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DIY 9.88 Enphase system EZ PZ!

BillG

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Apr 17, 2022
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Hi, in case anyones interested, I thought I’d chronicle my lo-buck grid tie system.

Just A couple years ago we got a bid to do a 7 kW system on our house and the price came in at $41,000 this seemed ridiculous to me so we put it on the back burner. Fast forward to last year, I started a job with a small solar company, I have never worked in Solar before however I’ve been in construction my whole life.

although I’m not an professional installer, I do own some heavy equipment (skid steer, backhoes etc) I ended up doing many complete groundmount systems (sometimes completely alone do to millenial/zoomer inability/willingness to work) So I’m not an expert, but I am competent in the trade. (at least the groundmount, site survey, commisioning, permitting side, roof work really is a young man’s game!).

anyway, here we go:
How much did it cost?
Well, keep in mind, I got somewhat good pricing from the contractor supply house because we bought alot of product from them (12 roof mounts and 1 ground mount per week)

BOM
26 380 watt Qcell duo9+
26 iq7+
xr10 rail(bought from another solar contractor on craigslistgetting rid of it for cheap)
Flashloc comp feet
Envoy combiner (no cell kit, got too much EMF already)
various parts railsplice, micro bolts, sunrunner clips etc etc
6 guage wire (i like to keep voltage drop under 1%)

Anyway, all in I’m under 14k including permit and plans which were 500 bucks even. (gotta love small red counties, my permit was issued OTC in 15 minutes for 200 bucks even!) You should expect to pay double that and wait weeks or months in some AHJ’s.


First pic is of array/string 1, 13 panels on my south elevation. Just completed that yesterday. Only took me 2 days, including a 55 foot attic run which actually was the hardest part. Assembling the array is really quite easy, anyone can do this if they’re reasonably fit. Humping the panels up a ladder alone was prolly the 2nd hardest part, but really not a big deal.
2nd pic is array complete. I have it temporarily hooked up to the envoy and I’m getting ok performance from 09:30-16:00.
My “380 watt” panels have not exceeded 305 watts though :(
next phase is array 2, this will be tougher as its a 12/12 roof. I will update as I progress if there’s any interest.
 

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Hi, in case anyones interested, I thought I’d chronicle my lo-buck grid tie system.
Congrats. You've done what I am looking to do! I just found this site and will draw lots of lessons from posts like yours.
I had seen "kits" on gogreensolar and they offered up IQ8 microinverters. So I watched a couple youtube videos on what those are and I learned that there's a big difference between them and 7's. Maybe you should have gone with the newer 8's.

One this I have little clue about is the main panel connection. Your system is 10kW - what type of breaker is needed for that? If you can explain that, I'd learn even more. Thx
 
Unfortunately, Iq8's were not available from my supplier (CED Greentech) when I bought the bulk of my system (purchased in December 21 so I could get the tax credit this year). The IQ8's are an amazing piece of tech!, Battery free, grid forming real time solar backup!

I looked at the specs, but not closely enough, even though the Iq7+ specs say up to a 400 watt panel, they don't say the 7+ cant really make use of any panel over 300 watts!(as noted by Sunshine above). My 9.88KW system is only producing 7.6kw in peak sun hours, I'm disapointed in that.

Breaker sizing is generally based on the "120%" rule. That means if you have a 200 amp bus panel, your solar backfeed cannot exceed 120% of 200amps.

200x1.2 := 240

so the maximum backfeed on my panel is 40 amps := 40 amp breaker.
Their are two ways to legally increase backfeed amperage:
1. de-rating my main breaker, which is fairly simple but requires pulling meter socket and would give me another 25 amps. The breaker alone will cost about 300 bucks.
2. MPU (Main Panel Upgrade) I have kicked myself since I built this house, I knew I should have put a 400 amp service, but I cut corners and threw in a 200. Now, 400 amp panels are 2000+

Since I work for a solar company, I have access to free used panels and free new (broken, scratched) panels. We frequently receive new panels with scratched or cracked glass, bent frames, etc. Landfills wont accept solar panels, they must be "recycled" which is expensive so I just take them home. Even those with cracked glass still work. So anyway, my plan is to add another string on a ground mount, with my existing setup... I know the safety/code Nancies wont like this, but I am not going to de-rate or do an MPU anytime soon. Due to trees, mountains, etc, my 3 strings will never see max sun simultaeneously so they will never produce more than 40 amps, but I will get a couple more hours of late sun on the GM string when my south string is shaded.

