Two different solar arrays to charge MPTT (EpEver Tracer 30A)

[ilithium1978]

Hello to everybody!

I have two solar arrays that will have to charge a 100AH lithium battery (LifePo4), before i was just using a cheap 30A PWM to charge 100AH lead acid battery so things were more simple.
I have configured the settings in Epever Tracer 30A with the add-on of MT50, i have lot of questions also about lithium charge that i will post in another thread.
Is it ok to charge from two different arrays and how should i play with the connections?
I understand that is winter but on a sunny day i will only get about 6-10A and this is about 150W max instead of 400W at least with this setup .. it takes ages to charge the 100AH lithium battery with such low current.
The setup is complicated cause i have some panels (in parallel) on the ground and another array (also parallel) on the roof. Both setup will connect to the same +/- of the MPTT controller.
Array 1 = 3x100 Fuji Fwave 320V that step down to 14.6 and then will go to the EpEver (those panels will give 320V but with step down will go to 14.6 Volt and then deliver to the MPTT)
Array 2= 5x50W 17V panels that will also go to the same +/- EpEver Tracer input for Panels

Some important notes: Charger is 30A maximum but all together will not boost more than 15A now in winter time. Specially the Fuji Fwaves will see not much sun.
Is it ok or is it worse for MPTT that one array is in more shady place and other array will receive more sun?
All of them connected in Parallel .. i plan to play also with the 5.50W in series (Can i have the 3x100W in parallel and somehow increase the current from the other 5x50W in series?)

Maybe should i take out the 320V from the roof for good as they do not seem to product good energy on winter?

Thank you!

 

[snoobler]

Arrays into the same controller need to have the same or highly similar Voc and Vmp.

What you describe does not sound workable.

Please link to technical data on the Fuji Fwave 320V.

Not sure how it's being stepped down, but 14.6V is probably below the MPPT range of the 12V SCC, and this may be a hinderance to their output. Additionally the 2nd array in parallel with the Fujis will be forced to work at the lower voltage and will produce 20% below what they would product on their own.

 

[ilithium1978]

This is what i thought also.. I think tommorow i will work with two options:
1) see if the step down converter can step it down to same voltage of the second array (arround 17V)
2) disconnect the 3x100 Fuji Fwaves from the roof and play only with the 5x50W and connect them in series. Actually i will only try the 4x50W in series so i will not overload the 100V peak of the MPTT controller. Or do you have something to suggest like 3 in series and 2 in parallel??

 

[snoobler]

2S3P or 3S2P will give improved low light charging (dawn and dusk) due to the higher voltage.

2S3P will probably be optimal, but if you have long wire runs to the SCC, 3S2P might be a little better.

 

[ilithium1978]

long wire, around 10M to the MPTT charge controller and i am really really thirsty now for amps during to winter/cloudy conditions.
I would be happy to get at least 15A for 4 hours on a sunny day (let's say from 11.00 - 16.00)
I will try your suggest, i am a little bit disappointment that i might have to disconnect the 3x100W on the roof but those were almost not taking sun at all so i think they were even affecting the other array that is taking sun (on a sunny day of course!)

Something else and please correct me if i am out of topic:
Is it ok that now i charge with slow current the lithium battery and it's almost never possible to reach 100% charge? (guess is better but need to ask)
Voltage is set correctly to 14.6 and MPPT will do it's job ... i am still learning how lithium suppose to charge !! (maybe i get low current sometimes (around 4A) because battery is approaching 100% ? )

 

[snoobler]

Since you're low PV current, it's unlikely that 2S3P or 3P2S will make much difference.

If you can regulate the Fuji to closer to the Vmp of the other array, that's what I would do. Poorly performing panels are better than none provided they don't take others down with them.

LFP doesn't care about charge current as long as it's below the rated (typically 0.5C or higher), and it's very common to charge them short of 100%.

They are quite happy hanging out at 50% SoC for years.

The only real concern is low temperature charging. They shouldn't be charged below 0°C.

 

[ilithium1978]

Snoobler thanks so much for your infos, much much appreciated cause just got the LifePo4 lithium battery and i am so worried!
With the old Lead Acid i wouldn't care so much , each array actually had different SCC and then both of them would charge the same battery (fujis had 30A cheap PWM and the normal voltage 5x50W a 15A cheap MPPT)
0C you mean ambient temperature?? The minimum would be maybe in the next months around 10C so i guess is ok?
Your suggestion is also correct and a bit concern for me also (about the 3x100 Fuji fwaves) that i should also find a way to balance with the other array and play good together. Cause the other array to be honest even in summer would give maximum 12A (and normally should give 16.5A)
Crappy old panels and even the x2 50W i found recycled and just added them to this array to give at least 3-4Amps more!

 

[snoobler]

0°C battery temperature.

With 5 panels, you're stuck with 5S with a MPPT capable of 150V or 5P.

I'd put the PWM controller back on with the FUJI's connected.

 

[DIYSteve]

I have two solar arrays also using two EPEVER Tracer BN series controllers. One is a 40a controller and the other is a 30a. Originally I purchased a 40a but they accidentally sent me a 30a, when I bought it to their attention they quickly apologised and sent me the 40a. I tried a few times to asked them if they wanted me to return the 30a or pay for it but they just kept replying with smiley faces so I eventually gave up and set up a second array and increased my setup to include a second array. I have a total of 1800 watts of panels set up in series pairs and increased my 12v AGM batteries to 985 Ah. I will go to lithium batteries in a few years when prices are more affordable but I want to eventually get another EPEVER Tracer BN controller and install a third array.
Since I changed from parallel panels to series to get about 38-40v incoming the current almost triples and charges the batteries much faster. I try to always use identical panels in series with one exception but all is working great.
Recently I added a 3000w (6000w peak) inverter to run my household fridge, computer, monitors PC and screens also on a good UPS), lounge entertainment system and a few other small things. My house lights are all LED lights straight off DC.
With the inverter I added a Victron Battery management system, 200 amp resettable fuse and an dual input auto switch to put everything back on mains when the Victron detects batteries drop below 12v and switch back on soar/inverter when batteries get back to 12.8v.
When you have a proper MPPT Solar Controller you should always use series pair panels, the efficiency is so much better not to do it.

 

[DIYSteve]

I have two solar arrays also using two EPEVER Tracer BN series controllers. One is a 40a controller and the other is a 30a. Originally I purchased a 40a but they accidentally sent me a 30a, when I bought it to their attention they quickly apologised and sent me the 40a. I tried a few times to asked them if they wanted me to return the 30a or pay for it but they just kept replying with smiley faces so I eventually gave up and set up a second array and increased my setup to include a second array. I have a total of 1800 watts of panels set up in series pairs and increased my 12v AGM batteries to 985 Ah. I will go to lithium batteries in a few years when prices are more affordable but I want to eventually get another EPEVER Tracer BN controller and install a third array.
Since I changed from parallel panels to series to get about 38-40v incoming the current almost triples and charges the batteries much faster. I try to always use identical panels in series with one exception but all is working great.
Recently I added a 3000w (6000w peak) inverter to run my household fridge, computer, monitors PC and screens also on a good UPS), lounge entertainment system and a few other small things. My house lights are all LED lights straight off DC.
With the inverter I added a Victron Battery management system, 200 amp resettable fuse and an dual input auto switch to put everything back on mains when the Victron detects batteries drop below 12v and switch back on soar/inverter when batteries get back to 12.8v.
When you have a proper MPPT Solar Controller you should always use series pair panels, the efficiency is so much better not to do it.

Sorry for the long winded reply