question

From previous answers both here on this forum and from a research paper I read - there is only a VERY MARGINAL benefit to have a separate MPPT - one for East and one for West.

I put one of my East/West installations on one 250/85 MPPT due to the cost saving of one Smartsolar over two.

If cost were not the driving factor as it seems from your explanation - Then I would rather install two MPPT's - one for east and one for west

Take special note that if using ONE MPPT on a East/West scenario - the modules on east and west must be identical in output and qty

I indeed have done the same, using MPPT 250/70 MC4 ve.can and will add my other string in parallel to this before I buy another controller. Its the only choice you have when running 48V battery. As the startup V is too close to the array Voc if you don't go above 2 panels per series in parallel array and 3 panels will exceed the MPPT 150 so its either MPPT250 with 3 panels series minimum or RS with minimum 5 panels in series. I didn't get the RS as its startup is 120Voc and the I don't think the invertor is as heavy duty as the Multiplus(II) and Quatro as it weighs nearly half. Just my observations. Also the MPPT in the RS doesn't talk to the network.

Bumping this thread as I'm having the same question. Two potential strings of 6 and 8 panels. If using the RS, I'd have each string in series, if using individual MPPT for each string, then probably 3s2p / 4s2p to keep the voltages in line.

@Lyndsay Cotton in the case of the RS, the 450/100 has two independent MPPT trackers so if set up with two strings on different elevations, it's fine, and that's what I'd have in my setup too.

It appears Victron would suggest leaning towards the RS unit as it's a "more modern" and provides total isolation between solar and battery which isn't the case with the other units. For that reason, I'm tempted to go that way as the cost of one RS isn't much different to two suitably sized SmartSolar MPPT units.

Hi i have x3 450/100 and very happy with the tracking they perform they start as the sun comes up and dont go off until it sets. I have 8x8 on one 6x8 on another and x6 on the third with room for expansion.

They switch between trackers well depending on what arrays have sun.

Well Pleased.

I was faced with this decision recently as well and ended up going with 2x MPPT 250/60 units. My array is entirely south facing on a single unshaded roof and consists of 6.8kWp of panels (425W * 16). I didn't want the complexity of combiner boxes and string fuses etc so I was limited to a 2x parallel configuration and since the Voc of my chosen panel is ~50V, I was limited to a 4x series configuration per string with the 250V controller. So essentially I have two sub-arrays configured as 2p/4s with Voc around 200V and Isc around 21A. In my case these sub-arrays are both south facing but they could equally have been east-west.

Here is the comparison I did at the time bearing in mind the RS 450/100 was slightly cheaper than two MPPT 250/60s at that time.

Pros of 450/100

• Aesthetically nicer looking with enclosed connections and Multiplus-like looks
• Includes display as standard
• Actively cooled (can also be a downside of course!)
• Cheaper RRP compared to two 250/60 units
• Isolation fault detection built in

Cons of 450/100

• All eggs in one basket if device was to fail
• Limited to 20A per tracker Isc (my panels are 21.48A) but can be up to 30A if correct polarity guaranteed. 250/60 can take 35A max each.
• Lower efficiency at 96% instead of “up to 99%"
• Lower total charging current of 100A vs 120A
• Limited to Voc equal to 8x battery float voltage which is 51V for Pylontech. So 408V max Voc. Not quite enough for 8 * 49.9V panels after temp compensation
• Installation requires 300mm of clearance above and below the unit. Not impossible for me but would need some things moved around my cupboard.

My 250/60s are performing very well indeed and I really like that I can shut down one unit for maintenance if I need to, while still generating from the other one. Already charged my 14.4kWh of battery storage from 27% at 6am this morning to 100% by 11am. Not bad in west central Scotland in late July on a partially cloudy morning! :)

HTH