Good evening from central idaho, I am going off grid and thought yeah solar will be easy enough, enter my humble pie. I seem to be having issues with my system. Right now on the roof I have two 40 volt panels rated at 355 watts and three 12volt panels rated at 50watts. At the moment they are wired in series but i have stuff on order to change that to parallel. That runs down to this my charge controller/ inverter from mpp solar. From that I have my batteries ( 5 12v deep cycle set up as 24v ) the 120 line runes to a breaker panel that then wires to the house. My problem is it won’t charge my batteries but it did before. And when I looked this afternoon with just the 355watt panels hooked up I have incoming wattage of 20? What am I doing wrong ?
Issues
- Thread starter Jgoodman
- Start date
Are you saying that all 5 panels (2 355W and 3 50W) are in a single series string? That's a problem. Just use the 2 355W panels. A series string must contain only the same (or very close) panels. Even if you put the 2 355W panels in one string and the 3 50W panels in a second string and you then tried to connect those two strings in parallel, I don't believe that will give good results either.
You state that you have 5 12V batteries setup in 24V. That's not possible with an odd number of batteries. The only possible way to create a 24V battery bank with 12V batteries is with an even number of 12V batteries.
You state that you have 5 12V batteries setup in 24V. That's not possible with an odd number of batteries. The only possible way to create a 24V battery bank with 12V batteries is with an even number of 12V batteries.
I have two batteries wired in series and three batteries wired in series then I paralleled those two banks together, it reads 24volts dc on my meter, I had a feeling about the 50 watt panels, will correct in the am
So if I parallel all my panels would that work to use what I have
Your battery setup just won't work. 3 12V batteries in series is 36V. 2 12V batteries in series is 24V. Trying to parallel a 24V battery and a 36V battery is bad.
Wire up just 4 batteries in 2S2P for a proper 24V battery. But it's important that each pair in series have the same voltage and state of charge before you put them in series. You should first wire all 4 in parallel and charge them up (at 12V) and let them settle. Then rewire in 2S2P. That, combined with dropping the 50W panels should get you much better results.
This all assumes one or more batteries aren't permanently damaged from having them setup incorrectly.
I don't think that will work but you should do some searching here on the results of paralleling different sized panels. Other people are far more familiar with doing that than I am.
@Jgoodman
Mixing the panels to feeda single MPPT controller is not possible due to the significant difference in output.
Five batteries cannot be configured for 24V, consider yourself lucky, as doing what you did is potentially dangerous.
You may want to disconnect everything for now and study not only electrical fundementals, but also their relationship to solar applications, or ask questions before venturing into the unknown.
Please don't take this as an attack, it's not personal, it's in the interest of your safety.
Mixing the panels to feeda single MPPT controller is not possible due to the significant difference in output.
Five batteries cannot be configured for 24V, consider yourself lucky, as doing what you did is potentially dangerous.
You may want to disconnect everything for now and study not only electrical fundementals, but also their relationship to solar applications, or ask questions before venturing into the unknown.
Please don't take this as an attack, it's not personal, it's in the interest of your safety.
TomC4306
Solar Obsessive
TomC4306
Solar Obsessive
Do you still have all 5 batteries hooked up?
By the by, I get that I’m over my head on this. That’s why I’m reaching out. There’s very little that I have found on solar application. I figured that I could find plenty but it’s proven difficult for me. I get electricity, I deal with it daily with AC. The solar application is absolutely foreign. I wouldn’t ask for the help without expecting some constructive criticism. Just wanting to get running is all. I will add a third battery to the two batt bank so they are balanced tonight, let them c
Yes, I need to get back to the property to change it
You should not make use of this system in any way until the battery configuration is resolved and you verify none of the batteries are ruined.
What do you mean by "add a third battery"? You have five. You can add one more for six. But make sure you have them setup in 2S3P, not 3S2P. The former gives you a 24V setup. The latter gives you a 36V setup.
Bob B
Emperor Of Solar
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What they are saying is that if you have a 24V system .... that would be 2 batteries in series .... not 3.
So, if you have 6 batteries, you will want to put them in pairs in series .... to make 3 24V batteries .... then put those three batteries in parallel.
3 in series is 36V ... not 24V.
The designation for that setup is 2S3P ... broken down to 2Series .... then 3Parallel.
So, if you have 6 batteries, you will want to put them in pairs in series .... to make 3 24V batteries .... then put those three batteries in parallel.
3 in series is 36V ... not 24V.
The designation for that setup is 2S3P ... broken down to 2Series .... then 3Parallel.
Here's a rough diagram. Each pair of batteries in a dashed box represents two batteries in series (the 2S). Two 12V batteries in series gives 24V. You have 3 pairs of these 24V batteries in parallel (the 3P). 3 sets of 24V batteries in parallel is still 24V but it's 3 times the amp hours.
The three series wires (horizontal in the diagram) between each pair of batteries should be the same length as each other.
The four parallel wires (vertical in the diagram) connecting the three pairs together should be the same length as each other.
The wires going off of the opposite corners are where you want to hook up your stuff to be batteries. It's best to connect to opposite corners when you have batteries in parallel.
The three series wires (horizontal in the diagram) between each pair of batteries should be the same length as each other.
The four parallel wires (vertical in the diagram) connecting the three pairs together should be the same length as each other.
The wires going off of the opposite corners are where you want to hook up your stuff to be batteries. It's best to connect to opposite corners when you have batteries in parallel.
Thank you so much for those explanations bob b and r maddy. That is exactly what I was looking for. Right now it’s hooked up with 2 banks of two batteries or 2s2p. The batteries in question are all healthy and I have 4 hooked up as I took the third in the one bank off so as long as I add the two batteries as a third bank as you have shown in your diagram I am golden. Sorry, I’m very new to solar and DC power
Bob B
Emperor Of Solar
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- Messages
- 8,870
There's a lot of people on here that know more about them than I do .... you will keep learn by asking questions and reading others posts.
Pretty soon you can answer questions.
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,844
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