Sanity Checking + Advice on SolarEdge

[aleenoor]

I'm not sure what there is to say at this point. The design with the Kaco is straightforward, two inverters gives you 4 mppt's, so you can make strings of 10 panels and land nicely in the voltage range the inverter wants to see. I'm not sure how monitoring works on those, but they have an ethernet port, so presumably there is something available. If you go with SolarEdge, maybe you lose a little bit less production to shade, but $1500 seems like a lot of ground to make up if you don't have any shade during the middle portion of the day. You get individual panel monitoring, which might be worth something to you, but you also get the risk of failure of an optimizer, which could be a headache if it happens in the middle of your array and you need to clear a path through good panels to get to it. Kaco's US division is relatively new, which is probably a point in favor of SolarEdge today given SE's current market share, but SolarEdge hasn't been around all that long either.

The Canadian Solar panels are slightly smaller than the Hanwha panels. It was enough of a difference to affect my installation, so I went with Canadian Solar. I'm not sure that you'll really see any difference between them in performance.

Thanks Sensij,
There is very little info on KACO online. I called them and the third time a tech-support guy told me that inverter has all monitoring built in and has a built-in web-server that can be accessed to view the monitoring data. It also comes with 5 year remote monitoring service from Meteo Control. There is a lot of money to be saved but the info on KACO is very scarce.

I have requested finals quotes on CS6K-295MS , KACOs and SE with shipping and will be making my decision soon.

Has your Canadian / SE equipment arrived ? how is your install coming along.

Also, while I have you, I want to check with you something that my installer is recommending. I have attached a crude diagram of my electrical setup. Initially, my installer was saying that we will need to de-rate the outside 200A breaker to 175A and then we can add (2x30A in case of KACO) to the inside main 1.

He later emailed me and said that we can add the 2x30A into the sub-panel 2, without having to de-rate the outside main breaker to 175A. That way all bus-bars will be below 125%. Finally, do you know what size breaker is needed for the SE 11400 inverter ? 60A or higher ?

Thanks again !

[sensij]

Thanks Sensij,
There is very little info on KACO online. I called them and the third time a tech-support guy told me that inverter has all monitoring built in and has a built-in web-server that can be accessed to view the monitoring data. It also comes with 5 year remote monitoring service from Meteo Control. There is a lot of money to be saved but the info on KACO is very scarce.

I have requested finals quotes on CS6K-295MS , KACOs and SE with shipping and will be making my decision soon.

Has your Canadian / SE equipment arrived ? how is your install coming along.

Also, while I have you, I want to check with you something that my installer is recommending. I have attached a crude diagram of my electrical setup. Initially, my installer was saying that we will need to de-rate the outside 200A breaker to 175A and then we can add (2x30A in case of KACO) to the inside main 1.

He later emailed me and said that we can add the 2x30A into the sub-panel 2, without having to de-rate the outside main breaker to 175A. That way all bus-bars will be below 125%. Finally, do you know what size breaker is needed for the SE 11400 inverter ? 60A or higher ?

Thanks again !

The SE11400A-US inverter has a max continuous output of 47.5 A. Therefore, it requires roundup(47.5 * 1.25) = 60 A breaker.

I don't understand why your installer is suggesting that by installing in sub-panel 2, instead of in main 1, you can avoid de-rating the main breaker. You are NEC 2011 right? (no rapid shutdown required). 705.12(D)(7) clearly states that for panelboards in series, the rating of the first overcurrent device is used for all busbar calculations. 2014 NEC has a few more options, but I still think you would need to derate the main if the main bus has only a 200 A rating.

My panels arrived on Wednesday, a week after placing the order. They came as a full pallet, in original packaging, plus two panels on top protected by cardboard and securely strapped to the pallet. I received the SE optimizers and other racking/mounting components as well, but held off on ordering the inverter in the hopes that the 7600H will be available by the time the rest of the system is installed and I'm ready for it.

I can't do any work outside the house until I get HOA approval, and with the 3rd party management company involved, that goes slow. I've been working on the interior conduit runs in the meantime... it has taken a few attempts to find a clean path from the attic down through walls into the garage.

[J.P.M.]

The SE11400A-US inverter has a max continuous output of 47.5 A. Therefore, it requires roundup(47.5 * 1.25) = 60 A breaker.

I don't understand why your installer is suggesting that by installing in sub-panel 2, instead of in main 1, you can avoid de-rating the main breaker. You are NEC 2011 right? (no rapid shutdown required). 705.12(D)(7) clearly states that for panelboards in series, the rating of the first overcurrent device is used for all busbar calculations. 2014 NEC has a few more options, but I still think you would need to derate the main if the main bus has only a 200 A rating.

