Need a little help with some numbers please?

Can someone please tell me what voltage these panels are....after a bit of research i think they are 24v nominal?

Just wondering how i should have them set up and with charger / inverter im should be looking at?

I want to start off with a 24 volt battery 7s60p 18650 setup to get things going and understand how it all works better etc. I wont be running a whole house just a small fridge and tv to start off in garage.

Very new to it all , thanks in advance.



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Well it is right there...
Open circuit voltage is 44,5V ( this is with full sun and no load on them )
And voltage with full sun and max load is 37V. (this is the nominal voltage )
The 1000V max system is the max voltage they can have in series ( like max 27 in series )
Your inverter solar input (mppt?) voltage will decide how to set them up ( parallel or series ora combination ) you can find this in the datasheet of your inverter.

Oh i see i thought it was all about the 12,24,48 der lol im off to a good start . Thanks for making it clear. Will need more researching.
Is there a recommended way to have panels as in 2s 4p or again it comes down to which pip i would like....?

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Yes, it is the pip ( or other) has the last word in this...

To keep in mind if you still need to buy a inverter:
Higher voltage ( more panels in series ) means thinner wiring between panels and inverter.
Panels in parallel are less sensitive to shadow on the panels.

Ok great. Cheers makes sense about the series vs parallel.

I got the panels basically for free so that's where im at with components, i also have a little bit of info i have learnt so far in here and usual Google / youtube.

Im leaning towards the 2424MSE (40A MPPT) type or similar , but now that i understand the values i think it may not be suitable. Total watts of panels is too much?

Is it better to start off with a separate charge controller and an inverter?




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Yes, you can consider this to be a 24V module. How many of them do you want to use? This dictates what kind of controller you should use. Inverter can be separate, depends on your use case and what you want to do in the future. If you stick to smaller units then you will likely use separate units. From around 1000W and up you can find combined charge controllers and inverters, below that they are usually separated.

Also with solar configurations you need to take in consideration all of your equipment. So look at the voltages your charge controller and when hooking up your panels the more you put in parallel the amps are additive and panels in series the voltage is additive.

Now with this in mind your cable size from your panels to the controller needs to be sized correcly. The lower you can keep the amps the smaller the wire you can use therefor the cheaper it is.

In a perfect world you would use all in series to get all the volts but low amps and run 10guage wire. But with shading issues on any panel can cut all current from the panels.

But it all depends on what you have\want to do.

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DarkRaven said:

Yes, you can consider this to be a 24V module. How many of them do you want to use?

Click to expand...

how do you figure since full load it says 37V ? To go to 24V he'd need something to drop the voltage down

That's what all solar charge controllers do, solar voltage is always above the system voltage. On my temporary 12V system the panel has a Umpp of 17.44V. To do effective DC-DC conversion you need a gap between the input and output voltages.

Have a look at the recommendations from the manual for my controller:



This shows the number of panels you should put in series, based on the type of panel and your desired system voltage.

The 2424 MSE has a solar panel input (PV input) maximum 100V - 40A. so you can have only 2 solar panel in serie (37vx2=74V).
If you go to 3S it will be 37v x 3 = 111v, it's to hight !
if you want to increase power you will have to connect other panel in paralele Maximum 2S - 7P (35,5A)
how many panel do you have .

cristof said:

The 2424 MSE has a solar panel input (PV input) maximum 100V - 40A. so you can have only 2 solar panel in serie (37vx2=74V).
If you go to 3S it will be 37v x 3 = 111v, it's to hight !
if you want to increase power you will have to connect other panel in paralele Maximum 2S - 7P (35,5A)
how many panel do you have .

Click to expand...

Hi everyone thanks for the replies...i see me being a little confused is ok now.. some websites i have looked at say i have a 24v panel under load. So now i probably better off looking at the pv numbers and match them.

So im thinking i can run the 2424mse panels at2s3p ? I will leave 2 panels off and just run 6 for now till i get more advanced with cells etc.

Will this work ? 2424mse with 6 panels in 2s3p?

I guess i also better confirm if this charger is ok with 18650 powerwall projects? Does it need different software or just a settings adjustment.

Cheers for you help.

Yes, it will be OK.
Your Solar panel system will be :

U = 37 x 2 = 74V (under load)
I = 5,1 x 3 = 15,3 A
it will give around : 1100W (under full sun)

The electric cable from panels to PIP must be at least 6mm2 (if it's a long cable go to 10mm2)
You wll have to set parameters in the PIP regarding your lithium lon 18650 battery

Excellent thanks for the extra info about cables.

Just one question about the amps you quote would the total be 2 x that into the pip ? 30amps.

Your panel can give 5,1 A full sun
2 panel in serie will give 5,1A full sun .
As you will run 3P, your amps will be 5,1 x 3 = 15,3 A.
so you will send to PIP solar input maximum 15,3 A (full sun)

It's always the same, connection in series affects voltage, connection in parallel affects current and 2s3p therefore means doubled voltage and tripled current

Cool i was thinking each string of 3p would both produce 15a 37v thenin series it would double....but its only voltage.... Man im definitely gonna need more research and questions before moving on. Really appreciate all your help and knowledge. All part of learning i guess.Thankseveryone.

Ps anyone else having trouble with taptalk ?

Lots of this is covered elsewhere, sorry if it's repeating/obvious for some....
Could you connect one of these panels direct to a 24V battery, yes, would that be a good idea? No.
Like the label says that panel will put out up to 44.5V. If you don't have a controller to stop it, this would fry a 24V battery eventually.
Remember Lithium cells are not tolerant of overcharging or over discharge & will die soon.
Sounds like you've figured out you do need a controller, great

Max power:
To get the most power out of a panel, the panel(s) need to run at their max point point for voltage & current.
Power = V x I.
If you direct connect that panel to a battery at 24V, Vpanel = Vbattery, current out would be somewhere between the short current (5.92A) & the max power current (5.1A), say 5.5A
So power into battery is only = 24 x 5.5A = 132W.
If you connected the panel via a real MPPT charger, the charger will let the panel work at it's max power point & deliver more current to the battery, eg Vpanel = 37V, Imax point = 5.1A
So power collected = 37 x 5.1 = 188.7 ie heaps more.
Real measured numbers are probably going to be a bit lower for many reasons but you get the idea.

With a charge controller, it needs to be able to take the max voltage & current the panels can put out.

So for the max voltage, this would be eg when the batteries get to full & little current is being pulled from the panels so they rise up to the Voc voltage (44.5V)
For two panels in series, double this & the controller will be getting nearly 90V at it's input. Three panels (133.5) would pretty likely cause failure of a 2424 MSE.

For the current in & out of the charger, with the controller running the panels at max point point, the amps out of the controller can be found like this:
Power in divided by battery voltage. ie Pin/Vbat = Iout
So Pin = 188.7 from above, Vbat =24V so it's 188.7/24 = 7.86A for one panel

If you put two panels in series at max power then numbers would be:
(37 x 2)V x 5.1A = 377.4W. Then MPPT charger does it's step down thing: 377.4 W in/24V bat = ~15.7A

If you did the panels 2s2p, (ie 4 panels in 2 series strings which are in parallel) then you'd be getting:
(37 x 2)V x (5.1 x 2)A = 754.8W. After the charger it'd be 754.8/24V = 31.45A
Keep an eye on the current the cables can take!

Hope that helps.