16. Solar, EV charging and heat pumps in the design

Important before you start. Avenler is an aid: it handles the PV system, the EV charger and the heat pump as part of the electrical design, but it does not replace the inverter manufacturer's design software, the installation instructions of the equipment or the utility's approval. Always check the type of protection against the standard in force and the manufacturer's instructions.

This chapter shows how the PV inverter with its strings, the EV charger, the heat pump and the battery storage get into the design, and what the program calculates and checks with them in the distribution board and at the supply.

Symbols and drawing

The Energy group of the toolbar contains the solar panel, the PV inverter, the battery storage, the EV charger, the heat pump, the PV combiner box, the DC isolator, the bidirectional meter and the load manager.

These are fine without a circuit: the solar panel, the PV combiner box and the DC isolator (the DC side belongs to the inverter), the bidirectional meter, the load manager (a marker for the whole project) and the battery storage (by default it counts as DC-coupled storage behind a hybrid inverter).
For the PV inverter, the EV charger, the heat pump and the battery storage you can enter the Rated power (kW) and the Number of phases in the properties; sizing uses them, and the rated power takes precedence over the symbol's default.
Automatic assignment… gives every PV inverter its own circuit ("Inverter – <room>"); without a phase count it assumes a three-phase 5 kW inverter. The battery storage gets its own circuit if you enter its phase count: it then counts as AC-coupled storage and is a source just like the inverter.

PV strings and their check

In the PV inverter's properties you can enter the inverter's Max. DC input voltage (V) and the design Lowest temperature (°C), and below them up to 12 strings: for each the Number of modules, the Module (Wp), the module's Voc (V) and the Voc temperature coefficient (%/K). Under the list the total number of modules and the power (kWp) are shown.

The Check in the calculator link opens the string mode of the public Solar PV DC calculator filled in with the string's data.
The check reports an error (PV string voltage too high) if the string's open-circuit voltage at the lowest temperature exceeds the inverter's DC input limit; this can damage the inverter. The calculation is the same as the calculator's: Voc · (1 + β/100 · (T − 25)) · number of modules. Without a temperature it uses −20 °C; without the inverter limit or the string data the rule does not run.

The EV charger's circuit and RCD

Besides power and phase count, the charger's properties have a Built-in DC fault current detection (RDC-DD) checkbox. Unless you set its own demand factor, sizing counts the charger circuit at its full rated power.

The board's Suggest from circuits gives every charger circuit its own RCD and MCB (a 2- or 4-pole RCD according to the circuit's phase count), preferably type B or EV; a type A RCD is accepted only if RDC-DD is ticked for the charger.
EV charger RCD type (error): the charger circuit's RCD is not type B or EV and the charger has no RDC-DD ticked, or the circuit is not behind an RCD.
Dedicated RCD for the EV charger (warning): the charger circuit's RCD also protects another circuit.

Check the selected RCD type and the charger's residual current protection against the standard in force and the manufacturer's instructions; the program's finding is an aid, not a decision.

Heat pump and battery

The heat pump is a high-power load: if it shares a circuit with another device, the High-power load on a shared circuit rule reports it. For the inverter and heat pump circuits the board gives a note (RCD of inverter and heat pump): the RCD type depends on the manufacturer, see the installation instructions of the equipment.

The battery storage can be drawn in two ways:

DC-coupled (behind the hybrid inverter): no circuit needed, the storage appears in the drawing and in the takeoff.
AC-coupled: connected to its own circuit it counts as a source, like the PV inverter.

The Inverter on a shared circuit rule warns if the PV inverter or the AC-coupled storage shares a circuit with a load (socket, appliance): the source needs its own circuit.

Supply limit and load manager

On the project page (Projects), in the Supply section, use the Supply data button to enter the utility connection's phase count and maximum incoming current. Without them the two rules below do not run.

Source circuits (inverter, AC-coupled storage) are sized by their protection and cable, but they are not added to the simultaneous load of the consumers.
Supply limit exceeded (warning): the combined simultaneous current of the main boards is higher than the maximum incoming current. If there is an EV charger, the program suggests a load manager. If the drawing contains a load manager, the current without the chargers counts, and a note shows how much current is left for the chargers.
Feed-in limit exceeded (warning): the total power of the source circuits is higher than the connection capacity (phase count × phase voltage × maximum incoming current). The utility's feed-in limit may differ: check with the utility.
For these findings the fix opens the Supply data window. The rules can be switched on and off and their severity set on the Check rules page; the board rules are on the Distribution board rules page.

Single-line diagram

On the single-line diagram the circuit of the PV inverter (and of the AC-coupled storage) gets a source symbol at the output (a circle with the letter "G" and a wave sign), and the EV charger's circuit an EV tag. The marking comes from the sizing data, so without sizing the usual output symbol is shown.

What the program cannot do

In NEC projects these energy rules do not run (the US PV requirements are for a later round).
The program does not produce the grid-connection permit documents for small generators (utility forms, connection documentation); that is a later development.
It does not calculate the allocation of the inverter's MPPT inputs, shading or yield: use the inverter manufacturer's design software for that. The voltage drop of the DC cable is given by the cable mode of the Solar PV DC calculator.
No separate rule checks the utility's single-phase inverter limit.