Att he moment I run 3 panels in series onto MPPT 150/35
The 3 come to approx 150V and seems to run about 8-9Amps.
I"m extending the array and need to decide what to do wrt my MPPT.
going from 8 x 330 => 8 x 400w.
Plan 1 was to go 2 parallel arrays of 4 in series, but that then needs a 200-250V MPPT,
Was thinking why not do 4 sets of 2 in series, that drops the voltage down to 100, within my current MPPT. but adding strings in parallel pushes my Amperage up…
so 4 x 8 = 32Amp, within my 35 limit, but the 4 x 9 or hot hot day of 4 x 10 will cause problems…
The MPPT’s are not cheap so trying to workout the best/cost plan.
looking at my history/last month, it seems i normally run between 20-30Amp.
looking at my 330 panels, history… on my north east array which is 6 x 330 in 2 strings of 3… i run 17amp…
so i’m thinking that little 150/35 is just just going to be to small… the numbers looking to close to limits.
This is only bad because of the MPPT that will limit it to max 35amps.
MPPT can do so much more but then those volts needs to be much higher. I am dead scared to approach even 140V on my MPPT because as you say, these things are not cheap.
But with such a substantial jump in PV output with the bigger panels, it would seem a waste or a fruitless exercise to keep the current MPPT.
EDIT: Reason I say it so finally, I’ve tried to mix and match, bah, it is a moerse effort and then one day you want to add more panels and the conversation starts again.
On top of that, the 250/85 or 100 will idle.
My case, had a 250/100, realised I can never max it due to space.
So I sold it, got a brand new 250/85 to match the max panels I can fit on it due to space, and that was the end of it.
As it stands I need to get them someone fitted next to house against a wall… and I’m going to be 10cm over one side.
Have to fit them in a landscape way as the house is 1 m from Neighbour/wall.
This allowing me only 6 to go there, will join them and replace the 3 on the roof right above to create the 8.
Understand the idea/plan to just get it done… keeping it simple.
I can def see the market for a unit somewhere in the middle…
by my math it is way bigger than i need, but gives me options. Was the unit that i was looking at before anyhow so all your comments just basically told me my original thinking was a good plan anyhow.
