How to calculate the amount and cost of electricity you use per month

Posted by Felix Okoli on Tuesday December 8, 2015 at 11:4:28:

How much electricity do you use at your home or office? How do you monitor your electricity usage? Knowing how much electricity you use can help you make plans ahead on how to use that power.

A lot of people in Nigeria make use of electricity and it is mostly supplied by the Power company popularly known as NEPA, an acronym for the defunct National Electrical Power Authority in Nigeria. Other sources from which Nigerians get their electricity from are power generators and solar panels. Do they really all know how much power they are consuming?

One of the easiest ways to know how much electricity you are using or through which one can monitor his electricity use is by making use of the installed electricity meters. Most homes have electricity meters installed on them and by reading them within a time based period, it is easy to know how many watts of electricity you've consumed in a given period.

The old version electricity meters were analog or mechanical based meters while the new meters were electronic or digital meters and they displayed electricity consumption on a digital screen unlike the mechanical ones which rotated vertically to display numbers.

The unit of expression for electricity consumed on electricity meters in Nigeria as in most other parts of the world is in KiloWatt hour (kWh) and it basically refers to the number of KiloWatts used within a time frame in hours. A kilowatt is a thousand Watts i.e. 1000 Watts and 1 kwh means that a thousand Watts has been used in 1 hr or that 100 Watts has been used in 10 hours and so on like that.

How many kWh does your TV consume per month? Let's assume that you have a TV that requires 100 Watts of power as input and you use it for 4 hrs a day for 10 days, if we want to convert that to kWh, we are going to get 100*10*4 = 4 kWh. Just by multiplying kw by hours, you'd get kWh. If you then use that TV for up to 30 days in a month, the the amount of electricity units it would have consumed in a particular month of 30 days would be 1.2kWh.

How much does electricity cost in Nigeria? It would depend on the tariff which is basically a variable cost expressed in Naira and relative to the amount of electricity used in kwh. As at May 2015 the tariff was about N15 per kwh in Lagos Nigeria and if your TV uses up to 1kwh per month, then it's costing you about N15 per month excluding other charges such as fixed costs and taxes.

Different electronic gadgets at your home or office would consume different amounts of power depending on the power specifications printed on their backs as well as on the number of hours they've been used. Deep freexers would consume more power than TV set, electric pressing irons would consumer more watts than a light bulb or radio and your microwave would require more power than your computer.

The easy way to know how much power you need and how much it would cost you is to simply monitor your electricity meter hat has been already installed for you at home and then multiply it by your electricity tariff for that month.

What if you wanted to know how much power each of your electronic gadgets really consume for a time period? Well this is also possible if you install an electricity usage monitor such as the P3 P4400 Kill A Watt Electricity Usage Monitor. The Kill a Watt meter would be first plugged into the socket while your electronic gadget would then be plugged into its socket so that any electricity that passes to your gadget would first have to pass through the Kill A watt meter and be measured for you. The Kill A watt meter comes with a visual display to show how much electricity that connected electronic device has used for a time frame such as 1 hr, 10 hours or days and so on depending on how long it has been connected.

When making use of an electricity usage monitor, it would allow you to know which of your gadgets uses the most electricity and which of them uses the least and I believe you can monitor them on a shorter as well as longer time frame. Some electricity monitors may also come with additional input parameters that allows you to input your tariff and other electricity costs so as to know the actual costs in your local currency. The monitor would display how many watts or kilowatts of electricity that has been used and you can then convert that to the cost by simply multiplying it by your electricity tariff.

Knowing how much electricity you use per month would allow you to plan for the future and decide better on how to source for power. It would allow you to decide whether to go solar, keep relying on grid electricity or your mechanical power generators.

Personally, at my home in Lagos Nigeria, NEPA supplies about 258 kwh of electricity to us per month and that costs us about N5000 since we also pay an additional fixed charge of N750 and a 5% VAT. This is excluding the fact that we also have to spend more than that per month on fueling electro-mechanical generators just to make up for the insufficient power supply. Ideally, I think we'd need be using up to 1000 kwh per month if electricity was available for 24 hrs a day. just to power basic stuff like fridges, lights and the TV. However I believe that as electricity supply improves in Nigeria, so will the demand for more electricity as people would now want to power more of their electronics.

The fact that I know how much electricity my home needs per month has made me to start thinking about investing in Solar energy. I'm considering an off-grid Solar power plan that could generate up to 1 kwh of electricity in a month. If one wanted to invest in a solar power system that could generate at least 1000 kwh of electricity per month in Nigeria, then he is going to have to spend at least N700k(about 2000 GBP) for that system. I have to say that it's a huge investment but if it's going to last for 25 years and would not need some replacement parts until after 10 years, it's still a wise investment because we don't know when NEPA will start supplying us with electricity on a full time basis. Given that fact that the cost of electricity in Nigeria keeps rising every year, it probably really makes send to invest in Solar energy for now.

How does a Nigerian save money on electricity? Well, if he is using a prepaid billing system, it would ultimately have to be by reducing the amount of kilowatts of electricity consumed and this would include avoiding or limiting the use of devices that use a lot of power such as microwaves, washing machines, pressing irons, boilers, deep freezers and so on.