SMA Sunny Boy & grid tie panels

[GarySaf]

This is probably a very beginner planning question, but I'm trying to understand how I might connect breakers for a grid-tie system.
I'm looking at a Sunny Boy 7.7-US with around 8.8 kw of panels (just a plain grid-tie with no backup)

The meter goes to a breaker / disconnect and from there to a main panel on the West side of a barn.
That panel has a 100 amp breaker that goes to a sub panel 200 ft away on the East side of the barn.

There are also 2 other sub panels on the North & South side and I am presuming they are all fed by the main panels but these aren't marked anywhere and are much older panels, so I not a 100% how they are powered.

First question: Can I connect the PV inverter/breaker to the sub panel (the one thats 200 ft away), or do it always have to be at the main panel?
That would just help me plan where to setup the Solar panels (closer to main panel or closer to sub panel)

Second question: If I were to plan on a larger Solar system with 2 x Sunny Boy's, can one Inverter/breaker go to the main panel and the other inverter/breaker go to the sub panel, or would that typically not be allowed for a grid-tie system?

If the inverters both have to connect to the main panel (assuming 240v 40a breakers from each Sunny boy), do they both go below each other at the bottom of the panel or one on the left and one on the right. In some places, i see that both breakers must be on the same side and also read that they should be on opposite sides for balance.

I might have a few more questions, but just preliminary planning/understanding/advice and just making sure I'm understanding correctly.

 

[Hedges]

PV breaker will be 40A.
You can put in any panel. But, that panel and all it feeds through back to meter are supposed to comply with "120% rule".
That means, main breaker plus PV breaker(s) can total up to 100% of busbar rating. PV breaker goes at far end of busbar, away from main breaker.

A 200A busbar and 200A breaker is allowed 200A x 120% = 240A, 240A - 200A = 40A PV breaker.
225A busbar x 120% = 270A, 270A - 200A = 70A PV breaker allowed.

Unless you had a smaller main breaker like 150A in a 200A or larger panel, difficult to support two SB 7.7

Panels down stream have to comply with same rule, but you could tap off before main breaker of sub panel to another panel or fused disconnect and connect Sunny Boy there. If the sub panel in question had only main lugs, put in a main breaker because it now has branch breaker of main panel plus Sunny Boy able to supply current in excess of its rating.

Yes, you could feed one SB into main, another into sub panel. But, if you need a single disconnect switch for both, that may be inconvenient. Alternatively, utility may allow no disconnect, but they could unplug meter to isolate your inverter, which is inconvenient in its own way.

No worry about balance with 240V inverter in 120/240V split-phase panel. That would apply to 120V inverter, or 120/208Y panel.

 

[GarySaf]

Thank you so much. I think I understand, but just to clarify.
The sub panel (down stream) is 125A and is fed by a 100A breaker from the main panel, so
125A busbar x 120% = 150A, 150A - 100A = 50A PV breaker?

Yes, you could feed one SB into main, another into sub panel. But, if you need a single disconnect switch for both, that may be inconvenient. Alternatively, utility may allow no disconnect, but they could unplug meter to isolate your inverter, which is inconvenient in its own way.

I didn't think about that. I'll try and relook at the PGE requirements today.

Much appreciated.

 

[Hedges]

Yes, you've got it.

I have a 100A panel in my new house. Was thinking of upgrading to 200A panel with 150A breaker, but now considering a box with just bolt-in 200A breaker, no busbar. That way no 120% rule. It can feed sub-panel and disconnect for PV. Disconnect will have PV aggregator panel.

 

[GarySaf]

Thanks again for the quick reply;

I have a 100A panel in my new house. Was thinking of upgrading to 200A panel with 150A breaker, but now considering a box with just bolt-in 200A breaker, no busbar. That way no 120% rule. It can feed sub-panel and disconnect for PV. Disconnect will have PV aggregator panel.

This is a little above my head for now.
It took me a couple hours just to read and be sure I understood what you were saying.
I've literally just more or less settled on the Sunny Boy for my needs and just starting to understand the electric panels.

Really want to understand as I may actually want to consider upgrading some of the panels as well.
The barn is really old and has a main panel, but all the labels are worn off and all the places for breakers are full, so I don't even know what type / rating it is.
Then there are 3 other panels and I think fed off this panel but I can't be sure apart from the one sub panel that's newer and has all the documentation from the inspection (this is the one I want to use for the grid tie PV).
The other 2 look so old, that I actually think it would be a good idea to upgrade them anyway..

