Grid Tied System - Design

[BillSunGen]

One item you haven't mentioned is surge/lightning protection. Barns seem to attract a fair share of hits as they are usually tall without a lot of trees around them. Nothing is guaranteed if there is direct strike but its definitely worth spending the bucks to try to get protection in place. I am impressed with the specs on the Midnight Solar SPDs and the construction seems to be step above others I have seen. If it was my system I would have one on at the combiner box on the roof and another, between the inverter and the subpanel in the barn. For good measure I also suggest one on the main panel but that is not as much PV related as general good practice to keep utility surges out of your panel.

Also look around for the recommendation on how to ground the wiring on the property. Sunking and others are the pros and have opinions on what is code and what is right and suggest you do some searching on older threads to get the latest and greatest. I think it involves putting in ground rod at the barn connected to the main house ground point via #4 copper laid in the conduit trench but as I said its worth doing the searching.

I will be including lighting protection. We do have lots of tall trees around too but that seems like the opposite of protection! The plan will be to use the midnite products, they have sold me with the comparison tests and seem legit. I don't understand the sizing but am sure I can figure it out from the internet or old posts. I was really surprised that it seemed like each combined array (set of strings?) required protection plus all the inputs downstream. My house actually has a full lightning protection system built in with rods through the eves and grounding wires presumably buried appropriately deep. We haven't had any issues but the owners before us (per stories from the neighbors) lost a lot of electronics to lightning. (They also stored chlorine in the unconditioned (read damp) basement like space that houses the electric panels and guess what, they rusted! so one of the first things we did was to replace those panels and inspect the house wiring and we added surge protection to each panel at that point as well. The lights are still on so i guess it is doing its job. And there is no more oxidizers stored there and it is now de-humidified too!) My concern is with the lightning system on the house has always been that it would attract the lightning to the house by giving it an easier path to ground.

Reading through the recent post on grounding I think this is the relevant point:

So what I am telling you is treat the panels as Air Terminals and take the Down Conductor directly to the GES bypassing everything. A straight dire route to EARTH good ole dirt. If you drive a rod to accomplish that, then it must be bonded to all other electrodes so as to make a common GES. It can also be routed to the GEC and bonded below the Meter Can just above or below grade. It comes down to how everything is laid out. A good layout will bring the Lightning Down Conductor straight down to the AC Meter Box so you do not have to drive another rod and go that extra expense and trouble.

Since I am adding an outbuilding, the barn, from a grounding standpoint I will probably need to treat the panels like lightning rods and connect them all directly to a new driven rod at that location. BUT like you said it will be important that I tie the barn grounding to my existing lightning and meter grounding at the house too.

[ButchDeal]

I have a photocell light control for the 3 W LED light in my phone booth. A similar size might work for a
porch light, I switch on a bulb for reading. Bruce Roe

also speaking of this we have a light sensor and motion sensor combination in our light post in the front yard. It has three candelabra lights. I put three LED bulbs in it and the thing wouldn't work at all. I had to switch one of the LEDS to a low watt incandescent for the sensor to work.

[BillSunGen]

Is that a Samsung Smarthings hub? My Frontier internet was down for a few days and the smartthings hub was completely useless. I quickly got away from that and only use it for a few inconsequential things now.

That is the crazy thing. It is just a TV, a 'Smart' TV but I don't have anything setup on it. Just how it came out of the box. I had to connect it to the internet to get it to turn on but then blocked it at the router the next day as all my other devices were operating at a crawl. It is amazing how many of the new devices have to have an internet connection to do something local. You want your doorbell to ring? Needs internet. Want to view your security camera? Needs internet. Want to read your newspaper? Needs internet (oh wait I still get the paper so that one works...) Same with the home automation stuff. It is neat, takes a lot more time than I have to setup, but all breaks if the internet isn't available. Makes it a bit fragile. Being able to configure something on a local subnet just isn't something that comes up in regular marketing materials but it is probably out there somewhere.

[bcroe]

I have some motion lights as well but I have a flag that, per flag etiquette, should be lit if
flying at night. I also want the front porch light on all night. Plus, I want the photocell signal for some HA functions.

I have a photocell light control for the 3 W LED light in my phone booth. A similar size might work for a
porch light, I switch on a bulb for reading. Bruce Roe

[peakbagger]

One item you haven't mentioned is surge/lightning protection. Barns seem to attract a fair share of hits as they are usually tall without a lot of trees around them. Nothing is guaranteed if there is direct strike but its definitely worth spending the bucks to try to get protection in place. I am impressed with the specs on the Midnight Solar SPDs and the construction seems to be step above others I have seen. If it was my system I would have one on at the combiner box on the roof and another, between the inverter and the subpanel in the barn. For good measure I also suggest one on the main panel but that is not as much PV related as general good practice to keep utility surges out of your panel.

Also look around for the recommendation on how to ground the wiring on the property. Sunking and others are the pros and have opinions on what is code and what is right and suggest you do some searching on older threads to get the latest and greatest. I think it involves putting in ground rod at the barn connected to the main house ground point via #4 copper laid in the conduit trench but as I said its worth doing the searching.

[ButchDeal]

Is that a Samsung Smarthings hub? My Frontier internet was down for a few days and the smartthings hub was completely useless. I quickly got away from that and only use it for a few inconsequential things now.

Wink Hub 2 has some local control capabilities.

Those only report every four hours. Unfortunately, that is what my installer put on mine.

