Best Solar Battery: How to Choose by the Figures

There is no single best solar battery. There is the battery whose voltage your inverter accepts, whose capacity covers your nights and whose discharge current carries your peak load. This guide gives no ranking and no award: it lists the five figures that decide, and reads them on the Voltronic batteries in our catalogue, exactly as their records state them.

Five figures that decide, in order

1. Nominal voltage. It must sit inside the battery window of the inverter. A 48 V inverter takes a 48 V or 51.2 V battery; a high-voltage inverter takes a stack of several hundred volts. Nothing else matters until this matches.
2. Energy in kWh. Energy used per day x hours of backup / 24. The sizing calculator works this out from your appliances.
3. Maximum continuous discharge current. Multiplied by the voltage, it is the power the battery can feed without tripping. A 48 VDC module that gives 150 A carries 7.2 kW.
4. Stated cycle life, and the condition it is stated at. A cycle count means something only with its temperature or its depth of discharge beside it.
5. Operating temperature, weight and enclosure. They decide where the battery can stand.

The Voltronic batteries, figure by figure

Three families come out of this table.

48 V modules for one home. The LIO 4805 and LIO 4810 are 48VDC modules with a full charge voltage of 52.5VDC, a design life above 10 years at 25°C and an operating range of 0°C to 50°C for charge and for discharge. They weigh 31.6 kg and 44.8 kg and talk to the inverter over an RS485 port.

51.2 V lithium iron phosphate. Both LIO II records state lithium iron phosphate cells. The LIO II-4810 stacks from one to four units, 5, 10, 15 or 20 kWh usable at 48, 96, 144 or 192 kg, with an operating voltage of 40 to 56 VDC, a charging current of 100 A maximum (30 A by default), an IP20 enclosure and RS485 plus CAN. The LIO II-4810E is the sealed one: IP65, 43 kg, up to 15 units in parallel, RS485, RS232 and CAN.

High-voltage stacks. The EnergyCube is built from 102.4 V / 50 Ah modules of 5,120 Wh under one controller box: two modules make the 205, six make the 605. Each record states 0°C to 55°C for charge and discharge, and a complete set weighs from 118 kg (205) to 328 kg (605).

One record disagrees with itself. The LIO II-4810E states a charge temperature of 0°C to 45°C in one row and 0°C to 50°C in another, and a discharge temperature of -20°C to 60°C (derating above 45°C) in one row and 0°C to 50°C in another. Both readings are printed on its page; plan for the narrower one.

Which battery for which load

Take a house that uses 25.4 kWh a day and wants the evening covered, 4 hours: 25.4 x 4 / 24 = 4.23 kWh. One LIO 4810, counted as 4.32 kWh usable, does it. That is the battery line of the house kit with evening backup.

For the whole night, 8 hours, the same house needs 8.47 kWh. The house kit with overnight backup lists one EnergyCube 305: 15 kWh in a single stack, at a voltage that needs a high-voltage inverter.

With no grid, the battery holds the full day. The off-grid house kit lists six LIO 4810 modules for 25.4 kWh. Six modules of 150A each sit far above the current its 11,000 W inverter draws from a 48 VDC bank.

Peak load is the check buyers skip. A single LIO 4805 gives 75A, which is 3.6 kW at 48 V. A house that peaks at 8,050 W cannot run from one, however few kilowatt-hours it needs.

Portable batteries are a different product

Queries about the best portable solar battery point to another line. The Portable Energy Bank records state 768Wh at 25.6 VDC, 1536Wh at 51.2 VDC and 2500Wh at 25.6VDC, each with a built-in MPPT solar charger. Their stated life is at least 2500 cycles for the two smaller units and at least 3500 for the largest, at 100% depth of discharge. They are on the Portable Energy Bank datasheet.

Read the record, then compare

Every figure on this page comes from a product record and can be checked on the family datasheets: LIO 4805 and 4810, LIO II-4810, LIO II-4810E and EnergyCube 205 to 605. The whole range is on the batteries page, and the comparison pages set two records side by side.

Each battery is ordered from its product page at the price shown there, and orders are collected in store in Dubai or Riyadh.