High Electricity Bill due to a Faulty Smart Meter

Findings

Conclusion: The building owner’s high electricity bill was due to a faulty Smart Meter connected to the switchboard.

Introduction

Green Wire Consulting were commissioned by the Owners Corporation of a large Apartment building located within St Kilda in Melbourne – to investigate the reason for an unusually high electricity bill for their premises.

As part of a detailed Energy Audit for the whole building – Green Wire Consulting monitored key switchboards & plant for 1-2 weeks using power loggers to gain data from analysis to ascertain the reasons for the high electricity consumption. At the end of the audit it was suspected that one of the smart meters was measuring too high & therefore focus shifted to confirming the accuracy of the existing smart meter.

Smart Meter Tested

In order to check that the existing Smart Meter was operating correctly, Green Wire Consulting attached their own Class 0.5 Smart meter to the same incoming power supply. Our Smart Meter generated 15min interval data in the form of a CSV file which was used by Microsoft Excel to plot the results in graphical format. The Electricity Retailer was contacted and the Interval data from their suspected faulty smart meter was requested from them covering the same testing period.

Smart Meter Data Analysed

The process of comparing both CSV interval data was undertaken to understand the differences in the data, and therefore revealing the differences between smart meters. The Graphs 1 & 2 below show both Smart meters capturing the same power consumption over the same time day.

Observations:

The above 2 plots ( red & green lines) appear similar in shape over time but different in scale, suggesting that the 2 smart meters are a factor or multiple out. Close examination reveals that they might be out by a factor of 4. To test this, the data from our smart meter was multiplied by 4 and re-graphed as shown below.

Faulty Smart Meter Found

Since both lines in the above graph (green & red) follow each other exactly, we conclude that the tested smart meter was reading exactly 4 times higher than our testing smart meter. This means that the Building Owners Corporation are receiving high electricity bills, which are 4 times higher than they should be. The smart meter fault is likely to be a programming error within the electricity retailer’s smart meter, because the error was measured as being out by a whole integer figure (i.e 4)

Outcomes

• Electricity Retailer to immediately organise for the existing installed faulty smart meter to be rectified.
• The Owners Corporation to receive a refund for all past electricity bills incorrectly billed.
• Since the Faulty Smart Meter was determined to be a electricity supplier problem, the Owners corporation has the right to be reimbursed from the electricity retailer for all fees charged by Green Wire Consulting’s that proved the error.