Solar Tracking Settings

Solar Tracking Settings

Solar tracking enables your EV to charge from your solar automatically. It can be configured to work in different ways. The availability of some features depend on the equipment you have installed.

NOTE: Solar tracking can be combined with scheduled charging and the price and renewables limits, and will be overridden by those settings. For example, if an Always Charge period is scheduled overnight, charging will occur at that time even though there is no solar and solar tracking is enabled.

Requirements

Solar tracking requires a supported solar inverter or battery, see Inverters.

Solar tracking works best for sites with a consumption meter but can function without one.

If your solar inverter includes a consumption meter then Charge HQ can track your excess solar. Excess solar is the part of solar generation that you are not consuming in your home and would otherwise export to the grid. If your inverter does not include a consumption meter then Charge HQ can only track the solar generation, although you can reserve a fixed amount of solar for household use (see the Solar Tracking Margin setting).

Advice

If you want to charge only from solar and avoid grid imports, select Solar Only mode. Be aware that charging will stop whenever the available solar is too low, and may not restart for 15 minutes (see Avoiding Contactor Wear below). Charging will not occur outside of solar hours.

If you want to charge mostly from solar and don't want to start and stop all the time, and don't mind some grid imports, select Solar + Grid. This may also be a better choice for those with smaller solar systems whose output may drop below the minimum level more often.

If you want to charge from solar during the day, then top-up overnight to the minimum charge level you need eg 50%, you can combine solar tracking with Scheduled Charging to achieve this.

Settings

Solar Tracking Mode

Solar Only: charging power will track available solar. If available solar falls below the minimum charging rate then charging will be stopped. The car will not charge from the grid (or battery if present).

Solar + Grid: charging power will track available solar. If available solar falls below the minimum charging rate then charging will continue at the minimum rate, with the shortfall being imported from the grid (or battery if present). Charging will stop outside of solar hours.

Note that Min Solar Generation and Min Excess Solar limits can cause charging to stop in either mode, if they are set.

Minimum Charging Rate

The minimum charging rate depends on your equipment:

  • Tesla (single phase): 5 amps = ~1.2 kW
  • Tesla (three phase): 2 amps = ~1.44 kW
  • Smart charger (single phase): usually 6 amps = ~1.44 kW although some models may be higher
  • Smart charger (three phase): 6 amps = ~4.3 kW. We are looking into reducing this.

Charge Priority

This setting determines whether excess solar is sent to the EV or the household battery first. It is available for those who have a household battery.

Battery (default): the household battery will be charged before the EV. This mode has some caveats:

  • When a Tesla is plugged in it will start charging immediately, regardless of any settings. It may take up to a minute for Charge HQ to detect that the vehicle is charging and take action.
  • Charge HQ will observe what the battery is trying to do, and will ramp down the EV charge rate until the battery won't take any more power. This may take several minutes to occur, during which the EV will take some of the power.
  • In Solar + Grid mode, the EV will constantly charge at the minimum rate even if the home battery is not fully charged, because the EV will not stop charging in this mode. This means the EV may also charge from the battery, although only at the minimum charge rate.

EV: the EV will be charged before the battery.

Advanced Settings

Advanced settings provide customisations for less common solar, battery and charging configurations. Most users do not need to change these settings.

Solar Tracking Reference

Excess Solar: only excess solar is used for charging. Excess solar = generation - household consumption. In other words, solar power is used by the household (and possibly battery) first, and any left over will be used for EV charging. This is the default setting when a consumption meter is present.

Solar Generation: all solar generation will be used for EV charging. Household consumption will be drawn from the grid. This is the implied setting when there is no consumption meter.

NOTE: this setting is only visible if a consumption meter is present. If no consumption meter is present then Charge HQ can only see the solar generation. In this case the Solar Tracking Margin setting may be useful.

Min Solar Generation

If set, charging will stop when solar generation is below this value.

This value defaults to 0.2 kW, which means charging will stop outside of solar hours in both Solar Only and Solar + Grid modes.

NOTE: this value is simply a threshold that causes charging to start or stop - it does not impact the charging power calculation.

Min Excess Solar

If set, charging will stop when excess solar is below this value.

This setting is generally only useful for those whose charging power can't be controlled, eg older Teslas. For most people this setting isn't useful because Solar Only mode will already stop when the excess solar is too low, and Solar + Grid mode will also stop outside of solar hours.

This setting is only available for those with a consumption meter.

NOTE: this value is simply a threshold that causes charging to start or stop - it does not impact the charging power calculation.

Solar Tracking Margin

This setting allows adjusting the charging power above or below the available solar, such that:

charging power = available solar - margin

This is intended to be used by those without a consumption meter to reserve some of the solar generation for household use. For example, if your home typically uses around 1 kW of power, you might set this value to 1 kW. Admittedly it is difficult to know how much power your home uses without a consumption meter :)

Negative values may be used. A negative value will cause charging power to exceed the available solar, leading to imports from the grid.

Three Phase Charger

This setting should be enabled if you usually use three phase charging with Charge HQ. This setting will impact the solar tracking calculations, especially before charging starts or if you have a smart charger.

Charge HQ will automatically enable this setting if it detects three phase charging. This is not always possible with all charging setups.

If you use both three phase and single phase charging at home then this setting should be enabled.

Negative Consumption

This setting should be enabled if your solar monitoring frequently reports negative consumption. This is usually caused by a second unmonitored solar inverter. This setting allows solar tracking to work properly when negative consumption is reported.

Charge HQ will automatically enable this setting if it detects negative consumption for at least 15 minutes. See Multiple Inverters for more details.

Consumption Excludes Charging

This setting must be enabled if your EV charging is not included in your consumption monitoring. In other words, if your solar monitoring can't "see" the EV charging. Only a small number of homes are setup this way.

Charge HQ does not automatically enable this setting - it must be enabled manually.

Avoiding Contactor Wear

Each time charging is started or stopped some switches (called contactors) in the vehicle and in the charger open or close. This is generally audible as a click or clunk sound. Contactors typically have a design life of a certain number of open/close cycles. We are aware of isolated reports of the contactors in chargers wearing out prematurely due to frequent stop/start cycles.

To help avoid this Charge HQ has delays to prevent frequent stop/start cycles when in solar tracking mode. In particular:

  • When the amount of solar drops below the minimum charge rate Charge HQ will wait 6 minutes before stopping the charge. This delay also applies to the Min Solar Generation and Min Excess Solar limit. This is intended to prevent charging from stopping every time a cloud goes over.
  • When charging has stopped due to low solar, Charge HQ will wait 15 minutes before restarting. You may force Charge HQ to restart earlier using a button on the home screen.

We are not aware of any reports of contactors in the vehicle wearing out prematurely, but we prefer to err on the conservative side with this potential issue.

If you don't want charging to stop and start during the day at all then you can use Solar + Grid mode.