Disconnecting Batteries with Solar?

Traveler7 wrote:

2oldman wrote:
There's no compelling safety reason for fusing solar. It's not like they are batteries capable of runaway amperage starting fires.

Well, A lightning strike on the panel might give you a compelling reason...

For sure.

I like that inline manual breaker that Denver Transplant linked to. Here: Inline breaker I used a Bussman manual breaker and they are twice that price. It sure is handy to have a switch on that circuit, though.

2oldman wrote:
There's no compelling safety reason for fusing solar. It's not like they are batteries capable of runaway amperage starting fires.

Well, A lightning strike on the panel might give you a compelling reason...

brulaz wrote:

Windy Nation Web Site wrote:
.. if you have 4 panels each capable of up to 15 amps, then a short in one panel can draw all 60 amps towards that short-circuited panel. This will cause the wires leading to that panel to far exceed 30 amps causing that wire-pair to potentially catch fire.

I suppose that's possible, but it's difficult to imagine any 15 amp panel sustaining a 60a load for more time than the wire.

I actually don't know too many people with 15a panels.

Thanks for the info!

Hi,

It is Pulse Width Modulation and essentially is a switch. That means it operates at about the battery voltage.

For LOTS of information surf here: https://www.victronenergy.com/upload/documents/White-paper-Which-solar-charge-controller-PWM-or-MPPT.pdf

EdTheEdge wrote:
What is a PWM controller?

EdTheEdge wrote:

What is a PWM controller?

In short it is one that operates at battery voltage and when it regulates (keeps voltage constant, absorption and float), it varries the width of the power pulse on ON and OFF, increasing OFF time means the power/current tapers as the batt charges at constant voltage. Pulse width modulation.

as opposed to MPPT that tracks the panel's power and tries to use its max power point and has internal gadgetry to convert this power to battery voltage for charging. It is my understanding that mppt controllers can be susceptible to damage if connected in the wrong order. max power point tracking

red31 wrote:

EdTheEdge wrote:
I have a Sunforce 30A solar controller When i replaced my house battery i called sunforce tech support and they told me "just replace the battery, disconnect and reconnect like normal". I did and it was not a problem.

Sunforce = PWM

The disconnect order warning is in many PWM controller manuals, these are the same controllers used in portable suitcases that would be a PIA to disconnect the panel/controller on a regular basis.

What is a PWM controller?

EdTheEdge wrote:
I have a Sunforce 30A solar controller When i replaced my house battery i called sunforce tech support and they told me "just replace the battery, disconnect and reconnect like normal". I did and it was not a problem.

Sunforce = PWM

The disconnect order warning is in many PWM controller manuals, these are the same controllers used in portable suitcases that would be a PIA to disconnect the panel/controller on a regular basis.

I have a Sunforce 30A solar controller When i replaced my house battery i called sunforce tech support and they told me "just replace the battery, disconnect and reconnect like normal". I did and it was not a problem.

2oldman wrote:
There's no compelling safety reason for fusing solar. It's not like they are batteries capable of runaway amperage starting fires.

True for most installations, but sometimes you should protect the wiring:

Windy Nation Web Site wrote:
Commercially made solar panels over 50 watts have 10 gauge wires capable of handling up to 30 amps of current flow. If you connect these panels in series, there will be no increase in current flow so fusing is not required for this string. This is not the case when you have panels connected in parallel, as when connected in parallel the system current is additive. For instance if you have 4 panels each capable of up to 15 amps, then a short in one panel can draw all 60 amps towards that short-circuited panel. This will cause the wires leading to that panel to far exceed 30 amps causing that wire-pair to potentially catch fire. In the case of panels in parallel, a 30-amp fuse is required for each panel. If your panels are smaller than 50 watts, and use only 12 gauge wires, and 20 amp fuses are required.