theHouserHouse
New Member
- Joined
- Sep 5, 2020
- Messages
- 27
I've read so much my head is spinning and I'm still not completely sure what size solar charge controller to buy. We have 8- 100 watt panels, each panel has VMP (volts) of 20.6 & IMP (amps) of 4.85. We are wiring them in sets of 2, in series, which brings the VMP to 41.2 and the IMP to 4.85 per set. Then putting the 4 sets in parallel which brings the totals to VMP to 41.2 and total IMP of 19.4. Whew!
I've read several ways of calculating for the solar charge controller. What's not clear is if the wiring configuration affects the calculation or not.
-If I use the # of panels (8) X panel watts (100) = watts of array (800), then divide the watts of array (800) by the battery volts (12) , and add 25%; I get 83.333 amps and would need a 100 amp controller.
-If I use the watts of the array (800) divided by the volts of the battery (12); I get 66.666 amps and would need a 80 amp controller.
-If I use the amps the panels are rated at from the sticker on the back (4.85) X the number of panels (8); I get 38.3 and would need a 40 amp controller.
-Or do I some how use the total amps after wiring up the panels in series and parallel, which is 19.4?
Good Golly I'm totally confused.
We have 10 gauge wire for the connection of solar panels and 8 gauge wire for the run down to the solar charge controller. We have purchased a 3000 watt pure sine wave inverter.
As batteries go we are still on the fence. We have 2- Group 24 deep-cycle sealed lead acid batteries on the tongue of the travel trailer. They are one year old 70 amp/hr, 12 volt batteries. Pretty much generic RV dealer batteries. We'd like to use these for awhile if we can. Not sure yet if they are big enough though. We plan to buy used lithium batteries, but are finding that selecting them is just a complicated as buying a charge controller. So any affordable battery suggestions is greatly appreciated. A new updated picture of our rooftop wiring diagram is included. Hopefully I don't have panels wired up wrong this time.
I've read several ways of calculating for the solar charge controller. What's not clear is if the wiring configuration affects the calculation or not.
-If I use the # of panels (8) X panel watts (100) = watts of array (800), then divide the watts of array (800) by the battery volts (12) , and add 25%; I get 83.333 amps and would need a 100 amp controller.
-If I use the watts of the array (800) divided by the volts of the battery (12); I get 66.666 amps and would need a 80 amp controller.
-If I use the amps the panels are rated at from the sticker on the back (4.85) X the number of panels (8); I get 38.3 and would need a 40 amp controller.
-Or do I some how use the total amps after wiring up the panels in series and parallel, which is 19.4?
Good Golly I'm totally confused.
We have 10 gauge wire for the connection of solar panels and 8 gauge wire for the run down to the solar charge controller. We have purchased a 3000 watt pure sine wave inverter.
As batteries go we are still on the fence. We have 2- Group 24 deep-cycle sealed lead acid batteries on the tongue of the travel trailer. They are one year old 70 amp/hr, 12 volt batteries. Pretty much generic RV dealer batteries. We'd like to use these for awhile if we can. Not sure yet if they are big enough though. We plan to buy used lithium batteries, but are finding that selecting them is just a complicated as buying a charge controller. So any affordable battery suggestions is greatly appreciated. A new updated picture of our rooftop wiring diagram is included. Hopefully I don't have panels wired up wrong this time.
