Fronius IG4000 Sting Inverter - question regarding string configuration

**bcroe** · 08-03-2023, 05:40 AM

The 500V maximum is the critical thing. The string OC voltage must NOT
exceed this. Remember that panel OC voltage will rise with colder temps.
I would stay away from the 500V number a bit, remembering that things
like lightning might induce a bit more than the system.

With Fronius here at 42 deg latitude, it would be possible to utilize 2 strings
of 8 panels, in parallel. Operation here has half the panels favoring the
rising sun, the other half favoring the setting sun. With each string capable
of 3200W, this orientation will limit peak power to something like the peak
input of the inverter, which is 4000W divided by the efficiency decimal. My
Fronius are about 95% or decimal 0.95, so peak usable input is 4000/0.95
or 4210W. Exceeding this a bit is not critical, the inverter will just clip down
to its rating. Orienting the 2 strings so the peak stays within 115% of the
peak inverter rating should be sufficient, check the inverter rating. Here at
42 lat I actually point them straight E or W with an elevation of around 60deg,
a good center compromise for sun rising and setting variations over the year.
Has been operational 10 yearrs.

2 reasons for the above orientation. First is to keep the inverter operating
at near peak for much longer than several hours near solar noon. Mine
are at peak 8 hours straight under good sun, for most of the year. The
other reason is to boost output under clouds, when light is dispersed and
orientation is not very critical. My day output under our frequent clouds is
around double a straight south facing array. This is achieved by operating
more panels, at less than optimum panel efficiency. But you already have
the panels, the racking and space for the panels might be an over riding
consideration. Mine are ground mounted in a snow rejecting arrangement,
again not practical on existing structure. Your latitude impacts the best
configuration for this approach. good luck, Bruce Roe

NScurve.jpg

**JanS48** · 08-03-2023, 09:28 AM

Thanks so much for the reply, I'm in North Smithfield RI at 41.9 lat. Very interesting how you set your orientation. For me the panels will be mounted on the roof of a ranch style house, One side gets sun much of the day where the other side gets a lot of early sun. I'll have to measure the exact orientation of each and get back to you. That may well work using two strings of 8 panels each in parallel. Thanks so much for the input - I'll get the exact roof orientation and a couple of pics.
Jan

**J.P.M.** · 08-03-2023, 10:26 AM

When it comes to the electrical side of residential PV design I pay a lot of attention to what Bruce has to say and usually learn something as a result. In those areas I disagree with him at what I'm pretty sure is my peril, but we differ on other things.
One of them being array orientation(s) and how to maximize annual specific output per installed STC W. which can usually be better accomplished, all other things being equal, with one optimum orientation. One other is that off optimal orientations will gather more diffuse solar energy, but because solar energy production under clouds is a rather small amount, it's not a large issue.
I readily admit that often the application will not allow one orientation, but intentionally splitting an array with the idea that doing so will increase annual output per installed STC W and, BTW, most likely increase system cost effectiveness as well as overall system efficiency and so, often become a foot shooting party.
So, I'd agree with Bruce that 2 ea., 8 panel strings is probably one good way to go, but if you have the room I'd put them all in the most favorable orientation. Doing the two suggestions below will help you understand why.

Because, as you write, you have little PV experience, I'd respectfully suggest you do 2 things. One is to download and read a free PDF copy of "Solar Power Your Home for Dummies" It's a bit dated but the technical stuff is still mostly good. The second is to download and familiarize yourself with something called PVWatts. It's a PV design model from the folks at NREL. Read all the info and help screens a couple of times. They can be a bit of useful education in themselves. You can be the world's best electrician and still not know much about solar energy and how to make the most of it. Knowledge is power.

Anyway, read the book first, then after you read the help screens on PVWatts, get your inputs right and make a few runs. For multiple orientations do a run for each orientation and sum the results. As you go along, come back here and ask questions your efforts generate.
While doing so, question everything everyone here says, even me. A lot of people have well intentioned opinions, some are not based on reality or experience.

Welcome to the neighborhood and the forum of few(er) illusions.

**Ampster** · 08-04-2023, 11:44 PM

If the goal is to optimize panel output per installed STC W then the above advice makes sense. However if there are different rates of credit for generation based on time of day then the financial equation could change the preferred orientation. This would make no difference financially for someone on tiered rates. However with TOU rates which have a higher rate in the afternoon, a more westerly orientation could produce more revenue than a pure South orientation even though the kWh production might be less.

