Noob question about charge controller

[Tallguy]

So, I have a 10a controller. If I attach 3 100w panels in series, I will in theory producing at 50+ volts. If I am producing 12v output, am I going to have over amp issues with the controller? Thanks, and remember, we learn from you, so please, if you are going to faceplant, do so quietly

 

[sunshine_eggo]

Depends on the controller.

If it's PWM, the controller will force the panels to battery voltage severely limiting power.

PWM controllers also can't regulate current, so if the 3 panels in series can output more than 10A, you'll burn out the controller. 100W panels typically only output about 6A, so no worries there.

If an MPPT controller, they limit their output to the 10A rating at battery voltage, so in most cases, it's a non-issue.

What you are describing is over-paneling. Victron publishes over-paneling criteria - never exceed Voc and the PV input current limit, and you're fine. Some controllers like EPEVER place an arbitrary 150% rule, i.e., if the panel is rated for 150W output @ 15V, don't put more than 225W on it (150% of rated).

 

[Rednecktek]

With a 12v system and 300w of panel, you're leaving about 2/3 of your power on the table. The rule of thumb for 12v systems is 10a of SCC per 100w of panel.

The controller should be at least 30a and MPPT to really utilize those panels.

Fortunately you don't need to spend $$Money on something like a Victron or Midnight, you just need to convert solar DC into battery DC. Pro tip: if it has USB ports on it, it's a cheapie PWM in disguise and ripping you off.

 

[sunshine_eggo]

With a 12v system and 300w of panel, you're leaving about 2/3 of your power on the table. The rule of thumb for 12v systems is 10a of SCC per 100w of panel.

The controller should be at least 30a and MPPT to really utilize those panels.

Fortunately you don't need to spend $$Money on something like a Victron or Midnight, you just need to convert solar DC into battery DC. Pro tip: if it has USB ports on it, it's a cheapie PWM in disguise and ripping you off.

Amazon prices:

Renogy 30A: $110
Epever 30A: $128
Victron 100/30: $128

What were you saying?

 

[Tallguy]

Depends on the controller.

If it's PWM, the controller will force the panels to battery voltage severely limiting power.

PWM controllers also can't regulate current, so if the 3 panels in series can output more than 10A, you'll burn out the controller. 100W panels typically only output about 6A, so no worries there.

If an MPPT controller, they limit their output to the 10A rating at battery voltage, so in most cases, it's a non-issue.

What you are describing is over-paneling. Victron publishes over-paneling criteria - never exceed Voc and the PV input current limit, and you're fine. Some controllers like EPEVER place an arbitrary 150% rule, i.e., if the panel is rated for 150W output @ 15V, don't put more than 225W on it (150% of rated).

Non issue melting wise, but not utilizing the full power produced?

 

[Tallguy]

Non issue melting wise, but not utilizing the full power produced?

If mppt, which it is.

 

[sunshine_eggo]

If mppt, which it is.

If an MPPT controller, they limit their output to the 10A rating at battery voltage, so in most cases, it's a non-issue.

What you are describing is over-paneling. Victron publishes over-paneling criteria - never exceed Voc and the PV input current limit, and you're fine. Some controllers like EPEVER place an arbitrary 150% rule, i.e., if the panel is rated for 150W output @ 15V, don't put more than 225W on it (150% of rated).