As of today, this month, my system is covering 98% of my usage, however, it's not June yet and we havent had to use the a/c.
 
Okay, you've both educated and confused me - that part about 120% rule and backfeeding into the grid....
So, let's say your 9.88kW system is producing 7.6 kW on a given day, and you have NO draw in your house (everything is turned off). This would theoretically allow the entire production to go back to the grid.

However, you are telling me that there is a limitation. I have no idea what you are talking about, what the math is here. Can you explain?
I do not know how to convert the AC kW that the panels/inverters are kicking out to the Amps that you are mentioning in the panel. I know theres a formula out there, something like volts x amps = watts?

So, if someone has 10 kW AC coming off the array, what kind of Main Panel do they/I need in order to get legal approval and in order to (sounds like you are saying) to send that max amount back to the Grid for full credit at year-end True-Up?

Thanks for adding, and helping me along the path.
 
PS: I just went out and looked at my panel. It's also 200A.
But this house has about 5 subpanels all over. I know that one of them for an expansion side of the house is on a 100A breaker. I was thinking of connecting solar on that side of the house, and into that subpanel. I noticed that the supply lines (cable) is super thick! So that was good. It's a long ways from the main panel on the shady side of the house.
 
I empathize with you on the IQ7 capability.
Take a look at this page, scroll down to the pictures of the 4 IQ7's listed - the Wattage Rating is a huge range, and it appears to be VERY misleading. I wonder if the same type of situation could occur when I buy my IQ8's, which have similar wide ranges just below the 7's.

 
Okay, you've both educated and confused me - that part about 120% rule and backfeeding into the grid....
So, let's say your 9.88kW system is producing 7.6 kW on a given day, and you have NO draw in your house (everything is turned off). This would theoretically allow the entire production to go back to the grid.

However, you are telling me that there is a limitation. I have no idea what you are talking about, what the math is here. Can you explain?
I do not know how to convert the AC kW that the panels/inverters are kicking out to the Amps that you are mentioning in the panel. I know theres a formula out there, something like volts x amps = watts?

So, if someone has 10 kW AC coming off the array, what kind of Main Panel do they/I need in order to get legal approval and in order to (sounds like you are saying) to send that max amount back to the Grid for full credit at year-end True-Up?

Thanks for adding, and helping me along the path.
If you have a 200 amp panel that 200 amp panel's bus bars and connections are rated for 200 amps.
(There are newer panels that have 200 amp service but they certify the panel itself to a higher rating like 240-250)

If you backfeed a breaker, lets say 40 amps, into that 200 amp panel you now have the potential to pull 200 amps from the service and another 40 amps from the backfed breaker. If everything was running at 100% you would have 240 amps running through that panel when it is only rated to manage 200 amps.

There is a rule that says you can increase the amount of amps running through a panel to 120%
That means 200 amp panel X 120% ='s 240 amps.
So if you added a 40 amp breaker you are good. 200 amps from main and 40 amps from backfed breaker.

If you needed to add a 60 amp backfed breaker you would now exceed that 120% rule. You would have 200 amps from the main and 60 amps from the backfed breaker. If everything was running at 100% you would have 200 amps from the main and 60 amps from the backfed breaker which is 260 amps which exceeds the 120% rule.

The way to fix this is to derate the main breaker to a smaller breaker. Lets say you changed your 200 amp breaker to a 175 amp breaker.

Your 200 amp panel is still rated for 120% of its maximum rated current which is 240. You add a 60 amp backfed breaker.
If everything is running at 100% you now have 175 amps from your main (which you limited/derated) and 60 amps from the backfed breaker.
175+60 ='s 235 which is under your 120% limit of 240 amps.

If you needed a bigger backfed breaker you would need to derate the main even smaller. You do get into issues when you derate where the AHJ starts to want load calculations to make sure your smaller main can still handle all your loads on that breaker. You can't just derate to 100 amps
to throw in a 140 amp backfed breaker without showing that 100 amps still meets 80% (I think) of your requirements.
 
Okay, you've both educated and confused me - that part about 120% rule and backfeeding into the grid....
So, let's say your 9.88kW system is producing 7.6 kW on a given day, and you have NO draw in your house (everything is turned off). This would theoretically allow the entire production to go back to the grid.

However, you are telling me that there is a limitation. I have no idea what you are talking about, what the math is here. Can you explain?
I do not know how to convert the AC kW that the panels/inverters are kicking out to the Amps that you are mentioning in the panel. I know theres a formula out there, something like volts x amps = watts?