**JanS48** · 08-05-2023, 12:35 AM

Some more info:
My house is built in sections, one section where I would be installing solar panels is similar to a 3 bedroom ranch with the roof being very accessible. What I call the sunny side is facing ssw @ 220 deg., the opposite side gets a lot of early sun facing NE @ 30 deg. I have ample room on the roof for installing solar panels. I kind of like the idea of installing two strings of eight in parallel on both sides of the roof.
Now per BCROE - if the panels input excess juice to the Fronius IG4000 it will simply 'clip' the excess - to be clear I did not find anything mentioning that in the Fronius manual. The reason I bring this up is that at around 10 am both roofs are in full sun, the panels would be producing 5,122 watts optimally. I'm fine with clipping the excess in the interest of producing a longer harvest time as long as it's safe for the equipment.
Other: In RI there is no discount time of use and the rate is a very high .22 per kw.

**J.P.M.** · 08-05-2023, 10:49 AM

Originally posted by Ampster

If the goal is to optimize panel output per installed STC W then the above advice makes sense. However if there are different rates of credit for generation based on time of day then the financial equation could change the preferred orientation. This would make no difference financially for someone on tiered rates. However, with TOU rates which have a higher rate in the afternoon, a more westerly orientation could produce more revenue than a pure South orientation even though the kWh production might be less.

One goal of my last post was to point out that trying to maximize annual output per installed STC W by intentionally using multiple orientations when NOT NECESSARY due to application restrictions such as roof orientations is the errand of the uninformed.

Ampster however, raises an entirely different point, and on that point he and I agree.

However, if the goal is to have, or to find, the array orientation that yields the greatest annual bill offset (for any CURRENT) T.O.U. billing scheme, that's a different subject than I was addressing.

But even so, there is usually one, and only one array orientation that meets that criteria (maximizing array annual specific output) as well.
That array orientation is a function of the (hourly array output*hourly rate in force for the corresponding hour) product integrated over 8,760 hours in any continuous 365 day year.
I've spent some time considering the problem and developed rather extensive, that is large (but relatively easy to produce), spreadsheets that use a PVWatts hourly output and my POCO's rate schedules to find the amount of annual "revenue" or bill offset an array at any orientation will produce per installed STC W.
I've spent some time in the past posting the particulars of how the spreadsheets are put together and the results.
The method ought to hold for any T.O.U. schedule and any location that has an available PVWatts output and a T.O.U. rate schedule.
Broadly speaking, the method points out that there is one orientation (and only one array orientation) that maximizes the annual revenue an array will produce in a location that has only one daily period of maximum hourly rate (such as the 4 P.M. to 9 P.M. time period for example).
That one daily max. rate time is what all the CA I.O.U. T.O.U. schemes are using at this time. If that changes to more than one max. time period per day, the spreadsheets still work and the single orientation to maximum bill offset will still be valid but the optimum array orientation will shift around some as will the increments of the change of bill offset per STC W from on one orientation to another.

BTW, at my location, using the latest SDG & E schedule DR-SES (T.O.U. for users with a PV system) and PVWatts (or SAM), the array orientation that produces the maximum annual bill offset per installed STC W is an azimuth of 209 degrees and an array tilt of 31 degrees. All other orientations produce less annual revenue, the farther away from those orientations, the greater the rate of revenue decline. I expect similar results in areas with similar climates and rate schedules.

Note, because all this uses modeled weather and irradiance data, it'll be no more reliable than the PVWatts (or SAM ) or other hourly modeled data.

**JanS48** · 08-05-2023, 12:33 PM

To JPM - wow you surly put a lot of work into all this. I see that my orientation of 220 deg. is not far off your's of 209 degrees. I'm guessing the angle of the roof is close to the 31 degrees you mention - I checked it's 30 degrees.
Again I'm a newbie here and as such still getting used to the acronyms and jargon being used but I'm getting there...

Other questions:
PV wire - If I go with the two strings in parallel my max continuous amps could be as high as 18. I'm going to be running that approx 150 ft back to the Fronius mounted in the basement near the electrical panel. Is #10 wire ok for that or should I go with #8 ?
Wiring - is it a good practice to bring the PV wires into a combiner box and then make the final run to the inverter?
Ground wire: Is a single #10 (or #8) ground wire ok ?

Racking - I'm leaning towards UniRac - anyone know of any good on-line tutorials on that? - I see some on u-tube but they don't seem too consistent.

