Hello bright minds,
Looking for some advice. I just ordered 12 panels (245watt) for dirt cheap and I am trying to determine the best hybrid configuration to get the most out of the panels.
So the combinations that are possible (using all 12 panels) that I have calculated out are 4S3P, 3S4P, and for fun 2S6P.
As you imagine, this results in different amount of voltages and currents available. I have a Victron 250/70 MPPT SCC so I'm good on going to any voltage amount up to 245V from the PV array. The panels are going to be in my backyard, mounted on a homemade bracket system. I run/use 24V and 48V batteries and inverters. I'm trying to figure out what is the best combination in terms of getting the max pwr into the batteries. On a sunny day the panels have a clear view of the sky from about 8 AM until 3PM at which point they need to be turned some to continue getting decent pwr (this is based of my 4x100watt 12V panels I have now). There are no shadows or obstructions throughout the day. Except for cloudy days ect... there's nothing impeding the panels from getting max efficiency besides the angle and direction.
I don know what is better for charging batteries or running an inverter. Higher voltage with a lower amperage, or a higher amperage with a lower voltage.
My PV's Voc = 37.8V and Isc = 8.63A.
For example with my current panels, on cloudy days, the Voc ( 22V ) is still high enough for charging 48V or 24V. For example sometimes its PV voltage is down as low as 60-70V at which point I get maybe 0.5 - 0.7A. But sometimes when the sun is much brighter, the solar voltage displayed can be in the 70's still but the current shoots up to essentially the panel maximum. So this might be flawed logic but it "feels" like amperage is more important than voltage to get that solar energy into the batteries. For example right now its a pretty cloudy day out and I'm getting 135 watts (out of 400 theorical max) solar voltage is at 75V and I'm seeing around 1.8 - 2.0 A being pushed to the batteries.
The 4S3P configuration would give me 151.2V and 25.89A.
The 3S4P config gives me 113.4V and 34.52A.
For fun as I doubt these are optimal but I calculated them too:
6S2P gives me 226.8V and 17.26A. (Victron SCC is rated for 250V PV input)
2S6P gives me 75.6V and 51.78A
These are all "on paper" calculations I know that real world these numbers will drop.
So what do you think is optimal for charging 24/48V battery packs?
To me it feels like 3S4P is the way to go, still crazy high voltage (w.r.t my packs 24/48 and my puney PV setup) and a solid amount of amperage. But I could be wrong so that's why I'm asking here!! I feel like 2S6P giving the most amperage would never happen even though 75.6V is sill higher than my batteries. I dont know the inner workings of a SCC as to how it provides the most charge. I would imagine too that in the 2S6P configuration if it got cloudy it would lead to little to no charging. Maybe I'm wrong, hence I'm here!
Side note:
I have a different SCC that actually allows you to not have to use a battery at all and you can connect an inverter directly to the SCC battery output, it regulates the DC output inside the SCC, this essentially lets you run an inverter 100% based on the PV output, of course if the sun doesn't cooperate whatever you have running off the inverter will lose power. I want to mess around with this to try and power some things during the day (even if just for a few hours) that are high engery consuming such as the fridge. I would need to ensure its going to be a super sunny day of course. That SCC does have a limit of 138-150V PV input so the 4S3P would be right on the edge, but likely be fine due to normal loses in efficiency. Interestingly enough the Victron 250/70 says that it can do the same, just not recommended (but no damage to the SCC will occur) and its clearly not something they consider normal use or talk much about. I'm curious though...I'm also curious about the other SCC that specifically is designed to allow this to work.
Will it work? Will it die after a few days? Will it burst into flames? Dunno! It's an EPEVER unit. I know Chinese and all that....but I have another one that I had purchased (mainly because they specifically have profiles and support NMC chemistry) and that SCC has worked/works great and given me darn close if not the 99-98% efficiency its rated for! I've been happy w/it for quite some time now. All my charging/solar operations happen when I am home for safety reasons. I work from home so I can always keep an eye on things. The battery packs I build are spread around the house powering various things. I rent so I cant do a proper install. This is a hobby basically. I was tired of having the 4x100watt panels and the low amperage/high charging times of my packs. So I kept an eye out and finally got a good deal (well we will see if indeed its a good deal or not) on some panels. I feel a little better about my purchase as when I checked the website not even an hour later, they were sold out!
Eagerly awaiting your advice. I'm going to start sketching out the frame I'm going to build to mount the panels and be able to rotate them and change the angle..