So, if someone has 10 kW AC coming off the array, what kind of Main Panel do they/I need in order to get legal approval and in order to (sounds like you are saying) to send that max amount back to the Grid for full credit at year-end True-Up?

Thanks for adding, and helping me along the path.

Here's my logic in building a sub 10k system when I knew I needed more.

In CA, the legislature passed a law to encourage residential solar and prohibit AHJ's from charging ridiculous permit fees and requiring silly expensive engineering, other hoops to jump through etc etc. Basically streamlining the permit process for small roof mount 10kw or less systems. So I pulled a permit for a 9.88 kw system, this kept me in compliance with the 120% rule and wouldnt necessitate a de-rate (which would be problematic for me as I have multiple sub panels too) or an MPU.


As far as your question about "limits", I think I wasnt clear, the "limit" refers to the cheap (10kw or less) permit class I chose described above. To answer your question, yes, if my house was using zero power, and producing 7.6 kw, it would backfeed 7.6kw (although smart meters dont seem to report the same amount going up stream as the enphase software reports... funny how that works...)



Ground mounts initiate a whole slew of fees, extra inspections, engineering etc.
 
I empathize with you on the IQ7 capability.
Take a look at this page, scroll down to the pictures of the 4 IQ7's listed - the Wattage Rating is a huge range, and it appears to be VERY misleading. I wonder if the same type of situation could occur when I buy my IQ8's, which have similar wide ranges just below the 7's.

You should read my thread over in the Residential Solar group about what I learned about installing an IQ8+ system with Sunlight Backup, and now battery backup. Enphase is a "relationship". Once you go with their product, you are locked into it and they hold the key.

Had I gone with a simple grid-tied system without the Sunlight Backup, it would've been "EZ PZ". But because I chose to do sunlight backup, I had to take a lot of additional certification courses to get Storage Certified. Sunlight backup requires 2 load controller boxes, (a pair of 3 pole contactors in a box) in order to function. I only purchased one, my mistake. It's confusing because with a battery they are not required, but without a battery 2 ARE required. I don't need 2. Rather than buy a 2nd load controller, I bought the IQ Battery 3T and installed that, along with the cell modem. For an EZ PZ grid-tied system the cell modem is not required, but when you add SB or Battery, it is.

Now, I need "them to allow me" to activate my system without my flying to TX or FL, or CA to take hands-on storage training. Considering I have 40 years of engineering experience working on battery UPS systems, I hear it's possible. If not, I have to get another certified Enphase installer to hook me up. Not cool! Definitely not DIY friendly. My loss is your gain, but it's very frustrating. After the fact, I now have a supplier for higher-powered 1500W, Listed microinverters where four of them max out a 30A branch circuit perfectly. I wish I had known sooner. EG4 batteries and a backup inverter would've been so much cheaper.
 
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If you have a 200 amp panel that 200 amp panel's bus bars and connections are rated for 200 amps.
(There are newer panels that have 200 amp service but they certify the panel itself to a higher rating like 240-250)

If you backfeed a breaker, lets say 40 amps, into that 200 amp panel you now have the potential to pull 200 amps from the service and another 40 amps from the backfed breaker. If everything was running at 100% you would have 240 amps running through that panel when it is only rated to manage 200 amps.

There is a rule that says you can increase the amount of amps running through a panel to 120%
That means 200 amp panel X 120% ='s 240 amps.
So if you added a 40 amp breaker you are good. 200 amps from main and 40 amps from backfed breaker.

If you needed to add a 60 amp backfed breaker you would now exceed that 120% rule. You would have 200 amps from the main and 60 amps from the backfed breaker. If everything was running at 100% you would have 200 amps from the main and 60 amps from the backfed breaker which is 260 amps which exceeds the 120% rule.

The way to fix this is to derate the main breaker to a smaller breaker. Lets say you changed your 200 amp breaker to a 175 amp breaker.

Your 200 amp panel is still rated for 120% of its maximum rated current which is 240. You add a 60 amp backfed breaker.
If everything is running at 100% you now have 175 amps from your main (which you limited/derated) and 60 amps from the backfed breaker.
175+60 ='s 235 which is under your 120% limit of 240 amps.

