Every month, when the electricity units in my building run low, someone tops up our shared prepaid meter, and the same question comes up in the group chat:“so who owes what?”

We each have a meter reader, but calculating everyone’s share is still a manual process. One person does the maths, and everyone else has to trust that the numbers are right.

Nira replaces that moment. It turns the meter readings into a clear breakdown of what each tenant owes. No manual calculations, no guesswork. Just a fair, transparent way to split electricity costs.

Shared prepaid meters are common in Nigerian cities, from apartment blocks and compounds to student hostels. Buying electricity units is the easy part. The hassle begins when it’s time to calculate each tenant’s fair share.

manual processIn my building, someone has to collect everyone’s meter readings and do the maths by hand. But it’s not as simple as subtracting one reading from another. Since the meters keep running, they have to reconcile previous readings with new ones to work out how much electricity each person actually used.

It’s a tedious process, prone to human error, and everyone else has to trust that the calculations are correct.

I started by designing around how we split electricity bills in my compound. I knew the frustrations firsthand, so I had a clear idea of what needed to change.

As the sole designer and engineer, I took Nira from a problem I experienced to a product I designed, built, tested, and shipped. Throughout the process, I focused on a few things that would determine whether Nira actually made life easier for the households using it:

• Accuracy: Prevent calculation errors and make discrepancies visible before a bill is settled.
• Efficiency: Reduce the 30–40 minutes spent calculating bills manually to just a few minutes.
• Adaptability: Support different household arrangements for splitting electricity bills, including shared expenses.
• Retention: Households continue using Nira every time they recharge, rather than returning to manual calculations.

To calculate each tenant’s fair share, I first needed a reliable way to know how much electricity they actually consumed. That presented two practical constraints:

• meter readerThe need for individual meter readers: Without one, there was no reliable way to tell how much electricity each person used. For households without existing readers, this meant buying and installing additional hardware before they could use Nira.
• Limited access to smart meter readers: Ideally, these devices would automatically send each tenant’s readings to Nira using IoT technology. However, they’re expensive and not readily available in Nigeria. The more accessible alternatives only display consumption, requiring someone to record the readings manually.

I couldn’t remove manual readings without increasing the cost of using Nira. So I kept that one manual step and automated everything that came after it: calculating each tenant’s share and making the breakdown accessible to everyone.

With manual meter readings still necessary, I narrowed Nira’s job down to one thing:

When we recharge, we want to calculate each tenant’s fair share based on their actual consumption, without doing the maths ourselves.

One tenant collects readings, enters recharge details, and calculates everyone’s share. Nira needed to make this quick and accurate.

This shaped Nira around a simple flow: enter the readings, Nira calculates everyone’s share, and share a breakdown everyone can verify.

Getting the numbers right wasn’t enough

The calculation needed to be accurate, but I also had to consider what happened after someone received their bill. If a tenant couldn’t understand how their share was calculated, we’d be back to the same problem of having to trust someone else’s numbers.

1. Start with actual consumption: Each tenant’s usage comes from the difference between their previous and current meter readings.
2. Respect existing agreements: Households should be able to split shared electricity according to arrangements they’ve already agreed on.
3. Account for every unit: A recharge session can’t be closed until individual and shared consumption reconcile with the units purchased.
4. Make the result inspectable: Every tenant should be able to see how their share was calculated without needing an account.

Automating the calculations was only part of the challenge. I still had to figure out how Nira could accommodate different household arrangements, account for how electricity was measured, and make the results accessible to everyone without requiring them to sign up.

One bill, different ways to split

Households already had their own agreements about shared electricity. My job wasn't to decide what was fair for them, but to make their agreements work within Nira.

I designed the calculation to support equal, percentage, and ratio-based splits. For example, a household with seven people benefiting from common-area electricity, but only four tenants contributing to the prepaid meter, could preserve its existing 4/7 arrangement instead of being forced into an equal split.

This introduced more flexibility into the calculation, but it meant households didn't have to change how they shared costs just to use the product.

Another way households measured electricity

During TestFlight, I discovered an assumption I'd made in the first version of Nira. I'd treated shared electricity as whatever remained after subtracting individual consumption from the total units purchased. That worked for households where shared usage wasn't measured separately.

But one household had a dedicated meter reader for its common-area electricity. They already knew exactly how many units they'd consumed, yet Nira had no way to capture that reading. The issue wasn't with the calculation itself. It was with my assumption that every household measured electricity the same way.