Cheers
Looking for some advice. I just ordered 12 panels (245watt) for dirt cheap and I am trying to determine the best hybrid configuration to get the most out of the panels.
So the combinations that are possible (using all 12 panels) that I have calculated out are 4S3P, 3S4P, and for fun 2S6P.
As you imagine, this results in different amount of voltages and currents available. I have a Victron 250/70 MPPT SCC so I'm good on going to any voltage amount up to 245V from the PV array. The panels are going to be in my backyard, mounted on a homemade bracket system. I run/use 24V and 48V batteries and inverters. I'm trying to figure out what is the best combination in terms of getting the max pwr into the batteries. On a sunny day the panels have a clear view of the sky from about 8 AM until 3PM at which point they need to be turned some to continue getting decent pwr (this is based of my 4x100watt 12V panels I have now). There are no shadows or obstructions throughout the day. Except for cloudy days ect... there's nothing impeding the panels from getting max efficiency besides the angle and direction.
I don know what is better for charging batteries or running an inverter. Higher voltage with a lower amperage, or a higher amperage with a lower voltage.
My PV's Voc = 37.8V and Isc = 8.63A.
For example with my current panels, on cloudy days, the Voc ( 22V ) is still high enough for charging 48V or 24V. For example sometimes its PV voltage is down as low as 60-70V at which point I get maybe 0.5 - 0.7A. But sometimes when the sun is much brighter, the solar voltage displayed can be in the 70's still but the current shoots up to essentially the panel maximum. So this might be flawed logic but it "feels" like amperage is more important than voltage to get that solar energy into the batteries. For example right now its a pretty cloudy day out and I'm getting 135 watts (out of 400 theorical max) solar voltage is at 75V and I'm seeing around 1.8 - 2.0 A being pushed to the batteries.
The 4S3P configuration would give me 151.2V and 25.89A.
The 3S4P config gives me 113.4V and 34.52A.
For fun as I doubt these are optimal but I calculated them too:
6S2P gives me 226.8V and 17.26A. (Victron SCC is rated for 250V PV input)
2S6P gives me 75.6V and 51.78A
These are all "on paper" calculations I know that real world these numbers will drop.
So what do you think is optimal for charging 24/48V battery packs?
To me it feels like 3S4P is the way to go, still crazy high voltage (w.r.t my packs 24/48 and my puney PV setup) and a solid amount of amperage. But I could be wrong so that's why I'm asking here!! I feel like 2S6P giving the most amperage would never happen even though 75.6V is sill higher than my batteries. I dont know the inner workings of a SCC as to how it provides the most charge. I would imagine too that in the 2S6P configuration if it got cloudy it would lead to little to no charging. Maybe I'm wrong, hence I'm here!
Side note:
I have a different SCC that actually allows you to not have to use a battery at all and you can connect an inverter directly to the SCC battery output, it regulates the DC output inside the SCC, this essentially lets you run an inverter 100% based on the PV output, of course if the sun doesn't cooperate whatever you have running off the inverter will lose power. I want to mess around with this to try and power some things during the day (even if just for a few hours) that are high engery consuming such as the fridge. I would need to ensure its going to be a super sunny day of course. That SCC does have a limit of 138-150V PV input so the 4S3P would be right on the edge, but likely be fine due to normal loses in efficiency. Interestingly enough the Victron 250/70 says that it can do the same, just not recommended (but no damage to the SCC will occur) and its clearly not something they consider normal use or talk much about. I'm curious though...I'm also curious about the other SCC that specifically is designed to allow this to work.
Will it work? Will it die after a few days? Will it burst into flames? Dunno! It's an EPEVER unit. I know Chinese and all that....but I have another one that I had purchased (mainly because they specifically have profiles and support NMC chemistry) and that SCC has worked/works great and given me darn close if not the 99-98% efficiency its rated for! I've been happy w/it for quite some time now. All my charging/solar operations happen when I am home for safety reasons. I work from home so I can always keep an eye on things. The battery packs I build are spread around the house powering various things. I rent so I cant do a proper install. This is a hobby basically. I was tired of having the 4x100watt panels and the low amperage/high charging times of my packs. So I kept an eye out and finally got a good deal (well we will see if indeed its a good deal or not) on some panels. I feel a little better about my purchase as when I checked the website not even an hour later, they were sold out!
Eagerly awaiting your advice. I'm going to start sketching out the frame I'm going to build to mount the panels and be able to rotate them and change the angle..
Cheers
