When using the zappi to manage renewable energy charging, a key feature ensures that it prioritises surplus energy from sources like solar panels or wind turbines to charge an electric vehicle (EV). However, when the surplus energy from these sources falls below a certain threshold, known as the Minimum Generation Level (MGL), zappi will automatically start to draw power from the grid to maintain the charging rate. This behaviour is particularly essential during instances where renewable generation is inconsistent, and it is designed to ensure that your EV charging continues without interruption. Here’s how it works and what you can expect.
Minimum Generation Level (MGL) and Surplus Energy
The MGL is the minimum amount of surplus energy, typically set by the user or installer, required for zappi to initiate or continue charging using renewable energy alone. By default, zappi’s MGL is set to 1.4kW, although this level can be adjusted according to your specific requirements or renewable setup.
When renewable energy generation (e.g., from solar panels) drops below the MGL, zappi recognises that there is insufficient surplus to charge the EV solely from renewables. At this point, zappi will temporarily switch to importing energy from the grid to continue charging.
Boost Mode and the Role of Stop/Start Delay
When zappi detects that surplus generation has dropped below the MGL threshold, it initiates a "Boost", allowing it to pull energy from the grid to make up the difference. This action is shown in the myenergi app with a “Boost” notification, indicating that grid power is being utilised for charging.
The switch to Boost mode is also regulated by a feature called the Stop/Start Delay, which sets the time zappi waits before making the decision to draw from the grid. The Stop/Start Delay prevents zappi from frequently switching between renewable-only charging and grid-import charging due to short-term fluctuations in generation.
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Default Delay: By default, the Stop/Start Delay is set to 30 seconds. This means that zappi will wait 30 seconds after detecting that generation has fallen below the MGL before switching to grid import.
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Adjustable Settings: If you find that generation is frequently fluctuating around the MGL, you may consider adjusting the Stop/Start Delay. Increasing the delay time can help minimise the frequency of transitions between modes, allowing zappi to rely on renewables as much as possible.
Practical Example
Suppose your zappi’s MGL is set to 1.4kW, and the current surplus from solar panels is 1.2kW. Because the surplus has dropped below the set MGL, zappi will for the duration specified in the Stop/Start Delay setting (e.g., 30 seconds) switch to Boost mode and zappi will begin to draw power from the grid to maintain minimum charging at the set rate, as shown in the myenergi app.
If the surplus generation rises back above the MGL threshold within the delay period, zappi will continue charging solely from renewables without switching to Boost mode. This ensures that renewable energy is prioritised while minimising unnecessary grid import.