Upgrading battery storage

DIY
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1

Hi,

I’m looking for advice on upgrading the battery storage in my off-grid home.

My current system consists of:

  • Victron MultiPlus 24/5000/120
  • Victron SmartSolar MPPT 150/170-Tr
  • Victron Color Control GX (CCGX)
  • Li-Gen 24V 210Ah LiFePO₄ battery (5.04 kWh)
  • 6 × Peimar SG310M solar panels (1.86 kW total)

Panel specifications:

  • 310W each
  • Vmp: 32.6V
  • Imp: 9.51A
  • Voc: 40.7V
  • Isc: 9.8A

The system powers a 55 m² off-grid one-bedroom SIP home. My current battery provides approximately 23 hours of runtime under normal household use.

I’d like to increase storage capacity and am considering either:

  1. Adding a second battery in parallel.
  2. Replacing the existing Li-Gen battery with a larger-capacity battery (around 10 kWh).

Questions:

  • What battery upgrades would you recommend for this system?
  • Is it better to add a second battery or replace the existing battery with a larger unit?
  • Are there any specific 24V LiFePO₄ batteries that integrate particularly well with Victron equipment?
  • Would a 24V 400Ah (≈10 kWh) battery be suitable for my MultiPlus 24/5000/120?
  • If I later expand the solar array from 1.86 kW to around 3.7 kW, would this change your recommendation?

Any advice would be appreciated.

Thanks.

2

Welcome to the community! Lots of helpful people here.

Can you why you want to upgrade?
e.g. share a bit about the loads eg what is consuming power? eg peak and average.

Adding a second battery seems like the easiest next step.

I’m sure other folks will chime in with additional comments.

3

Thanks Buzzy. I currently have 23 hours of battery life per day without solar. Small 1 bed modular home. Currently using a petrol generator to top off lack of sunshine. In 3-3:30 hours the battery will charge from 0 to 100%. In sunshine or using generator, A second similiar battery costs 2700 euro from a company in Tipperary. But I believe you can now pick up 24v batteries with 400oh which would be roughly 10kv. Cheaper option than parallel charging two identical expensive batteries.

4

Hmmmm auto-correct typos?.. guessing 24V 400Ah or 9.6kW.
2700 Eur seems a bit high. I did see this: LI24-210 24V 210AH lithium-ion battery Super Series with bluetooth high power BMS - Li-Gen for about 2100 Eur, and always good to support local manufacturers. Not sure how the BMSes will talk to each other.

Estimating your consumption is roughly 200Wh, agree more battery capacity would help, but then your tropical :palm_tree: Irish location means more sunshine power may be needed especially on cloudy days to keep things charged up.

I’m not going to suggest switching to 48V, as that is going to add a lot of cost in replacement equipment.

Maybe switch battery vendors and sell off the old battery to help pay for the upgrade?

5

if you want to spend money, i´d think about replacing the MP2 with a 48V version

If you have luck, you could sell the 24V unit almost for the price of a new 48V unit