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Solar, Home Battery & Backup Power

Views: 807     Author: China JB BATTERY      Publish Time: 03/30/2022      Origin:

With net metering your solar system will shut down if the utility power goes out, this is because they don’t want your solar system sending electricity to the grid if there is a potential issue with the grid creating a dangerous situation. If you want to use your Tesla solar system during a power outage, you need to have a home battery. This concept is referred to as “islanding” meaning your home is an island from the grid. Your solar will charge your home battery with any excess power during the day and you can use it at night or you can set it to store electricity for backup purposes.

A single Battery Energy Storage System can store 12.2 kWh (see part 1 for more background on kWh) and output a maximum of 21 amps for output of 5 kW on a continuous basis and 7 kW of peak power. Peak power is for certain appliances that may use more power to start up and then drop down to a lower usage level once they are running or just general flutuations in your power usage, but know that it cannot sustain that output long term.

During install of a backup power system you may need to identify your critical loads, the circuits in your home that will need backup power. What we have done is setup a critical load panel as a subpanel in our home, so the entire panel can be setup for the Battery Energy Storage System or setup with a Generator Transfer Switch which will allow us to connect a portable gas generator to a plug on the side of the house to provide power to that panel. Make sure you get the proper permits and install with a generator transfer switch and solar as they may not be compatible, if your solar thinks your grid power is on and starts sending power downstream you could damange equipment or create a hazard.

Here are some suggestions for a critical load panel:
/Medical Devices
/Broadband Modem/Router & Security System
/Garage/Gate Openers
/Water Heater (Tankless gas won’t work without power)
/Select Kitchen Outlets
/Select Lighting
/Select Outlets in bedrooms
/If you have a large enough generator you can also have your AC unit on backup power, this /may also be needed if you have people in your home who are medically temperature sensitive.
/Depending on the size of your generator it may be necessary to ration your power, for my purposes I may only be able to turn on one appliance at a time in addition to the refrigerator.

For some of these items I also recommend using an Uninterruptible Power Supply (UPS) like this to help power these devices for short power outages. I have my modem and router connected to one and it can keep it on for about 30-45 minutes for quick power outages.

Battery Energy Storage System

Battery Energy Storage System is a cool concept for home battery, here are some ways Powerwall can be used:
/Solar will charge your Powerwall during the day and you can use it to power your home at night or augment during peak power usage, especially useful if you don’t have access to net metering.
/To serve as a battery backup for your home, useful if you have medical devices in your home or cannot have the other power backup options I mentioned.
/I have read about people charging their home batteries at night on Time of Use (TOU) power plans and using them to power their home during peak hours. TOU means that, for example, using power at midnight is cheaper than using power at 6pm. It would take over a decade for this to make financial sense though. This setup is not paired with a solar system.
/If you just think this is really cool technology and want to have it and can afford it.

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