LG Chem RESU vs. Powerwall Battery Backup Comparison
Home solar batteries have seen major technological improvements since their inception. These improvements, when combined with the various solar incentives on the federal, local, and statewide levels, have made battery backup an option that the average solar-powered homeowner can afford.
However, the myriad whole house battery systems for solar panels available on the market today have made choosing the one that fits you best more difficult. Thus, we’ve created this battery backup product comparison to clarify the key differences between LG’s high-performing Chem RESU solar battery and Tesla’s highly esteemed Powerwall 2. At Go Solar Group, we offer three different pre-selected battery backup levels. The Tesla Powerwall 2 is our “Level 3” battery backup option.
Company Overview: Tesla or LG
Tesla and LG are the 2 most reputable companies in whole house solar battery backup.
While Tesla’s known mostly for its electric cars, they began offering battery backup for solar-powered homes and businesses in 2015. Also an industry trendsetter in the electric vehicles market, the brand has pioneered major industrial changes that could fundamentally alter the fabric of modern society.
LG Chem, a long-standing Korean tech company, has an illustrious history of quality technology made and sold at low costs. LG has produced lithium-ion solar batteries since 1999.
Battery Composition: AC and DC
The Powerwall 2 and LG Chem RESU have different battery compositions: The LG Chem RESU is a direct current (DC) battery, while the Powerwall 2 is an alternating current (AC) battery.
DC batteries store solar energy directly from the solar panels, which increases their efficiency. This is the case because they don’t need to convert back and forth between different electrical current types before solar storage is placed in the battery. The LG Chem RESU has 94.5 percent roundtrip efficiency, meaning it uses 9.45 kWh’s (kilowatt-hours) for every 10 kWhs of stored solar energy.
AC batteries typically have slightly lower efficiency because they convert DC from the solar panels to AC. Then the battery inverter converts the AC to DC when charging, and the DC to AC when discharging. The Tesla Powerwall 2 has a 90 percent roundtrip efficiency.
Comparing LG Chem RESU & Powerwall 2 Battery Specs
When adding battery backup, it’s important to consider capacity and max power rating, depth of discharge, max number of combined batteries, and battery settings.
Capacity and Max Power Rating
Customers must choose a solar battery that balances both the capacity and max power ratings; otherwise, it won’t last as long. Batteries with higher capacity will last longer but power fewer large energy-sucking devices at once. On the other hand, batteries with a higher max power rating can power more devices at once but won’t last long.
Powerwall 2 Capacity and Max Power Rating
The Powerwall 2 has a 13.5 kWh capacity and a 5.0 kW (kilowatt) max power rating. This combination of high capacity and high max power allows this home battery to keep the entire home running for several hours via excess solar energy gathered via the building’s array. If the homeowner has several Powerwall 2’s and meets the minimum energy usage requirements to make home solar worth it, this storage option will easily last several days.
LG Chem RESU Capacity and Max Power Rating
The LG Chem RESU has a capacity between 3.3 and 13 kWh, depending on the size chosen. It also has the same 5.0 kW max power rating as the Powerwall 2. These ratings mean the LG Chem RESU home battery can offer customers a range of energy storage options and almost as much total storage as the Powerwall.
While the LG Chem RESU has almost the same capacity and max power rating specs as the Tesla Powerwall, it has different restrictions. Unlike the Powerwall 2, LG Chem decided to limit their home battery load capacity to only include a few critical circuits.
Limiting the loads the battery supports helps increase the duration of the battery during an outage. However, it also means this home battery doesn’t cover all the home’s daily energy needs. Limiting loads doesn’t pose a problem if the battery only offsets some utility usage and provides emergency power.
However, to those planning on using battery backup for all their home’s energy needs, this solar battery may not be sufficient. The 2020 edition of the RESU, RESU16H Prime, fixes this problem by increasing the battery capacity to 16 kWh and the max power rating to 7 kW.
Depth of Discharge
Depth of discharge shows how much of a fully charged solar battery you can use. While ideally, every battery would discharge 100 percent of its stored energy, this often isn’t the case. Additionally, as batteries age, they release even less of their stored electricity capacity.
Tesla Powerwall Depth of Discharge
The Tesla Powerwall has a depth of discharge of 100 percent. It also has a warranty to discharge at least 70 percent of its capacity over 10 years.
LG Chem RESU Depth of Discharge
The LG Chem RESU has a depth of discharge of 95 percent. Its warranty guarantees at least 60 percent over 10 years. However, the 10-year warranty is contingent on the system providing less than 22.4 MWh. Homeowners have to use an average of 6.14 kWh or less per day to keep the 10-year warranty.
Solar Battery Comparison Overview
The LG Chem RESU works best for those who don’t use very much energy and need a system that can meet smaller solar energy storage demands. If you have an average-sized home, however, the Tesla Powerwall 2 will perform better on nearly all counts.
If you’re interested in solar for your home and would like to add a Powerwall 2, a Go Solar Group solar quote is a great place to start.