**bcroe** · 08-05-2023, 03:32 PM

10 ga is around 1 ohm per thousand feet, increasing a bit with
temp. If you feed 18A through around a 350 ft loop, Ohms law
says there will be 6.3V drop, about 113W power dissipated. So
decide if that efficiency is a reasonable tradeoff against larger
wire cost. Running 2 10ga pairs would reduce power lost by
half, but at some point combining to a single larger conductor
is cheaper. With operation at peak inverter capability the
entire sunny day, I spent the money to keep peak losses in the
DC and AC wiring to about 1% each. Bruce Roe

**J.P.M.** · 08-05-2023, 08:31 PM

Originally posted by JanS48

To JPM - wow you surly put a lot of work into all this. I see that my orientation of 220 deg. is not far off yours of 209 degrees. I'm guessing the angle of the roof is close to the 31 degrees you mention - I checked it's 30 degrees.
Again I'm a newbie here and as such still getting used to the acronyms and jargon being used but I'm getting there...

Other questions:
PV wire - If I go with the two strings in parallel my max continuous amps could be as high as 18. I'm going to be running that approx 150 ft back to the Fronius mounted in the basement near the electrical panel. Is #10 wire ok for that or should I go with #8 ?
Wiring - is it a good practice to bring the PV wires into a combiner box and then make the final run to the inverter?
Ground wire: Is a single #10 (or #8) ground wire ok ?

Racking - I'm leaning towards UniRac - anyone know of any good on-line tutorials on that? - I see some on u-tube but they don't seem too consistent.

As for work input, more than a hobby, but a lot less than a job and in a sense a busman's holiday for many years.
If I was having any more fun than this, I'm not sure I could stand it.

I'd suggest you read the book, download PVWatts and come back here with questions your education turns up before you go further.
If/When you do the PVWatts runs, Read and understand ALL the help screens and notes, use a 10% system loss factor and get the array as orientations as close to reality as possible. Then use the hourly output option and sum the results of the orientations for the modeled combined output. Anything over a combined total of 4 kW/inverter efficiency for any hourly total into the inverter will be "clipped" down to the inverter's (maximum) 4 kW output.
Due to how STC output is figured and system efficiency losses, and mostly due to the fact that an in-situ panel rarely sees as much as the STC input, expect a maximum array output of maybe 80-85% of the array's STC output and that probably for not more than an hour or less maybe 10-20 times /yr.
So, given less than optimal array orientations, I'd expect you'll be fine with a 4 kW inverter.
See the Dummies book for details.

BTW, are you an electrician by trade or a DIY'er ?

My array is similar in size to what yours may wind up being with 2 ea. 8 panel strings on separate MPPT's using Sunpower 327 W panels in one array and 1 orientation. It's a roof mount.
My inverter is a 5 kW PowerOne and I have an identical spare ready to plug and chug.
String inverters seem to be going out of style for what I think are B.S. reasons. You may want to consider getting a spare. They seem to last ~ 12 years more/less. Just Sayin'.

I (or my installer anyway) used 10 ga wire per string and combined the strings at the inverter.
My wire lengths are only about 75 ft or less. If I were you, I'd be more concerned about wire connections and splicing methods/integrity, but since you write like most of the equipment was free or a low cost acquisition, I'd be tempted to spring for 8 ga wire.

My racking is also Unirac. I specified using 8" standoffs for several reasons and double flashings for the posts. All that seems fit for purpose. I thought the clips were a bit flimsy but they seem fine after 10+ years.
Coming up on 11 years as of 10/13/23 and no roof leaks or problems so far.
BTW, have your roof inspected, checked and serviced if/as necessary BEFORE the array gets installed. A good install will last a long time. Give your roof a decent shot at lasting as long. Cheap insurance. I have a concrete tile roof and got it repapered. The roofer did the roof penetrations for the posts and set them per the drawings per agreement with the installer.

Don't forget to get building permits and inspections as required. Building depts. and inspectors are like Marines in the sense that they can be your best friends or your worst enemies. Ignorance of or ignoring municipal codes can be costly.
Also, find out about what your POwer COmpany (the "POCO") requires of a residential installation, or if net metering is available to residential users at all, and if so, what are the details.
Also design the array with access in mind, particularly as it pertains to snow removal (which is something PV vendors and the greenwash media seem to forget to mention). Snow does not always or even usually slide off arrays, particularly at relatively low slopes as you seem to have.

