“banner728.gif"

Let’s talk about the new Zesco electricity tariffs, load-shedding

[By Eng. Chisakula Kaputu]

I only remember those that owe me money when I am broke. Could this be the situation here with people only realising that their energy spend/ electricity costs are way too high because of the prevailing hard economic times/ low cash reserves? Or maybe not!

Let us look at a few facts and points to note: For most households, the load shedding hours have significantly reduced in these recent times. Granted, the load shedding inconvenience did inadvertently lead to less consumption. Basically, it was “forced energy conservation”, so it is possible that the reduced load shedding hours for the same usage patterns can lead to what would seem as “electricity finishing fast” (literally).

For most people, they still have not figured out/clearly comprehended the formulae for buying electricity units. And it is not their fault. Not everyone can and should immerse him or herself in understanding the buying formulae. In any case, it is the utility’s duty to inform beyond misinterpretation.

Basically, the new tariff structure since January 2020 (concerning the residential sector only) entails the following: R1 consumption up to 100kWh (lifeline) is at K0.47 per kWh; R2 consumption between 101 to 300kWh is at K0.85 per kWh; R3 consumption above 300kWh is at K1.94 per kWh.

Firstly, one needs to understand that there is a buying cycle that allows you to buy the first 100kWh (lifeline) at K0.47 per kWh whenever you choose to make the purchase in that cycle (a calendar month) irrespective of when in the month you make this first purchase. This also applies to the R2 consumption of a cummulative 200kWh at K0.85 per kWh as a subsequent purchase after one depletes the first R1 consumption of 100kWh. R3 Consumption kicks in after one depletes an accumulative 300kWh in one cycle and the highest rate of K1.94 per kWh then applies.

As a way of example and demonstration (spend in Kwacha):

For most households, energy efficiency and conservation practices are still alien to them.

Energy efficiency and conservation is a sure way to reduce on our energy/ electricity consumption and resultant costs. We need to start investing in energy efficient technologies and start practicing energy conservation measures.

Here are some scenarios to appreciate: Most homes that have boreholes, have installed both submersible pumps and booster pumps for their potable water. So, this means that every time the water faucet/tap is turned on (water consumption), electricity is also consumed to run the pumps (electricity consumption). For some households, their booster pumps run the whole day to deliver high pressure to the entire house (often at pressures they do not really require for the application). For some others, their water tanks often overflow hours on end (wasting water and electricity).

As crude as this may sound to some, a simple saving suggestion could be NOT always flushing the “loo for a pee”. Every time you turn a water tap or flush a toilet the pump kicks in. Other measures include ascertaining whether the pumps are correctly sized and not oversized. Another measure could be the installation of low flow showerheads, aerated faucets and dual flush toilets (for low-flush applications).

Other measures involve the hot water system; maintaining the geyser temperature at 55 degC (Remember that no one baths water at 55degC. that is why we mix with cold water to just 1 or 2 degrees above body temp of 36. 7degC). The reason we keep the hot water temperature at around 55degC in the geyser & hot-water system is to hinder any Legionella proliferation (bacteria growth).

Here are some quick water and electricity saving tips:

rain-water harvesting and grey water recycling for the garden bulk ironing and washing cold cycle washing machine; shut off completely (render out of service) all hot-water faucets in wash/hand basins and kitchen sink; put security lighting on photo-sensors and/or timers; use low wattage lights; unplug appliances in standby mode; invest in alternative heating and cooking fuel sources; install programmable timer switches where applicable; invest in a geyser blanket and insulate all hot water piping. Most households are on a prepaid electricity meter that has been in service for some time now.

First off, to my knowledge and understanding, the prepaid meters currently installed are not smart meters. So, basically, they do not entertain bidirectional communication (one cannot remotely access it or manipulate it). So, the question of the prepaid meters being remotely tampered/fiddled with is out of the question. What is however possible is that some of these meters may have drifted out of acceptable operating ranges. Simply put, they may require recalibrating. Meters are factory calibrated and certified to operate without any further recalibration in its entire operational life (normally that is). However, a meter may over time experience what is referred to as an accuracy drift due to environmental or other unknown factors. This is what would warrant a re-calibration and certification.

