DIY Grid Tie System 2 KW

donaldbitterman

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Nov 2, 2020
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28
Hello,

I recently bought 18 120W panels and a Solaredge 5000a (I think, no tag on unit) for $150 total. My power usage has always been relatively low (table w/ power & cost below) so I couldn't justify a solar system financially but I think going this way will let me pull it off.

My roof is flat w/ a elastomeric coating, I want to go the ballasted flat roof path for mounting.

I've called the city and utility and putting together the document packet and permitting will not be an issue.
Item 4 is the one I am really struggling with.

So far I have:
1. 18x 120W Solarex panels
2. 1x Solaredge 5000a grid tie inverter (unknown if it works, but I hope)
3. old NEMA cabinet to use for DIY combiner box.

I need to get:
4. Solar Edge DC-DC optimizers: Not sure what model, none go this low in wattage and I am thinking I can wire up multiple panels in a string to a few optimizers, but am also not sure of the requisite input voltage so can tell how to wire the strings up (# P, #S) or if this is something I have to do single panel per optimizer which would raise the cost prohibitively.
link w/ DC optimizers below
https://www.ebay.com/sch/i.html?_fr...70.l1313&_nkw=solaredge+DC+optimizer&_sacat=0

5. AC disconnect: Thinking of this or soemthing similar

6. Flat roof ballasted Mounts


7. Combiner Box: Was going to reference the video below, but first need to figure out number of strings which depends on question 4. I have a NEMA box I was going to use for the enclosure

8. MISC Components:
8.1 Wire (both outdoor and indoor rated)
8.2 MC4 adaptors/crimper tool (multiple panels have cut wires
8.3 Conduit (I can borrow the bender)




Solar edge 5000a.jpgSolar Misc.jpg




IMG_2868.jpgPanels.jpg

Solarex.jpg1616028496362.png
 

svetz

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Welcome to the forums!

$150 might be the lowest I've ever heard of to purchase a 2 kW system with inverter! Sure hopes it works, I'm going to tag your thread so I can follow along on your adventure! 🤞

I don't know anything about SolarEdge, but those eBay prices for optimizers look about the same as from a well-known vendor like AltE. The wattage on them looks high, at least compared to a 120W solar panel. Possibly they make optimizers you can hook a couple of panels into a single optimizer?

I'd say download the manual and check to see what the compatible optimizers are. Possibly other members will know. Ideally there's some way to test the inverter before spending any money on the optimizers.
 
Last edited:

Hedges

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I think Solar Edge uses a single string of up to 25 optimizers, probably no combiner needed.
I think 3, 100W panels could go in series on one optimizer (but check its specs.)

I haven't used ballast mounts. I have had things in the yard blow over. My city allows panels bolted to the roof (max 40# per attach point) without mechanical permit, but requires a mechanical permit for ballast mounting.
 

BenQ

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Sep 23, 2019
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Taking svetz’ advice I went to the alt-e website and pulled up the specs for the p320 optimizer which coincidentally lists the specs for the p370 optimizer that solves the # of cells problem :)

Unfortunately, I think putting 3 of your panels in series might be risky since the spec sheet clearly states a max voltage rating of 60V for both optimizers and your Voc for each panel is 21 which puts you 3 volts over max. Good luck!

serieshttps://www.altestore.com/store/inverters/inverter-accessories/solaredge-inverter-accessories/solaredge-power-optimizers-p41168/#SEDP320WMC4OPT
 

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BenQ

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Go with the p400 and you’ll be all set to make 3 panel strings and be well within specs :)
 

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Hedges

I See Electromagnetic Fields!
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Go with the p400 and you’ll be all set to make 3 panel strings and be well within specs :)

80 VDC, 10.1A

Could connect panels in parallel.
Depending on panel specs (e.g. 21Voc), up to 3s2p? Unless Rapid Disconnect has wattage limit as well.

If more than one string of optimizers in parallel, possibly parallel panels connected to optimizers shouldn't be done due to requirements for fuses, unless optimizers prevent backfeed. But 2 parallel panels (or series strings) into each optimizer should be OK for one series string of optimizers.

This spec sheet might be helpful. http://www.trichord-inc.com/pricing/frames/content/solar_power.pdf

On page 16 it says the MSX120 not sure if that is the same as your SX120 model. More importantly it says the panel has 72 cells... if the optimizer is a 60 cell optimizer then there might be a problem?

The lowest wattage panels were 21V 3A, but the highest (MSX-120) were 42V 3.9A
 

donaldbitterman

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Nov 2, 2020
Messages
28
Welcome to the forums!

