My 10.1KW System
mr.radon
Solar Expert Posts: 158 ✭✭✭✭✭
Well I've got the big part of my 10.1KW system today. 45 REC Solar REC225PE-US panels. I can confirm they come with MC 4 connectors. Thankfully...
I have yet to receive my Enphase inverters or ProSolar fast jacks. I'm building my own racking system, mainly using 1"X3" rectangular .125" wall tubing. A local supplier gave me the stock at a big discount.
Yesterday I got my mechanical permit, they checked all my stress calculations and verified I had a good mounting system.
Had a friend stop by who has an electrical license, he checked my wiring. Lots of updates to follow on that.
Have all the electrical lines pre-run in the attic spaces. All I need to do now is wait for the other parts to arrive.
Will post pictures when I get a chance.
I have yet to receive my Enphase inverters or ProSolar fast jacks. I'm building my own racking system, mainly using 1"X3" rectangular .125" wall tubing. A local supplier gave me the stock at a big discount.
Yesterday I got my mechanical permit, they checked all my stress calculations and verified I had a good mounting system.
Had a friend stop by who has an electrical license, he checked my wiring. Lots of updates to follow on that.
Have all the electrical lines pre-run in the attic spaces. All I need to do now is wait for the other parts to arrive.
Will post pictures when I get a chance.
Comments
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Re: My 10.1KW System
What kind of performance do you expect from your system with all the overcast weather you have?
I moved away after 15 years because the wife couldnt take the grey days. Here in Puerto Rico I get 1700 - 2200 watts with clear skys but only 200W on cloudy days. And realy cloudy days it drops to less than 50Watts! My system is 2050Watts. -
Re: My 10.1KW System
Should be making about 9000kWh/year. -
Re: My 10.1KW System
Glad your project is moving along. Snap some pics to share.
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Re: My 10.1KW System
how did you decide on the REC panels? I'm considering same for a smaller system. -
Re: My 10.1KW Systemhow did you decide on the REC panels? I'm considering same for a smaller system.
I was going to get 230W, but the distributor was willing to kick in free shipping on the 225W. Got them for about $500 and panel.
I heard great things about the Rec Group. Last year I wanted to do this with SCM panels, then they had the AE's, then the PE's.
I wish I could afford the Silicon Energy glass on glass panels made here in WA, but they are way to $$$. -
Re: My 10.1KW System
Status update:
The PUD approved my Interconnect agreement, glad I called them as they approved the wiring layout but never told me they didn't get the interconnect agreement.
Next weekend I'll be installing panels.
Today I got the last of the SolarMount I parts on the truck heading my way. I was looking at designing my own racks out of a local Al. However, after looking at my machining time (I have a mill, lathe, saws) I just could not see the $$$ savings. Then the company I was going through for the Enphase inverters said they had just started selling the SolarMount I line, then he threw in FREE shipping if I also bought the racks from him. Enphases only cost me $150.50/unit!
So I did a lot of design work this weekend, and laid out the racks on my roof, I've attached a PDF of the drawings. I also have detailed prints of the racks (42", 82", 122", 162" and 242") See the PDF on the foot spacing. The County questioned the 242" rack, but after running the numbers it passes even with the 18" over hang on the one side.
Here is the BOM:
010144M-001 Beam, 100 Series 144"-Mill Finish 27
002028C-001 MidClamp D,K 68
002004C-001 EndClamp D 52
003021C-001 Splice kit w/grounding 26
008000S-001 UGC-2 CLICKSYS Grounding clip 45
008010M-001 Enphase Mounting Kit 45
M190-72-240-S12 Enphase Mirco Inverter 45
IEMU-01 Envoy 1
005013C-0024 3" standoff w/ one flange conn 112
12920 Flashing, 12920 117 -
Re: My 10.1KW System
The panels in the driveway after they were offloaded.
