Trying too hard

[road glide]

Was 8-6-6 because a couple different brands?
Are you considering 8-11-6? How about 8-8-9, or are the angles wrong?

I wanted to way over-panel (like 50% over), putting two strings into each input. Each string of two orientations, bringing peak current back down to what it could handle.

I use 8, SunPower 327W panels per string, which stays under 600V. That's about 2500W STC.
With the 6000US and 8000US I got I can do pretty well with that, using 4 strings of two orientations. The 5000US, doesn't seem such a great fit; for now just have two strings.

No, all new Jinko's with 5 left over. I just didn't like the 10-5-5 that was on the SMA design sheet...I am considering 8-10-7 or 8-11-6 based on computations...If 5 are pointed SE, what is the diff from the other panels on the array catching shade? Shaded panels lose production

 

[Sanwizard]

Hello everyone.
First post so please do not flame me.
Have been building my retirement home off grid, on an Island that is boat access only. I'm a GC.
We are now at a stage that I want to get power from my PV instead of the generator.
The build is nearing completion, it has been build on weekend and on vacation time, 7 years now......
Purchased 34 PV panels which are 320w and plan on using a 48v battery set up.
Panels will go on my sea can and also on three ground mounts.
Also have a creek that has lots of water for 9 months of the year. Purchased a micro hydro cross flow type which is 3phase.
This will be producing zero when creek is dry in the summer time but up to 2000w in the winter.
Dump load will be hot water immersion heaters. Have two storage tanks of 1000L each. Each tank has 6 inputs.
Because construction will still be happening/never ending want to power a table saw, compressor and a chop saw as well.
The big decision is which brand of inverter. Doing the math looks like a low frequency inverter is what I should go with.
If something goes down I want to be able to do it at my place instead of lugging unit out of the sea can, onto boat then onto the mainland.
Do I use 2 inverters for redundancy ? One dies I still have power ?
Any suggestions here from this community would be very helpful.
Local suppliers want to sell their gear and want to send people over $$$$$. I want to do most of it myself so if something goes wrong I will be able to solve the issue myselp

Attached a picture from the start of our build, 2014.

Freaking gorgeous lot.

 

[Hedges]

No, all new Jinko's with 5 left over. I just didn't like the 10-5-5 that was on the SMA design sheet...I am considering 8-10-7 or 8-11-6 based on computations...If 5 are pointed SE, what is the diff from the other panels on the array catching shade? Shaded panels lose production

Two orientations in one string, you either get the lower current of the panels with off-angle from the sun (imposed on the whole string), or you get zero from those panels and the voltage & current the others can produce. If a slight angle difference not a big deal, but to be avoided if large angle difference. Best to have all in a string of a single angle. "Optimizers" can fix off-angle to some extent.

 

[road glide]

Two orientations in one string, you either get the lower current of the panels with off-angle from the sun (imposed on the whole string), or you get zero from those panels and the voltage & current the others can produce. If a slight angle difference not a big deal, but to be avoided if large angle difference. Best to have all in a string of a single angle. "Optimizers" can fix off-angle to some extent.

Got it (actually I wish the heat would go away and I could just go back to my 20 and my 5kw SB)...

 

[road glide]

Sorry Mike for Hijacking your thread....But IMHO....go SMA for Sunny Island inverters/charges 6048 and a Sunny Boy Inverter and don't look back

 

[Mike 604]

Mike..Go to facebook and join DC Solar Auctioned trailer forum. about 500 members. You will see what I am talking about. Some members are selling the entire cabinet for about 5 grand or thereabouts.....and there are many posts with install issues resolved....

Can you send a link to the facebook group please.

 

[Hedges]

One issue I noted with the cabinet is only a couple inches around each Sunny Island, not the 12" according to installation manual.
DC Solar did install a small vent fan. But Sunny Island will still be recirculating its hot air.
Not a problem for a couple thousand watts, but if drawing the full 12kW capability, it would heat up and derate. Besides shortening life.
I would suggest putting a roof over it to keep rain out, and leave doors open.

 

[road glide]

oops

 

[road glide]

Hope this works (on my phone)

DC Solar Auctioned Trailer Discovery | Facebook

This is just a forum for anyone with the DC Solar auction trailers to share their findings, meet and possibly collaborate with use of or modifying the systems.

www.facebook.com

 

[Sanwizard]

Can you send a link to the facebook group please.

Is there also a non-faceboook link? (Never opened an account, and never will)

 

[road glide]

Is there also a non-faceboook link? (Never opened an account, and never will)

Unfortunately not....

 

[road glide]

One issue I noted with the cabinet is only a couple inches around each Sunny Island, not the 12" according to installation manual.
DC Solar did install a small vent fan. But Sunny Island will still be recirculating its hot air.
Not a problem for a couple thousand watts, but if drawing the full 12kW capability, it would heat up and derate. Besides shortening life.
I would suggest putting a roof over it to keep rain out, and leave doors open.

