System Configurations, SMA Inverters, Shading, & more

**compchat** · 12-21-2015, 04:45 AM

Something like the Rainforest EMU-2 Energy Monitoring Unit

will allow you to monitor your meter if your electric company supports it. I have one on order form Amazon which is compatable with SDG&E.

With the Sunnyboy interver there is an iphone app that monitors it. Look in the app store for Sunny Portal.

I do have a question about the configuration of the Sunnboy inverter. I know it can be hooked up to the internet using CAT 5 cable. To do this I would have to punch a hole in my outside wall or run the cable through a vent into the garage and then through a wall into the house. I bought a wi-fi range extender thinking I could plug the cable into the extender and then connect the extender to the in house wireless router. To do this I would have to rain proof both the power supply and range extender. Other then putting the equipment in a plastic container is there an easier, quicker and less obtrusive way to do this ? Alternatively can I drill right through the outside wall into the room with the router ? How do I avoid wiring, piping etc. Can I somehow force the CAT cable through a closed window (this would be the easiest way)?

IOW I'm trying to connect the Sunnyboy 6000 TL-US to the indoor router and need to get the cable to the inside router OR use a wireless range extender outside which needs power.

Thanks

**cebury** · 12-21-2015, 05:55 AM

Hopefully you'll get a response from some of the experts here, but I'll chime in based on my limited education.

The mods don't care as much about including links as before. They are fighting the obvious spammers and are asking if you link to any solar vendors you link to their solarreviews pages instead.

Originally posted by MinorDeity

Anyway, after the installation was done it turns out that there is significant chimney shading on the South array until about 10:30AM every morning, and I estimate that this will be the case year around.

Where SolarEdge really shines (over string) is with small fixed shading, like from a chimney, that affects only a few panels (Naptown quote).

This situation would have been obvious to even the most casual observer during a proper site surve

It's possible they were ignoring the chimney shading because their intention (if not complete experience) was SolarEdge. Two of my installers also stated no shading issues and were mistaken (fixed rooftop AC and minor winter-only shading). This may amount to "no shading issues" by relative standards.

Perhaps when you convinced them to use string they forgot (or ignored it as your overriding request) to reconsider the significance of shading from the chimney. You knew the pro's and con's of string vs. module level and made your choice (being obvious for the most casual observer). Now you are trying to mitigate the consequences afterwards, which although is possible may not be easy to justify in your installers eyes. Fingers crossed + sounds like they want to satisfy their customer and not wave ITYS "wouldn't be an issue if you took our recommendation".

Along these same lines, do you know if it shortens the life of an inverter to operate it very close to its maximum usable DC power rating, or to incur occasional clipping?

You won't get a clear answer here, other than "probably", and I'd bet never from the manufacturer. There are inverter manuf. that state the optimal efficiencies are reached at maximum and warrant up to 25% oversizing. The fact they warrant that amount over max ratings is a good sign IMO. Other than this, I've seen the logical ponderings at this site "running at max should yield more overall heat which generally means less lifespan for electronics".

"California Solar Initiative Incentive Calculators" on the csi-epbb

That still works well but some of the equipment lists may be aging IME. The most recommended is clearly PVWatts, second to SAM (a free gigantic desktop app that is overkill for anyone but installers IMO).

SMA user who coded up some kind of TCP/IP application tha

You can do this with the major inverters to some level, dependent on which monitoring component is installed. There is SMA specific discussion here and here.

The largest and probably most pertinent portion of your post is dealing with your string layout. With 15E, 11S, 13W it does seem strange to have 10-10-10-9 string layout. But the experienced folks with the right software should be able to guide you there. If you don't get a reply, I suggest you start a new post, limit background details, and concentrate your request to that topic. I would also include the current layout -- even if it means scribbling something up to show which panels are on which string.

**sensij** · 12-21-2015, 10:57 AM

Originally posted by MinorDeity

Hello,

I'm new to this forum so I might as well start out big. Please excuse the verbosity but I want to make sure I don't leave out any pertinent information. First, here is a consolidation of the points covered in more detail my posting and about which I would like your comments, in whatever technical detail you care to provide... The more detailed the better...