I updated the recharge flow to accommodate households that measured shared consumption directly, while preserving the original approach for those that didn't.

The reconciliation rule stayed the same: every purchased unit still had to be accounted for before a session could close. That experience changed how I thought about Nira. Supporting different households wasn't just about offering different ways to split a bill. The product also needed to accommodate differences in how households collected and recorded their electricity usage.

Readings short of the units bought: 53.50 kWh unaccounted for

One account, everyone in the loop

For Nira to work, someone had to manage the household, but did everyone really need an account? I considered requiring every tenant to sign up, but that would mean convincing an entire household to adopt a new app just to split an electricity bill.

So I made a simpler choice: only one person needed an account.

That person could create the household, manage recharge sessions, and calculate everyone’s share. Everyone else could access a read-only link to see their bill and how it was calculated, without signing up.

Household can be shared with other tenants

I also added the option to share a screenshot of the final breakdown after each session, so tenants could get their bills directly in the group chat they already used.

The goal was to make Nira useful to an entire household without requiring everyone to become a user.

People move out. Their bills shouldn’t disappear.

In rented apartments, tenants come and go. I knew the people sharing a meter today wouldn’t necessarily be the same people sharing it months later.

But removing a tenant entirely would create another problem: their electricity consumption and contribution were already part of previous recharge sessions. Deleting those records could make past calculations incomplete or inaccurate. Keeping them active wasn’t an option either, because they’d continue appearing in future bill calculations.

So instead of deleting tenants, I designed Nira to let admins mark them as having left.Their previous bills and consumption records remain intact, but they’re excluded from future sessions. New tenants can also be added without affecting the household’s history.

The household could change without rewriting its history or compromising the integrity of the system.

Tenants who have left can be marked as left

Automation, for now. Manually entering readings takes more effort than having a meter report consumption automatically. It also leaves room for human error. But it means Nira can work with the affordable meter readers households already use, without depending on expensive or hard-to-find hardware.

Shared control. Giving one admin responsibility for managing recharge sessions creates a dependency on that person. But it also means an entire household can use Nira without everyone needing to sign up. Everyone can still see how their bill was calculated.

A little speed at the finish. Requiring every unit to be accounted for before closing a session can slow things down when readings don’t add up. But it prevents households from finalising a bill with unexplained consumption, even if that means spending a little longer reconciling the numbers.

Shipping Nira to the App Store was one thing. Seeing whether it actually made settling electricity bills easier was another.

I treated repeat use as the most meaningful early signal: this is a recurring monthly task, so a household returning for its next recharge is stronger evidence than a one-off download. I also watched for two failure signals: sessions that could not be reconciled and tenants questioning a final bill. The absence of reported disputes is directional, not a substitute for a larger trust study.

More than four months later, all six households that started using Nira are still using it, with more than 30 recharge sessions completed between them.

What previously took about 30–40 minutes of manual calculations now takes roughly 2–5 minutesto collect and enter readings. Once those readings are entered, Nira calculates everyone’s share with a single tap.

Across those sessions, no tenant has reported questioning or disputing how their bill was calculated. I also saw households successfully use different splitting methods and meter arrangements, including the setup that challenged my original assumptions about shared electricity.

Six households is still a small sample, but what encouraged me most wasn’t just that Nira worked for them. It was that they kept coming back to it whenever another electricity bill needed settling.

I started building Nira because I was tired of the hassle that came with splitting electricity bills in my compound. I thought I understood the problem because I experienced it every month.

But building Nira showed me how differently households manage the same responsibility.

Some split shared electricity equally, others use percentages or ratios. Some have dedicated readers for shared areas, while others calculate shared consumption from what’s left. And as tenants move in and out, households need to preserve the accuracy of their previous bills.

That understanding shaped Nira beyond the original bill-splitting experience. I added a history of completed recharge sessions and individual tenant profiles showing how much each person had spent and their average monthly electricity cost.

Users also began asking for ways to collect individual payments and purchase prepaid electricity directly through Nira. Neither is supported yet, but those requests revealed another part of the experience I hadn’t initially set out to solve: what happens before and after the bill is calculated.

The biggest surprise was discovering that a problem I’d set out to solve for myself was shared by other households.

I started by trying to make splitting electricity bills easier. Along the way, I realised I was building something that could help households manage them better.