Last week, Cyprus was faced with two serious disruptions to the electricity system. Thousands of consumers were without electricity for about an hour on Friday morning and for about 20 minutes early Saturday morning.
The first, according to what has become known, occurred due to a temporary loss of communication between the Distribution Control Center and the photovoltaic parks. The second was caused by a failure in the production system in the occupied territories.
In both cases, the system reacted in the same way. Simply put, it was forced to cut off electricity to a large part of consumers to ensure that a widespread blackout, which would be catastrophic, would not follow. As for the sources of the problems, there is no clear picture at the moment and it is something that is still being investigated.
"F tis Kyriakis" hosts today statements on the issue by the assistant director of the National Energy Control Center of the TSOC, Haris Zavallis, and the electrical engineer and consultant on electricity issues, Christakis Hatzilaou.
Mr. Zavallis, on behalf of the Operator, explains what happened during the two days when the power outages were observed and assures that the future operation of Energy Storage Systems is expected to provide increased reserves, mitigating the effects of similar incidents on consumers.
For his part, Mr. Hatzilaou rings the bell for Friday's incident and warns of serious risks in the event that a similar disorder occurs in spring or autumn, that is, at a time when conditions will not be as favourable as in summer.
What went wrong on Friday
The more serious of the two incidents was recorded at 10:40 on Friday morning, when there was a problem in the communication between large photovoltaic parks and the Distribution Control Center.
Large photovoltaic parks don't just generate electricity and inject it uncontrollably into the grid. Their production is monitored and controlled, so that the Control Center knows at all times how much energy is produced by the various sources and how much is consumed.
For this purpose, data for their production is constantly transferred from photovoltaics. These data are necessary so that operators have a real picture of the electrical system and can, whenever necessary, increase or decrease production. The data route is as follows: EAC receives it from the photovoltaic parks and transfers it to the Cyprus Transmission System Operator. On Friday, this chain presented a problem.
According to the Cyprus Transmission System Operator, due to the interruption of communication, the measurements received for the production of photovoltaics were incorrect. The EAC had spoken of the temporary loss of telecommunications connections between the Distribution Control Center and photovoltaic parks connected to the grid. This was followed by an abrupt cut-off of 165 megawatts of photovoltaic production, based on what the Assistant Director of the National Energy Control Center, Haris Zavallis, said in his public statements at the time.
As explained by the authorities, for the data of Cyprus, 165 MW is too large a quantity of electrical power to be lost in a very short time. Indicatively, an example was mentioned to understand the magnitude of the problem. The largest conventional unit currently in the Cypriot system is about 120 MW.
The scale should always be balanced
In order to understand why this loss almost immediately led to power outages, it is necessary to explain a basic principle of the operation of the electrical system. Electricity production and consumption must be constantly in balance.
One could imagine the electrical system as a scale. On one side is all the electricity produced at that moment by EAC units, photovoltaics and other sources of production. In the other is all the electricity that homes, businesses, hotels, factories and other consumers demand at the same time. The two sides must remain almost equal. If the scales start to tilt towards the side of electricity that consumers are asking for, then there is a problem.
On Friday, essentially on one side of this scale, 165 MW of production suddenly disappeared, while on the other hand consumers continued to demand electricity normally. If the decline continued uncontrollably, the problem could expand with an even greater loss of production and a chain reaction that could potentially result in a generalized blackout.
Cut-off as a protection measure and what we don't know yet
The reason for the power outage on Friday was precisely to prevent what was mentioned above from happening. When the system became aware of the sudden loss of production, it automatically activated its protections and began to cut off consumer load. In the example with the scale, weight was removed from the electricity side requested by consumers, as much as was needed to restore balance.
According to Mr. Zavallis, the process was carried out in six stages and a total of about 140 MW of consumption was cut, an amount that corresponded to about 14% of demand at that time.
So, the interruptions that the citizens saw were not the initial damage but a protection measure to avoid the worst. The system had lost about 165 MW on the production side and, to quickly restore balance, removed about 140 MW on the consumption side.
Here, another question now arises. Since there was a reserve available, as Mr. Zavallis had stated, why was their production not simply increased to cover the 165 MW that were lost? The answer given was that it was a matter of time. The sudden loss of such a large amount of electrical power affects the system in seconds. The protections must therefore react immediately so that there is no need for interruptions, which could not be done. That is why the immediate dumping of cargo was preceded in order to stabilize the system while the process of increasing production was in progress. When this was completed, the disconnected consumers reconnected.
Despite the relatively clear picture that has now been formed in terms of events, a key piece of the puzzle is still missing. This is because it has not yet been clarified exactly where the initial malfunction occurred, which resulted in incorrect data reaching the Control Center.
The first reports focused on telecommunications connections with photovoltaic parks, however, at the time of writing, the exact point of the failure had not been identified. In fact, according to the EAC spokesperson, inspections carried out by Cyta did not reveal a problem in its own telecommunications infrastructure. The investigation continues throughout the data transfer chain and involves the telecommunications provider, the company that installed the Control Center and other involved partners.
The connection with the occupied territories
The power outage observed on Saturday is not related to Friday's, according to the TSOC. The fault occurred in the production system in the occupied territories. In order to understand why a problem in the occupied territories affected consumers in the free areas, it needs to be taken into account that the two electrical systems are connected. The system of Cyprus is considered unified and reacts as one entity consisting of two parts. Part A is the free areas and part B is the occupied territories. The electrical connection works at two points in the context of the Confidence Building Measures.
