Thinking about going solar for my business, totally new at this.

[bonaire]

The whole point concerning optimizers and micro-inverters is that the up front expense will fully surpass string inverters in energy generated.
Everyone installing microinverters and optimizers will generate/produce 1000X the energy of string inverters over a 20 year lifetime.

I'm glad you like the technology, however we absolutely must get our terms correct for the benefit of those who are making a choice as to which system to select.

Please qualify this 1000X the energy claim. I would estimate maybe 5% more for the same module sizing over the lifetime of the inverters if there is no shading issues. Why pay over 5% more to get 5% more? I am with nwdiver in his advisement. Get the most modules possible at the lowest per-W price first, then figure out whether you need the additional costs of per-module optimization and if there are any clipping issues with the micros. You can see energy clipping at peak sun and cold days that is pretty heavy if sized wrongly. You can build a rock-solid string inverter system with relatively low costs (ROI is key here). You actually don't even need monitoring gear or special stuff to have a fantastically successful array. If you take the time to look at the health of the system every week or two, ensure that production is good and the modules relatively clean, you can beat production of a gearhead who does no cleaning of their modules in a dusty environment.

I like the Solaredge solution for its standby-power value and ability to clip-on a battery system for dark-hour battery standby capability. There's real good value with that.

 

[Garlan Garner]

Well, you're certainly entitled to your opinions.

I'm a little confused by your statements though. In one of your posts early this morning you specifically said that the optimizers are hooked together in series, giving you a DC positive and DC negative.

Then you went on to say that each optimizer was generating 350V DC on its own - which would require them to be hooked in parallel if you aren't going to get thousands of volts at the end.

Walter

Ok Watler, Its not my intent to provide a class on how this all works, but I'll do my best.

Watch this video. Watch minutes 10-12. On a solar edge system the optimizer / inverter connection will keep 350 or so volts on the bus regardless of how many optimizers are present and regardless of how many panels are shaded. The optimizers and inverter will communicate with one another to achieve this by 350V goal by adjusting the current levels of the optimizers to maintain that voltage. I'm not going into the "why" of it. That would take a week for me to fully explain in a classroom. Just accept that it works that way.
So.... Its not a simple add up the voltage of all optimizers and you get 350VDC. The optimizers adjust their input solar panel current to keep 350V or so as a constant on the bus.

That's why I said a long time ago that you can't mix and match optimizers and inverters from vendors because they don't communicate the same language to make this happen.

Watch all of the Solar Edge Training videos.

 

[Garlan Garner]

Please qualify this 1000X the energy claim. I would estimate maybe 5% more for the same module sizing over the lifetime of the inverters if there is no shading issues. Why pay over 5% more to get 5% more? I am with nwdiver in his advisement. Get the most modules possible at the lowest per-W price first, then figure out whether you need the additional costs of per-module optimization and if there are any clipping issues with the micros. You can see energy clipping at peak sun and cold days that is pretty heavy if sized wrongly. You can build a rock-solid string inverter system with relatively low costs (ROI is key here). You actually don't even need monitoring gear or special stuff to have a fantastically successful array. If you take the time to look at the health of the system every week or two, ensure that production is good and the modules relatively clean, you can beat production of a gearhead who does no cleaning of their modules in a dusty environment.

I like the Solaredge solution for its standby-power value and ability to clip-on a battery system for dark-hour battery standby capability. There's real good value with that.

I would encourage everyone to watch the training videos. I know they will take upwards to 4 hours to watch, but the full explanation is touched on in there.

The reason I said 1000X is because of shading. This is over a 20 year period.

Lets say you have 50 solar panels connected together in series. ( STRING ). The average panel has 60 solar cells in them. Sooo. that's 3000 solar cells connected in series on a string.
Now lets say a maple leaf blows on top of a single panel and covers up one of the cells. The current production of all 3000 cells will be severely degraded by that one leaf over that 1 solar cell.
The degradation of an entire string has been seen in the videos to restrict the current flow ( not voltage ) of all 3000 cells to 30% efficiency. That's a 70% reduction in current flow. Voltage is hardly affected at all but current is severely crippled.
Now leave that leaf up there over a few days. or multiple leaves.
or bird droppings ....dirt
or install a panel next to a chimney
or install a panel that is periodically shaded by a tree limb
or install a panel with a degraded solar cell ( micro fracture ) AND TRY TO FIND the culprit.. Good luck doing so while on a 33% sloped roof. I've tried it. Never again.

