6 x LE300's upgrade Petes Tasmanian stand-alone power system

Pete from Tasmania describes his experience upgrading his 12v lead-acid stand-alone power with 6 x LE300 batteries. Over to you Pete!

I run a small domestic off grid system with 1.8 kW of panels running through an MPPT controller charging three 12 volt 200 amp hour batteries in parallel. These run 12 volt DC light and power circuits in the house and a 2000 watt inverter which supplies AC to the house and shed. 

After about three years use one of the batteries was damaged; the system still worked but at reduced efficiency and capacity. As the whole battery bank needed replacing I was considering converting to lithium but was put off by the cost, recycling issues, use of rare metals, and some performance characteristics. I then discovered the BOS LE300. 

At first glance these seemed expensive for the capacity - each about 300 watt hours for $600, and how many would I need? But because you don’t have to cover your total load (though I decided I would), you don’t necessarily need many. The load on the lead acid battery and the charge/discharge rates are effectively halved and so in theory the lead acid batteries work half as hard and last longer and you don’t need as many of them either.  

I invested in six LE300s, giving me 1.8 kWh from these on top of my nominal 7.2kWh of lead acid (I think now reduced to 4 or 5 from damage). My daily usage is between 1.5 and 2 kWh per day with a maximum load of about 1.8 kW so when there’s sun the lead acid bank is hardly used; from September to April the LE300s are pretty much never fully discharged and are fully charged and the lead acid system is on float by early afternoon at worst. I’m in southern Tasmania and have shade problems on the panels in winter so have to run the generator sometimes; when I do the LE300s charge up quickly and the lead acids aren’t so deeply discharged so it takes less time, fuel and noise. Another benefit down here is the self-heating feature when the LE300s are cold. 

So, they have done what they said they would. Both the lead acid and the lithium batteries are optimally used and charged, maximising the lives of both. They have allowed me to extend the life of the damaged bank and when I do have to replace it, it can be smaller and thus cheaper. By not going all-lithium I’ve slightly reduced rare metal and recycling negatives and have built-in system redundancy, and the positive features of both lithium and lead acid chemistries. These things are clever German engineering and I’m pleased with their performance.