Need to understand house traffic and loading as it affects energy consumption

Is our present consumption typical and traceable & comparable to same time last year? We must take full cognisance of the “stay at home” necessitated by the COVID-19 pandemic and what that means in terms of our house traffic and power loading. Not only are we staying, and for some even working from home, others have taken on additional visitors that couldn’t leave possibly because of movement restrictions (the guest insisted they stay). Therefore, our electricity consumption could possibly be higher than “our normal”. Some of the other factors adding stress on our electricity budget include such ‘unnoticeables’ as increased laundry days and sleepovers.

Voltage optimisation and energy consumption

As a matter of the quality of power that is supplied to the residential consumer is (in this case) concerned, there are various applicable standards (national and international). One such local standard is the ZS 387 for power quality and reliability, international ones include EN 50160, IEC 61000. For a single-phase house, voltage is typically supplied at 220V AC and for a three-phase house; it is at 380V AC (with a maximum standard deviation of +/- 10%). However, know that there is an allowable tolerance (+/-10%) to the supplied voltage (range 198V to 242V AC).

Now, without going into the technical detail, know the following that; over-voltage and under-voltage beyond acceptable limits and over extended durations can cause problems. Causes of over and under-voltage include line faults, switching actions, etc. Voltage optimisation ensues that optimal voltage levels are provided as there is a correlation between higher supply voltage and energy consumption. As such, voltage reduction leads to reduced energy consumption (and conversely higher voltages lead to increased energy consumption).

Account & bill verifications, reconciliation and validation

This is an exercise one can undertake on their own. It entails a review of your historical utility bills or spending records. It also involves an exercise where one counts all their significant loads, records nameplate power rating, estimate operating hours and roughly calculate kWh consumption (per day, per month). Compare monthly consumption or spend; arrive at an average daily consumption (kWh per day) and use it as your base.

Conduct own prepayment/prepaid non-intrusive meter tests

In as far as the prepayment/prepaid meter is concerned, one can conduct their own “meter accuracy test” by doing the following exercises to check it:

Creep test – Turn off your power at your main distribution board (that would be your main circuit breaker denoted “MAIN” and possibly rated 60A) and check if the electricity meter is still clocking consumption. For most of these prepayment/prepaid meters, consumption is indicated by a red blinking / flashing light. The red-light flashes in pulses (with 1000 pulses equal to 1kWh). So, basically, there should not be any more flashing of this red light whatsoever.

Pulse count – This is laborious and tedious as it involves you counting how many red-light flashes/ pulses before the meter reading changes/decreases by 1unit or kWh. Knowing that 1000 pulses = 1kWh, one is able to see whether the count is accurate.

Load test – With the main circuit breaker turned on and all household loads turned off at the plug points, switch on only one load of known X rating (in kW) for, say an hour (1h); energy consumption should be XkWh (allow for minimal losses).

Check-metering- Particularly for Commercial & Industrial (C&I) customers, an investment in a check-meter that checks the Main Utility Meter would help in ascertaining the accuracy and correctness of the utility meter. Sometimes it is as easy as wrong current transformers (CTs) installed of the wrong ratio (multiplier). Sometimes, they are wrong settings that ought to be checked. Submetering can also be deployed within an establishment to identify and separate energy consumption to respective cost centres.

DNMD and Tariff optimisation

Declared or notified maximum demand (DNMD) and tariff optimisation applies to commercial and industrial customers (FYI only as residential customers).

Basically, your notified maximum demand is a contracted demand from the utility whose capacity one has to pay for. The deal here is to correctly size your maximum demand and avoid paying for excess capacity not utilised.

As for Tariff optimisation, this entails migrating your tariff to the most appropriate and cost-effective rate class you should be on to realise some cost savings. This is also applicable where Time of Use (TOU) tariff is at play (best to exploit standard or off-peak times against peak times).

Zsco’s role in customer relationship management

The national power utility, Zesco, is duty-bound to undertake a customer-centric initiative of a country-wide sensitisation and education programme in as far as new tariffs, prepayment meters, energy efficiency & conservation, alternative fuels are concerned and affect the end-user.

The author is an Energy Expert with over 25 years of experience (Industrial Mining, Academia, Power Infrastructure/ESI, Electrical consultancy and Energy advisory & consultancy. Reproduction of this article in full or in part without written express permission from the author is forbidden. Send your comments to: kaputuc@gmail.com, Whatsapp: +260 965 387166.

Leave a Reply

Your email address will not be published. Required fields are marked *