Otherwise, as I wrote: Other than don't do this yourself - at least not before a lot more education about PV design and how things get from photons to electrons - What Bruce wrote.

Take what you may want of the above. Scrap the rest.

**JanS48** · 08-06-2023, 02:04 AM

@ JPM - Thanks so much for the input. I will read PVWatts as you suggest. As for me, I'm 75 fairly healthy and consider myself to be a good electrician. I started out as an electrical engineer but then switched to sftware engineering for the past 30 years. Many years ago during my summers I did work for a union shop in Providence RI doing big building power installations. I'm also very good with computer hardware and electronics. My house is in 3 fairly large sections out in the sticks of Northern RI. The 16 Canadian Solar panels and the Fronius will be my first installation if that works as expected I'll be installing more panels on some other roofs. I'm working on getting a net-meter installed but I have neighbors that have done it 100% DIY, in checking my electric meter it is an old magnetic one that will in-fact run backwards. We just got a new roof installed so roof condition is not an Issue nor is easy access, In looking ahead I'd go with some of the higher wattage panels and individual enphase 8 inverters but that's down the road. Between my shop with welders, mini-split' heat-pumps, and recently a Tesla - my bill is in the mid 500's. A net meter is not going to do anything but make it legal.
I will take your advise on running both strings back to Fronius via #8 wire. The Fronius has PV disconnects built in but I was also going to isolate with a Midnight solar one as well.
In looking at installations near me all the panels are mounted close to the roof - I was planning on doing the same. I'm confident I can secure the 'El' brackets and flashing with no leaks.
Thanks again for your input.
Jan

**J.P.M.** · 08-06-2023, 10:23 AM

Originally posted by JanS48

@ JPM - Thanks so much for the input. I will read PVWatts as you suggest. As for me, I'm 75 fairly healthy and consider myself to be a good electrician. I started out as an electrical engineer but then switched to sftware engineering for the past 30 years. Many years ago during my summers I did work for a union shop in Providence RI doing big building power installations. I'm also very good with computer hardware and electronics. My house is in 3 fairly large sections out in the sticks of Northern RI. The 16 Canadian Solar panels and the Fronius will be my first installation if that works as expected I'll be installing more panels on some other roofs. I'm working on getting a net-meter installed but I have neighbors that have done it 100% DIY, in checking my electric meter it is an old magnetic one that will in-fact run backwards. We just got a new roof installed so roof condition is not an Issue nor is easy access, In looking ahead I'd go with some of the higher wattage panels and individual enphase 8 inverters but that's down the road. Between my shop with welders, mini-split' heat-pumps, and recently a Tesla - my bill is in the mid 500's. A net meter is not going to do anything but make it legal.
I will take your advise on running both strings back to Fronius via #8 wire. The Fronius has PV disconnects built in but I was also going to isolate with a Midnight solar one as well.
In looking at installations near me all the panels are mounted close to the roof - I was planning on doing the same. I'm confident I can secure the 'El' brackets and flashing with no leaks.
Thanks again for your input.
Jan

You're again most welcome.
Do the PVWatts thing as well. It'll give you some idea of what to expect in terms of system output. My dart throw is you'll get a modeled output somewhere between 1,000 and maybe 1,200 kWh/yr. per installed STC kW of PV panel. but not knowing more about the application that's no more than a rough (if semi-educated) dart throw.
BTW, is that 500 ($?)/month or per year ?

You have a lot to learn.
You will need a lot more than a new POCO meter to make an installation legal. If you intend on having have a net metering arrangement, the POCO will most definitely be involved since the agreement will be with them, as will the building dept.
And, as I implied with my comment about friends and enemies, the building dept can be of a lot of help if you don't come at them with an attitude.
Know that DIY does not eliminate the need to follow municipal codes and POCO net metering rules.
Most jurisdictions do require building permits for a PV installation. I bet yours does. Give them a call. As a respectful suggestion, I'd put a smile in my voice when/if you call them.
Most likely and anyway, the POCO net metering requirements will require a building permit. Reason: The POCO requires a building permit as some assurance that what's hooked up to their equipment is built correctly and also meets their requirements.
If you're thinking about skunking a DIY installation past both bodies, besides probably being unsafe, I believe that to be an exercise in futility. An array on a roof is a bit harder to keep out of sight than an unpermitted inside improvement to an inspector who happens to be cruising the area. The probability of getting away with it is pretty small. The consequences can be pretty large. If nothing else, the POCO will notice your change in usage.
Consider this too: If you ever make an insurance claim for fire or water damage (or anything for that matter) and the insurance co. finds out you have an unpermitted PV array, kiss off getting the claim honored.

