The verdict in three sentences
A chief executive who receives consolidated figures 3 weeks after month-end runs the group a month behind its subsidiaries. Power BI (around £12 per user per month) is enough when data is already clean and centralised. A custom web application (£40,000 to £80,000, delivered in 3 months) wins when you also need to collect subsidiary data, harmonise mixed systems such as Sage, Xero and Excel, and give access to more than 80 managers.
Why consolidation takes 3 weeks
In a typical London holding with 5 subsidiaries (distribution, construction, logistics, property, services), each entity keeps its books in a different tool. Distribution runs Sage 200, logistics runs Xero, two others email Excel files and the holding reworks everything by hand. Financial controllers spend 5 to 6 days a month copying, checking and reconciling, and the CEO discovers a slipping margin when it is too late to act.
The goal of an executive dashboard is not a pretty chart: it is next-day consolidation on about ten indicators (revenue, gross margin, available cash, overdue receivables, order book, headcount), with a group view and a drill-down per subsidiary.
| Criterion | Consolidated Excel | Power BI | Custom application |
|---|---|---|---|
| Consolidation lead time | 15 to 21 days | Next day if data is centralised | Next day, collection included |
| Sage, Xero, Excel connectors | Copy and paste | Via gateway and data warehouse | Dedicated connectors built |
| Input from subsidiaries without ERP | Emailed files | Not designed for it | Web and mobile forms |
| Mobile access | No | Yes (Power BI app) | Yes, mobile-optimised |
| Cost per user | Free | Around £12 a month | None (fixed fee) |
| Group-specific indicators | Fragile formulas | Yes, with a DAX expert | Yes, coded to your rules |
| Ownership | Yes | Microsoft licence | Your code and data |
The real 3-year cost
The maths depends mainly on the number of users and on whether you need to collect data nobody enters today. With 120 users (CEO, subsidiary MDs, department heads, controllers), here are 2026 orders of magnitude for London.
| Item (2026 order of magnitude) | Power BI + integrator | Custom application |
|---|---|---|
| Setup (warehouse, connectors, reports) | £20,000 to £35,000 | £40,000 to £80,000 |
| Licences (120 users x £12 x 12) | £17,280 a year | £0 |
| Cloud hosting | £2,400 a year | £2,400 a year |
| Support and maintenance | £1,000 a month | £1,500 a month |
| 3-year total | £115,040 to £130,040 | £101,200 to £141,200 |
| Time to go live | 6 to 10 weeks | 3 months |
In London, licences are cheap relative to development rates, so both paths cost about the same over 3 years and the choice comes down to function. Custom becomes worthwhile when subsidiaries must enter data in the tool, when you need workflows (approvals, comments, board packs) or when users exceed 250.
The scope of a 3-month V1
- Weeks 1 to 3: workshop with the CEO and CFO, choice of 10 to 15 indicators, written definitions (what counts as overdue, which margin), wireframes.
- Weeks 4 to 8: Sage 200 and Xero connectors, automated import of standardised Excel files, input forms for subsidiaries without ERP, central database.
- Weeks 9 to 11: group and subsidiary dashboards, alerts (cash below threshold, margin below target), PDF export for the board.
- Week 12: acceptance testing, access rights per subsidiary, controller training and go-live.
Mini case study
Need a professional website?
Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.
James, CEO of a 5-subsidiary group in London, measures the time lost: 4 financial controllers each spend 6 days a month on consolidation, or 24 person-days a month. At a loaded cost of about £350 a day, that is £8,400 a month, close to £100,800 a year. Because two subsidiaries have no ERP and must enter weekly data, he chooses a custom application at £58,000, plus £1,500 a month in support. After go-live, consolidation drops to 1 day a month. The project pays back in about 9 months, not counting the value of a decision taken 3 weeks earlier.
FAQ
Do subsidiaries need to change ERP to get a group dashboard?
No. Connectors read Sage, Xero or standardised Excel files as they are. Building one connector costs in the order of £4,000 to £10,000 depending on the tool.
Is data reliable if subsidiaries enter it themselves?
Yes, provided you add controls: mandatory fields, alert thresholds, sign-off by the subsidiary MD before 10 am. In our projects, reconciliation gaps fall below 1% after 2 months.
Does the app work on mobile on the go?
Yes. Screens are lightweight, under 500 KB per page, and dashboards load in under 3 seconds on 4G.
What does £1,500 a month of support cover?
Monitoring, daily backups, bug fixes and about 2 days of enhancements per month. New modules are quoted separately.
Can we start with Power BI and move to custom later?
Yes, and it is often wise. The data warehouse built for Power BI can be reused, cutting the cost of the custom build by 20 to 30%.
Let's scope your project. Tell us how many subsidiaries, which accounting tools and how many users you have: we will price a V1 between £40,000 and £80,000 with a 3-month plan. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
