Is it possible to overclock a victron 75-15 solar controller?

[marcello]

Hi
I have 3 x 100W panels in series on my Van's roof (to charge a 12v lifepo4), each panel can produce between 5-6A current at 18v. So it means I can produce between 15 and 18A max.
As you know the victron 75-15 is limited to 15A, but it would be great if I could reach say 16 or 17A... Is it possible?
I think in the app settings we can only set the current to 15A max, is there a way to circumvent this please? Thanks

 

[sunshine_eggo]

Hi
I have 3 x 100W panels in series on my Van's roof (to charge a 12v lifepo4), each panel can produce between 5-6A current. So it means I can produce between 15 and 18A max.
As you know the victron 75-15 is limited to 15A, but it would be great if I could reach say 16 or 17A... Is it possible?
I think in the app settings we can only set the current to 15A max, is there a way to circumvent this please? Thanks

No.

Consider that you're equating two different things. The PV current your panels can provide is not relevant to the 15A MPPT output. -15 means it can send 15A to the battery.

Power in = power out

Vmp * Imp = V_batt * I_batt

Vmp is higher than battery voltage, so Panel current will always be higher than battery current IF the charge controller can handle it.

300W /14.5V = 21A - that's the maximum theoretical output of a perfectly oriented panel at high noon on a perfect day.

Flat panels on a van roof with potential roof shading? No way you'll ever get peak power out of those panels. Never.

Also worth noting that your panels exceed the 15A PV input current limit of the unit:

 

[Will Prowse]

Agreed. Absolutely not.

 

[Rocksnsalt]

So I’m thinking the Victron 100/30 would be a better choice?
Or other charge controller that can handle over 20A, just in case extreme ideal conditions somehow occur.

 

[kayakingphotos]

Also worth noting that your panels exceed the 15A PV input current limit of the unit:

Panels in SERIES will multiply the short circuit current of the string?

if each panel is around 18 volts and 6 amps, wouldn't they produce 54 volts and still be 6 amps? As long as the open circuit voltage adjusted for temperature is below 75 volts, wouldn't that charger work? (obviously it will clip peak production to around 220 wats depending on battery voltage)

Patrick

 

[Rocksnsalt]

Panels in SERIES will multiply the short circuit current of the string?

if each panel is around 18 volts and 6 amps, wouldn't they produce 54 volts and still be 6 amps? As long as the open circuit voltage adjusted for temperature is below 75 volts, wouldn't that charger work? (obviously it will clip peak production to around 220 wats depending on battery voltage)

Patrick

Good catch, I missed SERIES in the op.

https://www.sunpoweredyachts.com/product-page/victron-energy-smartsolar-75-15

 

[sunshine_eggo]

Panels in SERIES will multiply the short circuit current of the string?

if each panel is around 18 volts and 6 amps, wouldn't they produce 54 volts and still be 6 amps? As long as the open circuit voltage adjusted for temperature is below 75 volts, wouldn't that charger work? (obviously it will clip peak production to around 220 wats depending on battery voltage)

Patrick

Good point.

Not everybody uses series/parallel correctly, and the effort to match the MPPT output to 3X the panel current strongly implied parallel.

On a van roof, if shading is possible, series may not be the best option.

 

[marcello]

Thanks guys for the help
I won't have any shading most of the time so series is the best setup for me.
6A is the max I will get at 18v so for 3 panels I'll get 6A at 54v.
The victron 15/75 is fine since it's for 15A at 75v, or I am missing something ?

Then since I have a 12v battery it means a current of 6*54/12 = 27A.
I know I'll never get this value since it is theoretical but maybe I can get 16 or 17A.
So it should be fine for the victron since it can handle 15A for the panels (meaning a lot more if converted for the battery).
I think I am confusing something but dont know what lol

 

[littleharbor2]

I thought I was losing it there till I read deeper into this thread. I'm surprised this one got by the pros here.

Your numbers are correct although you will have a potential Voc of 66 or higher depending on the expected low temprature in your area. You should be fine with 75 volts, max.

 

[PVorBust]

Panels in SERIES will multiply the short circuit current of the string?

No.
Panels in SERIES - the voltage ADDS, but the current remains the same. (the power ADDs)

Panels in PARALLEL- the current ADDS, but the voltage remains the same. (the power ADDs)

Nothing multiplies (ever).


The 75-15 will provide a max 15A charge current

 

[Q-Dog]

For 300 watts of panels at 12 volt, the Victron 100/20 would be a better fit.

 

[marcello]

Yes in series currents don't add.

Ok to be sure, the 15A limit of the victon is it for the panels current (in my case 6A) or for the battery current (in my case could be more than 20A theoretically) ?

If it is for the panels then I'm good so I can get more than 20A to my battery.
If it is for the battery then I will get 15A max.

 

[littleharbor2]

Yes in series currents don't add.

Ok to be sure, the 15A limit of the victon is it for the panels current (in my case 6A) or for the battery current (in my case could be more than 20A theoretically) ?

If it is for the panels then I'm good so I can get more than 20A to my battery.
If it is for the battery then I will get 15A max.

The 15 amp limit is for the input. The 75/15 rating on the controller is referring to the maximum charging output of the controller. You can over panel MPPT controllers, within reason without damage.. People do this , especially when solar conditions aren't optimum.

 

[pollenface]

You can add as many panels as you like, you won't get more than 15a to the battery. As stated above you'll get better results from 300w of pv with the 100/20 controller at 12v

 

[marcello]

The 15 amp limit is for the input. The 75/15 rating on the controller is referring to the maximum charging output of the controller. You can over panel MPPT controllers, within reason without damage.. People do this , especially when solar conditions aren't optimum.

By Input you mean the panels? And output the battery?
If so then it's fine I will only get 6A max at input.

Pollenface, yep I know but I have a limited budget, and all in all I know my panels wont produce much more than 200w so I dont think it is a useful expense for me.

 

[littleharbor2]

By Input you mean the panels? And output the battery?
If so then it's fine I will only get 6A max at input.

Pollenface, yep I know but I have a limited budget, and all in all I know my panels wont produce much more than 200w so I dont think it is a useful expense for me.

Yes and yes.

 

[marcello]

Yes and yes.

Thanks, so no need to overclock it, which is impossible anyway

 

[HRTKD]

Thanks, so no need to overclock it, which is impossible anyway

The Victron solar charge controllers are very programmable, but not THAT programmable.

I have 1,000 watts of panels connected to a Victron 100/20. To keep within the solar charge controller's limits I have them configured 2s2p in an east-west orientation.

 

[740GLE]

The Victron solar charge controllers are very programmable, but not THAT programmable.

I have 1,000 watts of panels connected to a Victron 100/20. To keep within the solar charge controller's limits I have them configured 2s2p in an east-west orientation.

100/20 and 1000w at what battery voltage?

How many Kwhr/day are you able to capture?

 

[HRTKD]

100/20 and 1000w at what battery voltage?

How many Kwhr/day are you able to capture?

12 volt system. It's my tent camping setup that uses my Board Build. I have no idea how much it pulled in per day. With two Interstate 12 volt Marine/RV batteries it kept things running good, powering my Starlink 24 hours a day and charging up phones and other small stuff with no problem.