Northarmgazer
New Member
- Joined
- May 16, 2022
- Messages
- 6
Hi Everyone,
I've just joined the forum in the hope that wiser people than me can help unscramble my thoughts after all the reading I've been doing.
I'm in what I think may be the unusual position of having solar panels on the way and already having a battery bank, but nothing in between.
The system I'm building is to run my shed off grid, intermittent use of the system. As money comes available I can always increase the size of the array in the future, but have to work with what I have for now.
My panels are 300w (peak 295) x 6, so lets say 1.8kw array for now. Peak VOC 39.7v. The battery bank is comprised of 2v SLA 1000ah batteries. I have enough to set up a 48v bank and have 11 spare (as back ups - the batteries are second hand) or obviously, 2 X 24v or 4 X12v.
The use of these batteries is non negotiable - in total they weigh 2.5 ton and I have moved them 3 times in the time I've owned them so I'm being stubborn here..
My preference is run a 12 v system based on cost and availability of "accessories" here. (I'm in Australia). I also already have all the shed lighting LED 12v globes so catering for this is essential.
I have struggled for a few days now trying to balance the needs of MMPT controllers with potential wiring formats for the solar cells, matching the specs of the solar to the Mppt's v.s the system voltage.
I have looked at:
Growatt SPF3500ES to run a 48v system - this is the cheapest and easiest option as it also has the inverter - but requires the solar array to run at 200v which I'm not keen on safety wise.
Growatt SPF3000TLHVM to run a 24v system - its basically the same price as above, but I could only run 5 of the 6 panels because of the total W size of the array it could handle
Epever 8415AN 80a controller running a 24v system. This would mean an inverter of 4000w (only size I could find with AC line out ports to wire to switchboard), so bigger than the Growatt. The inverter cost is about $700, bringing total cost to around $350 more than the Growatt. I would still have to run PV array voltage around 100v for the Mppt.
If I drop down to a 12v system and smaller amp controllers I'm looking at having to get 6 Epever controllers and then have lower required PV array voltages for the Mppt (down to around 30v min) so a bit safer from my perspective. But this comes at a cost of about $500 more.
Wiring distances are short from both panels to controller and controller to batteries. The battery linking cables and output cables came with them and are massive, I don't know their gauge, but they are thumb thickness!
I guess I'm trying to balance overall cost with the 'safest' operating voltages and ultimate system voltage.
My main concern running 48v (apart from running the 12v lights) is that if a battery dies the whole system is dead until I can swap out one of spare cells whilst I have them, where the 12 and 24v options mean I can just switch to another bank and still have more spares.
What would you do and why?
I've just joined the forum in the hope that wiser people than me can help unscramble my thoughts after all the reading I've been doing.
I'm in what I think may be the unusual position of having solar panels on the way and already having a battery bank, but nothing in between.
The system I'm building is to run my shed off grid, intermittent use of the system. As money comes available I can always increase the size of the array in the future, but have to work with what I have for now.
My panels are 300w (peak 295) x 6, so lets say 1.8kw array for now. Peak VOC 39.7v. The battery bank is comprised of 2v SLA 1000ah batteries. I have enough to set up a 48v bank and have 11 spare (as back ups - the batteries are second hand) or obviously, 2 X 24v or 4 X12v.
The use of these batteries is non negotiable - in total they weigh 2.5 ton and I have moved them 3 times in the time I've owned them so I'm being stubborn here..
My preference is run a 12 v system based on cost and availability of "accessories" here. (I'm in Australia). I also already have all the shed lighting LED 12v globes so catering for this is essential.
I have struggled for a few days now trying to balance the needs of MMPT controllers with potential wiring formats for the solar cells, matching the specs of the solar to the Mppt's v.s the system voltage.
I have looked at:
Growatt SPF3500ES to run a 48v system - this is the cheapest and easiest option as it also has the inverter - but requires the solar array to run at 200v which I'm not keen on safety wise.
Growatt SPF3000TLHVM to run a 24v system - its basically the same price as above, but I could only run 5 of the 6 panels because of the total W size of the array it could handle
Epever 8415AN 80a controller running a 24v system. This would mean an inverter of 4000w (only size I could find with AC line out ports to wire to switchboard), so bigger than the Growatt. The inverter cost is about $700, bringing total cost to around $350 more than the Growatt. I would still have to run PV array voltage around 100v for the Mppt.
If I drop down to a 12v system and smaller amp controllers I'm looking at having to get 6 Epever controllers and then have lower required PV array voltages for the Mppt (down to around 30v min) so a bit safer from my perspective. But this comes at a cost of about $500 more.
Wiring distances are short from both panels to controller and controller to batteries. The battery linking cables and output cables came with them and are massive, I don't know their gauge, but they are thumb thickness!
I guess I'm trying to balance overall cost with the 'safest' operating voltages and ultimate system voltage.
My main concern running 48v (apart from running the 12v lights) is that if a battery dies the whole system is dead until I can swap out one of spare cells whilst I have them, where the 12 and 24v options mean I can just switch to another bank and still have more spares.
What would you do and why?