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Re: My 10.1KW System
Why do you need so many purlins on your EN roof surface? Most rails are rated for 4-ft centers which means you can use every other joist for your standoffs. Some of the beefier rails (like the ProSolar 2 1/2" RoofTrac rails) let you do 6-ft centers. -
Re: My 10.1KW System
My PV Watts Numbers:
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Re: My 10.1KW SystemWhy do you need so many purloins on your EN roof surface? Most rails are rated for 4-ft centers which means you can use every other joist for your standoffs. Some of the beefier rails (like the ProSolar 2 1/2" RoofTrac rails) let you do 6-ft centers.
Snow load and wind load for being over a corner. Snow loads at 25psf, we have VERY heavy wet snow out here. Even with SolarMount I 2.5" beams and a high Moment of Inertia its close. I liked the 3" standoffs from UniRac as they had two lag bolts.
My max rail spacing is 41". I've had a PE (civil) look it over. When he considered it to be an "architectural element the rail spacing was even less. You can use the UniRac on line calculator too. They match pretty close to what we calculated. Even the County permitting office agreed with the rail spacing.
My roof joists are 24" centers.
If you note on the PDF showing the panels I've included the section where the rails need to support the panels (per REC Solar), sometimes the rail and support location don't match up....so I have to add support between the rails to lag bolt into. -
Re: My 10.1KW System
Just curious, how much is this installation going to cost you (gross) before any rebates, tax credits etc. -
Re: My 10.1KW System
9000 kw /yr so if you are paying .10 per kw the your electric bill savings will be roughly $900
I don't know the total cost but it seems like it's going to take several years just to break even.
No ? -
Re: My 10.1KW System
The return is based on the production incentive of $0.15/kwh plus avoidance of $0.0804/kwh (limited to what I use 10kwh/day) Including the 30% credit I will have a pay off in 14 years with a IRR of 6% over 25 years. Way better then T bills right now.9000 kw /yr so if you are paying .10 per kw the your electric bill savings will be roughly $900
I don't know the total cost but it seems like it's going to take several years just to break even.
No ?
With a smaller system that makes only 3300kwh/year the IRR would be 8% and the payoff would be in 11 years. Right now I only use about 3300kwh/year.
So why the bigger system? The bigger system I'm installing will allow me to charge my future electric car. When I add in converting a VW Rabbit to all electric and using it to drive to work (40 mile round trip) the IRR goes to 11% on the solar system + electric car.
The payoff goes down to 7 years. The avoidance of fosil fuels (gas) is huge.
The entire installation including fees but not labor (free labor, me + friends) is around $34.5K before the 30% credit from the Fed's. I still have to add up stuff like 2X4's and other misc items, been running to the hardware store about every other day for this or that.Just curious, how much is this installation going to cost you (gross) before any rebates, tax credits etc. -
Re: My 10.1KW SystemHere is the BOM:
010144M-001 Beam, 100 Series 144"-Mill Finish 27
002028C-001 MidClamp D,K 68
002004C-001 EndClamp D 52
003021C-001 Splice kit w/grounding 26
008000S-001 UGC-2 CLICKSYS Grounding clip 45
008010M-001 Enphase Mounting Kit 45
M190-72-240-S12 Enphase Mirco Inverter 45
IEMU-01 Envoy 1
005013C-0024 3" standoff w/ one flange conn 112
12920 Flashing, 12920 117
Good luck on this, it's quite impressive that you would be
able to do all this on your own.
Just a couple of things...
1. You are aware that the Enphase M190/240 needs an AC
branch circuit per every 15 PV panels?
2. Do you have any provision for lightning? My contractor
installed a lightning arrestor on the cutoff switch box plus
connected to a copper grounding rod that was plumbed
8' into the ground.
--
John -
Re: My 10.1KW System
Ah, yes - forgot about snow - something I don't have to worry about. How will you be joining your purlins to your existing joists? Would be interesting to see pics of your roof reinforcements.Snow load and wind load for being over a corner. Snow loads at 25psf, we have VERY heavy wet snow out here. Even with SolarMount I 2.5" beams and a high Moment of Inertia its close.
If you look at his west_roof_with panels.pdf document, he has 3 strings of 15.1. You are aware that the Enphase M190/240 needs an AC branch circuit per every 15 PV panels?
