Multiple Smart solar, older quattro and genset

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jontm asked Apr 3, '24

Multiple Smart solar, older quattro and genset

I am planning a solar installation with about 11 kWh of solar panels. This installation is planned to be installed in Norway on a tourist cabin that are only open in July and August.

Looking at the average daily solar hourly profiles for my location, the non optimal 270 degree azimuth and the fact that July and August is not the peak solar months I am expecting that having about 4-5 kW of MPPT capacity should be sufficient. The cabin is fully off grid so I would not be able to use any of the energy produced in the peak months anyway.

My current setup is an old micro Quattro 10000 VA 48 V. Connected to about 14 kWh of LiFePO4. Currently all of the energy comes from a 30 kVA diesel generator that is turned on when needed. I currently have a energy need of between 30-70 kWh per day, but hope to be able to lower it in the future with gas heaters for water and oil ovens for heating.

I have a couple of questions regarding this.

The Quattro and batteries are in the basement, would it be better to place the Smart Solar MPPTs in the basement close to the Quattro or would it be better to place them near the solar panels in the attic for example ?

How what will happen if the Quattro charges from the genset at the same time as the MPPTs ? How would I ensure that the charge limit of my BMS is respected ? Since I have an older old micro Quattro, it is my understanding that it does not work with DVCC ?

Would the genset charging potentially interfere with the MPPT charging causing one or more of the MPPTs to turn off ?

If I where to connect two or more Smart Solar MPPTs to my Raspberry Pi running VenusOS with VE.Direct-USB cables, would they be able to sync to each other and potentially the Quattro to make sure they are all on the same page on what is happening ? Or can they do any of this other Bluetooth ? I already use bluetooth for the communication to the BMS and use this for the SOC.

Are there any significant disadvantages with using several Smart Solar MPPTs compared to using a single bigger unit. I guess one disadvantage is cabling, but is it common to have issues with sync or the units not working well together ?

MPPT SmartSolar quattro 10kva

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matt1309 commented · Apr 04 at 09:08 AM

Hi @jontm

I'm no pro so take my answers with a pinch of salt.

1. I would personally prefer mppt closer to quattro (closer to battery/bus bar realy). My logic being the voltage will be higher from PV panels so you can use thinner wire and/or longer runs with less losses due to the higher voltage. Also attics tend to be warmer.

Yes you can use multiple MPPT's. Im not sure if this works via bluetooth however if you have ESS system then this "syncing" definitely works via ve direct.

I would say if you're having a large solar array you'll need multiple as one isn't big enough unless you go for the RS. I would argue there's probably benefit in having multiple for better maximum power point tracking etc. Only downside that comes to mind is the increased cost/double the wire runs.

I find Victron mppt's have relatively low input voltages so unless you go for the RS model you're limited to 250v. With large panels you could only really have 4 in series (maybe less if you've got really cold/sunny climate.

I'm not aware of such syncing issues. If the MPPTs are in a similar location ie same length wire runs from DC bus bars/battery. Then even without software syncing they should be synced pretty well as they'll be reading the same voltage on the battery side.

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