Solar Electricity and Battery Backup

The battery is the heart of a battery backup system, regardless of whether it is charged with solar panels, wind generators, utility power, or a generator. Battery backup systems have been around for a long time, but the Tesla Powerwall battery has sparked a huge amount of consumer interest. I have already written about what the Tesla Powerwall is and isn’t. Below we go into how any battery backup system works, the other required components, and some of the charging options with utility and solar power.

Mouse over the image hotspots to learn more about each component. (Note: on mobile devices, the hotspot text may appear below the images).

The Tesla Powerwall Battery

Inverter/Chargers – Power Conversion

Critical Loads

Solar Panels

Solar Charging Equipment

There are multiple ways that solar energy can get transferred to your Tesla Powerwall battery. Each has it’s advantages and disadvantages.

  1. The traditional way is to use a charge controller to maximize and regulate the solar energy delivered to batteries. Because batteries have maximum charging rates, too much solar power could damage the battery. Charge controllers work in tandem with inverter/chargers to deliver excess electricity to the utility grid. This is the most efficient way to charge batteries from solar panels, but the least efficient way to deliver excess energy to the electric grid.
  2. Grid-interconnected string inverters take the output of several solar panels and deliver power to your home and excess power to the electric grid. Through a process called AC coupling, the string inverter can also send electricity to your battery through the battery’s inverter/charger. This is an efficient way to deliver excess energy to the grid, but less efficient at charging batteries with solar energy.
  3. Microinverters take the output of a single solar panel, maximizing each panel’s output individually and monitoring performance. Like string inverters, microinverters can also be AC coupled to a battery’s inverter/charger. This is the most efficient way to deliver excess energy to the grid, but less efficient at charging batteries with solar energy.

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