How Does the Tesla Powerwall Work?
More homeowners are installing backup power supplies and grid-tied or fully independent solar systems, especially in California. It can draw power from either the conventional electric grid or solar panels and can store up to 14-kilowatt-hours (kWh) of electricity, which is enough to accommodate about half of the average home’s daily power needs.
Since power outages have become commonplace in Vacaville, CA, and across the state, interest in the Tesla Powerwall has been surging. There is still a lot of confusion surrounding this energy storage solution, though. Homeowners can read on to find out how the Powerwall works to start getting answers to their questions before they decide whether it is the right solution for their households.
Energy Storage With or Without Solar Power
The Powerwall can be installed as part of a grid-tied solar system or as a standalone unit that draws power from the conventional electrical grid. It is a fully-enclosed system that consists of a battery bank, an inverter, a connection point, and an advanced liquid cooling system, which cuts back on the need for additional accessories and simplifies the power storage system.
How It Works with Solar
When the Powerwall is connected to a grid-tied solar system, it is charged by the sun. During the day, the power generated by a full-sized solar array exceeds the needs of the household. The Powerwall stores the excess power for use at night when the sun is no longer producing light. The next day, when the sun comes back out, the Powerwall begins to charge again to create electricity for the home out of clean, renewable solar energy.
Most residential solar systems don’t rely exclusively on the sun, as in an off-grid system. Instead, they derive some or most of their power from the home’s solar array but pull any extra power needed from the grid. These systems are known as grid-tied systems. With a grid-tied system, the Powerwall still stores as much excess energy as possible, but any additional energy produced on sunny days when the house is not using much power can be sold back to the electrical company, offering the best of both worlds.
How It Works Without Solar
Not all homeowners who install the Powerwall use solar energy. Many Vacaville residents are just looking to increase their energy independence as a means of better weathering the area’s frequent power outages. Thankfully, the Powerwall can still help.
The Powerwall charges during the day when electricity costs in areas that offer time-of-use electricity rate plans tend to be lower. It stores that power until the rates go up, usually at night, at which point the home switches over to battery power. This helps homeowners save money on their monthly electrical bills while simultaneously taking advantage of an emergency backup system that will detect grid outages and automatically switch the power over to the Powerwall as the home’s main power source.
How Power Is Stored and Discharged
The Powerwall features a series of lithium-ion batteries, known for their longevity and ability to safely store and discharge large amounts of power. Each battery has multiple cells, and each cell has three components: a positive electrode, a negative electrode, and an electrolyte made from a lithium-cobalt oxide or a lithium iron phosphate compound. Lithium-ion batteries also have built-in electronic controllers that regulate charging and discharging.
When the battery is charging, lithium ions flow from positive electrodes to negative electrodes through the electrolyte. When they are full, no more ions can flow through the electrolyte. When the battery is discharged, the ions flow back from the negative to the positive electrode, generating power until they have all moved back and the battery is fully discharged.
How Power Is Converted
Like all batteries, lithium-ion batteries store DC, or direct-current, power. That power must be converted into AC, or alternating current, power. The primary difference between DC and AC power is that while the electric current only flows in one direction with DC power, it changes direction periodically with AC power.
The switch from DC to AC power occurs in the inverter, which is built into the Powerwall. The inverter in the Powerwall is powerful enough to handle the large amounts of voltage required to power a residential home. During a power outage, the electricity will flow to the home for as long as the battery has sufficient charge.
How Long It Lasts
The length of time a Powerwall can keep a home running without grid power depends on a variety of factors. These include average household electricity use, whether the backup power system is set to run the entire house or just essential appliances, how many units are installed, and whether homeowners have their backup power systems connected to solar arrays for daily recharging.
By most estimates, the Powerwall could power the average American home, which uses an estimated 30 kWh of energy per day, for up to eight hours. At that point, the system would need to be recharged either by a solar array or following the restoration of grid power to the home. Families that have higher power demands or want to be able to run their entire houses for longer than eight hours in the event of an outage can install more than one Powerwall unit for extra energy storage capacity.
The best way to figure out how much power the home would need to run is to contact a solar company that can perform an energy audit. Energy audits identify what devices and appliances in the household require power and which of them are considered essential during a power outage. The same solar contractor can also make recommendations about appropriate solar panel arrays for homeowners who want full energy independence.
The Powerwall is currently the best option for homeowners in Vacaville, CA, and elsewhere that want to install backup power systems to prevent problems during outages. It’s also one of the best options for families that want to make the switch to grid-tied solar systems. No matter what families need, Ambrose Solar can help. Get in touch today for a quote.