Look, you may have some experience and while some of it sounds like it crosses over, you also don't sound like you know enough about PV to do a professional level job of it with your current knowledge of the basics of PV.
For one thing, and as an example only, you will need a net metering agreement - it ain't an option - and from what you write, you will most likely need a new meter. Or, for another, it's usually a good idea - for several reasons to put at least 15 cm of free space between the roof deck and the bottom rail of the panels. Or, that increasing the size of an array can be more complicated than you think.

Without trying to sound any more like an asshole than I already may seem to be in this post, I don't believe I suggested 8 ga wire for what you're planning.
I did write something like since you got a low cost on the materials, if it was me, I'd be tempted to use 8 ga wire. That was based on the idea that thicker wire will involve less resistance. I also stated I'd be more concerned about wiring connections and splices without adding the reason why. I figured being an electrician and all as you stated, that you'd know why. I also wrote, at least by inference, that I'd defer to Bruce's greater experience in such areas at least on the idea that none of us is as smart as all of us.

**JanS48** · 08-06-2023, 12:53 PM

A comment: I have contacted the building dept. in my town, I don't know what you know about RI but we have a dual standard when it comes to building inspectors and contractors.
For example I was told that a minimum of 20" is required around all sides of the panel installation, also wiring from the panels to the basement must be in 1 1/4 in steel pipe. Fine - I can live with that, however I see new installations being done by contractors where they place panels almost to the edge of the roof and run the wires in plastic pipe often with a sizable section in flexible plastic pipe. There is clearly a dual standard going on here - discourage the home owner from doing anything and look the other way for contractors.

Besides being a software engineer I was also a professional landlord for a number of years, un-related to this I once inquired about installing / moving an oil tank - the plumbing inspector said sure just make sure you use 2" pipe - ever work with 2" pipe - it's a bear... So I eventually opted for a contractor to install a new oil tank in a different location, they quickly did the job in a few hours using 1 1/4 in pipe - when I asked they said that is all they use and have been doing it for 20 years, When asked about inspection they laughed and said they NEVER have even seen the plumbing inspector. Again, I'm in RI.

I'm confident that my wiring between the Fronius and my panel [200 amp] is correct. My bill BTW is currently $540. per month. I know I use a lot of juice and the Tesla didn't help.
I have been in touch with a couple of electricians that do the electrical panel side of solar installations, one assures me he can 'make it right' with the electrical inspector - again I'm in RI.

Regarding the 15cm from the roof to the bottom of the panels - I don't see any roof installations that high - I will surly research this before making a decision. One UniRac installation I viewed shows the L bracket going through a somewhat thick piece of flashing and then being attached to the rails. I'm guessing the panels would be about 4" (10cm) off the roof.

I do plan on jumping through whatever hoops necessary to get it worked out. My electrician advises in keeping it as simple as possible to start off with and then increase things once everything is working - that is my plan.

**J.P.M.** · 08-06-2023, 11:42 PM

Originally posted by JanS48

A comment: I have contacted the building dept. in my town, I don't know what you know about RI but we have a dual standard when it comes to building inspectors and contractors.
For example I was told that a minimum of 20" is required around all sides of the panel installation, also wiring from the panels to the basement must be in 1 1/4 in steel pipe. Fine - I can live with that, however I see new installations being done by contractors where they place panels almost to the edge of the roof and run the wires in plastic pipe often with a sizable section in flexible plastic pipe. There is clearly a dual standard going on here - discourage the home owner from doing anything and look the other way for contractors.

Besides being a software engineer I was also a professional landlord for a number of years, un-related to this I once inquired about installing / moving an oil tank - the plumbing inspector said sure just make sure you use 2" pipe - ever work with 2" pipe - it's a bear... So I eventually opted for a contractor to install a new oil tank in a different location, they quickly did the job in a few hours using 1 1/4 in pipe - when I asked they said that is all they use and have been doing it for 20 years, When asked about inspection they laughed and said they NEVER have even seen the plumbing inspector. Again, I'm in RI.

I'm confident that my wiring between the Fronius and my panel [200 amp] is correct. My bill BTW is currently $540. per month. I know I use a lot of juice and the Tesla didn't help.
I have been in touch with a couple of electricians that do the electrical panel side of solar installations, one assures me he can 'make it right' with the electrical inspector - again I'm in RI.

