diy solar grid tie

[foo1bar]

I just found out my main panel is top fed which I figured since my attic had the romex wire running all along it. So should I put my 30 amp breaker for my PV system on the right side? And and put my green ground and white neutral both on the same bus bar on the far right hand side?

First - is this your main panel?
Second - is this a combination meter+main panel?
Third - Is this picture upside down? "top fed" implies the feed (the wires electrically closer to the power pole) are connected at the top of the bus bar - this looks like the main breaker is connected at the bottom (but maybe you have the picture upside down)
4th - Where do you think the breaker for your PV system should be placed? Since you are asking that question I don't think you've done sufficient research to be able to do this as a DIY job and do it correctly.
5th - I'm drawing the same conclusion from your ground wire question - you appear to need to do some more learning about neutral/ground wires and main panels.

I STRONGLY recommend that you go do some research into your questions and then come back and say "I think I need to do X because of reason A, B and C. I was looking at webpage Y and Z that I came to this conclusion. " Or at least come back with "Y says to do this, Z says to do that. Which is right?"

[sdold]

I don't think the side matters. Your panel looks like its fed from the bottom. NEC and CEC Article 705 has the info on the interconnect, and signage too. Some of that varies by code though so you'd better find out which version Vacaville uses. In the 2016 CEC it's 705.12(D). I just thought of something, they might require an Arc Fault Interrupt breaker. And if you use one, the Enphase communication from the inverters might trip it. File that away in your memory for later if the breaker seems to trip for no reason.

[billy1]

Ok I think I'll go with the cheaper lower wattage panel.

IMG_20160929_142128.jpg IMG_20160929_142105.jpg



I just found out my main panel is top fed which I figured since my attic had the romex wire running all along it. So should I put my 30 amp breaker for my PV system on the right side? And and put my green ground and white neutral both on the same bus bar on the far right hand side?

[J.P.M.]

Ok, thanks for all the info guys. It seems more I learn more the rabbit hole gets bigger.

Renvu has a sale right now Solarworld 285 watt silver panel for $210.90 (0.74 cents watt) 6760 kWh year and Aleo 310 watt black panel for $269.70 (0.87 cents watt) 7353 kWh year. Either would be mated with Enphase m250. Both would work for me for my 15 panel setup and I my house uses 6700 kWh year, but the Aleo would "potentially" produce 593 kWh more per year on average which I thought would be nice to have if look at panel degradation for the future, but not sure if it's worth it. I used PVwatts with system losses 10%, inverter efficiency 96%, and DC to AC size ratio 1.1

What do you think?

On the PVWatts: As long as you get the orientations/shading right and remember that PVWatts is a model that only estimates long term average output good to maybe +/- 10 % or so for any actual yearly output, good to go. Also, it may be looking like panel degradation may be a less than the spec sheets say. How much ? I wouldn't oversize a lot based on panel degradation.

[billy1]

Ok, thanks for all the info guys. It seems more I learn more the rabbit hole gets bigger.

Renvu has a sale right now Solarworld 285 watt silver panel for $210.90 (0.74 cents watt) 6760 kWh year and Aleo 310 watt black panel for $269.70 (0.87 cents watt) 7353 kWh year. Either would be mated with Enphase m250. Both would work for me for my 15 panel setup and I my house uses 6700 kWh year, but the Aleo would "potentially" produce 593 kWh more per year on average which I thought would be nice to have if look at panel degradation for the future, but not sure if it's worth it. I used PVwatts with system losses 10%, inverter efficiency 96%, and DC to AC size ratio 1.1

What do you think?

[J.P.M.]

It has, that's what I was referring to when I said that the array must "have sound engineering behind the structure from the panels all the way to the ground".

Understood. Just reconfirming.

J.P.M.

[sdold]

Perhaps this has already been addressed, but an often forgotten part of the wind/seismic/external loading design is to check what the array is attached to (usually a roof) to make sure it too will handle the imposed additional loads and loading combinations, including imposed moment loads, particularly the uplift from wind, and especially if the array is not parallel to the roof.

It has, that's what I was referring to when I said that the array must "have sound engineering behind the structure from the panels all the way to the ground".

[sdold]

Overdesign is a poor excuse used by the ignorant to make up for sloppy engineering that can lead to expensive and perhaps (but in most situations, unknown) cases of possibly unsafe designs.

I agree, but in my case it was a good thing to do because of the way uplift loads would actually be carried. The way I calculated it for the AHJ, a mount point's uplift is shared equally between two screws, but in an actual uplift, it's initially carried by one screw, and there is an additional moment that is applied because of the shape of the tile hook. So the load is first applied to one screw, and then about the time that screw has backed out a couple of threads (which is all it takes to destroy the load carrying capacity of that screw/thread combo), the second screw begins to carry a load.

In other words, I don't think the second screw carries a tension load until the threads in the first screw have failed. I could be wrong about that, but I don't think I am.

The engineering examples I saw from the tile hook company didn't take this into account, but since I know how things work and knew that the two screws wouldn't be acting perfectly "in parallel", I kicked it up from 85 mph to 100. This had the dual effect of a) Decreasing the load carried by each mount, and b) Giving the AHJ the impression that it was solidly engineered. So in a case like this one, it is OK to do what I did. IIRC the loads at 85 mph can now be carried by a single screw with 150% margin, but I'm not positive. I think that is what I was shooting for.

Steve

[J.P.M.]

Maybe this will help: http://vacaville.granicus.com/MetaVi...&meta_id=61839

Foo1bar's advice was good too.

