Exterior Wall mount 1k array

[MTM98290]

I am planning to add three 350w (3s) 1050w at 108v to our Cabin system. We have 9.6 kw lithium batteries, 3k Growatt with 490w (4s) 1960w arraoy at 208v.

9 months a year it works great. Winter months have short days and low sun here. We are looking to add 3 Panasonic 350w panels that we picked up on clearance this spring. I can get Ironridge Xr10 rails and all hardware locally. I would like to use some sort of Quckbolt L brackets into wall studs to attach rails.

The main 1960w array faces SW.
The 2nd array will face SE due to trees, mountains, etc. This should give great early morning production before the main array comes into full swing. It will probably start significant charging much earlier in the day this way.

The new panels will have lots of reflected light from snow and clouds during the dark days of winter. 100w extra for 4 hours!

I have a Midnite Kid SCC for the new array and will tying it to main battery bank


The wall is T111 type stained plywood. I am thinking that there would be no issue with the modules being mounted 4" away from wood siding, but it seems wise to either put metal or concrete behind them. What would be a good material for this purpose? Thank you for any ideas or info.

 

[12VoltInstalls]

am thinking that there would be no issue with the modules being mounted 4" away from wood siding, but it seems wise to either put metal or concrete behind them

You don’t need anything behind them.
4” will be great even in hot summer.

 

[MTM98290]

You don’t need anything behind them.
4” will be great even in hot summer.

That would make it much easier. We can get them installed easily once the rest of the hardware comes in.

if this install goes well we may try and a couple vertical 450w panels facing west to try and get every bit of charge possible during winter.

Will we need to add another SCC for any reason, or can we use dissimilar arrays hooked to the same SCC as long as it doesn't exceed max Voc?

 

[12VoltInstalls]

Will we need to add another SCC for any reason, or can we use dissimilar arrays hooked to the same SCC as long as it doesn't exceed max Voc?

Yes and no.
In parallel it will suck the higher potential array down to the lesser wattage array potential, and of course series is best with identical panels and you have to consider the specs for max series.

My answer is no…

Many things that ‘can’ be done aren’t things that should be done.

Wiser folks may have alternative opinions, and ymmv

In my opinion I’d rather have another or several SCC’s in service versus unbalanced arrays.

 

[zanydroid]

In parallel it will suck the higher potential array down to the lesser wattage array potential,

Parallel is fine IF you match the voltage on each parallel string, or are OK with the loss on the higher voltage string when pulled down lower. If you can double production in exchange for losing 15% on higher voltage string it’s kind of an OK trade

Also need to be mindful of Max ISC or reverse polarity protection limit on SCC with parallel. Less of a guaranteed smoke show than Voc but can still be sad

 

[MTM98290]

Thank you for clearing that up. I have read it so many different ways, but your explanation makes perfect sense.

If we decide later add a third west facing array we will an another Midnite Kid to handle it.

We will add the 3 new modules and SCC soon. I need to figure out a terminal block to tap the new SCC into. I will run conduit to a Midnite Baby Box and 150v breaker to SCC. SCC to battery bus.

We will probably need add a shunt to keep track of battery accurately. I'm sure that the Growatt can dead reckon the SOC to some degree without it, but I can't imagine that it will work very well with and additional charge source. I am guessing that it would function fine but the data reported would be skewed by extra charging from a mystery (to the AIO) new array.

I am also concerned about the system charging batteries too high while a load is on, such as hot water heater pulling 1500w just as batteries are fully charged. I am thinking that when hot water heater the kicks off and the battery voltage raises in the absence of the 1500w load the bank could be overcharged.

Am I way off track with this thinking?

 

[12VoltInstalls]

Am I way off track with this thinking

can't imagine that it will work very well with and additional charge source

Someone may know: does the growat have the programming to track in/out wattage to evaluate state of charge? Or does it merely provide a representation based on voltage?
If the latter then it won’t matter.