The cost of a SCADA system is rarely just the initial purchase. Commercial platforms are typically licensed by tags, client screens and add-on modules, with annual support and upgrade fees on top. With custom SCADA you pay for development instead and keep the source code. The right choice rests on total cost of ownership, judged against your growth plans.
What really happens at the decision table
The usual story goes like this. A plant defines its SCADA needs and gets a quote from a systems integrator. The quote is sized for today's tag count and two operator screens, and it looks reasonable.
Two years later a new line is added and the tag count crosses a licence tier. The maintenance manager wants to monitor from their office, which means another client licence. Reporting, web access and mobile alerts are separate items. If the support agreement lapses, the upgrade to a version compatible with the new operating system is off the table.
None of this is hidden or unfair; it is how commercial software is sold. The problem is deciding on the first quote alone.
The opposite mistake is just as common: choosing custom SCADA because it is "licence-free, therefore cheap". If nobody plans who will maintain a custom system and how, the lock-in simply moves from the licence to the developer. We look at the same dilemma for business software in custom vs off-the-shelf software, and at how to avoid depending on one developer in supervising software contractors.
The cost of getting it wrong
Downtime shows how critical SCADA is. According to Siemens' The True Cost of Downtime 2024, an hour of unplanned downtime costs $2.3 million in a large automotive plant and $36,000 in fast-moving consumer goods plants. Who responds when the system fails, and how quickly, can easily outweigh the licence fee.
In-house capacity has to be part of the sum:
According to the TurkStat ICT Usage Survey in Enterprises 2026, only 15.2% of Turkish enterprises employ ICT specialists (10.8% of those with 10–49 employees), and 31.7% of those trying to recruit them reported difficulties.
In other words, most businesses have no team to build SCADA in-house or manage it in depth. Whichever route you choose, the continuity of outside support is a primary design criterion.
Scope discipline matters just as much. BCG's 2020 research, "Flipping the Odds of Digital Transformation Success", found that 70% of the digital transformations it studied fell short of their objectives. SCADA projects that start with "let's monitor everything" and no sharp goal overrun budgets whether the money goes on licences or development.
Commercial vs custom SCADA side by side
| Criterion | Commercial SCADA platform | Custom SCADA |
|---|---|---|
| Licensing | Per tag, client, server and module; usually an annual support/upgrade fee | No licence; a development fee plus an optional maintenance agreement |
| Cost of growth | Adding tags or screens can push you into a higher tier | Development effort for new screens or tags; no licence thresholds |
| Out-of-the-box features | Mature driver libraries, redundancy, ready-made templates | Only the features you need; missing ones are developed |
| Fit and flexibility | Customisation within the platform's patterns | Fits your process and business rules exactly; free to integrate with ERP/MES |
| Source code and data | Owned by the platform vendor; data format tied to the platform | Source code with the customer; data in an open database |
| Maintenance and support | Broad integrator network, vendor support | Depends on the development team; documentation and code handover are critical |
| Best suited to | Standard processes, sites wanting a wide integrator choice, heavy redundancy requirements | Growing or multi-site operations, specific business rules, sites hitting licence tiers |
Both sides have real strengths. Commercial platforms offer drivers refined over many years and a large pool of specialists; for many processes they are the right answer. Custom SCADA stands out where screen and tag counts will grow quickly, across multiple sites, and wherever SCADA data needs to flow freely into MES, ERP or reporting systems. Whichever route you choose, talking to machines and upper systems through an open standard such as OPC UA is what keeps that flexibility.
The choice is not always all or nothing either. At some sites, critical process control stays on the existing commercial platform while multi-site monitoring, management reporting and MES or ERP integration are built in a custom layer above it. That hybrid moves the part that keeps hitting licence tiers out without putting the running system at risk, and brings ownership of the data back in-house.
How to work out total cost of ownership
The fairest way to compare two proposals is to spread both over the same period and the same capacity plan. A five-year table is enough for most sites, with these rows:
- Initial investment: server and client licences plus integrator engineering on the commercial side; analysis, design and development on the custom side. Server hardware, networking and field devices should be listed separately for both.
- Growth: the tags and screens your planned new lines will add. For the commercial bid, note which licence tier that lands you in; for the custom bid, how much development effort those screens represent.
- Annual support and updates: support agreement and version upgrades for a commercial platform; a maintenance agreement for a custom system. For both, check whether response times are written down.
- Integration: extra modules or development needed to exchange data with MES, ERP or energy monitoring. How the budget builds up on the MES side is set out in MES software cost factors.
- Internal labour: the time and training of whoever runs the system. With solutions that demand platform-specific expertise, this line grows when that person leaves.
- Exit cost: if you want to change platform in five years, how easily do the tag list, screens and historical data move? Most tables leave this row out, yet it is the real measure of lock-in.
Filling in this table usually turns "which is cheaper?" into "which fits our growth plan?". If the totals come out close, the decision rests on qualitative criteria such as continuity of support and ownership of data.
Six questions to guide the decision
- How many tags and screens will you have in five years? Size the decision on planned capacity, not today's. Ask the commercial bidder about tier jumps and the custom bidder about expansion effort.
- Who needs access, and from where? Control room, management office, field tablets, remote sites. Each access point is a licence or development line.
- Which systems does it need to talk to? MES, ERP, energy monitoring, maintenance software. The more integration you need, the more an open data format matters. Where SCADA data goes in the layer above is explained in MES vs ERP, and the energy side in factory energy monitoring.
- Who responds to a failure, and how fast? Put this into written support terms; if you have no in-house team, it is the single most important criterion.
- Who keeps the source code and documentation? With custom SCADA, the source code, installation documents and tag list should be handed over; with a commercial platform, make sure the project files belong to you. We cover the contractual side in software contracts and source code ownership.
- How will security updates arrive? Whichever route you take, agree up front how operating system and component updates are applied and how network separation is built. For the detail, see our article on OT security for SCADA.
Your answers usually point to the decision on their own. If SCADA concepts are new to you, start with our guide what is SCADA. Where SCADA fits into a factory's wider digitalisation plan is shown in our Industry 4.0 roadmap for SMEs.
The decision is even sharper for solar plants built with inverters from several brands. Our guide to solar power plant monitoring explains how to collect data independently of the manufacturer.
How we handle this at Digital Bridge
Our approach within our SCADA and HMI service:
- A neutral needs analysis first. We review the PLCs, RTUs, protocols and growth plans on your site. Site assessments for Industry 4.0 projects are free. If you run a standard process and your team already knows a commercial platform well, we will say so.
- We build custom SCADA. With a custom SCADA developed by us, the source code belongs to the customer and there are no additional licence fees, so growth in tags or screens never runs into a licence tier.
- We deliver the same core functions. Connecting to PLCs from different manufacturers over Modbus, OPC UA, Profibus and Ethernet, real-time HMI screens, alarm and event management, a historian, role-based access, dual approval for critical actions and remote access over VPN are all part of our SCADA & HMI scope.
- We connect it upwards. We link SCADA data to our MES production management system and, where needed, to ERP and reporting tools through system integrations.
- We put maintenance in writing. Scope, phases and fees are set out in a written proposal; documentation and training are delivered at handover, and technical support is available 24/7.
Next step
If you have a commercial SCADA quote on the table, or a licence renewal is coming up, put the six questions above next to it and gather five years of tag, screen and support costs into a single table. If you would like to compare that table with a custom alternative, get in touch and we will assess your site together and produce a written scope.
Other articles worth reading before you decide are gathered in our complete Industry 4.0 guide.