My panels arrived on Wednesday, a week after placing the order. They came as a full pallet, in original packaging, plus two panels on top protected by cardboard and securely strapped to the pallet. I received the SE optimizers and other racking/mounting components as well, but held off on ordering the inverter in the hopes that the 7600H will be available by the time the rest of the system is installed and I'm ready for it.

I can't do any work outside the house until I get HOA approval, and with the 3rd party management company involved, that goes slow. I've been working on the interior conduit runs in the meantime... it has taken a few attempts to find a clean path from the attic down through walls into the garage.

Don't know if you are aware of this or not: The HOA has 45 days to approve/disapprove from date of your application to them. If no action on their part after that 45 days, your application is deemed approved. See the CA Solar rights act and other CA HOA law for time limits for HOA approvals. I'd assume the HOA is aware of these requirements, but if not, it's sometimes in the homeowner's better interests to let them (the HOA) discover their responsibilities under the law on their own. Just sayin', FWIW only.

[sensij]

Don't know if you are aware of this or not: The HOA has 45 days to approve/disapprove from date of your application to them. If no action on their part after that 45 days, your application is deemed approved. See the CA Solar rights act and other CA HOA law for time limits for HOA approvals. I'd assume the HOA is aware of these requirements, but if not, it's sometimes in the homeowner's better interests to let them (the HOA) discover their responsibilities under the law on their own. Just sayin', FWIW only.

<threadjack>
Thank you for the information, I didn't know that. The written policies haven't been updated for PV, as far as I can tell. It's only been 30 days, so not much basis for pushing. After seeing your note, I gave the HOA company a friendly call anyway, and was able to connect with the manager handling my application. She said she's been out of the office, but that it was approved, and she'd get an email to me today with the approval letter, and to watch for the hardcopy in the mail next week. Nice! If it stays dry tomorrow, I might be able to get up on the roof and starting chalking it out.
</threadjack>

[ButchDeal]

<threadjack>
Thank you for the information, I didn't know that. The written policies haven't been updated for PV, as far as I can tell. It's only been 30 days, so not much basis for pushing. After seeing your note, I gave the HOA company a friendly call anyway, and was able to connect with the manager handling my application. She said she's been out of the office, but that it was approved, and she'd get an email to me today with the approval letter, and to watch for the hardcopy in the mail next week. Nice! If it stays dry tomorrow, I might be able to get up on the roof and starting chalking it out.
</threadjack>

The written policy of the HOA is trumped by the state law...

you should start a thread so you can add photos as you build it out.

[J.P.M.]

<threadjack>
Thank you for the information, I didn't know that. The written policies haven't been updated for PV, as far as I can tell. It's only been 30 days, so not much basis for pushing. After seeing your note, I gave the HOA company a friendly call anyway, and was able to connect with the manager handling my application. She said she's been out of the office, but that it was approved, and she'd get an email to me today with the approval letter, and to watch for the hardcopy in the mail next week. Nice! If it stays dry tomorrow, I might be able to get up on the roof and starting chalking it out.
</threadjack>

You're welcome. More FWIW, and no more than respectfully suggested: Check updated Solar Rights legislation, re: shading, glare, etc. sounds like your HOA's mgmt. co. isn't the sharpest tool in the shed, but they, and your Board can still make life a PITA. I suggest be gentle with them as you are doing. See the net: "Davis-Stirling.com". Stuff your mother never told you. Not perfect, but not a bad quick ref. 10yrs. on the Arch. Rev. Comm. and that site has always agreed w/counsel. Keep the HOA informed, but not over-informed. If you can't dazzle them with brilliance, baffle them with B.S. Before you do either however, just read the CC & R's and bylaws and check that website as your needs dictate.

[Magius]

I just saw in another thread that it's inline with forum rules to post links (only) to your installer's solarreviews.com page. I previously emailed aleenoor the contact info for my installer, but in case anyone else comes across this thread and wants to know, I thought I'd leave that link. I went with Superior Solar: http://www.solarreviews.com/installe...stems-reviews/. IMHO, they fully deserve their perfect 5-star rating...

[aleenoor]

I just saw in another thread that it's inline with forum rules to post links (only) to your installer's solarreviews.com page. I previously emailed aleenoor the contact info for my installer, but in case anyone else comes across this thread and wants to know, I thought I'd leave that link. I went with Superior Solar: http://www.solarreviews.com/installe...stems-reviews/. IMHO, they fully deserve their perfect 5-star rating...

Marc,
Thanks again for sharing this. Very helpful indeed. I was looking at your output on SE yesterday and saw that some panels consistently hit peak wattage close to or over their STC of 320W. I know your strings are a mix of different angles and azimuths. Do you have detailed data available to you to determine if you would clip if they were all facing south ?

