Page Results > Energy balances
After the simulation of a solar power system, on the results page the energy balance is shown in a tree view.
Select either the main level or one of the subsystems to see the individual energy balance:
Energy balance : Energy balance of the entire system
Irradiance : the radiation system,
Configuration : the system that shows the solar generator and MPP tracker and
Inverter : Inverter with AC plug-in connection. Depending on the design, the solar system will include one or more subsystems.
If there is more than one Meteo system (i.e. module surfaces with different configurations), the individual balances will be calculated according to the corresponding service of the partial solar generator in relation to the overall surface of the system.
If there is more than one partial generator or inverter systems the individual balances are added together.
The arrangement of the energy balance in the tree view depends of the topology of the solar system.
A 1-1-1 topology is composed of the following:
1 Meteo system: all modules have the same configuration and the same radiation balance applies to all of them.
1 Partial generator system: the modules have the same design and are connected to one MPP tracker.
1 Inverter system: only one inverter is used.
The system has a 1-2-1 topology, if the modules are connected to two MPP trackers that are in turn hooked in to the same inverter.
A system with two module surfaces with different configurations and connected to their own inverters has a 2-2-2 topology.
Each balance zone has a start and end value that is shown gray and bold. The partial generator shows two additional intermediary values that serve to provide orientation.
The amount of the loss- (red) or gain (green) is listed between the starting and end values. The last column shows the percent deviation in relation to the total sum of the previous values.
Meteo
Global radiation - horizontal
The total global irradiance on the horizontal plain, an initial value taken from the climate data
Deviation from standard spectrum
Solar or photovoltaic measurements always assume a STC standard spectrum of AM1.5. Since the actual spectrum of irradiance of the solar module can be less favorable, one percent is automatically subtracted from the radiation performance.
Ground Reflection (Albedo)
The reflection of the solar radiation by the ground leads to gains in the energy balance which can vary depending on the set albedo and the orientation and inclination of the modules.
Orientation angle and inclination of the module plain
Depending on the orientation of the module in space, the global irradiance on this tilted plain can be higher or lower than the horizontal value.
Shading
The amount of radiation that cannot reach the solar module due to previous shadows.
Module-independent shading (only in 3D)
The percentage of solar radiation lost equally for all modules due to shading. This can be the case, for example, with a set shading by the horizon or with identically placed nearby shading objects.
Reflections on the module surface
Part of the radiation that reaches the solar modules is reflected on the surface of the module before it can generate electricity.
Global irradiance on the module
The amount of the solar radiation that actually reaches the cell material of the solar modules.
Conversion from Meteo to the partial generator
The global irradiance on the modules in kWh/m² multiplied by the total surface of the solar generator yields the solar global irradiance in kWh.
Sub-generator
Solar global irradiance
The global irradiance converted to kWh on the solar modules.
STC Conversion
The amount that is lost in the solar energy conversion by STC. Equals 100% - eta_STC
Solar nominal energy
The energy that the module would release under STC conditions
Module-specific partial shading (only in 3D)
All the losses caused by the individual shading of the PV modules are summarised here. The electrical losses are considered, and these can be considerably higher than simply the losses of solar radiation, depending on the shading situation and the module structure.
Low-light performance
The efficiency of a PV module changes when sunlight varies. This can lead to both energy losses and gains.
Temperature
The efficiency of a PV module also depends on its temperature. Generally, the higher the module temperature the higher the resulting losses. In cold regions this can also result in gains.
Diodes
As with every electrical component, energy is lost at the diodes that connect to the modules. A loss of 0.5% can be assumed.
Mismatch (manufacturer's data)
Since PV modules cannot generally precisely match the nominal energy value, a mismatch results in the connection that can be estimated at 2%.
Mismatch (configuration/shading)
Further mismatching can occur due to asymmetrical connections, connections between module planes with different configurations or uneven shading of the modules.
String cable
Ohmic losses in the string cables
DC Main Cable
Ohmic losses in the DC main cable
PV energy (DC) without inverter limitation
The DC solar energy that would be available with optimally configured MPP trackers and inverters.
Limitation due to MPP voltage range
MPP trackers have an input voltage range, within which they can search for the MPP. If the true MPP of the PV field lies outside of this range then a non-optimal MPP is found, which will lead to a loss of energy. In general, however, the resulting current in the PV field is lower, which is reflected in the calculations here.
Limitation due to max. DC current
Similar to limitation due to the MPP voltage range, in certain circumstances a limitation above the maximum permissible DC current is possible. Here too the minor ohmic losses are included in the calculations.
Limitation due to max. DC output
Similar to limitation of maximum DC current
Limitation due to max. AC output/cos φ
If the maximum permissible AC output of the inverter is exceeded or limited due to Feed-in limitation, it must be regulated here.
The same is true if due to the presence of a specific cos φ, the maximum feed-in capacity must be decreased. For systems with appliances or batteries the feed-in limitation takes place at the connection to AC mains and therefore does not appear in the enery balance.
PV energy (DC)
The DC PV energy produced
Inverters
Energy available at the inverter input
The energy available at the inverter input. Identical with PV energy (DC)
Deviation from input and nominal voltage
If the DC input voltage deviates from nominal voltage of the inverter, then the conversion efficiency will be somewhat reduced.
DC/AC conversion
The energy that is lost due to the conversion of DC voltage into AC voltage.
Energy consumption (standby, night)
The energy that the inverter takes from the grid when it is not feeding energy in.
AC cable
Ohmic losses of the AC cable
PV energy (AC)
The solar AC energy that can be used or fed to the grid