Have a few more questions, but just want to think this through. Thanks kindly.

 

[Hedges]

I like SMA equipment.
Plan where you would install Sunny Island if you want battery backup.

Here's what I am thinking of using for service entrance/disconnect, rather than a panel with branch circuit breakers:

Square D QO 200 Amp 2-Pole Outdoor Circuit Breaker Enclosure with QOM2200VH Breaker QOM2E2200NRB - The Home Depot

The Square D by Schneider Electric QO 200 Amp Outdoor Circuit Breaker Enclosure includes a two-pole QOM2 frame sizes circuit breakers 100-225 amp capacity for use as an exterior disconnect. This breaker

www.homedepot.com

For breaker panels, some come with 225A busbar and some with 200.
The QO panels > 100A are copper busbar and 100A & smaller are aluminum. Homeline are all aluminum.

 

[GarySaf]

Plan where you would install Sunny Island if you want battery backup.

I’m thinking of just a grid tie for now and perhaps consider a battery backup in a couple years.
This would be the first of two pv installs - one for the barn and a second for the home.
To keep the barn cost minimal, I figured just a grid tie would do as there is nothing I can’t do without for a couple days there if it had to.

I liked the SMA inverter, but the sunny island and battery setup is really quite a bit more than I can spend now.

For the house, I liked a Victron setup but it’s not UL so can’t grid tie.
I’m thinking of Schneider now, but not in a rush to decide.
Initially was considering a Sol Ark 15k, but just don’t know.

For around $1700-1800 the Sunny Boy looks perfect.
I think I need to over panel to around 10kwh to offset my barn usage and that’s why I was thinking of 2 Sunny Boy’s, though I know 1 Sunny boy can do 10,000 w+.

I was thinking if I got 2 Sunny Boys (3 MPPT each) I might be able to get a better overall production with more orientations.

The other thought right now is just to stick with one sunny boy and with the California Nem 2 metering, if I limit my usage during the peak 4-9pm times, I can make do quite well.

So, as you see, still just at the beginning of thinking this through and appreciate all the helpful kind replies.

 

[Hedges]

Think about how you would connect Sunny Island.
If using conduit, put in Tee so you can hang things off it without having to pull wires back out.
The Tee off to my sunny islands was after the PV aggregator panel, so AC wires route out and back through same conduit, are now about 100% fill, difficult to add some things I want.

I think European model Sunny Island, supporting external 200A bypass relay, may come to the US later. I would expect it to have features like export limit, which Sunny Boy Storage offers.
Price-wise, I got a bargain on mine because there are units liquidated from a bankrupt vendor.

Orientation - it is ok to parallel two strings of different orientations, about 2% worse than separate MPPT. But Imp of PV panels and MPPT current limits are likely to prevent that. It is a way to overpanel without clipping, instead take advantage of more hours. You may be able to do that to some extent with three MPPT, but I'd like to overpanel to 150% or so.

 

[GarySaf]

Think about how you would connect Sunny Island.
If using conduit, put in Tee so you can hang things off it without having to pull wires back out.
The Tee off to my sunny islands was after the PV aggregator panel, so AC wires route out and back through same conduit, are now about 100% fill, difficult to add some things I want.

really appreciate the suggestions - it’s some of this things for future I’ve been thinking about a lot.
You’ve given me a lot to work through for now - thanks for the help.

 

[GarySaf]

This is a couple week old thread and @Hedges had helped with some of my initial questions & just had a couple follow up questions as I think I have the final plan in mind.
The setup is looking like 3 x Sunny Boy 7.7 and each inverter connecting to a 40A breaker (3 x 40A).

It looks like I need to upgrade my main panel and the 1st question is, can 3 separate 40A breakers tie into the main panel for a grid tie?
I'm guessing not as I need to have an ac disconnect between the inverter & main panel.

2 - Does the below sound correct;
3 x 40A breakers from each inverter to a 225A busbar in a new 200A sub panel.

Subpanel connects to new main panel. Can the main panel also stay at 200A?
Then a 150A breaker from the main panel to the subpanel.

I'm calculating it as follows;
SubP 225amp busbar x 120% = 270A - 150A = 120A (3 by 40A breakers from each inverter)

I'm not sure this is correct and the right way to have 3 inverters for a grid tie.
Thanks so much -

 

[Hedges]

Visible blade disconnect is probably optional. Alternative is for utility to yank your meter.

