Which MPPT/PWM controller between sun panel and LiFePO4 battery?

[labora]

If there is an option, I STRONGLY recommend the Smart version with Bluetooth.

• Victron SmartSolar has Bluetooth
• Victron BlueSolar has no Bluetooth.

Isn't that confusing? Victron BlueSolar can be equipped with a separate Bluetooth dongle.

 

[labora]

Just one last thing: I've read some information on fusing or applying a breaker with panels in series. I've ordered a Victron SmartSolar MPPT 100|30 and two ordinary 405 Wp panels and 6 mm2 wire for use in series. Being able to disconnect between controller and panel is something I understand but the reasoning for a fuse or breaker... I don't get the reasoning so I assume no it is save not to use a fuse or breaker. Correct me if I am wrong please.

 

[MisterSandals]

so I assume no it is save not to use a fuse or breaker. Correct me if I am wrong please.

It’s not awful for a 2 panel array to not have a breaker or fuse but you will REALLY want to have a switch and a breaker is a good switch/fuse combo.

 

[labora]

It’s not awful for a 2 panel array to not have a breaker or fuse but you will REALLY want to have a switch and a breaker is a good switch/fuse combo.

I was in doubt using an extra set of connectors or using a breaker. In both cases there is an extra contact resistance (< 100 µΩ). A breaker has an additional power usage which can be neglected - which is not the case when using thermal fuses. So a breaker it is. I have values for Short Current and Max Power of the panel: Isc = 13.9 A and Imp = 13.0. I see people multiply by 1.25: 17.4 A. So a breaker of 20 A should do the job. How about that? And than the big question: What could ever make it trip (the part I don't get)? Lightning I understand but accidentally shorting a battery on the roof is not obvious

 

[mikefitz]

Actually it's a current source on the roof. Any series breaker or fuse in a series single string of panels will never trip/fuse, lightning excepted. It seems to make folk more comfortable with the system.
Note when maintaining the system the Victron controller can be disabled via the app.
Also note after the Initial connetion to to the battery the unit remembers the working voltage and is not confused by any subsequent disconnection from the battery.

Mike

 

[labora]

Actually it's a current source on the roof. Any series breaker or fuse in a series single string of panels will never trip/fuse, lightning excepted. It seems to make folk more comfortable with the system.

That confirms my thoughts, thanks for the tips.