Multiple Solar Controllers????

[goeasy123]

I'm getting confused. Please check my logic?

I want to put PV on the side rails. The original plan was 2 X 200W panels, one on each rail, wired in series into 1 MPPT. But the new plan is...

2 X 100W wired in parallel on each rail, 4 in total. This gives nominal 24V giving me a higher differential V between the 12V battery bank and the PV so the MPPT kicks in earlier... and less PV amps = less loss and thinner wire.

2 Victron 100/30's, one for each rail set. One Smart and one Blue. Do they both need to be Smart.

Both MPPT's are switched on their inputs simultaneously with a 4 pole 32A DC disconnect switch. Is this a problem?

Can I improve on this design?

[dksail]

You will want to wire each set of 2 panels in series to increase the voltage. You will need to refer to the panel specs to make sure the Vmp matches your controller when in series.

If you don’t have both Smart controllers, you will only get one on Bluetooth unless you buy a dongle for the blue one. Makes more sense to me if they are both Smart.

I would need more details on how you plan to fuse them and combine them before I can comment on the shutoff.

[goeasy123]

Originally Posted by dksail

You will want to wire each set of 2 panels in series to increase the voltage. You will need to refer to the panel specs to make sure the Vmp matches your controller when in series.

If you don’t have both Smart controllers, you will only get one on Bluetooth unless you buy a dongle for the blue one. Makes more sense to me if they are both Smart.

I would need more details on how you plan to fuse them and combine them before I can comment on the shutoff.

Sorry... I meant 'serial'. Well spotted.


I haven't use a Victron MPPT. I thought you only need one Smart to monitor the batteries, but I looks like you need a Bluetooth connection to set it up as well. Therefore get 2 Smarts. Am I right?


I'm thinking of using a DC switch like this https://www.ebay.co.uk/itm/32A-2-POL...-/224149506218


I assume 4 POLE means I can input the 2 PV circuits, switching both +ve and -ve wires and output the same (4 wire out). Then connect to a +ve and -ve battery bus with 2 x 40A midi fuses on the +ve ouputs as near to the bus bar as possible.


Can I get away without fuses on the PV feed to the MPPT?

[goboatingnow]

Yes. You need Bluetooth to facilitate synchronised mppt charging

[dksail]

I always include a disconnect between the panels and the controller. I do not fuse that connection. Provide the correct fuse between the battery and the controller. You can combine the outputs of the controllers essentially putting them in parallel, and then to the battery. I am not familiar with that 4 pole disconnect you mentioned.

[goeasy123]

Originally Posted by dksail

I always include a disconnect between the panels and the controller. I do not fuse that connection. Provide the correct fuse between the battery and the controller. You can combine the outputs of the controllers essentially putting them in parallel, and then to the battery. I am not familiar with that 4 pole disconnect you mentioned.

Thanks.


The original plan was for a Victron 100/30, but I've put the 2 x 100W in series into Victron's calculator and it says a 75/15 will do it, only with power limiting at low temperature (-10C). Is there any advantage in using an over spec'd (say a 100/30) controller over a lower spec?.... or was that just the sales guy trying to get me to spend more money than I needed to?


There's a big difference in price!!

[dksail]

I would think the 75/15 would be just fine.