Regarding the 15cm from the roof to the bottom of the panels - I don't see any roof installations that high - I will surly research this before making a decision. One UniRac installation I viewed shows the L bracket going through a somewhat thick piece of flashing and then being attached to the rails. I'm guessing the panels would be about 4" (10cm) off the roof.

I do plan on jumping through whatever hoops necessary to get it worked out. My electrician advises in keeping it as simple as possible to start off with and then increase things once everything is working - that is my plan.

I know nothing or less about RI and its building department authorities except that if they are run like other similar outfits in places I do know a bit about they have written policies that are usually based on common national standards and that's the official line they follow in disputes that cannot be resolved at the jobsite level with the inspector. The common standards are usually national or sometimes international in nature and are the product of a lot of work over a long time by pretty knowledgeable and experienced people. Such standards exist for the common good and are among the gems of modern ordered societies. Ignore them at your peril.
On a less esoteric plane, the other thing common to most of them, more or less, are the 2 golden rules of code inspectors: 1.) The inspector is never wrong. 2.) If the inspector is wrong, see rule #1.
What that can (but by no means always) come down to is that there are, as a practical reality not, as you write, dual standards but perhaps better described as a situation where there are potentially as many standards as there are inspectors.
You site a couple of situations. They are anecdotal and so mean little to code enforcement of your potential situation if questions arise with respect to code enforcement.
While such situations are probably not uncommon as examples of seeming or potentially unfair code enforcement, and I have no problem in believing such things happen at all levels of government and business, they have no meaning if questions of code interpretation arise in a particular application.
I also have no problem believing you know electricians who can "make it right with the electrical inspector." but know that there is a lot more to a code inspection than simply electrical. Part of what seems to be meaningless caution and conservativeness in a lot of such codes is in them as an attempt to cover such situations as you describe.
I'm not trying to be more Catholic than the Pope here, but I've worked with a lot of national and international codes over a long engineering career and while they are often frustrating (another code reality for engineers is: "live by the code, die by the code"), I quickly came to realize many years ago that we're much better off with them than without them. A residential example: In every house I've ever owned - and BTW I was also a slumlord for quite a few years - I've managed to find code violations in every one of them, some of which, in my professional opinion as a P.E. (mechanical, retired), and within my area or proficiency, I'd consider dangerous. As bad as all that is, and even with all the chicanery I've seen and know that goes on similar to what you write of, if my experience is not uncommon, I shudder to think what things would be like without codes and their enforcement.
I applaud you for your stated intent to "jump through whatever hoops are necessary...". I hope that includes the rest of the job besides any electrical panel work. If so, I'm sure you and the inspector can work together to come up with a safe, efficient and code compliant job.

On another subject, you mentioned that you got a good price on the equipment. Do you know that used equipment is not eligible for the federal 30% tax credit ?
More just sayin'.

Regarding the 15cm standoff from roof deck: As you'll find out when you read the Dummies book, PV panels operate more efficiently when they run cooler.
PV panels run cooler when they have better air circulation.
I've got empirical correlations that estimate the average temp. difference between an array and the immediately surrounding air and the panel to roof deck clearance for my array. It seems the correlation yields results similar to others I've seen in the open literature rooftop applications. Roughly speaking, an array with 15 cm. clearance will run about 3-4 deg. C cooler than one zero or vary low clearance. That will probably translate to about a 1 - 2% increase in annual array output.
Beyond about 10-15 cm clearance, further increases in clearance don't seem to make much difference in panel to ambient air temp. difference and so annual production increases from the array.
Other benefits of increasing under panel to roof deck clearance: Things under the array will stay dryer with less chance to mold and rot up as the years go by. Also, and even though it's not possible to get under an array with 15 cm clearance, some visual inspection is possible and may help to ward off problems. Also, rooting out pests like birds, squirrels and bee nests is also easier.

**JanS48** · 08-07-2023, 01:18 AM

Again, thanks so much for the comments and input. I don't plan on installing anything electrical or mechanical that is not code compliant and safe. I do not however share your enthusiasm for inspectors, over the years I've owned several businesses and still have several properties - inspectors have never been my friend.

Regarding the 30% tax credit yes I realize that will not apply to my installation but I won't be paying thousands for a contractor installation.

Fronius IG4000 Sting Inverter - question regarding string configuration

Fronius IG4000 Sting Inverter - question regarding string configuration

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