The questions you should ask them are about the code version followed, wind design speed used for the structural calcs, and possibly if an engineering stamp is required, although I might first submit my plans with thorough engineering on my own to see if it flies. They have the state-mandated "checklist" on their website, which basically says it must meed electrical code requirements and have sound engineering behind the structure from the panels all the way to the ground.

If you can't get any of the info, maybe just design it for 100 mph wind, no snow load (unless you're on Mt. Vaca) , CEC 2016, and see how they like it. Get it as absolutely correct and complete as you can before submitting so they take it seriously

Perhaps this has already been addressed, but an often forgotten part of the wind/seismic/external loading design is to check what the array is attached to (usually a roof) to make sure it too will handle the imposed additional loads and loading combinations, including imposed moment loads, particularly the uplift from wind, and especially if the array is not parallel to the roof.

An example, if a bit off this application: I once had a new engineer under my supervision who designed a lifting lug that was good for 10,000 lbm dead lift or so (as I recall), but it was welded to a 3/16" st. stl wall of a vessel that would have failed on lift even though the vessel only weighed about 3,000 lbm or so. The lug was adequate for the lift, but where it was attached (the vessel wall)would have failed. That, BTW, is why is an example of why they're called EIT's (engineers in training) and working under P.E.s.

For this wind loading, a bit of overdesign is OK, but I'd not, for example, use a 100 MPH design speed in a 70 MPH zone, so you don't wind up with more overdesign than practical, as a small example: with required screw embedment that's more than the rafter depth, and never without checking the other required design criteria such as exposure factor, importance factor, etc. per the ASCE specs.

Overdesign is a poor excuse used by the ignorant to make up for sloppy engineering that can lead to expensive and perhaps (but in most situations, unknown) cases of possibly unsafe designs.

[sdold]

Maybe this will help: http://vacaville.granicus.com/MetaVi...&meta_id=61839

Foo1bar's advice was good too.

The questions you should ask them are about the code version followed, wind design speed used for the structural calcs, and possibly if an engineering stamp is required, although I might first submit my plans with thorough engineering on my own to see if it flies. They have the state-mandated "checklist" on their website, which basically says it must meed electrical code requirements and have sound engineering behind the structure from the panels all the way to the ground.

If you can't get any of the info, maybe just design it for 100 mph wind, no snow load (unless you're on Mt. Vaca) , CEC 2016, and see how they like it. Get it as absolutely correct and complete as you can before submitting so they take it seriously

[foo1bar]

Hm - looks like I found Vacaville's CEC amendments.

http://www.codepublishing.com/CA/Vacaville/

http://www.codepublishing.com/Ca/vacaville/Vacaville14/Vacaville1420254.html#14.20.254

[foo1bar]

I'm still scratching my head because cities in general can add special requirments, but my city refuses to tell me what they are.

Probably they aren't refusing to tell you - you just didn't ask that *specific* question.
"Hi, I'm Bill Smith. I need to know if Vacaville has any amendments to the electrical code or if it's just the vanilla California Electrical Code".

What you probably asked was an open-ended question that is essentially asking the building inspector for advice - and they can't/shouldn't give advice.
What they should do is tell you "Item X is not up to code because of Code section Y"
The general assumption is that the builder generally knows what he is doing, and will get things mostly right - and the inspector is just there to catch mistakes that can happen.
It's not the inspector's job to give advice - especially on things where it may not even be a question of code.

I'd start by figuring out what you're going to do.
Create detailed plans of what you're doing. You'll need both mechanical plans and electrical plans.
The mechanical plans you will need to calculate that your fastening to the roof is sufficient. (I used IronRidge racking and used their tool to figure what was sufficient number of fastening points, etc. ) You'll also need to figure out what conduit is needed / how the wires are getting to the roof.

The electrical plan you can probably find a number of sample plans and adapt them to your needs.

Once you have the plans made including various details on fastener method, grounding methods, etc, you can take your plans to the building dept. You will review the plans with their plan reviewer who will hopefully say "This all looks good." Or he/she will ask that you add additional details. Or point out issues with your plans that you'll need to address.

I'd recommend watching some videos, doing some reading, and you may even want to do some installing as a volunteer. Before I did my install I spent a Saturday volunteering for Sunwork out of Milpitas. Job site was in Sunnyvale. They do have some jobs farther north - and there might be a similar non-profit nearer to you.

[billy1]

I just spoke to the building inspector in person in Vacaville and he said due to a city ordinance passed last November, he cannot answer any of my questions and the city would rather I pay someone to install. Talk about being in a rock in a hard place, that explains why the inspector didn't return my voicemail and email. He did suggest I look online for "how to install solar" to get a template for the paperwork to submit and to read title 24. I'm still scratching my head because cities in general can add special requirments, but my city refuses to tell me what they are. I did speak to 3 separate installers in the past month and they all said with micro inverter setup, they can run the wires directly into the main service panel without a separate disconnect and and that the fire setback is 3 feet on left, right, and ridgeline.

[sdold]

It depends on wind zone, exposure category, the pullout strength of the mount, the framing method and species, snow load, rail manufacturer requirements, etc. ASCE 7-10 along with wind speed and snow load numbers from the Building department will get you going. On mine, I got the wind speed/snow load requirements from the city, designed to the next higher wind speed, and chose the number of mounts to satisfy the uplift loads plus a generous fudge factor. Be aware that there might be fire setback or even seismic requirements. That's why it's important to have a conversation with the building inspector early on.

[billy1]

ICalcs looks like a windows program. I have linux and chrome os pc's. I just looked at unirac builder I'm thinking a roof hook every 48" ? (rafter is every 24")