To backfeed your main panel with 120A of breakers, 120% rule could be complied with using 225A busbar (120% = 270A) and 150A main breaker. In main panel.

Same math for a sub-panel if used, except I think if "PV aggregator" with no loads, a 125A panel could be used.

If you put 3x 40A breakers in main panel and fed just one hot wire of each through a 3-blade disconnect, that would shut the inverters off. May or may not make the utility happy that it is isolated, if they pour over the design. But it will pass their functional test.

My recommendation is to make provisions for adding Sunny Island battery backup, with critical loads (and PV) panel, and important loads panel (fed through load-shed relay.)

To do that, put PV on that 225A panel with knife switch. 125A backfed breaker on main panel (unless multiple orientations reduce peak continuous current to 56A, for 70A breaker which allows 200A main breaker.) If using conduit, include one more more Tee so you can add Sunny Island later.

Interlocked breakers on main panel allow it to be manually switched important loads panel, also backed up by battery.

3x SB 7.7kW totals 23kW, which requires 4x SI for pass-through. You could get by with 2x SI if you arranged for only one SB after SI, other two SB wired after knife switch. When on-grid, only one SB backfeeds through SI, so under 56A limit. When you throw breakers so 2x SI backfeeds main panel, they will then manage all three SI. You'll need a PV aggregator panel after knife switch, also a disconnect between knife switch and SI.


If replacing main panel, consider a meter & 200A main breaker with no branch circuits, so no 200% rule there. That's what I've bought for my new property (similar in my old property)

CA PG&E Interconnect Application Questions -Sol-Ark 15K

Hello, I have a few questions about the California Interconnect NEM Application for PG&E. It’s been challenging to work through it. I’m doing a self-install and will be using the Sol-Ark15. 1. The section “Please provide the Method of Transition” open or closed? Should it be...

diysolarforum.com

Planning the (permitted) system upgrade for my house

I couldn't tell in the video. But, I hope that you corrected the grounding and bonding in those panels. They are sub panels and the neutrals should be separated from ground. The part of the main panel that is outside is integral with the part inside - the main breaker section outside has no...

diysolarforum.com

 

[GarySaf]

Thank's so much. I'll keep this post in mind when planning.

If replacing main panel, consider a meter & 200A main breaker with no branch circuits, so no 200% rule there. That's what I've bought for my new property (similar in my old property)

That's a great point and I do need to replace the main panel.

My recommendation is to make provisions for adding Sunny Island battery backup, with critical loads (and PV) panel, and important loads panel (fed through load-shed relay.)

I've been thinking about planing for the Sunny Island's. Every time I price everything, I always think I'll just stay Grid tied for a while to avoid the cost for the Sunny Island's but know i'll have to deal with this down the road..Man, those things are expensive, especially if I end up needing more than 2.

Thanks again for all the advice.

 

[Hedges]

Sunny Islands are $5700 msrp, $4700 street price.
But you can get liquidation units on eBay, some new in the box. around $2500. They may or may not officially be warrantied through SMA (possibly a limit from date of manufacture), but in practice SMA has even replaced faulty units.

There has also been a listing of a box with 2x SI and other stuff, asking price $7000. It doesn't have a "make offer" button, but you could contact hi and offer $5000. But know what shipping will be, large and heavy vs. individual 150 lb boxes.

If you have cash to invest.
I would expect European model to show up here eventually, likely with new features useful for our grid and net metering situation, but at full price.

4x SI is the simple solution to supporting > 13.4 kW of Sunny Boy on-grid.
Off grid, 2x SI supports 24kW of Sunny Boy.
That's why I suggested a topology where only one SB connected through SI while on grid, three when off grid.

SMA's official instructions for Sunny Boy 7.7-US in grid-backup is to set it for Rule 21. But their SMA America arm has said in video to instead set it for off-grid. That suggests it has issues with Rule 21 and Sunny Island. I have concerns with off-grid setting when connected through SI relays to the grid (what happens if relay welds shut?)

Sunny Boy 7.7-US with around 8.8 kw of panels

8.8 kW STC might barely hit 7.7 kW AC on the best days (cold and bright)
I would suggest consider MPPT input voltage and current limits, see if you can over-panel to 10kW for single orientation, 15kW with multiple orientations of PV panels. If connecting more than one SB costs a lot more, over paneling a single one with multiple orientations could give most of the same kWh/year.

If you install 2x SI, will want a 70A 2-pole breaker for 56A continuous load. The 225A panel with 200A breaker is a perfect fit.

