I'm having troubles setting up my Meter Account to show summated import and export consumptions, and also broken down by TOU periods.

I have 4 Generators in the power station, which are individually metered, and the meters are connected in such a way that the exported energy is positive kWh on the meters. When the generators are used as pumps, the meters import energy, measured as negative kWh, since the dynamos are effectively used as pumps. They connect to a busbar.

Then I have 2 transformers, that feeds from the busbar to the house of the factory of the power station. The power exported to the house is measured positive. This only ever flows from the busbar to the house.

The same busbar also feeds the grid, which is not metered. (of course there are various transformers at various places, does not affect the measured energy much)

To work out how much energy was provided to or used from the grid, I want to summate the readings from the generators, and subtract the readings to the transformers to the house. 4 meters positive, and 2 meters negative, in relation to the busbar.

How do I set that up in PNPSCADA? I want the following consumptions over a month:
Total

(Total)

Peak

Standard

Off-Peak

(Peak)

(Standard)

(Off-Peak)

(where values in parenthesis are negative values, in other words what energy the power station as a whole imported from the grid, and value names that are not in parenthesis represents positive values, in other words energy that the power station provided to the grid.)

However, then it becomes difficult to set up the tariff to clearly differentiate between positive (P1) energh and negative (P2) energy, since the meters are not all orientated the same way in relation to the common busbar.

We tried various register configurations in the Tariff Line Items, looking at both P1 and P2, but it was a mess, the TOU registers did not add up to the Total. Sometimes it would work the one way around, but not the other, and vice versa.

However, we had to harmonize the installation first, in terms of some meters that were connected in reverse.

So what we did to solve that, is we added a separate Meter Account for the transformers, and both meters were added with a portion of -1.

Then we added a Summation Meter to that.

This effectively summated the P1s of both Transformer meters into P2 of the Summation Meter, and the P2s into the P1 of the Summation meter, harmonizing the direction of the energy.

Then we removed the two transformers from the original summation account, and added the Summation Meter.

This solution worked.