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Thread: PV design software

  1. #11
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    There is no software that is going to spit out an SLD that you can use to get a permit that I know of. The best I have seen will give you something that you can use to start from to make your own SLD after you do a little massaging. But for residential you really can get by very well with PVWatts for getting an idea of the energy production. NREL's SAM is a good free program if you need more horsepower.

    The plan set companies can be great for getting inexpensive plan sets to get a permit. Do not confuse PV design services with engineering services though. Two completely different animals and while PV design is fairly inexpensive, engineering is not. That's one reason engineers almost never get involved in residential work outside of the occasional structural review. A residential project budget just can't pay for licensed engineering work. I've had contractors come to me with stories about how an AHJ is making them get an electrical PE stamp on their residential plans and there is just no money in the project for an engineer. I feel sorry for those in that situation.

  2. #12
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    Quote Originally Posted by five.five-six View Post
    How do you select your modules? The variety available is overwhelming.

    See whats available from your local supply house that specializes in PV. CED Greentech is a popular option. See whats in stock then do some homework based on those options. SunPower, LG, Qcells, seem to be safe residential options now-a-days.

    As previously stated, producing an appropriate drawing set using virtual means is dicey. I've NEVER seen a respectable set come from the el-cheapo options online that outsouce to a drafter overseas. Find a designer/engineer at a local solar company and ask if he would do some work on the side, or perhaps the supply house could direct you to a local freelancer.

  3. #13
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    Quote Originally Posted by BandGap1.1eV View Post
    See whats available from your local supply house that specializes in PV. CED Greentech is a popular option. See whats in stock then do some homework based on those options. SunPower, LG, Qcells, seem to be safe residential options now-a-days.

    As previously stated, producing an appropriate drawing set using virtual means is dicey. I've NEVER seen a respectable set come from the el-cheapo options online that outsouce to a drafter overseas. Find a designer/engineer at a local solar company and ask if he would do some work on the side, or perhaps the supply house could direct you to a local freelancer.
    I found this outfit, they don't seem el-chepo but they do seem reasonable. Their office is inside my territory.

    https://yoursolarplans.com/services/

  4. #14
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    The top-tier modules (SunPower, Panasonic, Canadian Solar — depending on what you consider “top tier”) are all going to have 25-30+ year service lives and warrantees. You should pick based on price, availability, and if they face the street, appearance. I’m trying to get a local installer to do my new-to-me house and they prefer front-contact (“wires where you can see them”) panels because they are cheaper. I hate them and I like my house.

    As for design — DO NOT let software, or an idiot, design any layout that can be seen by anyone who can make your life miserable. I worked for a manufacturer who gave us an “employee discount” and the installers they partnered with designed some of the ugliest arrays I’ve ever seen. If you can use microinverters or DC optimizers, do that. But also, don’t be hesitant to add a module or two (if you’re using panel-level electronics) if it balances the appearance of the array. Dittos for moving a stack over a ridge if you’ve got a stack that’s making your array look ugly. Design the layout by hand, then feed it to software.

    I know this isn’t “electrical”, but I’m tired of ugly solar and the stuff is as cheap as can be these days — I paid $1,000 for 175 watt modules 12 years ago and 300+ watt modules are less than 1/4th that price today.
    Julie in Austin

    Born to brew, forced to work ...

  5. #15
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    So, I did find a local outfit who produced a submittal package for me for $250

    I looks very good and I expect it will sail through plancheck.

    The. Only thing is that I had given them drawings with 3 strings of 9 modules for a total of 27

    the drawings they returned had 1 string of 14 and another string of 13.

    They said that SolarEdge will work wit different sized strings.

  6. #16
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    Quote Originally Posted by five.five-six View Post
    So, I did find a local outfit who produced a submittal package for me for $250

    I looks very good and I expect it will sail through plancheck.

    The. Only thing is that I had given them drawings with 3 strings of 9 modules for a total of 27

    the drawings they returned had 1 string of 14 and another string of 13.

    They said that SolarEdge will work wit different sized strings.
    They are correct, and most SolarEdge inverters do not have fused inputs. If you have three strings, many AHJ's will insist that you fuse them, even though Solar Edge says it isn't required. They did you a favor.

  7. #17
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    Quote Originally Posted by five.five-six View Post
    So, I did find a local outfit who produced a submittal package for me for $250

    I looks very good and I expect it will sail through plancheck.

    The. Only thing is that I had given them drawings with 3 strings of 9 modules for a total of 27

    the drawings they returned had 1 string of 14 and another string of 13.

    They said that SolarEdge will work wit different sized strings.

    Were these stamped drawings for $250?

    my god if PE's are stamping drawings for 250 bucks I don't want to live in this country anymore

  8. #18
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    Quote Originally Posted by Designer69 View Post
    Were these stamped drawings for $250?

    my god if PE's are stamping drawings for 250 bucks I don't want to live in this country anymore
    Plenty of PEs out there who are running stamp shops. A contractor once told me of a PE up in Napa who was retired who would stamp his plans for a few bottles of good wine. Very hard to find and prosecute stamp shops too.

  9. #19
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    Quote Originally Posted by ron View Post
    Wow, Engineering is pretty cheep in your area. Do they sign/seal the drawings too?
    Oh, I am not talking about engineering or stamps.

    $300 for a DRAWING. By a drafter.....an Autocad jockey or architect is sufficient.

    Their job isn't to know what the contractor or engineer needs to calculate or to know much about design and calcs, just to organize it pretty like.

    We only need an engineer if tilted rack (wind loads), sub standard roof framing or custom racking.

  10. #20
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    KISS solution

    Single line diagram: A single line diagram is not a complex thing. I made some objects in MS Powerpoint PPT (panel, array, conductors, combiner) and I just copy and paste for the systems that I have designed.

    Drawing panel layout: I capture an image from Google Earth (GE) and use the measurement tool in that app to get the roof dimensions. I create a panel of the appropriate size (you need a little trig here because the roof rake) and copy and paste. I scale it to 1/100 (e.g., a 40" panel in landscape is 0.4"; the other dimension on a 6 and 12 roof is 60" in plan view (0.6" in PPT) for a 67" panel, in Excel the calc is: Plan Dimension =Panel Length*cos(atan2(12,6)); for a 3 and 12 roof, Plan Dimension =Panel Length*cos(atan2(12,3)) ). Use the Align and Distribute tools in PPT to neaten up the drawing after the approximate layout is complete. Panel gets pasted on top of GE image.

    Designing panel layout: National Renewable Energy Lab (NREL) has tools that allow you to compute power at various latitudes and array orientation. Then you have to consider the potential for shade and the use of string versus microinverters. For example, I have one string where a few panels have reduced output at times due to shading from a chimney, and another string with late afternoon shading, on a few panels, from a tree. I went with microinverters to eliminate and overall 10 - 20% reduction on those strings that would have resulted if I went with string inverters. I also like the microinverters because of the safety factor, ease of design and panel level monitoring.

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