In my case, I have all 40 of my (proposed) panels facing S at 26.6 degrees. Should I assume my system as a whole WILL hit its STC wattage. It makes me think twice about under sizing my inverter. (11.8kW DC to 10kW AC). I do not want to clip.

[J.P.M.]

In my case, I have all 40 of my (proposed) panels facing S at 26.6 degrees. Should I assume my system as a whole WILL hit its STC wattage. It makes me think twice about under sizing my inverter. (11.8kW DC to 10kW AC). I do not want to clip.

You may well hit or even exceed the S.T.C. rating with your output, but it will be for what's probably a very slight fraction of the ~ 4,380 hrs. of the year the sun is above the horizon. If/when that occurs, the loss will be something like a few% or so of total potential output at that time. So, a small number (a bit of time/4,380) multiplied by another small number (lost instantaneous output/total actual output) is a very small number. Most of that overproduction, if it occurs at all, will probably be on a clear, sunny, cool, windy day will be around this time of the year. You may also see a spike or 2 lasting a minute or two at other times due to cloud reflections, but not many folks see a lot of sense increasing inverter size to handle those situations. If in doubt about being limited by the inverter, check with your installer, and check the price increase to upsize the inverter vs. how much more revenue a larger inverter will allow by getting rid of a small amount of clipping. Also know that slight clipping will probably disappear after a few years due to system/panel performance degradation.

One other way to go: Since the real name of the game is the most cost effective way to lower an electric bill, and not necessarily solar for its own sake, and since most arrays are oversized due to ignorance of how to cost effectively size an array anyway, if your array is not yet built, , there may well be some logic in decreasing the number of panels as a scheme to eliminate clipping. Do that, and you'll probably get a bonus of a lower LCOE (Levelized Cost of Electricity) for the array.

[sensij]

Marc,
Thanks again for sharing this. Very helpful indeed. I was looking at your output on SE yesterday and saw that some panels consistently hit peak wattage close to or over their STC of 320W. I know your strings are a mix of different angles and azimuths. Do you have detailed data available to you to determine if you would clip if they were all facing south ?

In my case, I have all 40 of my (proposed) panels facing S at 26.6 degrees. Should I assume my system as a whole WILL hit its STC wattage. It makes me think twice about under sizing my inverter. (11.8kW DC to 10kW AC). I do not want to clip.

Where do you see panels hitting 320 W? I just looked at his SolarEdge portal, and on a good day like April 8, the south facing panels are reporting around 300 W.

[Magius]

Where do you see panels hitting 320 W? I just looked at his SolarEdge portal, and on a good day like April 8, the south facing panels are reporting around 300 W.

The one thing I most dislike about the SE portal is that it only retains per-panel data for the current week. If you were able to see back to my absolute best day or two, my south facing panels have occasionally produced as high as 335W, and maintained numbers higher than 320W for an hour or so at a time .

The best example I can point to in this current week would be on 04/07. Starting at 12:30, a few of the south-facing panels are ~321-323W, and this continues through the reading at 13:00. So for about a half hour, a couple of panels were beating their 320W STC value by a couple of watts, no big deal. On most days, they never make it even that high, more typical is to top out right around 300W, just like sensij points out. The couple times I saw them get into the 330's was only due to the abnormal cold front that came through last month. It was in the 50's outside instead of the low-80's, so that's where the extra 10-15W came from.

Do you have detailed data available to you to determine if you would clip if they were all facing south?

I do not have "detailed data", however I can say without doubt that my system would clip if I pointed all 57 modules due south. I have 18.24kW of module going into 15.2kW (2x7.6) of inverter, or an oversizing factor of 20%. It was designed that way specifically because of my three azimuths, and the strings were balanced across the inverters to even out the load throughout the day as the sun moves east to west.

The highest I've ever seen one of my inverters peak is just over 8kW, and the highest combined total around 15.8-15.9kW. Of course that's over a short time period, and the SE inverter is rated to exceed the 7.6kW "continuous" rating for short times like that. However, only 12 of my modules are aimed south, so if I took the other 45 of them and pointed them south, picking up an average of 20% more production from each, that would boost my overall system production by almost 16%. In that scenario, my observed peaks of ~15.8kW would jump to something like 18.29kW, far more than the two inverters are capable of outputting.

So yes, my system would absolutely clip if I pointed all the modules due south, but it was not designed for that. I would have designed it with larger inverters and less oversizing had that been the expected layout. Also, for what it's worth, PVWatts can estimate energy lost to clipping by playing with the inverter sizing variable. In the end, it's not worth worrying about a few watt-hours of clipping a few days a year, since you more than make up for it with increased production during low-light conditions and cloudy days.

[sensij]

The one thing I most dislike about the SE portal is that it only retains per-panel data for the current week. If you were able to see back to my absolute best day or two, my south facing panels have occasionally produced as high as 335W, and maintained numbers higher than 320W for an hour or so at a time .

