Second system extension extension.

[Moxi]

One thing I would say if you go for a wheeled frame try to get soft or pneumatic wheels as the solid rubber castors do vibrate the panels a bit over anything but the flattest of ground.

Moxi

[nowty]

I did a hot disconnect of the 4th string today once we had house shading on the panels and sure enough the wattage at the Victron dropped which nicely confirmed yourself & Stinsy back on page 1 & 2, parallel independent strings.

Some years back I did the hot connect / disconnect thing (not recommended folks ) many times to prove or disprove a technical report which said something along the lines of you can put two identical strings in parallel into a single MPPT which face different directions and different slopes and you only lose about 1% of the max power compared with if they were in two independent MPPTs.

My own experimenting proved it was not only true but you can even use different types of panels as long as the total voltage of each string is similar.

For example these 6 panels on my solar shed,


are in parallel with these 5 panels on my ladder store (its not a ground mount, honest ),


And as even with heavy shading, as long as 3 out of the 5 ladder store panels are in full sun my SMA shade management function works nicely, drops the voltage from around 200v down to 130v and keeps the full string current without any panel optimisers.

And before anyone suggests blocking diodes, NO YOU DONT NEED ANY F'ING BLOCKING DIODES.

[Joeboy]

One thing I would say if you go for a wheeled frame try to get soft or pneumatic wheels as the solid rubber castors do vibrate the panels a bit over anything but the flattest of ground.

Moxi

In my remaining mind I see small scaffold wheels, lockable. It's absolutely pouring down now and of course pitch black. Next clear spell I will get the tape measure out. On the upside I'd likely keep the 4th string on deck so swiftly fixable in.place. Still to decide tween skids or wheels. Mmmn, skids,...inexpensive.

[marshman]

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[nowty]

Marshman, the max current will not be exceeded, it will just limit at 11A and work at a slightly higher voltage. I often had this with one of my systems which at one time in the past was 3 parallel strings going into a max MPPT current of 15A and in summer it regularly limited at the max 15A even though it would have gone to around 20A if it could in the most optimum conditions.

[marshman]

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[nowty]

Thanks Nowty, will look into this further. At a max of 11A it would limit the max power from both arrays to around 4.2kW - which I guess makes sense as the inverter spec for total PV power is 8kW across 2 MPPT inputs. That would mean I "loose" a potential 1.6kW when in full sun - which can never happen with an E-W array! So I think some measurements and "hot swapping" is required when I get all the panels up.

Also when the inverter is current limiting, the voltage will be slightly higher, more than max power V but less than open circuit V. So you will probably lose less than you think. And when its flat out in summer your not going to worry about small losses during those times.

[marshman]

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[Joeboy]

Had great Saturday, started building my skidable 3 panel ground mount. Every bit of it (apart from the 20 mtrs of 4mm cable) is repurposed or X stock from my shelves.

[ALAN/ALAN D]

Was trying to work out the Azimuth Angle Adjustment of the panels. Need to know if the satellite dish is pointing at Astra 1 or Astra 2.


Astra 2 Satellites. The satellite alignment should be at 28.2E.
Astra 1 Satellites.align the dish to19.2E

Will try and get a life one day.