Though I do wonder how you will be joining panel 2-01 to the rest of the string - looks like you'll be running the wires into the attic and splicing them together in there?
Nice - you'll probably end up adding at least another $500 in misc hardware - something always comes up and another trip to the local hardware store is needed.The entire installation including fees but not labor (free labor, me + friends) is around $34.5K before the 30% credit from the Fed's.
Anyway, $3.50/watt is a great price excluding labor. My 3.24 kW Enphase system came out to $4.32/watt counting the same things as you. Having bigger panels helps as it reduces the cost of the inverter - if I were to do it again I'd try harder to get 220-230W panels that were close in price to the ET panels I got - my panels/racking cost $2.76/watt to my door. -
Re: My 10.1KW SystemThough I do wonder how you will be joining panel 2-01 to the rest of the string - looks like you'll be running the wires into the attic and splicing them together in there?
I already have the junction box installed and wired in the attic. I have five points I'm bringing electrical wires off the roof and into the attic. I have wiring to these five points already installed. I'll be making the splices from the inverter wiring to the attic wiring in the boxes installed on the roof.
So for the WN solar panels I'll have two sets of splices. Into the #1 Array feed and the #2 Array feed.
I'm using 1" electrical plumbing and a sealed box. -
Re: My 10.1KW System
That makes sense - so did you buy extra Enphase pigtails for those split-string splices (where you have 1 string on multiple facets)? -
Re: My 10.1KW SystemThat makes sense - so did you buy extra Enphase pigtails for those split-string splices (where you have 1 string on multiple facets)?
Each drop down has one Enphase interconnect, 6' pigtail except for the one, that has two. (for the 1-15:1-01 & 2-01) Kinda silly to have that one all on its own, but it is a 4X4 square.:roll: -
Re: My 10.1KW System
The last few days I got all the rafters marked from the inside. I made a drill jig to drill the 3/16" pilot holes for the 5/15" lag bolts for the Solarmount (Unirac) 3" standoffs. Unirac sent me their print of the part so I could make the jig.
Also installed about half the supports between the rafters.
I've drilled through the roof in pushed up 3/16" dowels which now gives me a great idea where to drill the holes I can't reach from the inside.
Earlier I had my electrician friend over. He said I could use the 10AWG ground wire that is part of the 10-3 bundle (ROMEX) as the ground from the attic to the panel. I only need to run the 6 AWG wire from the racks to the attic. Bond the two wires up there.
I also found that I do need a knife blade 2 - pole disconnect switch. Have one on order. After talking with the PUD (my utility) engineering office they said they only require the disconnect switch on systems OVER 10K. Mine is 10.125K. As on the electrical side I'm good to go.
I decided to use a 1" service entrance head. This allows me to easily get the Enphase interconnect and the 6AWG ground wire into the attic and allow easy maintenance.
Next weekend I'll be installing the hardware on the roof minus the panels. Will post some pictures, hope the rain holds off... -
Re: My 10.1KW System
That's what I did and what what one guy I've talked to usually does. The main reason for the #6 on the roof is to make the wire big enough that it won't easily break since it's exposed bare wire.Earlier I had my electrician friend over. He said I could use the 10AWG ground wire that is part of the 10-3 bundle (ROMEX) as the ground from the attic to the panel. I only need to run the 6 AWG wire from the racks to the attic. Bond the two wires up there.
He did have a problem with one inspector that made him run #6 all the way to the grounding rod, though.
You going to use one of those bonding split nuts to tie them together? -
Re: My 10.1KW SystemThat's what I did and what what one guy I've talked to usually does. The main reason for the #6 on the roof is to make the wire big enough that it won't easily break since it's exposed bare wire.
He did have a problem with one inspector that made him run #6 all the way to the grounding rod, though.
You going to use one of those bonding split nuts to tie them together?
After my friend showed me the NEC code that provided the reasons behind the 6AWG gauge for being "unprotectect" it made sense.
I don't know what a bonding split nut is. I was going to install a 5 terminal ground bar to a 2X4 and use it. -
Re: My 10.1KW System
Here is a split nut for electrical splices. They are nice because you can open it up and attach to a long ground run without having to cut the long wire run (generally splicing ground wires is frowned on by NEC/building inspectors).
