New 5kW system, SMA inverter or SE optimizers

[df0rster]

I am still working through approvals and designing my system.

I had almost purchased an SMA 6kw string inverter and was made aware of a new sale on SE optimizers.

below are my options, SE w/ optimizer option is about $100 more

5.2kW of peimar 325W panels (16) plus p320 optimizers, plus SE HD wave 6kw inverter
5.2kW of peimar 325W panels (16) (or any other panels) plus SMA 6kw inverter

My questions are:

1. Other than shading issues, what are the main SE advantages, I don't have shading issues.
2. Will I get any better performance to make it worth the additional labor involved of installing the optimizers?
3. Any other equipment required for the optimizer method?
4. Which inverter is better quality?

Any other suggestions or something I am missing?

Thanks!

[NukeEngineer]

I am still working through approvals and designing my system.

I had almost purchased an SMA 6kw string inverter and was made aware of a new sale on SE optimizers.

below are my options, SE w/ optimizer option is about $100 more

5.2kW of peimar 325W panels (16) plus p320 optimizers, plus SE HD wave 6kw inverter
5.2kW of peimar 325W panels (16) (or any other panels) plus SMA 6kw inverter

My questions are:

1. Other than shading issues, what are the main SE advantages, I don't have shading issues.
2. Will I get any better performance to make it worth the additional labor involved of installing the optimizers?
3. Any other equipment required for the optimizer method?
4. Which inverter is better quality?

Any other suggestions or something I am missing?

Thanks!

If there's no shade to worry about, then it's somewhat a toss-up. If there is shade, SE (or micros) will always beat a regular string.

In my opinion, however, I found installing the optimizers to be relatively minimal additional work. The key points in that process that added a slight slowdown were:
1) How far apart they mount from each other. I just measured the width of my panels, plus 1/4" for bracket, then Sharpied marks on the racking for where each one should go. Of course, these locations have tons of tolerance, like a foot or so. (took probably 20 mins total time for all 40 panels)
2) Sliding in the mounting bolts for an entire row onto the racking. My IronRidge racking uses regular hex-head bolts, which must be slid in from the very end of the racks, no mid-way insertion. (took probably 20 minutes)
3) Getting the torque setting on my battery drill to closely match the spec'ed value. Just had to try a setting, test with torque wrench, adjust up or down until the drill was closely matching desired value (maybe 5-10 minutes to configure drill)
4) Making darn sure that I collected the QR codes from the right optimizers, in the right order, and that they STUCK to my paper. In fact, I both grabbed the stickers, and used their app to record the locations, just in case one of these two methods failed. I did NOT want to have to lift panels later because I got an optimizer serial in the wrong location. (probably 45 minutes total for phone QR scan, and sticker grab)

However, knowing that there's only 10 volts at the end of my strings in bright daylight.... priceless! There's something to be said for the safety of having that feature.

[ButchDeal]

Do yu need rapid shutdown in yur area? If so the added cost is going to be quite abit in the SMA system vs built in on the solaredge system.

also why are you putting in a 6kw system with just 5,2kw of solar? You should be on a 5kw inverter unless yu have some other reason.

[TAZ427]

I am still working through approvals and designing my system.

I had almost purchased an SMA 6kw string inverter and was made aware of a new sale on SE optimizers.

below are my options, SE w/ optimizer option is about $100 more

5.2kW of peimar 325W panels (16) plus p320 optimizers, plus SE HD wave 6kw inverter
5.2kW of peimar 325W panels (16) (or any other panels) plus SMA 6kw inverter

My questions are:

1. Other than shading issues, what are the main SE advantages, I don't have shading issues.
2. Will I get any better performance to make it worth the additional labor involved of installing the optimizers?
3. Any other equipment required for the optimizer method?
4. Which inverter is better quality?

Any other suggestions or something I am missing?

Thanks!

1.) SE w/ power optimizer advantage is Rapid Shutdown built in if it's required in you location (you'd have to buy a separate Rapid Shutdown box for the SMA)
2.) Well if you get any shading at all that causes a full string to drop, instead of a panel to be drop or be taken offline, then you're likely to see the difference quickly. If this never happens, then you're not likely to see it. Got a chimney, vent pipe, tree, dormer, ... sticking up that is going to block a panel or two on a daily basis and knock the generation out of a full string, then you want power optimizers, if not then I wouldn't be as concerned. The labor shouldn't be signficant - mount to the same mounting brackets, and connect w/ a click - peal and stick QR code onto paper in the right location.
3.) The only additional items would be the power optimizers.
4.) I'm sure which is better quality can be debated, but they're both good quality as far as my research has given. I like Solar Edge HD 99% efficiency over 97.5 for SMA Sunnyboy's and 12yr default warranty on SE over 10yr default on SMA.

FWIW, you should be able to use a 5kW inverter and never (or close to never) clip. Unless you've got them on perfect angle on perfect day and all facing one direction, you'll likely never reach clipping point. Use PVWatts for your setup, look at the max of the DC Array output, (drop their 14% loss down to around 10%) and I'm willing to bet you're not exceeding 5k on the DC Array side at any point.

[df0rster]

However, knowing that there's only 10 volts at the end of my strings in bright daylight.... priceless! There's something to be said for the safety of having that feature.

Great info, Thanks!

I didn't know the dc optimizers converterd down to 10v. Does this mean we have to use larger wire from the panels to the inverter? Right now I have it at 10 awg on two 220 ft runs from the panel string to the inverter.

[df0rster]

Do yu need rapid shutdown in yur area? If so the added cost is going to be quite abit in the SMA system vs built in on the solaredge system.

also why are you putting in a 6kw system with just 5,2kw of solar? You should be on a 5kw inverter unless yu have some other reason.

I'm not sure if I need rapid shutdown. The only specific requirement called out by the PoCo is I need a lockable AC disconnect at my meter to disconnect my service from them. There are no municipal codes where we are in rural OK and the PoCo just specifies to follow NEC.

As far as sizing, I will likely use 20 panels because that will easily fit on my shop roof. so it will be closer to 5900w.

[NukeEngineer]

Great info, Thanks!

I didn't know the dc optimizers converterd down to 10v. Does this mean we have to use larger wire from the panels to the inverter? Right now I have it at 10 awg on two 220 ft runs from the panel string to the inverter.

Sorry, I should have qualified that statement. That's only when the system isn't operating (installation, maintenance, repair, etc.). Each optimizer puts out 1v to essentially indicate that it's alive. My system consists of 4 strings of 10 panels each, so I only have 10 volts showing on my strings if I power down. Once powered, the strings operate at around 390v.

As for your wire size, 10awg is probably in the ballpark, but you'd need to run a voltage drop calculator to confirm. 5900w / 390v = 15.12a, then just plug your distance and amperage into a web-based calculator. Don't go over 2% voltage drop, but a better number is below 1%.

[df0rster]

Sorry, I should have qualified that statement. That's only when the system isn't operating (installation, maintenance, repair, etc.). Each optimizer puts out 1v to essentially indicate that it's alive. My system consists of 4 strings of 10 panels each, so I only have 10 volts showing on my strings if I power down. Once powered, the strings operate at around 390v.

As for your wire size, 10awg is probably in the ballpark, but you'd need to run a voltage drop calculator to confirm. 5900w / 390v = 15.12a, then just plug your distance and amperage into a web-based calculator. Don't go over 2% voltage drop, but a better number is below 1%.

No worries, if I had read it a little closer I would have understood.

As it is, 10 panels per string at 220 feet, the solar design tool site is showing about 2.1% drop using 10 awg. If I up it to 8 awg is goes down to 1.3% drop per string.

moving the inverter closer and running AC wire for the 220 feet means I have to run a 4awg for the same loss (1.3%). And I don't get to keep the inverter in the house where its much cooler.

So I can either run an 8awg per string or run a single 4awg if I locate the inverter in the shop. I'll have to figure out which is more cost effective.

(sorry getting off topic)

[ButchDeal]

Great info, Thanks!

I didn't know the dc optimizers converterd down to 10v. Does this mean we have to use larger wire from the panels to the inverter? Right now I have it at 10 awg on two 220 ft runs from the panel string to the inverter.

they drop the voltage to 1V per optimizer when in shutdown mode, otherwise it is over 350V