$150 might be the lowest I've ever heard of to purchase a 2 kW system with inverter! Sure hopes it works, I'm going to tag your thread so I can follow along on your adventure! 🤞

I don't know anything about SolarEdge, but those eBay prices for optimizers look about the same as from a well-known vendor like AltE. The wattage on them looks high, at least compared to a 120W solar panel. Possibly they make optimizers you can hook a couple of panels into a single optimizer?

I'd say download the manual and check to see what the compatible optimizers are. Possibly other members will know. Ideally there's some way to test the inverter before spending any money on the optimizers.
Thanks,

Along with the help of a few folks on this forum and a bit of research I found out I have to go with new/recent manufacture optimizers, and then I was crunching the numbers the permit costs etc, and this would push me to 2k+ to finish out a grid tie system.

I am now going to take the inverter, sell it. I also have a lot of 18650's I will sell, then use that to set up a Electrodacus bases grid assist system and skip the permiting, etc. This will give flexibility to move the system, and also fiddle with some non typical applications (water heating, etc.).
 

donaldbitterman

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Nov 2, 2020
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This spec sheet might be helpful. http://www.trichord-inc.com/pricing/frames/content/solar_power.pdf

On page 16 it says the MSX120 not sure if that is the same as your SX120 model. More importantly it says the panel has 72 cells... if the optimizer is a 60 cell optimizer then there might be a problem?
I believe mine are 60 cell, right now I am going down the route of using electrodacus DSSR20's. This is the perfect application for this w/ dirt cheap panels that are oversized so I can get generation through a wider shoulder for the day.
 

snoobler

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Thanks,

Along with the help of a few folks on this forum and a bit of research I found out I have to go with new/recent manufacture optimizers, and then I was crunching the numbers the permit costs etc, and this would push me to 2k+ to finish out a grid tie system.

I am now going to take the inverter, sell it. I also have a lot of 18650's I will sell, then use that to set up a Electrodacus bases grid assist system and skip the permiting, etc. This will give flexibility to move the system, and also fiddle with some non typical applications (water heating, etc.).

Did you discover that you had to buy an optimizer/shutdown module for each panel for $50 or so?

NEC 2017 PV module shutdown requirement stinks.
 

donaldbitterman

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Did you discover that you had to buy an optimizer/shutdown module for each panel for $50 or so?

NEC 2017 PV module shutdown requirement stinks.
Yup, section 690.1 in NEC 2017, did in any hope of going with used optimizers, and any hope of economically tying in these with my previous planned configuration.

I need to try to keep this as off grid as feasible going forward
 

Hedges

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Mar 28, 2020
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Yup, section 690.1 in NEC 2017, did in any hope of going with used optimizers, and any hope of economically tying in these with my previous planned configuration.

I need to try to keep this as off grid as feasible going forward

Is rooftop the only location you can mount the panels? If ground mount, no rapid shutdown needed.

Does SolarEdge require optimiziers, or if a series (or series/parallel) array of panels fits within voltage limits of inverter, can it work without optimizers?

For rooftop mount, there are rapid shutdown units that take 4 panels. If you connect 3, 120W panels in series they may fit within the voltage/current limit of one modern panel (and RSD limits), so a 4-panel RSD unit could handle 12 panels. Just two should complete your system, maybe $200 (plus whatever control sends the keep-alive signal). (assuming non-SolarEdge because optimizers not required.)
 

donaldbitterman

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Joined
Nov 2, 2020
Messages
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Is rooftop the only location you can mount the panels? If ground mount, no rapid shutdown needed.

Does SolarEdge require optimiziers, or if a series (or series/parallel) array of panels fits within voltage limits of inverter, can it work without optimizers?

For rooftop mount, there are rapid shutdown units that take 4 panels. If you connect 3, 120W panels in series they may fit within the voltage/current limit of one modern panel (and RSD limits), so a 4-panel RSD unit could handle 12 panels. Just two should complete your system, maybe $200 (plus whatever control sends the keep-alive signal). (assuming non-SolarEdge because optimizers not required.)
I don't have much land. My only free space is a flat top roof or on top of the pergola.
 

Hedges

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Find out if you can do without RSD when mounting panels on pergola. The purpose is fireman safety when they walk on roof (perhaps also when spraying water on it.) An attached patio roof may or may not be required to have RSD. If detached it shouldn't be required.

In case of flat roof, you'll have to find a way to keep it water tight. "Ballasted", with weights holding array down against wind is one approach. Another guy had a flat garage roof with parapets, so suggested tying rails to the parapets, but he was concerned that was a trip hazard for firemen.
 
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