Hi, I'm upgrading an offgrid system for a cabin in the Southern part ofNorway and I thought of sharing my plans for sanity check, well that isif anyone is interrested in commenting 
It willhave a load averaging 1500wh/day for the lights, TV and a 220v fridge, at times a power tool or vacum cleaner can be plugged in the inverter but i would use the generator for prolonged use of power hungry appliances.
This will be based on a battery packfrom an I-Miev EV,this will be arranged as a 24V system in a2x6P7S configuration with 80x LEV50N batteries 3,7V/50Ah totalising 15500Wh.
For the BMS I'm planninga Batrium with 14 cellmon 8mm. I need to experiment a bit but initially I'm thinking of keeping the batteries between 3.4 and 4V this should be close to 80%DOD and 80%SOC. The BMS will open the PV circuit when batteries have reached 4V.
For the charging and invertingI'm very tempted to go for an Akspert MEX3k24 regulator/charger/inverter, this is a Voltronic system thus same as MPPSolar.
My existingpanels 2x180w are meant to fill up the batteries between each visit witch are say once a month, mostly for aweek end each time. Here up North there is too little light for charging in winterfrom November to January. The inverter does have a significant own consumption when used in such a small system, it's possible it will usemore power than generated by the PV in winter. Again this is something I'll have to measure but as a fallback solutionI may want toturn off the inverterall together when leaving the cabinand just leave a smaller MPPT regulator charging the batteries during thedarker months.
What i worry most of is the noise . If possible I want my system in theexisting closet for batteries witch is in the middle of the cabin. I'm hoping the fans are not running too often and too hard with a small load connected.
Have anyoneexperiences with using Akspert/MPPsolar 24V/3000Wwith little loads, are they then quiet and not too hungry ? The specs says <10W in standby but even 10W is already too much for the small panels.
Else, anyone wants to shoot some bullets at my plan ?
It willhave a load averaging 1500wh/day for the lights, TV and a 220v fridge, at times a power tool or vacum cleaner can be plugged in the inverter but i would use the generator for prolonged use of power hungry appliances.
This will be based on a battery packfrom an I-Miev EV,this will be arranged as a 24V system in a2x6P7S configuration with 80x LEV50N batteries 3,7V/50Ah totalising 15500Wh.
For the BMS I'm planninga Batrium with 14 cellmon 8mm. I need to experiment a bit but initially I'm thinking of keeping the batteries between 3.4 and 4V this should be close to 80%DOD and 80%SOC. The BMS will open the PV circuit when batteries have reached 4V.
For the charging and invertingI'm very tempted to go for an Akspert MEX3k24 regulator/charger/inverter, this is a Voltronic system thus same as MPPSolar.
My existingpanels 2x180w are meant to fill up the batteries between each visit witch are say once a month, mostly for aweek end each time. Here up North there is too little light for charging in winterfrom November to January. The inverter does have a significant own consumption when used in such a small system, it's possible it will usemore power than generated by the PV in winter. Again this is something I'll have to measure but as a fallback solutionI may want toturn off the inverterall together when leaving the cabinand just leave a smaller MPPT regulator charging the batteries during thedarker months.
What i worry most of is the noise . If possible I want my system in theexisting closet for batteries witch is in the middle of the cabin. I'm hoping the fans are not running too often and too hard with a small load connected.
Have anyoneexperiences with using Akspert/MPPsolar 24V/3000Wwith little loads, are they then quiet and not too hungry ? The specs says <10W in standby but even 10W is already too much for the small panels.
Else, anyone wants to shoot some bullets at my plan ?
