Myth Buster - Hot Water Geysers - Take 2

Having published the first findings on monitoring hot water geysers, the research continued. You will recall that a wifi-smart meter to the geyser circuit at a residential home and connected to the Tuya Application, where it is possible to control the operation from my smart phone. The wifi smart meter was installed mid June, where the first week was set to a 24/7 operation (the status quo operation) and one week of "timed operation" from the wifi smart meter. The two week period data showed very little difference in electricity consumption, although it was understood the period was too short to make any meaningful conclusions. The research therefore continued in July 2021 (24/7 operation) and August 2021 (timed operation).

The result: 140 kWh Saving in Electricity, which in August 2021 is worth approximately R122 per month and R1,460 a year. That's a solid 19.60% saving by controlling the time of use!

The following graphs clearly show the quite different consumption patterns for the 24/7 operation to the specific period timed operation.

Importantly (as noted in the graph for Aug 2021), the timed operation was set between 01:30 to 04:30 for the 7 days of the week, defined by ESKOM as OFF PEAK hours, where the grid has less demand. It will be seen that on only one day of the month (15th August - a Sunday) was the operation not able to cope with the hot water demand. All other days of the month, the Off Peak Operation easily satisfied the demand.

The effective saving was approximately R120.00 for the month and R1,500 per year, which may not be considered significant. However, bearing in mind Eskom tells us that there are 5.4million geysers installed in South Africa, the benefits to Eskom and the grid could be enormous.

The research will continue as we are assuming that during the winter months, more electricity will be needed to heat the tank, when compared with the summer.

NOTE: The main reason for carrying out this research is to understand if it is possible to operate geysers at schools during specific hours, as with many schools now looking to install Solar PV Systems, 100% of the schools' hot water needs will be provided by the Solar PV System.

We will continue to update the data periodically on this blog. In the mean time. do feel free to contact us for further details: