Hi,
I am looking for some advice on a friend’s household solar setup.
Existing setup is approx 10 off 80w panels, a Plasmatronics PL60, 1050AH flooded lead acid batteries. It is a 24v setup. Single item connected to the load is an Inverter approx 3000 watts.
Problem with the setup is a couple of times they have run the batteries down. Reg reported 23% remaining after
Easter.
System runs the household power (500 litre fridge, microwave, TV, toaster, fans etc) but not lights, separate 12v solar setup for lights.
There is no backup generator.
We have 8 off 6v 125AH sealed lead acids. I.e. can be configured as 24v 250 AH.
Simply paralleling these batteries would not be recommended. I rang Plasmatronics for advice and was told about the Second battery control option of the PL60. This involves an external relay to switch the solar negative from the PL60 to the second set of batteries.
Basically solar is connected to the PL60 while Batt 1 is being boosted, when Batt 1 reached the float state the external relay operates & connects the solar to Batt 2. When Batt 2 reached max voltage or Batt 1 drops below float voltage then the relay releases & solar is connected back to the PL60. In other words the PL60 charges Batt 1 and any spare
solar power is used to charge Batt 2. It was suggested to only connect half the solar via the relay so when the relay operates half the panels are connected to the PL60 & half are connected to Batt 2.
While this setup would work
well charging both battery banks, it is a holiday house & both batteries would be fully charged when the house is empty, I have the following reservations about this setup.
This setup is only for running one device, the inverter. Only Batt 1 is connected to the inverter, so for Batt 2 to supplement the setup a battery changeover switch would be needed to connect Batt 2 to the inverter. This of course introduces operator error; the changeover switch would have to be changed to Batt 2 to relieve Batt 1. Then the switch would have to be changed back before Batt 2 was fully discharged. If Batt 1 was run down to 50% then the switch changed then the PL60 would be charging Batt 1, Batt 2 would be running the inverter but would not receive any charge until Batt 1 was fully charged. With Batt 2 being a quarter the size of Batt 1, I could see operator error causing Batt 2 to be fully discharged before the switch is changed back for Batt 1 to run the inverter.
Does anyone have any suggestions on how else to connect this setup? Ideal setup would be for the inverter to be able to use all the battery capacity (1050 + 250 AH) without any operator input to changeover.
Thanks
From Marty.