1. Panel configurations (min, max, orientation);
2. SMA OptiTrac performance & enabling/disabling;
3. Significance of chimney and vent pipe shading;
4. Sunny Portal Web Site;
5. System calculators/formulae;
6. Inverter monitoring;

I have calculated the minimum and maximum number of panels suitable for use with the SMA SB6000TL-US-22 inverters and found it to be 8 and 14, respectively. I used the formulae provided on the CivicSolar Website (after I corrected some errors in them) to do these calculations. (Do you know of a better way?) I'd provide the URL but I understand that newbies to this forum are not supposed to do that. The only issue I have with an 8-panel string is that, although they supply enough voltage to reach the inverter's start voltage of 150v, they may not always supply enough to reach the inverter's "Rated MPPT Voltage" of 210V. I tried to find out from SMA's level 1 technical support agent what the significance of operating below this voltage would be and if any derating information was available, but I might as well have been talking to someone at Jack-in-the-Box, and the wait would have been much less (and I'd at least have gotten a Jack-Taco). I then left a message for their higher level tech support to contact me, but of course they never did. The potential issue I have with a 14-panel string is that I don't know if it's advisable to operate that close to the limit of the cold weather open circuit voltage, especially if there should be an extremely cold morning sometime. Along these same lines, do you know if it shortens the life of an inverter to operate it very close to its maximum usable DC power rating, or to incur occasional clipping?

A 14 panel string of those panels has a Voc @ STC of 535 Vdc. With an increase of ~1.6 Vdc per 1 deg C decrease in temp, that means the minimum temp must not drop below -15.5 deg C. I don't think you said where your daughter is located, but the minimum temperature indicated on this map is a good reference for determining the design minimum temp.

I would recommend staying away from the minimum string length on any string that might see shade. If the shade causes some or all of the current to route through the bypass diodes, the string voltage will drop by the number of cells being skipped. If this happens in summer, when warmer temps are already causing the voltage to drop, the overall voltage could be much less than what the design at STC suggests.

In this thread, how SMA inverters operate when they are above the min DC range but below the min MPPT range is discussed. It looks like the MPPT range is mostly to support marketing the inverter at a higher average efficiency, and when you drop out of that range you can expect to slide down the efficiency curve.

Originally posted by MinorDeity

Aside from my 8-panel and 14-panel concerns are issues related to increasing or decreasing the number of South-facing panels. On the one hand South is obviously the best azimuth in the Northern hemisphere. On the other hand, South is the array that gets chimney shading until about 10:30AM every morning, so any panels I add to it will not be operating at their full potential until after that. However, moving South panels to the East or West will also reduce their output. So, which choice is better? Is the amount lost by shading greater than the amount lost by an East or West azimuth? I don't know how to calculate for such a shading issue. If it were not for this concern I would think the 13E+13S+13W configuration would be the best compromise.

Based on what you've said, I'm thinking you'll be better off with the panels facing south, even with the chimney shade. The best way to figure it out is to get a shade analysis with something like a Solmetric SunEye... your installer might have one if you ask.

Originally posted by MinorDeity

SMA OptiTrac?
By reading SMAs OptiTrac propaganda one would think that it's a panacea for chimney shading problems (and possibly world peace, too), but many forum posts I've read seem to indicate that it has little or no practical effect. I considered re-contacting SMA for more technical details and test information about this, but given my previous experience with them I decided it would be a waste of time. What is your experience in such situations? I understand that OptiTrac can be enabled/disabled over the Internet, but currently the only Internet access to the system I have is via SMA's Sunny Portal Web site, which doesn't give access to inverter settings. What is the cheapest way to get appropriate access?

If you have the WebConnect card installed in the inverter (which maybe you do, since you are asking about TCP/IP access later, and have data in SunnyPortal), you can install SunnyExplorer software on a local PC to access data and inverter settings.

Originally posted by MinorDeity

Other shading:
One East panel has a 6" long shadow from a 2" diameter vent pipe all day. I'm assuming that it's best not to take any unnecessary chances and this panel should be moved. There is a similar situation in the West side but there is also a 6" diameter sheet metal vent there; that shading is only in the morning. Do you think any of this shading might be significant?

The amount you lose in the morning and evening will be less than if you had mid-day shade, of course. Shade in wintertime tends to be worse because the sun is lower, but in the summer it might not shade much at all. Moving panels away from shade is generally a good idea, although once you are able to get bettering monitoring/comparisons in place it will be easier to tell how much is being lost throughout the year.

