Do you see a curve in your solar system app that rises in the morning, stays almost flat at midday, and drops later? This pattern alone does not prove there is a fault. It may be related to the inverter’s power limit, an export limitation setting, or a different operating condition.
Before asking for a larger inverter or a settings change, you need to clarify which measurement the app is showing and why it is being limited. The guide below will help you gather useful information for your installer, without touching the equipment.
First, check exactly what you’re looking at
The solar panels’ generation power and the power fed into the grid are not necessarily the same. Some of the energy may be used on the property or, depending on the system, charge the battery. A flat line for grid feed-in does not necessarily mean total generation is flat.
Check the chart’s name and unit. kW describes power at a given moment, while kWh describes energy over a period. Also check whether the readings are updating and what time interval the view uses. If a reading has remained at the same time, first check the connection and data.
For a broader overview of monitoring, see our guide to solar PV monitoring. Here, we focus specifically on the different causes of a limited power peak.
Case one: the inverter’s conversion limit
The inverter converts the panels’ direct current into alternating current. When the panels’ available power exceeds what the inverter can use under the specific conditions, it may limit its operation. This phenomenon is often called clipping.
The technical explanation from Sandia National Laboratories explains that the limit may be achieved by changing the panels’ electrical operating point. This does not mean that unused energy is stored somewhere for later.
The panels’ rated power in kWp and the inverter’s output power do not have to be numerically identical in every properly designed installation. However, there are specific electrical compatibility limits. Ask the designer to explain the relationship between the two values and the estimated annual clipping losses.
A flat peak close to a particular value is a sign worth investigating, not a sufficient diagnosis. The installer needs to compare it with the model, active settings, and recorded data.
Case two: grid feed-in limitation
In a system with zero or limited feed-in, generation may be adjusted to comply with the permitted limit. Fronius describes dynamic power reduction as a function that takes the property’s consumption into account before limiting the inverter.
That is why it is important to review generation, consumption, feed-in, and battery status at the same time, if these are recorded. If feed-in is being limited, it does not automatically follow that you need a more powerful inverter. First, you need to confirm which control is being activated and whether it is operating as intended for the installation.
The options for managing surplus depend on the equipment and configuration. Do not change feed-in limits or protective settings yourself, and do not run appliances unnecessarily just to increase the generation reading.
Case three: temperature-related power reduction
Sometimes the inverter reduces power to protect its internal components from overheating. This is called thermal power reduction or temperature derating, and is different from clipping caused by the conversion limit.
SMA explains the role of heat dissipation, ventilation, shading, and the recommended clearances. Actual limits and behavior vary by model. There is no single temperature threshold that you can apply to all inverters.
From a safely accessible position, you can check whether the area around the device has become cluttered or whether its exposure to sunlight has changed. Do not open the enclosure or attempt improvised cooling. For basic space requirements, see where to install the inverter.
What to send your installer
- The date and times when you noticed the limitation.
- A screenshot of the full daily curve, with units and labels visible.
- The value at which the power appears to level off.
- Consumption, feed-in, and charging curves, if available.
- Any event codes and the time of the last update.
- Whether the issue was present from the beginning or appeared recently.
Ask for an explanation of the cause, duration, and impact on energy over the whole year. A momentary power peak is not enough to decide whether to upgrade. For illustration only, a difference of 1 kW lasting half an hour corresponds to 0,5 kWh; estimating annual losses requires much more data, not multiplying one day by 365.
When a technical inspection is needed
If the limitation appeared suddenly, is accompanied by repeated warnings, or remains unexplained, request an assessment. The pattern in the chart does not rule out other causes. Avoid repeated restarts without guidance and any work on cables or panels.
At Solar Home, we design the system based on your space, equipment, and needs. Contact us to discuss the details of your installation and what investigation or study is needed before you decide on any changes.
