Lithium

Lithium batteries on this page, by system type

• 48V-class batteries (51.2V nominal, DC-coupled): the UZ Energy IG-16K-U 16kWh and RUiXU Lithi2-16 16kWh cabinets, the SimpliPHI 6.6 48V and the PHI 3.8 48V. They connect to a 48V battery inverter or hybrid inverter, which charges them from solar, the grid or a generator.
• 24V batteries (DC-coupled): the PHI 3.8 24V for smaller 24V inverter/charger systems.
• High-voltage stack (GoodWe): GoodWe Lynx Home FH-US 3.2kWh modules, three to six per tower (9.6 to 19.2kWh), plus the required GoodWe PCU control unit. They work only with supported GoodWe hybrid inverters.
• AC-coupled (Enphase): the Enphase IQ Battery 5P, IQ Battery 10C 10kWh and 10C 5.0kWh unit. Each has built-in microinverters and connects to the home's AC wiring as part of an Enphase IQ system, not to a 48V DC bus. Check each product page for the Enphase system equipment it needs.
• SimpliPHI accessories: the SimpliPHI 6.6 battery controller (one per stack), EnergyTrak control system and floor mount base. These support a SimpliPHI bank and don't replace the battery modules.

How to choose a lithium solar battery

1. Start with the inverter. A 48V battery inverter or hybrid takes a 48V-class (51.2V) battery. A high-voltage hybrid needs the battery its maker approves. An Enphase IQ system uses Enphase batteries.
2. Size usable energy to your loads. Add up the watts of the circuits you want to run and the hours you need them, then compare that to each battery's usable kWh. Our guide to sizing a battery bank walks through the math.
3. Plan expansion. Parallel only identical batteries the manufacturer allows. Don't mix 24V and 48V packs, brands, or lithium and lead-acid on one bus. See series and parallel battery connections.

What else a lithium battery system needs

• Hybrid inverters or off-grid inverters: many hybrids include MPPT solar charging, for example the Solis 16kW Hybrid for 48V DC-coupled designs.
• Charge controllers: a standalone MPPT controller when you DC-couple an extra array to the bank.
• Cable and wiring: battery interconnects and fusing sized for continuous and surge current.
• Monitoring and control: displays, gateways and sensors for state of charge and production.
• Solar panels: an array sized to the inverter or controller charge limits.

FAQ

LiFePO4 lithium solar batteries: 48V-class cabinets and packs, 24V PHI, GoodWe Lynx high-voltage modules and Enphase AC-coupled IQ Batteries. Compare all chemistries on solar batteries.

Why Are Lithium Iron Phosphate Batteries the Best Solar Batteries?

To see why lithium iron phosphate batteries became the standard for renewable energy storage, compare them with the previous standard, lead-acid.

Compared to lead-acid, LiFePO4 solar batteries are:

• Deeper cycling: rated for 80 to 100% depth of discharge (DoD), compared with about 50% for lead-acid, so more of the nameplate capacity is usable.
• Longer lasting: many LFP batteries are rated for thousands more cycles than lead-acid batteries in the same daily use. Check each battery's cycle and warranty rating.
• Lower in lifetime cost: with deeper and more cycles, the cost per kWh delivered over the battery's life is usually lower, even though the upfront price is higher.
• Maintenance free: no watering, equalizing or cleaning corroded terminals.
• Easier to install indoors: sealed LFP batteries don't vent gas the way flooded lead-acid does. Follow the manufacturer's installation rules and local code.
• Lighter: easier to ship, move and install for the energy stored.
• Protected by a built-in BMS: the battery management system monitors state of charge and protects the cells from voltage, current and temperature limits.

One limit to plan for: LFP cells shouldn't be charged below freezing unless the battery has a built-in heater, as the RUiXU Lithi2-16 does. Check the low-temperature charging limit on the spec sheet for cold installs.

Compared to NMC (lithium nickel manganese cobalt), LiFePO4 batteries are:

• Longer lasting with less cell degradation when cycled deeply.
• More thermally stable: LFP cells have a much higher thermal runaway threshold than NMC cells.
• Less dependent on cobalt and nickel, which helps keep cell costs down.

Best applications for lithium solar batteries

• Full-time off-grid homes get deep daily cycling and long cycle life.
• Part-time off-grid homes such as vacation homes benefit from little maintenance during infrequent use.
• Remote cabins and equipment benefit from lighter weight and sealed construction.
• Backup power for grid-tied solar benefits from high usable DoD, which keeps the battery count for critical loads down. See battery backup systems.

Lithium solar battery chemistry

"Lithium batteries" include lithium metal batteries, which are not rechargeable and not used in solar systems, and rechargeable lithium-ion batteries. Three lithium-ion types are most common:

• Lithium iron phosphate (LiFePO4 or LFP): long cycle life, tolerance of deep discharge, and thermal and chemical stability. This is the chemistry used in the solar batteries on this page.
• Lithium nickel manganese cobalt (NMC): higher energy density and low self-discharge, with higher thermal runaway risk. Common in electric vehicles and power tools.
• Lithium cobalt oxide (LiCoO2 or LCO): very high energy density but shorter life and prone to thermal runaway. Mostly used in phones and laptops.

New to batteries? Start with what solar batteries are, read about SimpliPHI lithium batteries, or compare lithium with lead-acid batteries. Questions? Book a Technical Support Call for one hour of personalized help.