Originally posted by MinorDeity

Sunny Portal Web Site:

I'm not very familiar with SunnyPortal. In my opinion, a better site for comparisons is PVOutput.org. Members in San Diego (71 at last count) have even created "Team San Diego" so that local comparisons are very easy to make.

Originally posted by MinorDeity

Yearly system production calculator:
My installer (not my daughter's) uses the "California Solar Initiative Incentive Calculators" on the csi-epbb Web site (no URL because I'm a newbie) to determine system expectations. I have no problems with this but I was just wondering if there are other such calculators the might be recommended. There is a link to such a calculator in another place in the solarpaneltalk forums, but that link is dead.

Use PVWatts. If you run the model with "Premium" panels, "Roof-mount" if appropriate, and 8-10% loss, you'll get results that agree well with what unshaded live systems using quality equipment typically produce.

Originally posted by MinorDeity

Other Inverter Monitoring:
I read an article some time back about an SMA user who coded up some kind of TCP/IP application that let him monitor real time inverter information on his computer. I don't know if he used C, C++, C#, Java, or what, but those or any others are fine with me. Do any of you know anything about doing this?

Google SBFSpot. Several members with SMA inverters on PVOutput's Team San Diego use it.

**sensij** · 12-21-2015, 11:05 AM

Originally posted by compchat

Something like the Rainforest EMU-2 Energy Monitoring Unit

will allow you to monitor your meter if your electric company supports it. I have one on order form Amazon which is compatable with SDG&E.

With the Sunnyboy interver there is an iphone app that monitors it. Look in the app store for Sunny Portal.

I do have a question about the configuration of the Sunnboy inverter. I know it can be hooked up to the internet using CAT 5 cable. To do this I would have to punch a hole in my outside wall or run the cable through a vent into the garage and then through a wall into the house. I bought a wi-fi range extender thinking I could plug the cable into the extender and then connect the extender to the in house wireless router. To do this I would have to rain proof both the power supply and range extender. Other then putting the equipment in a plastic container is there an easier, quicker and less obtrusive way to do this ? Alternatively can I drill right through the outside wall into the room with the router ? How do I avoid wiring, piping etc. Can I somehow force the CAT cable through a closed window (this would be the easiest way)?

IOW I'm trying to connect the Sunnyboy 6000 TL-US to the indoor router and need to get the cable to the inside router OR use a wireless range extender outside which needs power.

Thanks

This would probably be better asked in a separate thread. I've found that with a SolarEdge inverter, you can fit a small TP-Link pocket router (generally $15, sometimes as low as $5 on sale) operating in AP client mode inside the inverter's disconnect. Client mode supports the connections you've described. Putting it in the inverter takes care of the rainproofing, and since it doesn't have an extermal power supply, it can be compactly connected to the AC lines in the inverter that tie to the service panel, using a small inline fuse to protect the smaller conductors. The SMA disconnect looks big enough to fit it, but I'm not sure.

**MinorDeity** · 12-26-2015, 10:53 PM

Thank you to everyone who responded. The information was very useful. Ray

**compchat** · 12-31-2015, 03:47 AM

Ray

I did the network connection with my two sunny boy inverters myself. I had to remove the cover panels to get to the network "webconnect cards". This meant removing a total of 8 screws on each inverter (need a special screw driver).

I have a 5000TL-US22 and a 6000TL-US22. I plugged in the CAT cable to the A input in the 6000, ran a second cable from the B output to 5000 TL inverter. Then I connected that cable to the A input of the 5000 inverter. Then ran the first A cable from the 6000 inverter to the garage and hooked it up to a wireless access point. The WAP connected to my ASUS router without a hitch. Works perfectly with Sunny Portal (both iphone and internet). Fairly easy and straighforward. No reason to drill through the house/garage to connect to the router. Just ran the cable under the small garage door.

BTW make sure the inverter is off for 5 minutes before removing the panel. All AC disconnects off. I also have a Voltage Detector to make certain there was no remaining voltage in the portion of the inverter I worked on.

Oh and there are you tube videos on how to do this produced by Sunny Boy (however they don't discuss using a wireless access point or repeater).

System Configurations, SMA Inverters, Shading, & more

System Configurations, SMA Inverters, Shading, & more

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