Working out usage of electric consumption with PV

D

Doing it for the kids

Member

• Jul 23, 2017

• #1

i have had a few issues with my leecy board as posted on the main sub.

Last year we used about 44,000 kWh on all the farms subbmeters. This was used from 8-5 mon fri, so usual working hours mostly.

However, my PV produced about 45,000kwh in the same time frame.

Obviously I have used some of the grid but with no export meter I would love to try and estimate what grid use we may have incurred?

The main grid meter has not been fully working hence the need to solve this.

Any help very welcome, I'm negotiating a 15k bill

 

E

e3120

Member

Mixed Farmer

Location

Northumberland

• Jul 23, 2017

• #2

Difficult, given your main meter probs. Does your PV generation meter log HH data (it might, even if not used for anything)? You'd still need to extract it, but this is surely possible. Or do you have some other monitoring of your PV? The reason this detailed generation data could be useful is that you could then assume average usage of the 44k units over the working hours and overlay the generation data for the same period (hence HH being ideal), and approximately deduce how much was imported. Whether this approach would stand up to intense negotiation is another matter.

 

Exfarmer

Member

Location

Bury St Edmunds

• Jul 23, 2017

• #3

DECC would suggest 50% usage to be a fair figure, I would go for that figure in your situation. I would also be looking at the cost per unit, £15K for 45,000 units suggests 30 p / unit, whereas 8 p would be nearer the mark

 

D

Doing it for the kids

Member

• Jul 24, 2017

• #4

Thanks both.

I am not sure what you mean by HH but I get a monthly report which details production / day.

£15k was based on some random estimate that they used to make my usage 77,745!. No one seems to understand the maths they used, it was more like finger in the air stuff, hence I want some science behind it.

 

Exfarmer

Member

Location

Bury St Edmunds

• Jul 24, 2017

• #5

Is there any reason to suggest your total consumption has been any different from the annual usage before this meter was changed.
Do the sub meters measure the total consumption, or is there any consumption, say personal, or your own business, that is drawing before the sub meters?
Obviously the PV will be making an impact as its production will be included in the Sub meter figures.
Have you no figures from the rogue meter also, to back up your case? It should be possible to read both the import and export.

 

D

Doing it for the kids

Member

• Jul 24, 2017

• #6

I don't have an export as in reality we wont get the chance to shift much back to the grid.

the rogue meter wasn't accurate enough to use.

95% of all usage is metered, all to commercial units and boiler house, resis on different meters thank god!

new units were added at the start of the problem so previous history of no relevance.

I think I am on a strong footing as they have no idea what the usage was and didn't expect me to supply a spread sheet of monthly readings from the day it happened!

Thanks

 

E

e3120

Member

Mixed Farmer

Location

Northumberland

• Jul 24, 2017

• #7

Doing it for the kids said:

Thanks both.

I am not sure what you mean by HH but I get a monthly report which details production / day.

£15k was based on some random estimate that they used to make my usage 77,745!. No one seems to understand the maths they used, it was more like finger in the air stuff, hence I want some science behind it.

Click to expand...

HH is half-hourly metering, where the energy flow is measured and logged for each half hour period. Would have been useful to overlay with the usage allocated to the same periods (by assuming flat from 8-5) and then deducing how much came from PV/Grid. Might be worth enquiring if more detailed data is available. You could do it at a daily level but, as you know, the generation profile over the day can vary significantly.

 

akaPABLO01

Member

• Jul 24, 2017

• #8

Switch your solar off on a dank day count up all units used (supply meter) this'll be a typical days draw usage, not when the farm is shut down/non operational.

Measure usage from 8am to 5pm (supply meter)

Switch solar on and read your supply meter same times and then it'll give you an idea. Throughout the year you'll have an idea of your draw to guesstimate a solar usage.

This'll depend on whether you're a dairy farm (consistently using) or if you summer dry (heavy summer user).

Experiment with it.

Supply meter is your billing meter not solar generation meter.

 

D

Doing it for the kids

Member

• Jul 24, 2017

• #9

akaPABLO01 said:

Switch your solar off on a dank day count up all units used (supply meter) this'll be a typical days draw usage, not when the farm is shut down/non operational.

Measure usage from 8am to 5pm (supply meter)

Switch solar on and read your supply meter same times and then it'll give you an idea. Throughout the year you'll have an idea of your draw to guesstimate a solar usage.

This'll depend on whether you're a dairy farm (consistently using) or if you summer dry (heavy summer user).

Experiment with it.

Supply meter is your billing meter not solar generation meter.

Click to expand...

Good thinking. I can do this now as the solar is all off anyway so I will have a good overall idea

what's the difference between a billing meter and supply meter then? I have two. one is the smart meter which I think sends the production data and the second is the official meter that gets read. I think they read the same?

 

akaPABLO01

Member

• Jul 24, 2017

• #10

Doing it for the kids said:

Good thinking. I can do this now as the solar is all off anyway so I will have a good overall idea

what's the difference between a billing meter and supply meter then? I have two. one is the smart meter which I think sends the production data and the second is the official meter that gets read. I think they read the same?

Click to expand...

Total import - primary and billing, day night rates is my guess