Thoughts on this off-grid solar/battery/inverter set up

Hello - I’m wondering if you could tell me if the system outlined below is a good quality/size set up for an off grid home in alpine Victoria that has a house of approx. 170m2 internal area and a cottage of approx. 100m2 internal area. Also, if the age of the set up means we would need to replace certain elements in the next few years. Any feedback would be very useful - thank you in advance.

Batteries: 12 x 2volt 1500 Ah Hoppecke 12 OPzV Solar batteries (Gel)

Inverter/charger system are all Out Back Power Systems products

2 x VFX3024E Inverter/Charger, Continuous power rating at 25C ambient is 3000VA (so total of 6000VA)

1 x Fleximax 60 Charger controller
1 x Fleximax 80 Charger controller

1 x Out Back Power Systems Mate system controller and display

1 x Out Back Power Systems Hub 10.3

1 x Outback Power Systems FLEXnet DC

The Hub, Mate and FLEXnet are used for monitoring, controlling and programming the system.

A total of 3500 watts of solar panels consisting of 8 x 190 watt panels (through Fleximax 60) and 8 x 250 watt panels (through Fleximax 80)

We use 2 x Honda 20i sine wave inverse generators to recharge batteries when needed.

When the system runs the house only we essentially have 3 days of power storage from the batteries. Even an overcast day will generate power from the panels keeping the batteries above 90% nominal charge, we try to not go below 80% state of charge as this is most beneficial for the batteries.

The system is approx 10 years old.

Hi @Bosscher

Are you purchasing a house with this system installed on it? I imagine the batteries will be coming to the end of life if they are the original ones?

@Svarky will be better to answer.

Hi @Marty
Yes, we’re looking to purchase a property with this system. Thanks for the feedback re the batteries.

Could you give me an idea of what it would cost to replace the batteries for a system this size?

@Bosscher, a large 24V 1500Ah battery bank of this size (36kWh) would typically cost around $10,000 for a direct replacement. However, you could upgrade to a lithium battery system for a similar price and get the extra benefits of much higher efficiency, no partial state of charge issues, plus a 10-year warranty.

Thanks @Svarky for the info, we’ll look into the lithium batteries

As per my understanding lithium batteries are chargeable batteries that are used with solar panels to store excess solar energy.
Lithium batteries generally cost around $9000, but the price can be vary based on your requirement and manufacturer.
To understand the efficiency and the durability of a battery you can check the previous performance of the manufacturer.

Thank you for your reply, Amit

@Bosscher Your most welcome!