Solar SCADA, Data Acquisition and Plant Control in Pakistan

# Solar SCADA, Data Acquisition and Plant Control in Pakistan: Lessons From a 5 MW Government Plant

Most solar plant owners in Pakistan get one number from their monitoring: how many units the plant made yesterday. That number cannot tell you whether the plant performed well, which inverter is losing energy, or whether a cloudy day or a fault is to blame. Answering those questions takes three things working together: data acquisition at the plant, a power plant controller, and a SCADA that turns the data into decisions.

This guide explains what each layer does and what a good solar SCADA should show, using real data from a 5.2 MWp solar plant at a government facility in Pakistan, where GFE delivered the SCADA.

The three layers of solar plant monitoring and control

1. Data acquisition. A data logger or acquisition system at the plant reads every inverter, energy meter and weather sensor, typically every few seconds, and stores the data locally so nothing is lost if the internet drops. If this layer is weak, everything above it is wrong.

2. Power plant control. A power plant controller (PPC) sends setpoints back to the inverters: export limits, curtailment, and active and reactive power targets at the point of interconnection. It is what keeps a plant inside its grid limits and sanctioned load.

3. SCADA. The supervisory control and data acquisition (SCADA) system is the operator's view. It shows live and historical data, calculates performance, raises alarms and lets operators issue commands.

At this plant, NeoTAQ neoLog handles data acquisition and control on site, deployed and configured by GFE. The SCADA was designed and developed by GFE on atvise, a browser-based platform built on OPC UA, so operators can see the whole plant from any web browser, on site or remotely. Keeping acquisition and control close to the equipment, and the SCADA focused on analysis, is what keeps the data trustworthy.

Five things a solar SCADA should show you

1. Actual output against expected output

The most useful chart on a solar SCADA plots two lines: what the plant is producing, and what it should be producing under the sunlight measured on site at that moment. At this plant, the expected line comes from a loss model set at a performance ratio of 80%, refreshed every 5 minutes.

When the actual line tracks above the model, the plant is healthy. When it drifts below, even by a few percent, the plant is losing energy to soiling, a tripped string, an inverter fault or a grid limit, and the chart shows it on the day it starts. Without a model line, a cloudy day and a broken inverter look exactly the same.

2. Performance ratio, calculated live

Performance ratio (PR) compares a plant's measured output with what its rated capacity should deliver under the sunlight it actually received. It is the core quality measure in IEC 61724-1, the international standard for PV performance monitoring:

PR = (AC power ÷ rated DC power) ÷ (plane-of-array irradiance ÷ 1,000 W/m²) × 100

On one afternoon at this plant, 2,667 kW of output from 5,200 kWp under 602 W/m² of irradiance gave a live PR of 85.2%. A good SCADA also guards the calculation, setting PR to zero below 50 W/m² so dawn and dusk readings do not distort it, and reports an energy-based PR for the day and month. Here the daily PR was 82.2% and the monthly PR about 79.2%, which are the figures to compare between plants.

Heat lowers PR. Module temperature that afternoon was 43 to 46 °C against a 25 °C test condition, and crystalline modules typically lose around 0.3% of output per degree above it. That is why summer PR in Pakistan usually reads lower than winter PR, and why a temperature-corrected PR is the fairer comparison across seasons.

3. Output per inverter

A plant total hides a weak inverter. This plant has 16 string inverters, and the SCADA shows each one's live output side by side. In one snapshot, fifteen sat between 161 and 179 kW while one was at 141 kW, about 16% below the median. The screen cannot say whether that is shading, soiling or a string down, but it sends the O&M team to the right inverter first instead of checking all sixteen.

4. Where the power goes

The grid panel shows solar generation, grid import or export, and site load together, along with the status of the point of interconnection meter and any active curtailment. At this plant, generation and load matched at about 2,700 kW, so every unit was consumed on site with zero export and no curtailment active.

This is where data acquisition and power plant control meet. The controller acts on the meter readings, and the SCADA shows the operator what it did and why. For sites under gross metering or with export limits, this view is essential. We cover the control side in more detail in our guides to zero export control and active and reactive power control.

5. Weather measured on site

Satellite weather data is rarely precise enough to judge a plant hour by hour. This plant has its own meteo station measuring plane-of-array irradiance, ambient and module temperature, wind and humidity, and its readings feed the expected output model and the PR calculation directly. That settles the most common argument in solar O&M, whether a low day was the sun or the plant, in seconds.

Snapshot from the plant

Readings from the GFE SCADA at a 5.2 MWp government solar plant in Pakistan, 12 October 2026, mid-afternoon:

• Live output: 2,667 kW at 602 W/m² irradiance
• Peak output that day: 3,983 kW
• Performance ratio: 85.2% live, 82.2% for the day, about 79.2% for the month
• Energy that day by mid-afternoon: 22.8 MWh, or 4.38 kWh per kWp
• Energy in the first 12 days of October: 221.8 MWh
• Availability: 91.7%, with all 16 inverters on grid and communicating
• Grid: zero export, all generation consumed on site

The figures reconcile: 22.8 MWh across 5,200 kWp is 4.38 kWh/kWp, and against the 5.33 kWh/m² of sunlight received that gives the 82.2% daily PR. Numbers that check each other are the clearest sign of clean data acquisition.

Frequently asked questions

What is the difference between a SCADA, a data logger and a power plant controller? The data logger collects and stores measurements from inverters, meters and sensors. The power plant controller uses those measurements to send setpoints back to the inverters, such as export limits or power factor targets. The SCADA is the operator's view of both, with dashboards, performance calculations, alarms and commands.

Does a small commercial solar system need SCADA? Not always a full SCADA, but every system above a few hundred kW benefits from proper data acquisition and a performance ratio view. Without them, faults show up in the electricity bill months later instead of on the day they happen.

What is a good performance ratio for a solar plant in Pakistan? It depends on season and temperature, since heat lowers PR. This plant ran at a daily PR of 82.2% and a monthly PR of about 79.2% in October. Compare plants over the same period, or use temperature-corrected PR.

Can a solar SCADA control the plant as well as monitor it? Yes, when it is connected to a power plant controller. At this plant, NeoTAQ neoLog executes control at the plant, and the atvise SCADA by GFE gives operators visibility of control states such as curtailment and export.

Talk to GFE about SCADA and plant control

GFE designs and commissions SCADA, data acquisition and monitoring, zero export control and solar O&M for solar, hybrid and industrial sites across Pakistan. If your plant only tells you how many units it made yesterday, talk to us about seeing the rest.