If you have an owner login to the monitoring portal, your installer can give you full access to the available reports. Using the "charts" tab, I can see every data point that was ever sent by the inverter for each individual optimizer, showing panel voltage, optimizer voltage, current, power, and energy.

You can use detailed data like this to confirm whether deviations in performance are the result of irradiance (high or low current) or temperature (high or low voltage). When voltage is spiking, that is usually an indicator that the mppt is dealing with rapidly changing conditions (clouds, sometimes other source of shade).

The data can all be downloaded into spreadsheets, although if you want data over an extended period of time, it is kind of a pain. The timestamps in the data dump provide insight into the data freshness problems that limit the utility of the playback screen you are familiar with.

Here is a screenshot showing current and voltage for one particular optimizer on 4/14/2015 report.JPG

[J.P.M.]

The one thing I most dislike about the SE portal is that it only retains per-panel data for the current week. If you were able to see back to my absolute best day or two, my south facing panels have occasionally produced as high as 335W, and maintained numbers higher than 320W for an hour or so at a time .

The best example I can point to in this current week would be on 04/07. Starting at 12:30, a few of the south-facing panels are ~321-323W, and this continues through the reading at 13:00. So for about a half hour, a couple of panels were beating their 320W STC value by a couple of watts, no big deal. On most days, they never make it even that high, more typical is to top out right around 300W, just like sensij points out. The couple times I saw them get into the 330's was only due to the abnormal cold front that came through last month. It was in the 50's outside instead of the low-80's, so that's where the extra 10-15W came from.



I do not have "detailed data", however I can say without doubt that my system would clip if I pointed all 57 modules due south. I have 18.24kW of module going into 15.2kW (2x7.6) of inverter, or an oversizing factor of 20%. It was designed that way specifically because of my three azimuths, and the strings were balanced across the inverters to even out the load throughout the day as the sun moves east to west.

The highest I've ever seen one of my inverters peak is just over 8kW, and the highest combined total around 15.8-15.9kW. Of course that's over a short time period, and the SE inverter is rated to exceed the 7.6kW "continuous" rating for short times like that. However, only 12 of my modules are aimed south, so if I took the other 45 of them and pointed them south, picking up an average of 20% more production from each, that would boost my overall system production by almost 16%. In that scenario, my observed peaks of ~15.8kW would jump to something like 18.29kW, far more than the two inverters are capable of outputting.

So yes, my system would absolutely clip if I pointed all the modules due south, but it was not designed for that. I would have designed it with larger inverters and less oversizing had that been the expected layout. Also, for what it's worth, PVWatts can estimate energy lost to clipping by playing with the inverter sizing variable. In the end, it's not worth worrying about a few watt-hours of clipping a few days a year, since you more than make up for it with increased production during low-light conditions and cloudy days.

FWIW, what you write seems to make sense and pretty much line up with what I've observed w/ my stuff.

More FWIW, this time of year, under clear skies, at the time of daily min. incidence angle for my array, my panel temps. measure approx. and somewhere between 25 - 30 deg. C. higher than ambient temp. at min. incidence angle time, depending mostly on P.O.A irradiance and wind vector.

[Magius]

If you have an owner login to the monitoring portal, your installer can give you full access to the available reports. Using the "charts" tab, I can see every data point that was ever sent by the inverter for each individual optimizer, showing panel voltage, optimizer voltage, current, power, and energy.

Thank you Sensij for clarifying that. I do actually have full access to my portal and I've played around just a tiny bit with the charts and reports features. I didn't realize though that I could go back in time and get historic data points that aren't available in playback anymore. That should be fun to play with, thank you! Can the API pull down those same historic data points, or are you limited to exporting them from the charts interface? I wouldn't mind doing a bulk data pull once a month, etc., to dump all that historic data to Excel...

Fun side story, I was the first person ever to ask my installer for increased portal access so that I could run charts and reports, and also the first to ask them for my API key. My PM wasn't really sure what the API key was, so she asked their IT department about it, and they got a little freaked out like "what is this customer going to be able to do with that key if we give it to him?". In the end, it was the electrician who had done the install and talked with me on-site that calmed everyone down and essentially said "whatever this customer wants just give it to him, he's an engineer"

[sensij]

Thank you Sensij for clarifying that. I do actually have full access to my portal and I've played around just a tiny bit with the charts and reports features. I didn't realize though that I could go back in time and get historic data points that aren't available in playback anymore. That should be fun to play with, thank you! Can the API pull down those same historic data points, or are you limited to exporting them from the charts interface? I wouldn't mind doing a bulk data pull once a month, etc., to dump all that historic data to Excel...

No, optimizer data are not available through the API.