Your bus bar would have to be "threaded" on to the 6 awg home run wire--difficult to do and a pain if you forget one bus bar.
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: My 10.1KW SystemHere is a split nut for electrical splices. They are nice because you can open it up and attach to a long ground run without having to cut the long wire run (generally splicing ground wires is frowned on by NEC/building inspectors).
Your bus bar would have to be "threaded" on to the 6 awg home run wire--difficult to do and a pain if you forget one bus bar.
-Bill
Thanks for the link. I've never seen one of those. Actually I don't need a 6AWG "home run" wire. My electrician said that since the ground wire in my 10-3 bundle is protected I only need the 6AWG on the roof for the panels where it is unprotected. He mentioned that the 10AWG ground wire is WAY oversized for the 15A circuit. So at my service panel only the three ground wires from the three 15A circuits are coming in.
He did suggest I use the 6AWG ground wire to feed from the service panel to the disconnect switch ground lug and from there to the meter ground lug and from there to the 200A House panel. -
Re: My 10.1KW System
split bolts, as they are properly called, are available in many places like lowes, home depot, and even hardware stores if you don't have an electrical supply store nearby. check pricing before you buy as it varies widely per size and place of business and for #6 wires to be joined $10 is a bit expensive for one. -
Re: My 10.1KW System
Sorry, Niel is correct, split bolt. The link I gave was just for a good picture--Have no idea about the vendor or their pricing (which does seem high).
-Bill "words ain't my strong suit" B.Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: My 10.1KW System
Well I'm ready for next weekend when I have a bunch of friends coming over to help install my racks. I installed all the purlins and predrilled from the inside out where ever possible. This gave me a great datum to measure from and drill the holes I could not get to from the inside.
Question I have (either way I'll be adding 3M 5200 sealant and covering with flashing):
1) Bolt the 3" standoffs directly to the top of the roof
2) Cut away the tabs to the felt covering, then bolt on the 3" standoff
3) Only cut away the tab material if the 3" standoff would be straddling a seam so I'm bolting onto a "flat" surface
Some pictures....
Here is a 162" long line predrilled for five hardpoint attachments. All within +/- 2mm!
I made a drill jig to help drilling.
Some of the Purlins installed.
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Re: My 10.1KW System
Nice! Keep posting the pictures. -
Re: My 10.1KW System
I found the answer to my question in the UniRac guide:
Standoffs (Figure 10) are used to increase the height of the
array above the surface of the roof. Pair each standoff with a
flashing to seal the lag bolt penetrations to the roof.
Use Figure 11 or 12 to locate and mark the location of the
standoff lag screw holes within the installation area.
Remove the tile or shake underneath each standoff location,
exposing the roofing underlayment. Ensure that the standoff
base lies flat on the underlayment, but remove no more material
than required for the flashings to be installed properly.
The standoffs must be firmly attached to the building structure. -
Re: My 10.1KW System
Nice pics! So you drilled all your standoff pilot holes from the inside with a long drill bit where possible? Good idea - ensures that you hit the center of the stud which can some times be problematic as studs are often not straight!
BTW - back to the ground-wire bonding:
I've noticed that most split bolts rated for 6awg aren't rated for 12ga wire - I think you may find that some 12ga romex actually uses a 14ga ground!
Polaris makes insulated connectors specifically designed for bonding a larger wire gauge to a smaller one - you don't need the insulation for the ground wire, but looking online they're not too expensive and then you'll know you have a solid connection.
Look for ISR-1/0 which is an inline splicer UL rated for 1/0-14ga wire. -
Re: My 10.1KW System
Working on installing supports (purlins) on the Southern West face. This is by far the hardest part of my attic to get to. About 75% done with the drilling for the supports. Have a bunch of people coming over this weekend to help install the racks.
The slide in. The orange wire is the 10-3 run back to the service panel.
Before support install:
Seven supports predrilled ready for install (predrilling makes it easier to do the final drill through the roof.
Supports installed and drilled:
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