I'm not sure why I said 3x SB, you said two. Except that 2x SI supports only 1x SB 7.7 (or 2x SB 6.0), but 4x SI supports 3x SB 7.7

 

[GarySaf]

Thanks for the reply - you seem to always give me a new and better way to think about this setup.

GarySaf said:
Sunny Boy 7.7-US with around 8.8 kw of panels

8.8kW was the initial idea, but just rethinking everything for future planning and getting locked into the nem 2 interconnection agreement, i've been thinking about 20kW now - I can probably over panel and get away with 2 Sunny Boys, but I think PGE or the county won't allow me to go over the 7.7 rated capacity without matching a PV size.

I'm not sure why I said 3x SB, you said two. Except that 2x SI supports only 1x SB 7.7 (or 2x SB 6.0), but 4x SI supports 3x SB 7.7

That's probably me who confused you somewhere - I keep going between 2 - 3 SB's.

But you can get liquidation units on eBay, some new in the box. around $2500. They may or may not officially be warrantied through SMA (possibly a limit from date of manufacture), but in practice SMA has even replaced faulty units.

That's a great perspective - I really never thought to try eBay. I might have to wait though as the SI's aren't Rule 21 compliant and probably wont' get approval from PGE https://solarequipment.energy.ca.go...+America&ModelNameID=-1&Submit=Search&Rows=25
*PGE said the same - won’t approve application with the Sunny Island.
I like SMA for just being able to start with reasonably priced inverters and building from there.
Everything of the Schneider setup is Rule 21 complaint but a 10-12k minimum entry cost.

 

[Hedges]

No reason you can't over-panel. Just don't exceed Voc (adjusted for coldest temperature) and don't exceed Isc.
But approval for more is good. I'm just not sure what PG&E will do if we install 50% of what we said we would.

Your breaker panel (120% rule) and PG&E would be the limits on peak wattage you could export.

Sunny Island used to be approved, UL-1741. Taken off the list now that UL-1741-SA is required.
That should just mean it can't be the inverter for net metering. It is still UL listed, as are many UPS (the function it can provide).
Did PG&E explicitly address Sunny Island?

Put in your reservation and installation using the Sunny Boy which is approved.
Plan to use Sunny Island as an addition later for backup if desired.
If you want to store PV production in the afternoon and backfeed later during peak rates, the current US model Sunny Island isn't approved and isn't capable either (except with external control, not a supported product.)
Some other product would do that better. You can figure it out later, unless you want to grab Sunny island now while it is half price.

I've read that UL-1741 Supplement B goes into effect April 1st.
Sunny Boy 7.7 kW -41 series is approved today, but does not meet Supplement B. Wonder if that means, although NEM 2.0 is available until April 14th, this inverter can't be used for a reservation after April 1st?

I do most of my shopping on eBay. I buy new old stock when I can.
I discovered Santan solar there (PV panels), also StellaVolta (inverters and more.) Both also have their own web site.

 

[GarySaf]

Thanks - I definitely want to keep it simple for the initial application and once approved make and adjustments down the road while having Nem 2 locked it.
The thing with speaking with PGE is that they want a simple single line diagram, that just shows the major components and I want to keep it as simple as possible so I don't get caught up in "deficiencies" and the people on phone I spoke to concern me about over-paneling etc.

I figured that spending the extra $1500-2000 on an extra Sunny Boy is probably better than them saying that the inverter sizes don't match PV array. Or anyway, I won't build this out until the summer so perhaps I can make any adjustments if needed.

Put in your reservation and installation using the Sunny Boy which is approved.
Plan to use Sunny Island as an addition later for backup if desired.

That's what I figured - I'll just get everything installed and as you said, just plan on everything that could need upgrades.
I figured perhaps Sma will have a different approved option later this year.

PGE definitely said no to the Sunny Island for an approval.

I've read that UL-1741 Supplement B goes into effect April 1st.
Sunny Boy 7.7 kW -41 series is approved today, but does not meet Supplement B. Wonder if that means, although NEM 2.0 is available until April 14th, this inverter can't be used for a reservation after April 1st?

I better just get my applications in before March 30th, I didn't know this.

I'm installing 2 20kW systems. One for the barn, workshop, irrigation pumps on a separate meter (above with SMA grid tied)

I need a second application in for the home, and all the critical stuff at my property such as lights, gates and well water. That system definitely needs battery backup, so I'm thinking of going with all Schneider's DC coupled with around 30kW battery backup.
I just haven't fully planned that out. Was hoping to submit the barn application this week and the home application next week (both are on separate meters and PGE confirmed 2 separate applications are ok)

I do most of my shopping on eBay. I buy new old stock when I can.

