diy solar

diy solar

residential DIY grid-assist install -- 2kw roof array + Growatt 3k 24v + 24v chins batt bank

I would appreciate anyone's insight into the Growatt data logging. my system is not capable of more than 27.7amps in full sun with x1.25 temp correction applied. why the heck does the Growatt think it's charging at 62amps on the dashboard? volts seems to be reporting right at 84v variable on the sun.

nevemind...
actually, it's reporting the battery charging amperage. so, lets say 1400w PV input / 24v battery bank= 58.3amps
 
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A lovely installation. Only thing I see is the sheet metal screw cover thingies over the roof brackets which appear to tuck under the shingles. you don't usuallu do that with only a 4/12 roof pitch, however the panels above help break the rain, plus you don't really have risk at that location on your structure. Nice mechanical job! A few more batteries?
 
kanelr said:
A lovely installation. Only thing I see is the sheet metal screw cover thingies over the roof brackets which appear to tuck under the shingles. you don't usuallu do that with only a 4/12 roof pitch, however the panels above help break the rain, plus you don't really have risk at that location on your structure. Nice mechanical job! A few more batteries?
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flashing is required on residential installs regardless of pitch. besides, it's just good practice to prevent any possibility for leaks

probably not more batteries, at least not right now. i'm going to let it go for a few months and see how things fare during the winter. that is what will dictate storage capacity.
 
42OhmsPA said:
What racking did you use? Mind sharing where you purchased, if you ordered online.
Click to expand...

It's standard channel strut. for transparency, it is not listed for solar application for residential install and I do not advocate that anyone install it. I will continue to point everyone to ironridge.com, which I'm told, has distributors all over the USA.
 
okay... couple other final details to update on related to the DC ground-fault-protection breaker. I purchased a now-discontinued Midnite Solar MDNC-GFP-63 polarized breaker. installation is pretty straight-forward and is required for NEC compliance.

yes... on this breaker only the + is disconnected

IMG_3026.jpeg

here you can see both the PV out and the negative battery feed as a 14awg THHN single out. I'm going to tidy this up with a negative busbar, at some point.
IMG_3027.jpeg

negative terminal connection on the battery....
IMG_3029.jpeg


additionally, here's how I terminated the protected 8/2 THWN wire PV input to the Growatt. I wanted to retain the MC to keep it visually consistent with the attic feed. this is probably not acceptable nor legal, but the Growatt does not have provisions for conduit input.

IMG_3028.jpeg
 
x98myers7 said:
It's standard channel strut. for transparency, it is not listed for solar application for residential install and I do not advocate that anyone install it. I will continue to point everyone to ironridge.com, which I'm told, has distributors all over the USA.
Click to expand...
Thanks for the reply, now that I stare at the pics again I can see it... I've been leaning heavily towards strut, I'm not worried about listed, I care about functionality, longevity and cost.
I priced out ironridge, and Tamarack so far and I'll purchase Tamarack over Ironridge if I don't go with strut. It seems better, in my opinion.
If you were doing it all over again, would you still use strut?
 
42OhmsPA said:
Thanks for the reply, now that I stare at the pics again I can see it... I've been leaning heavily towards strut, I'm not worried about listed, I care about functionality, longevity and cost.
I priced out ironridge, and Tamarack so far and I'll purchase Tamarack over Ironridge if I don't go with strut. It seems better, in my opinion.
If you were doing it all over again, would you still use strut?
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There’s a reason it’s popular for ground mounts. It’s strong, easy to work with and available everywhere. For the current application, I’m satisfied with it.

I haven’t priced out iron ridge, but some people claim 17’ rail sections are $50 if you pick it up. That’s a dang good price. Grainger has aluminum strut available which is double the price but no worries for rusting.
 
okay, the system has been performing as expected. I implemented solar assistant and am very happy... however... that's going to change soon. I'm retooling the components to be separate components so I have proper AFCI....

with that... the Midnite Classic 200 has been ordered.

next up will be re-implementing the battery connections as I need to convert to 8ga THHN from the Midnite and will be installing 200amp positive and negative terminal blocks for power distribution. The Growatt will remain as the inverter and grid-charger, for now. I haven't decided if i'm going to replace it yet.
 
In a parallel bank the main cables are supposed to be connected at opposite ends of the bank, so in the above picture the main positive cable should be connected to one battery and the main negative connected to the other battery, where as it appears both are connected to the battery on the right.

It's to help with current sharing across the bank, not sure how big of an issue it is with only two batteries but thought I'd mention it. Wasn't attacking your build at all sorry if it came off that way.
 

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Charleswgibbs said:

Hope that link works! If not just Google victron wiring unlimited and download the pdf, the relevant pages are 18 - 19 it explains it better than I could ;)
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The Victron Wiring Unlimited is an excellent document. I learn something every time I read it. My favorite battery bank wiring system is to use busbars. My understanding is with good connections and same gauge & length of wire to each battery, each battery is charged/discharged the same no matter how many at least in theory.

Pike makes a really good bus bar.

https://www.amazon.com/dp/B08JKXKF3Q
 
Thanks for posting, this is very informative.

I'm in michigan. Suncalc shows 208deg azimuth and 28deg tilt. PVwatts estimating peak production of 6500wh per day.
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Are these the azimuth and tilt for your roof? Where on suncalc did you get this info?

Any idea how much someone might charge to do an install like this?
 
solar_trees said:
Are these the azimuth and tilt for your roof? Where on suncalc did you get this info?
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yes, these are input from your roof. i have 6-12 roof pitch, which is roughly 27deg tilt

and yes.... azimuth is the angle (direction) your array will face relative to due north. so, place the center of the pin on suncalc.org where you want your array, then slide the hour indicator until it's perpendicular to your array. example... note the yellow line, it's not quite due south... so the azimuth is ~170deg.


Screen Shot 2022-09-12 at 9.41.51 AM.png
 
solar_trees said:
Any idea how much someone might charge to do an install like this?
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you probably won't find many installers that will take on a small off-grid system like this.

honestly, going the DIY route is NOT that hard to do and be compliant.

There are a few things to my system that will need to be done to make it compliant and permittable:
1. install AFCI capable charge controller = $700
2. listed racking = $350
3. install RSD = $600
4. install listed inverter/charger = $1200

the gray zone is the batteries. there are (essentially) no UL listed options... or, at least no affordable options. your AHJ will dictate what is or is not acceptable. my recommendation for DIY would be to install the system as "grid-assist" only, then install the batteries to make it off-grid after it is permitted/approved.
 
Can you explain a little bit more how the ground fault breaker is wired. Trying to figure out the best way to protect my PV panels from ground fault.
 
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