Anyway.... a leaf /dirt / cracked cell / on a solarpanel - covering up a solar cell that degrades the current by upwards to "lets say" 50% on 3000 solar cells connected in series FOR 20 YEARS- would very easily have service degraded up to 1000X when compared to either a micro-inverter system or an optimizer system. I was being modest with 1000X. 4 years ago SMA ( the string inverter king ) published this very fact and then started to make their own optimizer / inverter equipment.


Watch the training videos. They explain what I'm saying in much more detail.

 

[Garlan Garner]

I helped make these videos over 4-5 years ago.

Its interesting to watch these videos now because current Solar Edge technology is tremendously more advanced that these videos. The facts and numbers are still true...its just that things like Fire Safety Shutdown is tremendously faster and voltage levels are much higher now - upwards to 450V on the bus. There are 3 phase inverters now upwards to 20KW. wow...

 

[Saghost]

Ok Watler, Its not my intent to provide a class on how this all works, but I'll do my best.

Watch this video. Watch minutes 10-12. On a solar edge system the optimizer / inverter connection will keep 350 or so volts on the bus regardless of how many optimizers are present and regardless of how many panels are shaded. The optimizers and inverter will communicate with one another to achieve this by 350V goal by adjusting the current levels of the optimizers to maintain that voltage. I'm not going into the "why" of it. That would take a week for me to fully explain in a classroom. Just accept that it works that way.
So.... Its not a simple add up the voltage of all optimizers and you get 350VDC. The optimizers adjust their input solar panel current to keep 350V or so as a constant on the bus.

That's why I said a long time ago that you can't mix and match optimizers and inverters from vendors because they don't communicate the same language to make this happen.

Watch all of the Solar Edge Training videos.

So I watched the video in minutes 10-12, and it said exactly what I thought, and exactly what I thought I'd been saying - the voltage at the inverter is the sum of all of the optimizer output voltages, with all the optimizers hooked up in series as a string.

Those output voltages have nothing to do with the panel voltages, and may not all be equal, but combined they all add up to the total at the inverter.

(I did learn some interesting bits about how SolarEdge has it set up to accomplish this - the inverter communicating a desired current and the optimizers each setting an output voltage to maximize power at the current they've been told.)

 

[Garlan Garner]

So I watched the video in minutes 10-12, and it said exactly what I thought, and exactly what I thought I'd been saying - the voltage at the inverter is the sum of all of the optimizer output voltages, with all the optimizers hooked up in series as a string.

Those output voltages have nothing to do with the panel voltages, and may not all be equal, but combined they all add up to the total at the inverter.

(I did learn some interesting bits about how SolarEdge has it set up to accomplish this - the inverter communicating a desired current and the optimizers each setting an output voltage to maximize power at the current they've been told.)

And that sounds to you like a String Inverter system?

Let me help you with the definitions. The definition of a system is determined by the relationship that the panels have with one another - not the relationship between the parts of the system.

I'm done.

 

[JMG]

*Tilts head in* OP here!

Thanks for the interesting read! My head is a little spinning, but I think I have a better understanding of everything.

So would your suggestions be to go with the SolarEdge Inverter with DC Optimizers and maybe have them increase the size of the system a little bit? He has it at a 8.55 kw DC system and is estimating that it will cover 82% of my energy offset.

I have a flat metal roof (maybe slightly pitched) and 4,000 square feet of roof with zero shade.

To the question about my energy price, its not .20 per kw, but that is just what my total bills are after all fees/taxes etc. It does seem relatively high compared to my house electricity prices compared to kw usage.

And I know I'm always supposed to get two quotes, but I just may go with this guy because he was so responsive. I left 4 emails and 1 voicemail to 5 other companies and no one responded. I'm just in a very rural area of TX.

Thanks again for the information and education!

 

[Garlan Garner]

*Tilts head in* OP here!

Thanks for the interesting read! My head is a little spinning, but I think I have a better understanding of everything.

So would your suggestions be to go with the SolarEdge Inverter with DC Optimizers and maybe have them increase the size of the system a little bit? He has it at a 8.55 kw DC system and is estimating that it will cover 82% of my energy offset.

I have a flat metal roof (maybe slightly pitched) and 4,000 square feet of roof with zero shade.

To the question about my energy price, its not .20 per kw, but that is just what my total bills are after all fees/taxes etc. It does seem relatively high compared to my house electricity prices compared to kw usage.

