MYTH: “I Have an Inverter & Battery, therefore My Grid (PHCN) Bill Should Reduce!!!”

CASE: INVERTER & BATTERY (W/OUT SOLAR PANELS)

Honestly from an expert point of view, this has to be the funniest statement I have heard/read from a client 😅.

I quite get though.

Excuse me Sir…, ever heard about ‘Law of Conservation of Energy’?….
It says: Energy cannot be created nor destroyed, but can only be transferred from one form to another. You can’t eat Ur cake and have it. We’ll come back to further buttress this.

Here’s the fact: Your Grid Bill (PHCN Bill) will rather increase (maybe slightly) than reduce if you are using just an Inverter & Battery (w/out a solar panel).

Here’s why: Let’s say for instance when U bought ur battery it was low on purchase (0%), the moment Ur RoadSyd Engr connects it to ur Electrical system, it begins to act:

- A Load (just like Ur TV and AC) consuming PHCN units (Grid bill), but just that this time around it saves (Energy Storage) it rather than utilize it. Typical of what Ruminant Animals do, they eat a lot of grass and store in the Rumen (Energy Storage), and then Regurgitate it for future use.

- An Energy source, when there is no Power Supply from the grid (PHCN), and Ur devices takes Energy from the battery.

So now U see that the Energy U start to use from Ur battery wasn’t just falling off from Heaven, it was transformed from one form of Energy from the Grid (Electrical) to another Energy form (Chemical) into the battery.

PS: For our non-science student readers, there’re various forms of energy, and one form can be transformed to another.

E.g. Ur generators at home does, Chemical (fuel) to Mechanical (Rotor & Stator) to Electrical (Alternator) then to Ur appliances. Please just ignore/skip this part if it doesn’t make any sense to U, I’ll Understand.😅

So, now we have at least established that the energy U used from the battery was still an energy from the grid, & it doesn’t reduce Ur grid bill at the end of the month, what it just does for U is, it saves a grid energy that U have paid for in Ur battery, so U can use at Ur own convenience. Pay for it, Save & Use Later!

Now here’s why I said Ur grid bill at the end of the month might even be slightly higher: LOSSES!.

If for instance U saved 9.6kWh of energy from grid, and at our current rate of ₦48/kWh, it would cost you:

= ₦48/kWh x 9.6kWh = ₦460.8

Small Engineering Class: This process of saving energy from the grid to Ur battery is what we call RECTIFICATION.

Converting (Rectification) this 9.6kWh AC energy to DC Energy into Ur battery, there are conversion & efficiency loses, so at the end of the day, U might end up just saving 9kWh (0.6kWh lost).

Now, when U now plan to utilize the 9kWh DC energy in Ur battery, we have to also converter it back to an AC energy for Ur appliances to be able to use it. This process is called INVERTING. There are also conversion loses here, and we just have about 8.94kWh (another 0.6kWh lost).

So most ‘INVERTER’ as we would generically call it, can either do RECTIFICATION or INVERTING, or even both (contains the devices doing the both), depending on the design.

Grid Energy (Alternating Current) ← → Battery Energy (Direct Current)

So from calculations above, we literally bought 9.6kWh at ₦460.8;

Now U were only able to save 9kWh during RECTIFICATION, that’s about = ₦48/kWh x 9kWh = ₦432

Now after INVERTING, we had 8.94kWh which is = ₦48/kWh x 8.94kWh = ₦429.12

Basically we lost ₦460.8 — ₦429.12 = ₦31.6

So for U to accurately have 9.6kWh available to U from Ur battery, we need to probably purchase about 10.8kWh. The 9.6kWh needed would have cost U ₦460.8 if U were planning to use it immediately from the grid & not save in our Battery, but would now cost U: ₦48 x 10.8kWh = ₦518.4 because U need to save it in the battery.

This same analogy applies to also when U are using Ur Gen, but a different calculation pattern. More in term of quantity of fuel/diesel. Say it would cost U 3Ltrs of diesel/fuel to get 9.6kWh to use instantly, now due to the loses stated earlier, if we need to save & use 9.6kWh in our battery, we would need to generate about 10.8kWh from the Gen which would in turn cost us about 4Ltrs.

Basically, the main essence of having an Inverter & Battery is so U can have Energy to use when there’s no Grid (PHCN) or Gen, and not necessarily save cost 😎.

I hope I didn’t confuse anyone 😅.