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Greetings folks,
Looking for some answers on adding more panels to a system I put together about seven years ago. This was my first solar project and built this for a small off grid cabin in the hills of East Tn. I only went 12v since this was my first build and here are my components. I'm using an Outback 80amp Flex max, purchased four 190 watt grape solar panels, 36.2V and 45.4Voc. I could not put all four panels in series as it would have been over the 150V max of the Outback so I put them in two series of two panels each, series/parallel. I have a total of 760W of panels and for a 12V system the max is 1000w, lucky to see about 500w being produced on average day being what it is here in E Tn. The panels run to a breaker box on the outside of the mount and so each series of panels has its own 20a breaker and I also have a 3rd slot and this is where I'm wanting to add two more panels and thus where my questions begin.
1. I've always heard that when adding additional panels you need to try to match within about 10% of the existing panels voltage, is this still the best rule of thumb?
2. I've read where it is very common to oversize a system for the very reasons I mentioned above, because you will hardly ever make 100% (especially in my lat/long). My question is how much can I go over and be safe? I have heard folks say that a system is only going to take in the amount of amps that it can use and so not to worry about this side as long as you keep your volts below your max. Would you agree?
I ask these questions because I have found 2 used panels that are extremely close on the volt side 37.3v, 46.8 Voc. They are poly whereas my original are mono, guessing this does not matter as volts are volts regardless or is it not a good idea to mix and max poly with mono panels. The panels are much larger in watts than I need being 335w ea which would make my total system 1430. And before anyone says I need to go to a 24v system I am aware and would agree however lets just say its not in the cards now as I'm not looking to invest in a new inverter and my current battery config will not allow with only three 12v 200AH ea batteries (LifeP04).
I have learned a ton from this my first project and would do things a lot differently now knowing what I know but just trying to see if I can add those two extra panels and be ok? The panels are 2 years old and a decent price at $275. My goal is just to hit that 1000w max input while I'm at that location.
TIA
Looking for some answers on adding more panels to a system I put together about seven years ago. This was my first solar project and built this for a small off grid cabin in the hills of East Tn. I only went 12v since this was my first build and here are my components. I'm using an Outback 80amp Flex max, purchased four 190 watt grape solar panels, 36.2V and 45.4Voc. I could not put all four panels in series as it would have been over the 150V max of the Outback so I put them in two series of two panels each, series/parallel. I have a total of 760W of panels and for a 12V system the max is 1000w, lucky to see about 500w being produced on average day being what it is here in E Tn. The panels run to a breaker box on the outside of the mount and so each series of panels has its own 20a breaker and I also have a 3rd slot and this is where I'm wanting to add two more panels and thus where my questions begin.
1. I've always heard that when adding additional panels you need to try to match within about 10% of the existing panels voltage, is this still the best rule of thumb?
2. I've read where it is very common to oversize a system for the very reasons I mentioned above, because you will hardly ever make 100% (especially in my lat/long). My question is how much can I go over and be safe? I have heard folks say that a system is only going to take in the amount of amps that it can use and so not to worry about this side as long as you keep your volts below your max. Would you agree?
I ask these questions because I have found 2 used panels that are extremely close on the volt side 37.3v, 46.8 Voc. They are poly whereas my original are mono, guessing this does not matter as volts are volts regardless or is it not a good idea to mix and max poly with mono panels. The panels are much larger in watts than I need being 335w ea which would make my total system 1430. And before anyone says I need to go to a 24v system I am aware and would agree however lets just say its not in the cards now as I'm not looking to invest in a new inverter and my current battery config will not allow with only three 12v 200AH ea batteries (LifeP04).
I have learned a ton from this my first project and would do things a lot differently now knowing what I know but just trying to see if I can add those two extra panels and be ok? The panels are 2 years old and a decent price at $275. My goal is just to hit that 1000w max input while I'm at that location.
TIA
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