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Six 290w solar panels for a 24v 1700w system using a 100/50 CC?

Thegreywizard

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Ok so I'm trying to figure out what my solar panel array should be.

I'm building a 24v Lifepo4 system, from my research it has a max input voltage of 1700w. I'd like to max this out as much as possible.

I think I'd rather have as fewer panels as possible, so I'm more interested in 6 290w panels than 17 100w panels

So I was considering these 290w panels for $150:


These panels have a Voc of 38.8

I was thinking of going with a Victron 100/50 charge controller because at $323, that's a great affordable price for top tier tech. So I was hoping it would work with my 24v system.

So I could run these 6 panels in 2s3p

How many Parallels can you run on a single charge controller?

Max Voc would be 77.6 and I live in Ohio, so that leaves plenty of room for cold temps doesn't it?

That would keep me under the max voltage, while still giving me plenty of headroom.

But technically 290x6=1740w

But is this ok to be over the 24v systems max input wattage of 1700w?

Is a 50 amp Charge Controller going to be enough?

How do I determine how many amps 6 of these 290w panels would utilize?

Thank you.
 
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you can run as many parallels as you want. the charge controller will only output what it can handle. so 1400W for the 100/50.

1700W of panels with a 1400W controller is a pretty good match
 
Ok thanks for that info.

I thought the 24v system was capable of 1700w, so you're saying the charge controller has a ceiling on it's capable input watts as well?

Is it wasteful to have 1740w available for a 1400w ceiling? Should I look at reducing the system by a panel?

The price on that Victron 100/50 is pretty killer at $323, but would it be worth upgrading to the next size up to max out the 1700w a 24v system is capable of?

What about the amps, how do I determine if 6 of these panels will leave enough head room on a 50amp CC?
 
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the charge controller has an output limit of 50A. it'll pull as much power as it can from the panels until it reaches its limit. a 1700W setup might only be able to supply 1000-1300W where you are
 
Ok so maybe I should up the panel array to 8 panels then, 2s4p

This would give me 2320w total and should be able to pull the max 1400 then pretty efficiently for my 24v system for a northern Ohio climate.

But what exactly is the 50A output tied to?

I'm trying to determine if I would need a 60A or 80A controller?

I think the Victron 100/50 should do the job, but I'm just not clear what the 50A is tied to. I know you generally don't want to max out amps like you do watts and it's always good to give yourself some head room so you're not blowing anything.
 
the 50A is what the mosfets on the inside can handle. victron is quality so there's enough overhead to run it to the max
 
I would go for 60A or 80A for future expansion and also to have head room. 50A (or 60A, or 80A) is the maximum batteries charging current the SCC can supply to the batteries.
 
Ok but I'm still confused as to what is creating these amps so I can add them up for a full system spec

Is it the solar panels themselves that are creating the amps the 50A is referencing?

If so what do I need to look at on the panel specs to figure out what each one is putting out to make sure I'm under the 50A threshold?
 
Ok so I'm not sure what voltage the panels are to choose the right ones on that calculator.

I don't see anything mentioned on those REC's I linked to in my first one.

Should I just assume they are 12v or are these larger panels above 250v usually 24v?
 
Ok but I'm still confused as to what is creating these amps so I can add them up for a full system spec

Is it the solar panels themselves that are creating the amps the 50A is referencing?

If so what do I need to look at on the panel specs to figure out what each one is putting out to make sure I'm under the 50A threshold?
The current rating on a SCC is the maximum output current rating. The voltage rating is the maximum input voltage. That is pretty confusing when you are starting out, so don't feel bad. The Victron you are looking at can take a maximum input voltage of 100V, and can output up to 50A.

You CAN NOT exceed the max input voltage without harming the SCC. On the other hand, the SCC will limit itself to the max output current of 50A, so you don't have to worry about that. For this reason it is common to "over panel" a system, having potentially more power into the SCC than it will use, and you don't have to worry about the SCC as long as your parallel / series configuration of panels doesn't exceed the max input voltage. This can be a good idea, since panels are cheap and you can potentially max out the power out of the SCC for more of the day and under less than ideal solar conditions.
 
Ok so I'm not sure what voltage the panels are to choose the right ones on that calculator.

I don't see anything mentioned on those REC's I linked to in my first one.

Should I just assume they are 12v or are these larger panels above 250v usually 24v?
You choose custom and then enter the actual numbers (Voc, Isc, etc) for your panels.

You don’t enter 12 or 24V for the panels. That’s not one of the values being asked.
 
Ok so I'm not sure what voltage the panels are to choose the right ones on that calculator.

I don't see anything mentioned on those REC's I linked to in my first one.

Should I just assume they are 12v or are these larger panels above 250v usually 24v?
I hadn't ever looked at the victron calculator. It seems you should pick "custom" for the panels, and the specs (Vmp, Imp, etc.) are in the spec sheet on the right side of the page you linked to.

Edit: I guess I replied a few seconds after @rmaddy. Great minds think alike! ;)
 
You can search how MPPT works.
 
If you're comparing a number of different panels for best solar charge controller fit when using the Victron calculator, download the spreadsheet version. You can enter a set of custom panels on one of the last tabs/sheets. That will allow you to flip between panels without having to re-enter data.
 
Ok so maybe I should up the panel array to 8 panels then, 2s4p

This would give me 2320w total and should be able to pull the max 1400 then pretty efficiently for my 24v system for a northern Ohio climate.

But what exactly is the 50A output tied to?

I'm trying to determine if I would need a 60A or 80A controller?

I think the Victron 100/50 should do the job, but I'm just not clear what the 50A is tied to. I know you generally don't want to max out amps like you do watts and it's always good to give yourself some head room so you're not blowing anything.
the 50a is the max amps on the output side... so at 24v x 50a= 1200 watts MAX 28v x 50a= 1400 watts MaX...... so at low battery charge you can only get 1200 watt... near the very end of charge you can get 1400w max no matter on how many panels you have.

also the 100 is max input Voltage (which I think you understand)
 
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