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kittysmitty
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# Posted: 25 Apr 2023 16:43
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Thought I would start a new Post, this is a follow up to My Post "Maximum System Voltage" So I have picked up these two panels, specs attached. So what specs do I need in a charge controller? I want to wire in series to reduce wire size and loss. Thinking 80 amps? Input voltage at least 100 or better with 150. Your thoughts and comments please and Thank You
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gcrank1
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# Posted: 25 Apr 2023 18:51 - Edited by: gcrank1
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Voc = 49.09 (round up, call it 50)
It will spike in cold, add a 20% safety overhead = 60.
2 panels in series (in series voltage doubles, amps stay same); the scc needs to accept 120v input so you dont blow it in a cold weather spike. With that high an array voltage it will pose danger when working with it but can be placed well away for best solar exposure as the line losses will be reduced considerably (and smaller gauge wire can be used).
Current/Amps at max power = 10.27 (you are lucky to see 80% of that, just the nature of the beast).
What voltage dc to the bat-bank are you doing?
An mppt scc will take the array voltage and turn it into your bat-bank voltage IF you match them; ie, dont use a 24vdc output scc if bat bank is 48v.
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Brettny
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# Posted: 25 Apr 2023 20:34
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With that array voltage I wouldnt use any thing with less than 150v input. Why the 80a? Do you expect to add more pannels?
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kittysmitty
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# Posted: 26 Apr 2023 05:42
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gcrank1 The battery bank is currently 12 volt. My understanding with most MPPT SCC they will select the voltage to match the battery,
Brettny. The reason for 80 amps the panels would/could deliver 60 to 70 amps to the batteries. Is this correct?
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Brettny
Member
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# Posted: 26 Apr 2023 06:22
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Quoting: kittysmitty Brettny. The reason for 80 amps the panels would/could deliver 60 to 70 amps to the batteries. Is this correct
The specs would be about 68A at 12.5V. How ever if you get even 90% of the rated pannel output I would be very happy. It also dosnt include the MPPT/CC loss. Most CC you can over pannel. A 60A CC may be totally fine.
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gcrank1
Member
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# Posted: 26 Apr 2023 08:24
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My mppt scc will do 12 or 24v output, Not 48
Gotta check All the specs, do not assume Anything.
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Steve_S
Member
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# Posted: 26 Apr 2023 10:41
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I am sorry to say but this is terribly backwards...
First, you look at the battery system and what it will take to charge the batteries in question. This is how many Amps and how many hours in a typical day it takes to recharge them. For example, a 12V/100AH Lifepo4 Battery can take a MAX of 50A Charge for 2 hours to completely charge from 0% SOC. Or it can be 25A for 4 hours and so on...
Once you know how many Amps & Hours it will take then you work out what sized Solar Controller is needed to deliver the required amperage over the time (sun-hours) that are available in YOUR REGION. Then the next step is to work out how much solar input to the Solar Charge controller is required for it to do its job.
Virtually all Mid to High Grade SCC (Solar Charge Controllers) can service 12,24,48 Volt Battery Banks and they Auto-Sense what the battery voltage is when they startup and adjust accordingly. Note that not all SCC's are capable of this (becoming rare now).
Battery Chemistries are tricky when it comes to charge capacities. LFP is simple to work out because they can discharge at 1C Rate and take a Max of 0.5C Rate charge input. Therefore a 100AH Battery can discharge at 100A for 1 Hour and take 50A for 2 Hours to charge... Although we recommend to not exceed 0.3C or in this example 30A for just under 3 hours as that keeps the battery cells cooler and will prevent deviations within the cells.
Solar Controller vary a lot and you can find really cheap ones that work but not too well or go for serious Tier-1 Products which are very efficient and completely manageable. Note that a Top Quality 1st Tier SCC can cost up to $1,000 ea ! and YES, you get what you pay for !
Good General SCC's are available from EPEver, Triton & so one. Each will have specs for how many Watts/Amps are required to deliver the correct charge for the battery system. A few have online tools to work out how to optimally configure a solar array such as Midnite Solar Sizing tools (expensive Tier-1 Products).
IF you really want accurate and correct answers, then please provide all the information....
Battery Sizes & Type...
Target Voltage for Batteries 12/24 o 48V
Inverter Sizing in Output Watts
And any other relative info.
Good Luck.
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