If you needed a bigger backfed breaker you would need to derate the main even smaller. You do get into issues when you derate where the AHJ starts to want load calculations to make sure your smaller main can still handle all your loads on that breaker. You can't just derate to 100 amps
to throw in a 140 amp backfed breaker without showing that 100 amps still meets 80% (I think) of your requirements.
Keep in mind, the rule applies to the PANEL’S max rating, not the main breaker main rating.
Many 200A panels are rated at 250A eaton’s CH panel, SquareD’s QO panel, and I think GE copper buss panels all are rated far above the 200A limit the breaker has. Check the nameplate/sticker on the panel itself. Especially on he 40\80 panels.
Sure, many of the 20\40 panels are at the limit at 200, but there are exceptions there.

I don’t have the experience with solar you have, but as a full electrician, I plan to add to my skill set to it.
 
If you have a 200 amp panel that 200 amp panel's bus bars and connections are rated for 200 amps.
(There are newer panels that have 200 amp service but they certify the panel itself to a higher rating like 240-250)

If you backfeed a breaker, lets say 40 amps, into that 200 amp panel you now have the potential to pull 200 amps from the service and another 40 amps from the backfed breaker. If everything was running at 100% you would have 240 amps running through that panel when it is only rated to manage 200 amps.

There is a rule that says you can increase the amount of amps running through a panel to 120%
That means 200 amp panel X 120% ='s 240 amps.
So if you added a 40 amp breaker you are good. 200 amps from main and 40 amps from backfed breaker.

If you needed to add a 60 amp backfed breaker you would now exceed that 120% rule. You would have 200 amps from the main and 60 amps from the backfed breaker. If everything was running at 100% you would have 200 amps from the main and 60 amps from the backfed breaker which is 260 amps which exceeds the 120% rule.

The way to fix this is to derate the main breaker to a smaller breaker. Lets say you changed your 200 amp breaker to a 175 amp breaker.

Your 200 amp panel is still rated for 120% of its maximum rated current which is 240. You add a 60 amp backfed breaker.
If everything is running at 100% you now have 175 amps from your main (which you limited/derated) and 60 amps from the backfed breaker.
175+60 ='s 235 which is under your 120% limit of 240 amps.

If you needed a bigger backfed breaker you would need to derate the main even smaller. You do get into issues when you derate where the AHJ starts to want load calculations to make sure your smaller main can still handle all your loads on that breaker. You can't just derate to 100 amps
to throw in a 140 amp backfed breaker without showing that 100 amps still meets 80% (I think) of your requirements.
A less expensive way to maximize your backfeed capability is with a line-side tap. Milburn makes Dual-Lugs for inside the residential meter box. You need to call the utility and schedule a shutdown, typically first thing in the morning they will show up and pull out the meter. Typically, they won't provide the services needed. What is needed is a licensed electrician present to remove the existing lugs and install the dual lugs and the following: Prior to the shutdown, install a 200A or smaller, Fused, Visible-open, NEMA 3R, Disconnect Switch next to the meter. Visible open means that if you open the door, you can see that the contacts are open. It does not require a window. Have your rigid conduit ready to go, and once the meter is pulled, you're on the clock to get the conduit in, pull the wire to the switch, install the new lugs in the meter box and make your interconnection from the switch directly to the grid. Then they will come back out at a scheduled time to reconnect you, put the meter back, and seal it.

Some utilities allow you to install up to 25kW in a residential system. That's 104A x 1.25 = 130A fuse! You can't backfeed that much through a 200A panel, so this is the alternative.
 
FYI I bought some iq8's on ebay for a great price but I cannot use them because... The envoy combiner box version 3 does not support mixing 7's and 8's but the combiner box 4 does apparently. Anyway, my system is now producing 67kwh/day. However my first "true-up" was 1700 bucks. I live in a rural area, large house, 13 seer a/c. detached garage, with office above with mini split A/C 20 seer, my shop with 240v service, some EV charging, 2 full size refers, 3 small refers, 1 full size freezer... But my nemesis is having 3 females running the electric clothese dryer seemingly 24x7 at 7,000 watts! That being said, the solar has brought our yearly average cost for power down to about 125 a month, which is a great relief over the 5-600 dollar monthly bills in summer pre-solar. If I was alone there would be no a/c running and no electric clothes drying and I'd be getting nice checks from PGE!

I am now gathering parts to take my shop off grid completely. EG4 split phase inverter, 24 salvaged BP Solar 230 watt panels, 8 Thundersky 40 ah lipo batteries no BMS's (which is just silly because my former business partner was issued a patent for Li BMS back in 2010)..., we manufactured a few hundred of them custom fit to the Thundersky brand which was all we could get at the time. Anyway, my goal is to bring my true up down to zero, taking my shop offline and improving my existing solar output. (iq7a's will increase existing panel output 27% mas o menos...)
 
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