I am definitely going to take a look., I saw the $7k listing you mentioned with all the equipment and it's very tempting as I can probably pick it up too.

I have some UL approved panels I got at a good price, so I have on order 3 pallets of 32 panels per pallet (96 panels) 405w each.
So, all I need to do is plan sizes (based on recent loads and what max I could get approved) and divide them between the 2 projects.

I can probably build out the first system in the summer and the second system by early next year.

 

[Hedges]

Sure, enough SB for the reservation. Maybe you install fewer. Maybe a new model comes out.

I suppose Schneider has been used with PG&E. Maybe that counts as attached storage, maybe that depends on how it uses the batteries. I don't know how more involved, especially permitting and listed ESS.

I think you could program SB for slightly reduced power, so 2x 7.7 don't exceed 2x SI's 13.4kW (56A) relay.
The European SI works with external 200A transfer switch. I would think it would do the peak-shaving and time-shifting features, also comply with new codes, but I haven't dug into details.
I'll us current model SI (I have a dozen), and under NEM 2.0 it isn't particularly important to export from battery.
I think about SBS for storage that gets cycled, don't know yet what "other" batteries that are economical might work with it. I would put it away from the house.

You're split-phase not three phase?

If you can pick the thing up, saves on expensive shipping. Make an offer - buy the inverters and get he rest for free?
The breaker panel is cheaper "Homeline"; I prefer QO with copper bus.
Midnight Classic is 250V, that has its benefits but handles fewer watts than the lower voltage ones.
Design does not meet SMA guidelines for cooling. Keeping door open would help. Duct air so it doesn't recirculate (while exhausting some), better to feed cold fresh air in.

 

[GarySaf]

I’m single phase on both meters.

The listing is definitely tempting - thinking about it. Don’t really mind if most it is just unusable if the overall deal is good. But more importantly, after your post I’ve realized to look out for stuff on eBay. If not this then stuff down the road too.

Ya, I wouldn’t really worry about the export from battery too if I got SI’s but mainly don’t want 20kw of potential power just being wasted when the grid is down. It tends to happen in the summer or peak winter when I could just have that power run air conditioning and some lights if nothing else.

—-Design does not meet SMA guidelines for cooling—-
I was just going to use that box for something around the ranch and just take the SI’s out and buy everything else new. Maybe the cheaper breaker panel somewhere else or perhaps down the road a small off-grid Solar to run something arbitrary.

 

[Hedges]

The purpose of my SI and small AGM battery is primarily to light up an island grid so SB can power the house, including A/C. Also make it through the night (but only if my power hogs are turned off.)
Much of the available power will go to waste, but that's OK. PV costs half what the cheapest batteries cost, so I'd rather over-panel and float a small battery.
It's nice to have everything run, at least while the sun shines.

"well water" Determine starting surge and size your battery & inverter accordingly.

I wired my system with rigid and flexible water-tight conduit. It is outside, with a couple provisions to protect SI from getting water inside. (European model has no breaker or SD card, and is 3R). Other people have used a wiring trough, probably cheaper and less work. Just do it so the connections to SI allow them to be removed if necessary. I will look into that for my next place.

You may find listings on Craigslist as well (just don't get set up for robbery). I tried search string:

"Sunny Island" site:craigslist.org

This guy is posting in multiple locations, but says the units are in Northern California:

SMA SUNNY ISLAND 6048-US INVERTER - general for sale - by owner

New in box SMA SUNNY ISLAND 6048-US INVERTER. Haven't taken it out of the box, but we can take it out when we meet. Everything is unused. I have two for sale. Located in Northern California. We can...

medford.craigslist.org

SMA SI6048-US-10 Sunny Island 6048 Solar Inverter/Charger 120VAC...

I have some new in the Box SMA SUNNY ISLAND INVERTERS. 48-VOLT input 6000w output. $2900 each. They have the 10 year extension of warranty. They are priced at a super deal. I have several available...

akroncanton.craigslist.org

 

[GarySaf]

I just read the below now - wow, a dozen!
current model SI (I have a dozen), and under NEM 2.0

Seriously your posts have me rethinking the Schneider for the house setup and just stick with sma everywhere. That would definitely help with getting stated quicker and building up from there.