If you have a Tesla EV and a Powerwall, Tesla’s Charge on Solar feature lets you charge from excess solar so you can drive on sunshine. Integrated directly into the Tesla app, it’s beautifully presented and easy to configure.
Depending on the operational mode your Powerwall is set to, it will choose whether to prioritise charging of your EV or Powerwall.
Charge HQ uses Tesla’s official third-party app service to enable solar EV charging. It’s compatible with most major solar inverter brands (and works without a Powerwall).
The initial configuration is a little more complex with many more settings to adjust. This affords more direct control over how excess solar is used.
Solar charging requires a paid subscription.
Charge on Solar is an easy to use set and forget solar charging option for Tesla EV & Powerwall owners.
Charge HQ provides more flexible controls for optimising the use of solar for EV charging (including those without a home battery).
Tesla Charge on Solar requires a:
Charge HQ requires a
Charge on Solar: With the Powerwall set to Self-Powered mode, excess solar is first used to charge the EV before charging the Powerwall. In Time-Base control mode Tesla autonomously adjusts prioritisation based on your energy tariff. This can result in either the EV or the Powerwall getting charged first, or both at the same time on any given day. It's a little black box, but Tesla is well positioned to optimise charging given their expertise and data about your home and EV energy usage patterns.
Charge HQ: users can set the charge priority to be EV or home battery. A priority charge limit allows you to define up to what level of charge the EV or home battery should maintain priority. e.g. Set home battery priority to 50%, after which EV gains priority until full, then reverting back to the home battery.
Charge on Solar: to manually initiate charging, requires the grid charge limit to be changed, and the scheduled charge limit disabled (if used).
Charge HQ: toggle the app to Charge Now and Auto mode.
Charge on Solar allows a single scheduled start time each day (or a departure time).
Charge HQ can be configured with multiple daily schedules with both start and end times. Blockout schedules can be added to prevent charging during peak periods.
Charge on Solar doesn’t currently provide reporting on how much EV charging occurs from solar. The Powerwall charge stats report on total energy use for EV charging.
Charge HQ’s charge stats include a breakdown of energy sources for all EV charging (from solar, grid or battery).
Charge on Solar updates charging power every 10 seconds to match excess solar power.
Charge HQ updates every 1+ minute depending on the data update frequency of the solar data source.
Whilst faster update frequency improves solar tracking performance, 95%+ efficiency is typically achieved with 1-minute updates.
Charge on Solar natively supports multiple Tesla EVs. The first vehicle plugged in is prioritised until the charge limit is reached.
Charge HQ doesn’t currently support multiple vehicles from a single account. Multiple accounts can be used with multiple vehicles with ad-hoc sharing of excess solar between accounts.
Charge on Solar is free of charge.
Charge HQ requires a paid subscription, starting from $7 AUD or $5 USD per month (less if paid annually).
Both are software-based products with over the air updates. Many new features and improvements will be added over time.