My cabinet is sheltered already and I leave the doors open, also have cabinet thermostat set. Back when the DC auctions were hot and heavy, I would NOT bid on a trailer where the SI's were outside. They are not engineered for that.
That being said, down the road I may revamp my ground mount to 10 -10 strings and leave C string open for future. But my 5.0kw has an array limit of 8k. My 10 talesun 240w already on the trailer rack (which could be ground mounted) would put me at 8800 total array, although 2400w would be facing southeast. I would need a SB 6.0kw to be under SMA guidelines....The main array 20 Jinko 320's are facing South-SouthWest at 32 degees slanted.

 

[Hedges]

I would need a SB 6.0kw to be under SMA guidelines

Which guideline? Imp? You can go well over and it would just clip production. Multiple angles of panels would reduce peak and eliminate clipping.

 

[road glide]

Which guideline? Imp? You can go well over and it would just clip production. Multiple angles of panels would reduce peak and eliminate clipping.

Max allowable PV Total........Total PV array is 9600 on 6.0. On my 5.0 it is 8000. So with 30 panels (20 x320 and 10x240)I would be at 8800, even though String C would be facing South east. I read your posts since last fall...You have multiple angles don't you?
Are saying if I go over 5000 watts it would clip out? Last spring I saw the SB do 5050 when conditions were right. so it was probably clipping then with my 6400 array. I think SMA doesn't want too much overfeed where it would harm the SB inverter....Their Specs are 9.6kw max on the 6.0 and 8kw on my 5.0 (array)

 

[Hedges]

10A operating limit per MPPT input should be followed, and max voltage, but I don't think the 8000W spec for PV is so important.
Yes, I have multiple angles. If some of your strings are different angles, for a first-order calculation I'd determine area presented to the sun. PTC vs. STC further reduces what's produce most of the time. If that still exceeds 5kW by more than wiring and inverter efficiently loss, then there will be clipping some seasons. But if a 90 degree angle, 8000W x 0.7 = 5600W so it wouldn't exceed 5000W and wouldn't clip.

 

[road glide]

Just did the calcs....8.3 amps on string A & B and 7.9 on C. Max volts on the two bigger strings was 517 each and 479 on the South East string. Do you have different angle strings wired into a single MPPT? You were pretty clear about not doing that. You probably have each angle with its own MPPT.....

 

[Mike 604]

Hope this works (on my phone)

DC Solar Auctioned Trailer Discovery | Facebook

This is just a forum for anyone with the DC Solar auction trailers to share their findings, meet and possibly collaborate with use of or modifying the systems.

www.facebook.com

It worked thanks, joined pending approval.

 

[road glide]

It worked thanks, joined pending approval.

Pobby is the moderator and he, Keith B and Kevin P among others are like encyclopedias but talk and relate in common terms. I've noticed there are a couple of guys who are very savvy about communication systems Bill P for one. But most of us just want a SIMPLE workable system with out trying to build a NASA flight vehicle...
One other thing....my Sunny Boy inverter is the latest model offered 5.0KW US - 41 and has a WLAN user interface that I can view on my desktop.
The Sunny Island's do not have this but it's doable. I don't need it because the darn things just perk along on their own once configured. Pretty amazing. The main thing is the Sunny Island's magically throttle the SB inverter without you aware unless you are standing watching the menu.
The reason is when loads are necessary the Sunny Island takes more and when loads are down the Sunny Island throttles down the Sunny Boy inverter. And it's quick. And any excess goes to charge batteries if needed. When we run the coffee pot, microwave, dryer...the Sunny Island, well it's instant and when done it slows back down.
Lastly, when you become a forum member...there is a FILE search at top of page on the forum. We've all contributed documents, manuals pertaining to what we are doing...
My wife relates...Our Sunny Boy 5.0 and ground mount array 6.4 are like the hydro-electric dam providing power and the Sunny Islands are like the Power Co distributing it.

 

[Hedges]

Just did the calcs....8.3 amps on string A & B and 7.9 on C. Max volts on the two bigger strings was 517 each and 479 on the South East string. Do you have different angle strings wired into a single MPPT? You were pretty clear about not doing that. You probably have each angle with its own MPPT.....

You don't want different angle panels in a single string.

I do have different angle strings on a single MPPT. Sure, you get more power if they have their own. But with two strings of different angles you can get more watt hours from an MPPT, more value for your money.
SMA did a test, determined you lose 2% of production. Now that SCC or GT inverter is a large fraction the cost of PV panels, I think you come out ahead.

You can't parallel another string on a single MPPT without clipping at its maximum current, but if two MPPT are connected in parallel you could have 3 strings. In the case of newer Sunny Boy with 3 MPPT into one inverter, it is possible that fully loading each MPPT with one string is far enough over inverter wattage that you can keep the separate and get sufficient overpaneling.

 

[Mike 604]

Hi Dinky
Start of the install, not completed but we did get 90 ft of pipe in. Still more to go.