PV metering Q's

romex jockey

Senior Member
Location
Vermont
Do any of you have to deal with something like this ?>

If so, is there a meter manufacturer that provides some sort of all inclusive 3-pack?

~RJ~
 

jaggedben

Senior Member
What a bunch of nonsense. I'm sorry you have to deal with that.

I don't have any specific tips. There are multi-meter banks available but I'm not sure it'll make sense for you. Note that your meters may end up in different locations and that the one on the left is the service meter, so might be there already.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
I don’t know why they are doing it that way.
a net meter, then the others to deduct from net at avoided wholesale cost?

at any rate, I doubt you will see an all in one enclosure because every utility is different on their interconnects(or so it seems).

we only require two. One that is a purchase at retail, the other we pay at wholesale. No net metering allowed.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Do any of you have to deal with something like this ?>
Yes, in more than one jurisdiction. In Austin, where PV production (all of it no matter where it goes) is paid for by the utility and consumption (no matter where it comes from) is paid for by the customer, there is no other way to meter it.
 

pv_n00b

Senior Member
Location
CA, USA
Is this setup assuming that the backup loads have an alternative supply from the main panel when not being supplied from the battery? Some kind of transfer switch? Otherwise to get to the backup panel the power would have to go through both meters from the main panel.
 

jaggedben

Senior Member
Is this setup assuming that the backup loads have an alternative supply from the main panel when not being supplied from the battery? Some kind of transfer switch? Otherwise to get to the backup panel the power would have to go through both meters from the main panel.
Your question is right on. If this setup is trying to measure PV production and consumption a la ggunn's description of Austin, it seems unlikely to do so accurately. It picks winners among the available technologies.
 

romex jockey

Senior Member
Location
Vermont
Is this setup assuming that the backup loads have an alternative supply from the main panel when not being supplied from the battery? Some kind of transfer switch? Otherwise to get to the backup panel the power would have to go through both meters from the main panel.
Yes, it's in the inverter

~RJ~
 

romex jockey

Senior Member
Location
Vermont
Yes, in more than one jurisdiction. In Austin, where PV production (all of it no matter where it goes) is paid for by the utility and consumption (no matter where it comes from) is paid for by the customer, there is no other way to meter it.
So how do you do it where you are ggunn?

~S~
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
So how do you do it where you are ggunn?

~S~
Pretty much as in the drawing. Fortunately, the Austin Energy grid is very reliable and they don't have a TOU (time of use) tariff, so not many people in Austin buy battery backup/assisted PV systems. When our customers ask about buying one we try to talk them out of it because it nearly always is a waste of their money.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
It's a bit convoluted, but Austin Energy pays for all energy produced by a PV system whether is is used immediately by the customer, sent back to the grid, or pushed into batteries. AE also charges the customer for all energy consumed by the customer, no matter where it comes from. The payback and consumption charges per kWh are different. There's no way to keep track of it all unless there are three meters.

The rate that AE pays for PV produced energy is the same for every customer, but the rate a customer pays for energy (again, no matter where it comes from) is tiered.
 
It's a bit convoluted, but Austin Energy pays for all energy produced by a PV system whether is is used immediately by the customer, sent back to the grid, or pushed into batteries. AE also charges the customer for all energy consumed by the customer, no matter where it comes from. The payback and consumption charges per kWh are different. There's no way to keep track of it all unless there are three meters.

The rate that AE pays for PV produced energy is the same for every customer, but the rate a customer pays for energy (again, no matter where it comes from) is tiered.
How much do they pay for pv energy?
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
9.7 cents per kWh. It's about the same as the lowest tier tariff.
Wow. That’s about retail here.
we pay about 4.5 cents for all solar produced through one meter, and charge retail for all consumption from wherever it’s produced with the other meter.
2 total.
 

wwhitney

Senior Member
Location
Berkeley, CA
It's a bit convoluted, but Austin Energy pays for all energy produced by a PV system whether is is used immediately by the customer, sent back to the grid, or pushed into batteries. AE also charges the customer for all energy consumed by the customer, no matter where it comes from. The payback and consumption charges per kWh are different. There's no way to keep track of it all unless there are three meters.
If batteries are AC coupled, what is the use case/tariff case that requires the third meter? With just two meters, one net and one PV production, then battery charging would be reflected as increased consumption and charged at consumption rates; and battery discharging would reduce consumption and be credited at consumption rates. Is that not allowed?

If batteries are DC coupled, then with two meters, battery charging would result in reduced PV export and be effectively charged at PV rates; and battery discharge would result in increased inverter export and be credited at PV rates. Does this case require a third meter, and if so is it a DC meter for the batteries?

Cheers, Wayne
 

jaggedben

Senior Member
Pretty much as in the drawing. Fortunately, the Austin Energy grid is very reliable and they don't have a TOU (time of use) tariff, so not many people in Austin buy battery backup/assisted PV systems. When our customers ask about buying one we try to talk them out of it because it nearly always is a waste of their money.
So does Austin Energy somehow link the two meters on each side of the inverter to interpolate the PV production? Because otherwise they won't get a real count of it.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems

romex jockey

Senior Member
Location
Vermont
It's a bit convoluted, but Austin Energy pays for all energy produced by a PV system whether is is used immediately by the customer, sent back to the grid, or pushed into batteries. AE also charges the customer for all energy consumed by the customer, no matter where it comes from. The payback and consumption charges per kWh are different. There's no way to keep track of it all unless there are three meters.

The rate that AE pays for PV produced energy is the same for every customer, but the rate a customer pays for energy (again, no matter where it comes from) is tiered.
Convoluted would be an apt term ggunn. But do these poco's make the rules, or do they solicit some regulatory bureaucracy to do so?

I'm just starting to read this> https://puc.vermont.gov/

where's the aspirin? :(~RJ~
 
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