Yes but if you read the comment i replied to, he only has cell phone internet and wanted a LESS chatty monitoring option. This IS that option.

[DrLumen]

I suppose outdoor lights are there for the convenience of the owners, and to discourage those who
should not be there. I found motion triggered lights do both much better. The average power is so
low, I can have a lot more of them, than all night lights. You can circle my place, and never be in
the dark. Bruce Roe

I have some motion lights as well but I have a flag that, per flag etiquette, should be lit if flying at night. I also want the front porch light on all night. Plus, I want the photocell signal for some HA functions.

My guess is that most internet of things developers are on fiber or just plain stupid when it comes to caring about network efficiency (To name specific ones I am looking at Samsung as the worst in my house). So the geek side of me loves the data and the cool interfaces, reporting, and management but if it can't be done locally it probably isn't for me.

Is that a Samsung Smarthings hub? My Frontier internet was down for a few days and the smartthings hub was completely useless. I quickly got away from that and only use it for a few inconsequential things now.

Some like SolarEdge have a cell modem option for monitoring.

Those only report every four hours. Unfortunately, that is what my installer put on mine.

[bcroe]

I have been running a pair of Fronius IG Plus string inverters here for 5 years, no failures. They are
over paneled quite a bit. Of course no individual panel monitoring. No hands on experience with
optimizers here. Bruce Roe

[ButchDeal]

On the permit side, I plan on doing both (of whatever the final design is) at the same time and will be fully permitted and by the book. As I read it Dominion can't write the rules if it isn't connected to 'their' grid. But yes, I understand it is a whole different cost/benefit set of decisions on that one.

the power company does not write the requirements for the permit, the AHJ does and you still have to meet the code requirements on or off grid
the off grid will have zero return on investment. Your cost benefit analysis for the off grid side is easy.

On monitoring, any system that allows direct access to the data is a plus for me. My internet connection is through 3g/4g on a cell phone and most 'smart' devices are EXTREMELY chatty with their network traffic. My guess is that most internet of things developers are on fiber or just plain stupid when it comes to caring about network efficiency (To name specific ones I am looking at Samsung as the worst in my house). So the geek side of me loves the data and the cool interfaces, reporting, and management but if it can't be done locally it probably isn't for me.

Some like SolarEdge have a cell modem option for monitoring.

[BillSunGen]

ButchDeal you are correct I was confusing the optimizers and the micro inverters. I know i started with the optimizers but i guess looking into the enphase systems I just lumped them all together at some point in my head. Good to know on experience with the Fronius, I am a bit sensitive on 'capacitor' issues. I had two fairly expensive motherboards fail due to what is now apparently known as the Capacitor Plague according to Wikipedia (https://en.wikipedia.org/wiki/Capacitor_plague). For SMA I speced out a Sunny Boy 5, Sunny Boy 6 combination but that would have required a combiner box as well and (in theory) was getting close on the 10 kW limit but would probably have been fine after loss adjustments. The Fronius seemed simpler so was leaning that way. Is there anyone here who is a fan of the Fronius systems?

On the permit side, I plan on doing both (of whatever the final design is) at the same time and will be fully permitted and by the book. As I read it Dominion can't write the rules if it isn't connected to 'their' grid. But yes, I understand it is a whole different cost/benefit set of decisions on that one.

On monitoring, any system that allows direct access to the data is a plus for me. My internet connection is through 3g/4g on a cell phone and most 'smart' devices are EXTREMELY chatty with their network traffic. My guess is that most internet of things developers are on fiber or just plain stupid when it comes to caring about network efficiency (To name specific ones I am looking at Samsung as the worst in my house). So the geek side of me loves the data and the cool interfaces, reporting, and management but if it can't be done locally it probably isn't for me.

[ButchDeal]

I suppose outdoor lights are there for the convenience of the owners, and to discourage those who
should not be there. I found motion triggered lights do both much better. The average power is so
low, I can have a lot more of them, than all night lights. You can circle my place, and never be in
the dark. Bruce Roe

I prefer motion lights for the same reason.

[bcroe]

Case in point... I have ~492 square feet of solar panels and still need a photocell to control the outdoor lights.

I suppose outdoor lights are there for the convenience of the owners, and to discourage those who
should not be there. I found motion triggered lights do both much better. The average power is so
low, I can have a lot more of them, than all night lights. You can circle my place, and never be in
the dark. Bruce Roe

[ButchDeal]

Case in point... I have ~492 square feet of solar panels and still need a photocell to control the outdoor lights.

You could just as easily control the lights with cloud based pv monitoring if you wanted to, Or any of the weather/time based rules from IFTTT or other such services.

[DrLumen]

Case in point... I have ~492 square feet of solar panels and still need a photocell to control the outdoor lights.

[ButchDeal]

I have to bring this up as the monitoring of SE data was mentioned. I really dislike SE monitoring as it is all cloud based. They pretty much make it mandatory that access of MY data has to go through them. While I don't sit on my array and only check the status ~2-3 times per week (not counting my automated data pulls), there have been more than a few times recently that the SE site has been down. Without a lot of hook and crook and wedge and shimmy, there is no way to directly get real time, granular data locally from the inverter. If monitoring is going to be important then you may do some looking into the SE monitoring/reporting strategy before making a decision.

Nearly all grid tie inverter monitoring solutions are cloud based. A few have some limited local access these are mostly in older models and are going away.
solaredges monitoring is just about the best monitoring of any of the systems available though.