When the meter reports itself: PV production reporting for OKTE
Situation
An operator of a photovoltaic plant with roughly 1.3 MW of installed capacity files a monthly production report with OKTE, the Slovak electricity market operator. The inputs used to be prepared by hand: a technician exported data from the certified billing meter, which keeps only about 31 days of 15-minute records in a circular buffer – miss the window and the history is gone. On top of that, the meter’s clock drifts, by tens of minutes over time, so the time series gradually parted ways with reality.
Solution
The system reads the plant through two independent branches. The technology branch collects live telemetry from the inverters, the plant’s own meter and the weather station over Modbus TCP and drives day-to-day operation. The metering branch connects directly to the billing meter via M-Bus and a TCP gateway – the authoritative source for reporting. The two branches validate each other. Every hour the system harvests the meter’s memory into a permanent archive, so the billing meter’s data now exists forever, not for a month. Clock drift is detected automatically by cross-correlating the meter series with the time-accurate inverter series, and the report is corrected by shifting whole 15-minute periods – the values themselves never change, only their placement in time.
How we read the numbers on this site: The figures in these studies come from people inside those operations – engineers and managers who dug the savings out of their own data. They are not audited or officially approved; companies do not publish numbers like these. That is why we do not name the customers, and why every figure says where it comes from.
Result
On the first day of each month the system generates the production report in the format OKTE prescribes – 2,976 fifteen-minute periods, including daylight-saving months – checks it for completeness and e-mails it to the parties involved. The technician’s manual monthly routine is gone entirely. The data is held in three layers: the meter’s memory, a disk queue that re-sends automatically after an outage, and a control replica on a second server; missing periods re-read themselves from the meter after a failure. Correctness is evidence, not assumption: nightly archives are byte-identical with the technician’s manual export, a control consumption window agrees to within +0.013 %, and the report’s daily totals match the meter to the kWh. And because consumption across the site is sub-metered, connecting the PV plant closed the complete energy balance: the system can allocate energy costs to each production order individually, including the share covered by the plant’s own solar generation.
Honest numbers
Deployed in the summer of 2026. We do not name the customer; the operator runs a PV plant of roughly 1.3 MW. We publish no financial figure for this deployment – the benefit is the replaced manual work, a permanent auditable archive beyond the meter’s memory, and a replicable pattern for other producers with certified billing meters. The platform licence is not included in any calculation on this site.