In basic terms, sunlight is captured by your solar panels then converted into energy that you can use for your home. As that energy flows into your house, it is used by your appliances and any excess energy is stored in the Powerwall. Once the Powerwall is fully charged, additional electricity your system generates on top of that is sent back to the grid. When the sun goes down and your solar panels are not producing energy, your Powerwall will provide electricity to power your home.