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How to Choose a 12kW Solar Inverter in South Africa

A 12kW inverter is the right size for large homes, farms and small businesses that run pumps, air-conditioning or several heavy appliances at the same time. This guide covers what to check before you buy, and how to size the batteries and solar panels that go with it. The Sun Pays has supplied solar power systems in South Africa since 2007 and sells from Rayton, Gauteng.

1. Is 12kW the right size for you?

Add up everything that can run at the same time, then add 25 to 30% headroom for motor start-up surges. Pumps, compressors and air-conditioners draw several times their rated power for a moment when they start, so a surge rating matters as much as the continuous rating. Not sure? Use our solar system sizing calculator or send your appliance list to our technical team.

2. Single-phase or three-phase?

Check your supply first. A single-phase inverter works on a single-phase 230VAC supply. If your property has a three-phase supply and you need to power three-phase equipment, you need a three-phase inverter, so speak to a technician before you order.

3. Battery voltage and battery size

The inverter and battery must use the same system voltage. A 48V inverter works with 51.2V lithium (LiFePO4) batteries and with lead-acid banks. Lithium batteries should talk to the inverter through BMS communication (CAN or RS485).

Battery current is where 12kW systems go wrong. At full load a 12kW inverter draws roughly 250A from a 48V battery bank. A single 51.2V 100Ah battery is rated for 100A maximum discharge, so you need about three in parallel to run the inverter at full power. Most homes rarely run at full load, but a bank that is too small will trip or wear out early. Batteries can be added later.

4. Solar input

Look at three numbers: the maximum solar power each input accepts, the maximum open-circuit voltage, and the MPPT voltage range. Panel voltage rises on cold mornings, so keep every string safely below the maximum open-circuit voltage. Dual MPPT inputs let you split panels across two roof faces.

5. Room to grow

Check how many inverters can be connected in parallel. Starting with one and adding more later is cheaper than oversizing on day one.

6. Warranty and local support

Ask who services the unit in South Africa, what the warranty is, and who pays for transport on a warranty claim. A cheaper unit with no local support can cost more in the end.

The 12kW inverter we stock: MUST PV19-12048 EXP

  • 12000VA / 12000W pure sine wave output, 24000W surge, 230VAC single-phase
  • 48VDC battery system, lead-acid and lithium with BMS communication
  • Dual MPPT, 6000W + 6000W maximum solar input, 90 to 450VDC MPPT range, 500VDC maximum open-circuit voltage
  • Up to 150A solar charge and 150A AC charge
  • Up to 6 units in parallel
  • Colour LCD with USB, RS485 and Wi-Fi monitoring
  • 2-year manufacturer warranty (transport to The Sun Pays for warranty claims is at the customer's cost)

See the MUST 12kW inverter, current price and stock.

Batteries to pair with it

Frequently asked questions

How many batteries does a 12kW inverter need?

To deliver full power from batteries you need about 250A of discharge capability, which is about three 51.2V 100Ah lithium batteries in parallel. For typical home loads, fewer can work, but size the bank to your real load and how long you need to run.

Can a 12kW inverter run a borehole pump?

Yes, if the pump's start-up surge is within the inverter's surge rating. Check the pump's rated and starting current, and see our pump selector.

Where can I buy a 12kW inverter in South Africa?

The Sun Pays sells the MUST 12kW inverter from Rayton, Gauteng, with delivery across South Africa and local technical support. Delivery is free within 100 km of Rayton on orders above R5,000. Call 012 734 0915 or WhatsApp 082 515 1655 (messages only), Monday to Friday 07:30 to 16:00 and Saturday 08:00 to 12:00.