When production was lost in the occupied territories on Saturday morning, the balance of the connected electricity system was affected. Initially, the disposal of consumer cargo in the occupied territories, i.e. part B', was activated. However, as the frequency was also affected in the free areas, automatic protections were also activated in Part A. About 20 MW of consumer load was cut off in the areas controlled by the Republic of Cyprus. And again, that is, the system did essentially the same thing it had done on Friday.
The connection to the occupied territories may, in some cases, result in power outages on one side, while the fault has occurred on the other. Nevertheless, it is considered crucial for the safety and stability of the electrical system, as it helps prevent a generalized blackout, offering greater room for reaction in the event of a serious disruption.
Haris Zavallis: Increased reserves in the future
Assistant Director of the National Energy Control Center of the TSOC"As already announced, the outage of Friday 21/08/2026 was caused — according to preliminary data from the EAC's Distribution System Operator (DSO) — by a temporary loss of communication between the Distribution Control Center and the photovoltaic parks. This resulted in the transmission of incorrect production data to the TSOC and the inability to control the commercial parks, which automatically triggered the dumping of consumer load. The electricity supply was fully restored within an hour, while the exact causes of the incident are still under investigation by the DSO.
The failure of Saturday 22/08/2026 (05:11 a.m.), which is not related to the previous incident, was caused by a failure in the network within the occupied areas, which led to a loss of production in this part of the system not controlled by the TSOC. As the electricity system of the whole of Cyprus is synchronized, it instantly affected the free areas as well. Protection systems were activated immediately and effectively, activating the automatic consumer load rejection scheme to balance production with demand and restore frequency.
This reaction is the technically appropriate practice in the event of similar unforeseen failures of conventional units or other parts of the electrical network, regardless of the point of occurrence.
In this regard, it is reported that the future operation of Energy Storage Systems (by the TSOC and individuals) is expected to provide increased reserves, mitigating the impact of similar incidents on consumers."
Christakis Hatzilaou: August 21 is a strict warning
Electrical engineer, electricity consultant"The serious incident of the failure on August 21 did not highlight any inherent problem of photovoltaic systems as a technology. Instead, it brought to light critical questions about how the rapidly increasing photovoltaic penetration is integrated, managed, and controlled in Cyprus' electricity system.
This is not a simple technical fault that has been repaired and can be put on file. This is an incident that directly affected thousands of consumers in various regions, raising issues of prevention, operational readiness, institutional responsibility and effective accountability.
The key question is not why communication was lost, but why a telecommunications failure turned into such a large loss of photovoltaic production and reached the end consumer.
The EAC's ex-post announcement on the promotion of a back-up telecommunications link is certainly positive. At the same time, however, it raises a self-evident question: why is such a measure taken after the interruption and not before it?
Was there already some backup coverage, and if so, why did it fail to work? If there was none, who had assessed the level of redundancy for the telecommunications control of such a high-power photovoltaic production as sufficient?
Backup coverage in critical telecommunications infrastructure is not a luxury or a technical improvement that is added after the first damage has occurred. It is a key component of the safe operation of the electrical system.
In addition, having a backup connection alone is not enough. A secure system must have predefined safe transition mechanisms. In the event of a loss of communications, PV parks must, where required by the technical requirements and the design of the system, be able to switch to a predetermined safe operating state, so that the loss of signal does not lead to a sudden and simultaneous loss of a significant part of the output.
The investigation must answer whether such a mechanism existed and why it did not limit the consequences.
The search for responsibilities cannot be limited to the physical point of occurrence of the fault or to the respective telecommunications provider. The entire chain of planning, permitting, control and supervision must be examined.
Who set the technical specifications for the connections and who was responsible for their installation and maintenance? Who certified that there was sufficient reserve and who assessed the risk of the parks losing communication with the Distribution Control Center? Was there a safe operation mechanism and, if so, was it activated as designed?
The Cyprus Transmission System Operator, the Distribution System Operator (EAC), photovoltaic park operators, telecommunications providers and the Cyprus Energy Regulatory Authority are involved in this chain. The responsibilities are different and must be defined on the basis of the applicable rules, technical requirements and contracts.
The possibility that the responsibility is shared does not mean that there is no responsibility. On the contrary, it requires it to be determined precisely who should have done what and who checked whether this was actually done.
The authorities must explain with data how close the system has reached the limits of safe operation and exactly what protection mechanisms have been activated.
At the same time, it is necessary to consider what would happen if the same incident occurred under different conditions: a spring or autumn day, with lower demand, higher photovoltaic penetration and a different mix of modules in operation.
In particular, it needs to be examined whether, under conditions of lower inertia (i.e. fewer conventional units in operation), a corresponding loss of production could cause a more severe frequency disturbance or even a generalized blackout. This cannot be answered with general assurances. It requires a technical study and publication of the conclusions.
The incident must be fully investigated and the conclusion made public. Not with general references to a "technical problem", but with specific answers.
What exactly happened and what safeguards were there? Which ones worked and which failed? Was there a backup telecommunications connection and/or a secure operation mechanism? If there was, why didn't it prevent or limit the loss of production? Who was responsible for each stage, from design and technical specifications to operation and maintenance? What concrete measures will be taken now and what are the clear deadlines for their completion?
If omissions are found, there must also be an attribution of responsibility. Otherwise, the message will be that even a serious disorder that reached the consumer can be closed with a formal apology and an announcement of new measures.
Cyprus cannot afford to continue like this. On August 21, the system avoided the worst. This should act as a stern warning and not as an alibi. The next time may not happen under the same favourable conditions – and then it will be too late for excuses."
