Electrical validation
Before simulating, the engine checks that each string is compatible with the inverter under the extreme conditions of the location. These are the usual design checks for a PV array.
Checks
| # | Rule | Worst case |
|---|---|---|
| 1 | String Voc at cold temperature ≤ maximum DC voltage of the inverter | Cold: the voltage rises |
| 2 | String Vmp at hot temperature ≥ minimum MPPT voltage | Heat: the voltage drops |
| 3 | String Vmp at cold temperature ≤ maximum MPPT voltage | Cold |
| 4 | Current of the parallel strings (Imp) ≤ 1.10 × maximum MPPT current | – |
| 5 | Isc of the parallel strings ≤ 1.4 × maximum MPPT current | – |
| 6 | Number of inputs used ≤ inverter MPPTs | – |
| 7 | DC/AC ratio ≤ maximum (1.4 by default) | – |
Design temperatures
| Temperature | Default | Use |
|---|---|---|
| Cold design temperature | −10 °C | Maximum Voc and Vmp |
| Hot design temperature | 70 °C | Minimum Vmp |
Both can be configured in Advanced settings. You can ask for the cold temperature to be calculated automatically from the local climate (yearly minimum with a margin).
How the voltages are calculated
- Voc at temperature T: Voc · N_series · (1 + β_Voc · (T − 25 °C)), where β_Voc is the module's Voc temperature coefficient.
- Vmp at temperature T: Vmp · N_series · (1 + γ · (T − 25 °C)). The Vmp coefficient is not in datasheets, so it is approximated with the Pmax one (Vmp ≈ Pmax/Imp and the current barely changes with temperature); it is the most unfavourable criterion at hot temperature.
Messages
If something does not comply, the application shows the reason with the specific values, for example:
- «String Voc at −10 °C (812 V) > inverter Vmax (800 V)»
- «String Vmp at 70 °C (148 V) < Vmppt_min (160 V)»
- «Combined Imp (20.4 A) > MPPT Imax (16.0 A)»
Maximum and minimum number of modules
The engine also calculates:
- the maximum number of modules in series (from cold Voc and from cold Vmp against the MPPT maximum),
- the minimum (from hot Vmp),
- the maximum number of parallel strings per MPPT (from current),
- the maximum total number of modules from the DC/AC ratio.
This is pre-design
The validation uses datasheet data and design temperatures. It does not replace the final check with the manufacturer's specifications and the construction project.
Is something missing or wrong? Write to us at hola@radiaris.com. Last reviewed: 26 October 2026.