG&E is correcting this and will apply the correct credits. I wondered why I have been making grid payments since PTO was issued in Dec. Thanks

 

[Redhill_qik]

I am having trouble understanding how I can generate 1678.7 kWh of Solar Energy with 973.2 kWh of Home Usage and have a from Grid of 127 kWh.

It seems to me I should have banked 705.5 kWh into the PG&E grid.

It appears that you are thinking that solar - home = grid or that 1678.7 - 973.2 = 705.5 kWh and you are not considering the following:

• Your solar is not generating 24 hours a day
• Your Powerwalls are not providing power to home at all times that solar cannot cover the home usage
• Your Powerwalls consume energy just sitting there (about 0.25kWh/day per Powerall)
• Your Powerwalls need to recharge and do so at a 90% efficiency

Generation sources

• Solar = 1678.7 kWh
• Powerwalls = 310.2 kWh
• Grid = 127 kWh
• Total = 2115.9 kWh

Load sinks

• Home - 973.2 kWh
• Powerwall - 14.5 kWh (29 days * 0.25 kWh * 2 PWs)
• Powerwall recharge - 344.7 kWh (310.2 kWh / 90%)
• Total = 1332.4 kWh

Net for Grid is 783.5 kWh = 2115.9 kWh - 1332.4 kWh which is pretty close to the 785.5 kWh that is reported, so the Powerwall loss were a little less than expected.

Edit - I see that your actually problem is that PG&E never switched you over to a NEM plan, but the above still holds for reconciling the spreadsheet.

 

[Ampster]

What am I missing?

To make it even more complicated you have to think about two buckets. One, the kWhrs that are banked and two, the dollars that may be banked. Because the dollars are credited at different rates as they are produced and deducted at different rates as they are used the dollars and kWhrs may not be easily reconciled. it addition to the Minimum delivery charges there are also Non Bypassable Charges that are added to the rate for the kWhrs that you consume. Those are not offset by other dollar credits. Typically on page 4 of a PG&E bill is a section that summarizes your Nem Charges for each month. It is in the middle of the page and titled "Summary of NEM Charges". Powerwall users may get a different bill.

 

[sorka]

What am I missing?

For 29 Billing Days I was billed by PG&E 127 kWh that shows on the Tesla download data.

I am having trouble understanding how I can generate 1678.7 kWh of Solar Energy with 973.2 kWh of Home Usage and have a from Grid of 127 kWh.

Obviously I am not understanding the Tesla data spread sheet.

It seems to me I should have banked 705.5 kWh into the PG&E grid.

Can someone help me understand how this spreadsheet balances.


View attachment 663467

Are you looking at the BOD or something else on the PG&E site? You need to look at the BOD.

 

[sorka]

Since you have Powerwalls, you need to look at the detailed billing when it is available. The header should look like this:

View attachment 663514

And also that Februrary 17th is NOT the first service day in the period.