As many of us know, Tesla in 2016 pushed the solar world and home energy storage systems into the mainstream market. The announcement of roof glass for home installation and the Powerwall in 2015, made energy generation and storage more appealing and aesthetic for the common consumer.
Since then, Tesla has been upgrading their products with the last available models (as of this blog publishing) – Solar roof tiles V3 and the Powerwall 2.
The Powerwall 2 is an AC battery with a capacity of 13.5 kWh. It features a 5kW continuous and a 7kW peak power output, and a unique liquid cooling system that differentiates it from every other commercial home battery of the market.
The Powerwall (PW) utilizes lithium nickel manganese cobalt oxide (NMC) batteries, which has the advantage of a higher energy density per cell. The pack consists of the 2170 lithium cells, manufactured at the Gigafactory in Nevada, such as the ones used on the Tesla’s cars. And the PW2 features a rectangular, easy to handle pack that can be wall or ground-mounted.
AC vs DC Batteries
In the market, an AC battery consists of a battery pack that has an integrated hybrid inverter. While the DC batteries are battery packs that need an additional inverter to feed your AC system at home.
This hybrid inverter is a bidirectional charger/inverter capable of operating in on-grid configurations. This configuration reduces your power consumption throughout the day, and it’s even able to sell your generated excess energy to the grid.
Tesla’s Powerwall has the advantage that it can operate with ‘almost’ any additional solar inverter. So it can be compatible with an existing solar installation at your home.
Common competitors of the Powerwall for the home battery market are – Hybrid Sonnen Batteries and LG chem RESU.
Sonnen is a well-known Germany battery manufacturer having its production base in Germany, California, and South Africa.
Their hybrid Sonnen Batteries 8.1, are scalable with 2kWh steps, from 6kWh up the 16 kWh presentation, which surpasses the nominal capacity of the PW. Its inverter can deliver up to 5.5 kW continuous power output, but only up to 6.4kW peak compared with the PW inverter. These batteries use the more common Lithium Ferro Phosphate (LFP) cells, which are considered to be safer than the NMC.
LG Chem is the Korean division in charge of chemical products, batteries included, of the giant LG. It has production facilities in South Korea, China, and the US.
Their household product called RESU batteries use L&S cells and have one of the lowest prices per watt in the market. The RESU 13 with a nominal capacity of 13.1 kWh, compete with the PW and the Hydrid Sonnen battery directly.
LG chem RESU utilizes Laminated Lithium Polymer cells, which can be laminated and stacked (L&S), to make one of the most lightweight and compact batteries.
The following table compares some important features of each battery.
As for the solar generation, Tesla offers its solar roof tiles, which have been upgraded to the V3 model in October 2019.
The solar tiles are like mini solar panels, covered by tempered glass. These panels can be mixed with existing tiles to give the appearance of a normal roof unlike solar panels from other companies that ruin the overall aesthetics with big bulky panels.
In order to be eligible for the Tesla solar tiles installation, you must have a roof pitch from 2:12 to 20:12, meaning your rooftop must be at an inclination from 14° to 60° from ground level.
Tesla’s solar panels are made in collaboration with Panasonic offering an industry-leading efficiency of up to 19.4%.
As expected, Tesla’s solar panels are based on overall aesthetics. The black anodized aluminium frame together with the skirting of the mounting makes it look like a real premium product.
The typical AC on-grid system configuration for the Powerwall is as follows.
The backup gateway controls the operation of the system, allowing remote monitoring, and controls interconnection with the electrical grid, automatically managing the transition to and from a backup operation. The Backup gateway averages a price of up to 1700 US$.
In this configuration, the house can have ‘almost’ any existing photovoltaic scheme and interconnect with the Powerwall.
Sonnen hybrid batteries follow the same configuration of the Tesla’s Powerwall, featuring their Backup Box, which limits the continuous output of the system up to 2.5 kW, and serves as the backup gateway of the Sonnen batteries. This additional component can add up to 1500 US$ to the total price.
As an alternative, LG chem RESU battery needs an external inverter as the one offered from SolarEdge, the StorEdge. This DC-coupled solution functions as a hybrid inverter, automatically storing unused solar power and charging/discharging the battery for lowering power consumption or during a power outage. The StorEdge is listed at 4495 US$.
Tesla offers high quality and competitive household products.
Their battery, the Powerwall, shines throughout the market as one of the best energy storage solutions, comparable or even better to top competitors.
As for the Solar tiles, Tesla’s product is a luxury option which makes more sense in case you’re looking for a roof replacement, and you’re considering the overall aesthetics of a solar generation system to match roof tiles. The average 5kW Tesla’s solar panels system can repay itself in about 9 to 13 years, depending on your location. If you add tax credits (depending on state and federal taxes), the payoff can be in as short as 5 – 7 years.