And I know I'm always supposed to get two quotes, but I just may go with this guy because he was so responsive. I left 4 emails and 1 voicemail to 5 other companies and no one responded. I'm just in a very rural area of TX.

Thanks again for the information and education!

I would certainly go with optimizers / SolarEdge.

Its the latest technology and will give you the best return on your investment over time.

More importantly - you will be able to easily integrate DC batteries into the system with minimal costs. The newest SolarEdge inverters will also manage power outages and automatically switch from battery to Commercial AC...thereby keeping you from having to buy all kind of sensing and switching equipment as you would have to do with micro-inverters and String Inverters.

 

[Garlan Garner]

So I watched the video in minutes 10-12, and it said exactly what I thought, and exactly what I thought I'd been saying - the voltage at the inverter is the sum of all of the optimizer output voltages, with all the optimizers hooked up in series as a string.

Those output voltages have nothing to do with the panel voltages, and may not all be equal, but combined they all add up to the total at the inverter.

(I did learn some interesting bits about how SolarEdge has it set up to accomplish this - the inverter communicating a desired current and the optimizers each setting an output voltage to maximize power at the current they've been told.)

Please Saghost. You still aren't listening or paying attention.

The 350V on the bus is not a sum of voltages of the optimizers. It just isn't. You can have 10 optimizers or 50 optimizers....it does not matter. Each optimizer puts out 350V on the bus. I don't know how much more plain it can be.
The only thing that changes is the current output of each optimizer.
In the same way....microinverters don't adjust the AC output voltage. Its always 120V per side. Whether you have 1 microinverter or 1000 of them ..... the output voltage is the same.


Each optimizer puts out 350V and adjusts its output current to keep the 350V going.
The new optimizer/inverter combos have variable voltages upwards to 450V that are instructed by the inverter as to what voltage to put out.

 

[Saghost]

Please Saghost. You still aren't listening or paying attention.

The 350V on the bus is not a sum of voltages of the optimizers. It just isn't. You can have 10 optimizers or 50 optimizers....it does not matter. Each optimizer puts out 350V on the bus. I don't know how much more plain it can be.
The only thing that changes is the current output of each optimizer.
In the same way....microinverters don't adjust the AC output voltage. Its always 120V per side. Whether you have 1 microinverter or 1000 of them ..... the output voltage is the same.


Each optimizer puts out 350V and adjusts its output current to keep the 350V going.
The new optimizer/inverter combos have variable voltages upwards to 450V that are instructed by the inverter as to what voltage to put out.

Oh, I'm listening, and very much paying attention.

The problem is that what you're describing isn't physically possible with the wiring connections you have, and isn't what your own video shows. Here's a pair of screen captures from your own video, around minute 11 and around 12:40. You'll note that he is providing voltages for each module in series, none of which are 350V, but all of which add up to 350V.

The first is a symmetric example, with each of the ten modules putting out 35V, totaling 350V in series.

The second is an asymmetric example, with one panel almost without power. So it puts out 7.6V, while the other 9 step up to 38V - 9*38 = 342 + 7.6 = 349.6V - all additive, all in series.

 

[miimura]

I was going to stay out of this, but..... Why can't you guys see that you're both right? The inverter collects the data from the optimizers and commands a current for all the optimizers such that all the voltages will add up to 350VDC. The Voltages across each optimizer don't have to all be the same but they do stack up in the string to total 350VDC.

 

[nwdiver]

I'm done.

I think... I think we need to calm down and take a deep breath. There's a bit too much tech dogma here...

This isn't a 'one-size-fits-all' thing...

There's situations where the best choice could be a string inverter... could be central inverter with optimizers... it could be micros. I'm not a fan of micros... IMO they pack to much into a small package but the failure rate isn't terrible. If you don't have a place to mount a central inverter or don't want to then Micros are pretty much the only choice. I personally like having a central inverter... for one it saves you from the expense of a gateway...

I've installed string inverters exclusively since my primary objective is ROI and all my projects so far have not had shading issues or multiple angles. If it's a complex roof layout or there's a chimney or tree that could cast a shadow on a few panels then spending the extra cash for a Solar edge system would be worth it.

All PV modules have bypass diodes... so while temporary shading on one panel will lower the power output of the entire string... it won't kill it. The MPPT point of most modern panels if they're at the same angle facing the same direction will be pretty close, you're not going lose much by averaging a string. Module level MPPT is better... but it's easy to exaggerate by how much.