SMA offgrid. wanting to increase pv

[kaidensinclair@hotmail]

Gday

seeking some advice regarding increasing my PV input on my fully offgrid system.

current system:

1x Sunny Island 8.0H-12
1x Sunny Boy 5.0 -1AV-40
1x Sunny Boy 5000tl
approx 14kw solar panels
2x BYD bbox 13.8kw lipo

from my understanding i am maxed out on the amount of pv input my single SI can handle.

i have just come across a 2nd hand SI 8.0H-12 with a pair of sunny boys for a price i cant refuse. Am i able to intergrate both SI into the 1 system (master/slave??) to increase my PV?

 

[kommando]

Yes as they are both 12's you can double PV with the benefit of twice the output rate. Keep current one as the master but tell it that it now has a slave, tell the other it is a slave before connecting it to the master.

 

[kaidensinclair@hotmail]

Thankyou sir!

Yes as they are both 12's you can double PV with the benefit of twice the output rate. Keep current one as the master but tell it that it now has a slave, tell the other it is a slave before connecting it to the master.

 

[Hedges]

PV rated wattage 1.4x Sunny Boy wattage is reasonable. Actual output of panels under warm conditions may be 70% to 90% of rating, so not over-paneled at all.

You can over-panel, allow clipping during hours/seasons of high production and get more during times of less sun than your present array.

If you feed each Sunny Boy a PV string oriented SE and another oriented SW, you can reasonable put in panels 2.0 to 2.5x wattage rating of Sunny Boys, because their current will peak at different times.

With Master-Slave Sunny Island, you can tell the slave to sleep when its power isn't needed, reducing consumption from 25W to 4W (at least that feature and wattage is correct for US model, check your manual.)

You can never have too many SI or SB, good to at least have spares on the shelf (I need more storage!)

2x 13.8kWh LiFePO4 - you want more production, is that for daytime usage? Are batteries already getting full?
These sound like about 2.5 hours production, so at least during summer I would expect PV production is getting curtailed unless you use it as it is made.

 

[kaidensinclair@hotmail]

PV rated wattage 1.4x Sunny Boy wattage is reasonable. Actual output of panels under warm conditions may be 70% to 90% of rating, so not over-paneled at all.

You can over-panel, allow clipping during hours/seasons of high production and get more during times of less sun than your present array.

If you feed each Sunny Boy a PV string oriented SE and another oriented SW, you can reasonable put in panels 2.0 to 2.5x wattage rating of Sunny Boys, because their current will peak at different times.

With Master-Slave Sunny Island, you can tell the slave to sleep when its power isn't needed, reducing consumption from 25W to 4W (at least that feature and wattage is correct for US model, check your manual.)

You can never have too many SI or SB, good to at least have spares on the shelf (I need more storage!)

2x 13.8kWh LiFePO4 - you want more production, is that for daytime usage? Are batteries already getting full?
These sound like about 2.5 hours production, so at least during summer I would expect PV production is getting curtailed unless you use it as it is made.

Appreciate the reply Hedges, I wish my original installer had given me this information

All my panels at the moment are north facing (location: sth east VIC, Australia)
Ah well, I'm stoked about the price I paid for the 2nd SI+2SB
II think I'll definitely set up the next panels East/West!!

Mainly wanting the extra panels for winter time/bad days.
On sunny days we have no issue charging the batteries to 100%. That being said I'm looking to atleast double my battery capacity in the near future.

 

[Hedges]

Oh, right, Australia. South of the Equator so oriented NE and NW

Of course East/West does more in summer, would produce less in winter than North. You can check an insolation calculator to see what does best for middle of winter.
I've read that straight up is better with cloud cover when clouds are the source of illumination. Still going to be a small amount.

Can't really blame the installers, manufacturers said all panels in the array feeding a single MPPT had to be oriented the same. It was installers and users who observed the PV power curves show Vmp doesn't drop much with reduced illumination.

SMA conducted a test comparing separate MPPT for strings of different orientation vs. all on one MPPT, and separate MPPT gave about 2% more total kWh. They've since taken down the white paper, unfortunately.
Multiple strings of different orientation gets more use out of a single MPPT by running it hard more hours.

Panels in one series string, all need to be same orientation.
Strings in parallel, OK to be different orientation, just same/similar Vmp.

Shading is to be avoided, but if one string has about 10% of its panels shaded it still works OK paralleled because Vmp doesn't change that much. If 50% shaded, the difference with separate MPPT will be significant.

Since you have multiple MPPT per inverter you can check the voltage/current/power specs of each MPPT and allocate accordingly.
Some models allow paralleling some MPPT (for one model, A & B can be paralleled but not C). Could be useful if 2 parallel PV strings is too much for one MPPT but 3 parallel strings is OK for two MPPT.

 

[toms]

Good job finding a used Sunny Island 8.0 at a reasonable price! Let me know if you come across any more..

Good advice given here on how to put it to use.

I’m starting to see a few cheaper units (Growatt / Goodwe etc) come up in the $100 range, and I picked up a 7.5kwh power plus battery and Selectronic / Fronius inverter combo for $1k (including 5kw of PV / cabling and racking)

With the current legislation regarding grid connected batteries in Australia it is certainly becoming dirt cheap to have off-grid power.

There is an endless supply of low kwh Sunnyboy inverters available for <$100, i’m hoping in a few years plenty of people begin upgrading their Sunny Islands