MOL · capability 05 of 08
Metering points calculated from existing meters.
A virtual meter is a mathematical metering point: a load calculated from meters that already exist. MOL treats it like any other meter, with readings, a profile, a tariff and a bill, but there is no instrument, no CT (current transformer), no installation and nothing to fail.
Aggregation by vector sum gives correctly diversified demand.
Aggregating meters in a spreadsheet usually goes wrong at this point. Two supply points each peaking at 400 kVA do not give a site peak of 800 kVA, because they almost never peak in the same half hour. Adding the demand figures overstates the charge, sometimes substantially.
MOL aggregates by vector sum of active and reactive power, interval by interval. The correctly diversified maximum demand of the combined load then follows directly from the totals, which is how the utility calculates a summated account.
- Common-area apportionment
- One virtual meter totals the landlord's load so that it can be recovered from tenants pro rata on a defensible basis, rather than estimated by floor area.
- Measurement and verification
- An energy-saving intervention needs a before and after measurement on the same boundary. A virtual meter defines that boundary without rewiring.
- Parent and child hierarchies
- Intake, sub-board and tenant. MOL models the hierarchy and reconciles each level against the level above it.
- Unmetered and unmeterable points
- Where a physical meter is not feasible, or would cost more than the load it measures.
Recovering the cost of standby generation.
Shopping centres are now built with enough local generation to run the whole centre, not only the lifts and the emergency lighting. Tenants expect to keep trading through an outage, and a centre that cannot offer this loses tenants.
This creates an accounting problem. Generating from diesel costs several times what the utility charges, and the cost is incurred by the tenants who were trading at the time. Recovering it through a flat service charge means the tenants who closed subsidise those who stayed open.
Conditional virtual meters
Each tenant's consumption is split by the source of supply at the time.
01
One virtual meter records a tenant's consumption only in the intervals when the generator meter shows the generator was running.
02
A second records the same tenant's consumption in every interval when the generator was idle and the utility was supplying.
The two are billed on different tariffs, one at the cost of utility supply and one at the actual cost of generation. Each tenant pays for the diesel generation it consumed, in the half hours in which it consumed it.
This runs entirely in software, on the metering already installed. There is no duplicated reticulation, no separate emergency board per tenant and no control system. The alternative is a second set of meters and wiring for every tenant in the centre.
See this applied to your own data.
PMT will run it against a month of your readings and show you the results.