Why am i getting this much amps?

[Mickie]

I have 2 solar panels connected in series the specs are in the pics. How ever on my charge controller im seeing over 20amps. Why is the amprage that high?

 

[Mattb4]

W=VA

The watts incoming from the panels at a higher voltage will produce higher amps at battery voltage.

 

[upnorthandpersonal]

Always remember:

 

[sunshine_eggo]

Power in = power out

V_in * I_in = V_out * I_out

Since your panel voltage, V_in is higher than battery voltage, the battery current at battery voltage will be higher than the panel current.

At battery: 27.9V * 16.2A = 452W

which is really close to the 440-463W power reported by the MPPT.

Using your panel numbers:

2X Vmp = 70V
1X Imp = 9.79A

In a perfect situation, you would get 70*9.79 = 685W

685W at battery votlage would be, 685W / 28V = 24.5A

 

[Mickie]

W=VA

The watts incoming from the panels at a higher voltage will produce higher amps at battery voltage.

Shouldnt the Amps stay at the max amp for 1 of the panels? Or am i not understanding correctly?

 

[Mickie]

Power in = power out

V_in * I_in = V_out * I_out

Since your panel voltage, V_in is higher than battery voltage, the battery current at battery voltage will be higher than the panel current.

At battery: 27.9V * 16.2A = 452W

which is really close to the 440-463W power reported by the MPPT.

Using your panel numbers:

2X Vmp = 70V
1X Imp = 9.79A

In a perfect situation, you would get 70*9.79 = 685W

685W at battery votlage would be, 685W / 28V = 24.5A

This explanation helps

 

[sunshine_eggo]

This explanation helps

Of you had a PWM controller, they work by shorting the panels to the battery, not by converting high voltage/low current to low voltage/high current. In this case you would not see current above panel specification UNLESS you had the two panels in parallel. In that case, you would see no more than 2X panel current.

 

[Mickie]

Of you had a PWM controller, they work by shorting the panels to the battery, not by converting high voltage/low current to low voltage/high current. In this case you would not see current above panel specification UNLESS you had the two panels in parallel. In that case, you would see no more than 2X panel current.

Yea this is the reasoning i had in mind y i kept wondering why the amprage went up that high. Thanks for vlearing this up for me.

 

[Mickie]

That being said. I now have 2.5mm² wire running from my panels to charge controller. Would it be good to change from the 2.5 to 6mm²?

 

[chrisski]

I use a voltage drop calculator to see if it’s worth it.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

This one is AWG, not mm2.

I don’t know until the numbers are ran.

 

[sunshine_eggo]

That being said. I now have 2.5mm² wire running from my panels to charge controller. Would it be good to change from the 2.5 to 6mm²?

2.5 is just under 13 gauge and can just handle 10A, so you should be good; however there may be losses. 6 is closer to 10awg and can handle 30A. If you ever plan to expand the array or want to do a long run, 6 would be preferred.

 

[Mickie]

2.5 is just under 13 gauge and can just handle 10A, so you should be good; however there may be losses. 6 is closer to 10awg and can handle 30A. If you ever plan to expand the array or want to do a long run, 6 would be preferred.

I will be expanding to a 2s2p array eventually.

 

[DIYrich]

Shouldnt the Amps stay at the max amp for 1 of the panels? Or am i not understanding correctly?

Let's say your panels are at 480v @ 1 amp. That would be 48v @ 10 amps to the battery (less conversion loss).

 

[sunshine_eggo]

I will be expanding to a 2s2p array eventually.

With 2P, your panels could put out 20A. >3.31 would be needed. 6 would be better.

 

[Mickie]

With 2P, your panels could put out 20A. >3.31 would be needed. 6 would be better.

Yea i will be changing to 6mm² before i go 2s2p.

 

[Pierre]

Another reason why I prefer a large series string of PV panels - you trade high voltage , low current at the panels for a lower voltage but large current at the battery. Also , I can then switch the PV 250v over to the heating element in the water tank using timer switches and the thermostat.