I've just had a good look through this and I'm going to try mine in series - I just need to check for my own sanity... Does the mppt controller regulate the voltage down to 12v to suit the 12v batteries I have? Weirdly, even in parallel my panels are reading as 18v.
Yup! They're magical! Just make sure you connect the battery FIRST so the controller knows what voltage it's supposed to work with. With some controllers if you plugged in the panels first it thought you had an 18v battery and cooked!
That makes so much more sense thanks so much for taking the time out to write that in a way I (as a layman!) can understand. I feel like I was avoiding series purposefully to avoid cooking the battery but perhaps that's something I read with my original pwm controller but I can't remember for sure. Series seems like the way to go, can't wait to get them re-jigged... I'll be up there tomorrow! ?Yup! They're magical! Just make sure you connect the battery FIRST so the controller knows what voltage it's supposed to work with. With some controllers if you plugged in the panels first it thought you had an 18v battery and cooked!
When in parallel the VOLTS stay the same to the lowest common value (which is why mixing & matching can be a bit problematic) but the AMPS going out add up together. So, 3 panels at 100w rating are probably something like 20v @ 5a. 20v * 5a = 100w. 3 in PARALLEL will be 20v * 15a = 300w!
When in SERIES it's the other way around, so those same panels would be 60v * 5a = 300w because the AMPS stay the same but the VOLTS add together.
The MPPT is going to convert that voltage and amperage coming in to whatever volts you need going out at however many AMPS the controller and/or panels can produce. In your case, and this is all perfect world concept math here, you'd have 60v * 5a = 300w coming in, but your battery wants 12v to charge, so the MPPT is going to take that 300w and put out 25a because 12v * 25a = 300w.
The MPPT controller will try to start charging the battery as soon as it has enough voltage to work with. When your panels are in PARALLEL that means all 3 panels have to get over 12v before anything happens. In SERIES each panel only has to get over 4v because 4v *3 panels = 12v. Now that cloudy day is producing jjjuuusstt enough power to at least get Something going into the batteries.
Like I said, Magic!
And rough concept napkin math. ?
Yup! They're magical! Just make sure you connect the battery FIRST so the controller knows what voltage it's supposed to work with. With some controllers if you plugged in the panels first it thought you had an 18v battery and cooked!
When in parallel the VOLTS stay the same to the lowest common value (which is why mixing & matching can be a bit problematic) but the AMPS going out add up together. So, 3 panels at 100w rating are probably something like 20v @ 5a. 20v * 5a = 100w. 3 in PARALLEL will be 20v * 15a = 300w!
When in SERIES it's the other way around, so those same panels would be 60v * 5a = 300w because the AMPS stay the same but the VOLTS add together.
The MPPT is going to convert that voltage and amperage coming in to whatever volts you need going out at however many AMPS the controller and/or panels can produce. In your case, and this is all perfect world concept math here, you'd have 60v * 5a = 300w coming in, but your battery wants 12v to charge, so the MPPT is going to take that 300w and put out 25a because 12v * 25a = 300w.
The MPPT controller will try to start charging the battery as soon as it has enough voltage to work with. When your panels are in PARALLEL that means all 3 panels have to get over 12v before anything happens. In SERIES each panel only has to get over 4v because 4v *3 panels = 12v. Now that cloudy day is producing jjjuuusstt enough power to at least get Something going into the batteries.
Like I said, Magic!
And rough concept napkin math. ?
Thanks! I'll definitely have a look at this today! I'm pretty sure the open circuit for each panel is 20v... So 60v for all three in total. Will check the mppt, not sure on that. I know it's a 30amp controller that's about it.Do check that the total open-circuit voltage of your series string does not exceed the maximim input voltage of your MPPT (which may vary with the system battery voltage, check the manual).
Go over voltage and the Magic Smoke may exit
Wow brilliant and ah thanks! ??That's 176.9 Watts, pretty good for a 200W system
The "kWh" figure is how much energy your panels have generated and banged into your batteries.
Cheapie leisure batteries? Those are Flooded. The only effective difference for you between Sealed and Flooded is that the Sealed (AGM) won't do the 15v equalization charge once a month. I wouldn't worry about changing the max voltage or anything unless you're having to refill the water a lot.
Rednecktek - you're a lifesaver. I didn't expect to need to 'maintain' the batteries, not a topic I've come across even in my hours and hours of research for the solar setup.
