SolarEdge minimum number of active panels to produce?

[adoublee]

Thanks for the data. String voltage appears very much as expected. The dip in the panel DC voltage to around 7V at 10:30am supersizes me a little - especially if every panel in the string did the same. It's hard to believe the MPPT caused that or that everything went dark. Current did not spike during this voltage dip, so not sure how power was maintained and rising through this either as shown on PVoutput. Have you noted/seen if string voltage can exceed the total of all panel voltages (a voltage boost included in optimizers)?

Also, the talk about a "self-sustaining power supply" a la SMA's secure power supply got me wondering what the smallest number of panels could be used to support the 1500W at 120VAC from the smallest HDwave inverter. Specs don't say anything other than needing a minimum 8 panels/optimizers, but you seem to know they don't lock out operation with only 6 connected.

[inetdog]

Just from the data shown it looks like an optimizer can go as low as 8V ouput without shutting down and as high as 58V.
Do you have better information on what the top and bottom limits are?

I would think that a partially shaded panel in an otherwise sunny string would require the optimizer output to go below 8V to keep that panel producing. I wonder just where the threshold is.

[adoublee]

Just from the data shown it looks like an optimizer can go as low as 8V ouput without shutting down and as high as 58V.
Do you have better information on what the top and bottom limits are?

I would think that a partially shaded panel in an otherwise sunny string would require the optimizer output to go below 8V to keep that panel producing. I wonder just where the threshold is.

Spec sheets indicate maximum output voltage. 60V for most, 85V for the P405 for thin film panels.

I believe the output voltage can drop to any value needed to maintain (panel's MPPT wattage) / (inverter's desired string voltage), but have a hard time believing the optimizer can "boost" the voltage if the panel is not receiving enough sunlight to activate a normal Voc.

[inetdog]

... but have a hard time believing the optimizer can "boost" the voltage if the panel is not receiving enough sunlight to activate a normal Voc.

That statement does not seem to make any sense.
If the available I from the panel is not enough to operate the electronics of the optimzer at the input voltage the optimzer requires, the optimizer cannot run.
What that has to do with "activating a normal Voc" is beyond me.

[ButchDeal]

Thanks for the data. String voltage appears very much as expected. The dip in the panel DC voltage to around 7V at 10:30am supersizes me a little - especially if every panel in the string did the same. It's hard to believe the MPPT caused that or that everything went dark. Current did not spike during this voltage dip, so not sure how power was maintained and rising through this either as shown on PVoutput.

you are looking at ONE panel voltage dropping. It was dropping as the others were getting sunlight over the roof line before it. Thats why the one optimizers output voltage dropped but the same panels increased.
As they all started locking in at higher voltage and current levels the inverters output increased.

Have you noted/seen if string voltage can exceed the total of all panel voltages (a voltage boost included in optimizers)?

You can see voltage boost on the optimizer at 10:30 for this optimizer the input (panel output) dropped to about 5V but the optimizer output was 35V and climbing.

Also, the talk about a "self-sustaining power supply" a la SMA's secure power supply got me wondering what the smallest number of panels could be used to support the 1500W at 120VAC from the smallest HDwave inverter. Specs don't say anything other than needing a minimum 8 panels/optimizers, but you seem to know they don't lock out operation with only 6 connected.

It doesn't matter what HDWave or standard SE inverter you have the absolute minimum is 6 optimizers. The recommended minimum is 8 though.

I don't understand your relation to SMAs secure power supply though.

[ButchDeal]

Just from the data shown it looks like an optimizer can go as low as 8V ouput without shutting down and as high as 58V.
Do you have better information on what the top and bottom limits are?

I would think that a partially shaded panel in an otherwise sunny string would require the optimizer output to go below 8V to keep that panel producing. I wonder just where the threshold is.

well optimizers can output as little as 1V and I have heard from techs that the high is 60V.

[adoublee]

It doesn't matter what HDWave or standard SE inverter you have the absolute minimum is 6 optimizers. The recommended minimum is 8 though.

I don't understand your relation to SMAs secure power supply though.

Well I've thought about using the secure power supply like feature to regularly produce daytime power without battery (overspending on inverter capacity). 1500W is the max, so I may or may not want a full out panels serving this. Inverter spec sheets list minimum of 8. It looks like their 60V max optimizer output and 350Vish minimum input voltage drive the 6 number, which in theory could be even lower if the 350V could be lower for 120VAC secure power only.

[ButchDeal]

Well I've thought about using the secure power supply like feature to regularly produce daytime power without battery (overspending on inverter capacity). 1500W is the max, so I may or may not want a full out panels serving this. Inverter spec sheets list minimum of 8. It looks like their 60V max optimizer output and 350Vish minimum input voltage drive the 6 number, which in theory could be even lower if the 350V could be lower for 120VAC secure power only.

you seem to be confusing SMA and SolarEdge.
SolarEdge does not have Secure power feature.
You have a StorEdge option which requires a battery for backup
The 350V DC will drop if the line voltage is lower than 240V AC but the solaredge inverters do not do 120V. With StorEdge they get 120V with an autotransformer add on for backup capabilities.

Note that even at 240V AC I have seen the DC much higher than 400V.

[adoublee]

you seem to be confusing SMA and SolarEdge.
SolarEdge does not have Secure power feature.
You have a StorEdge option which requires a battery for backup
The 350V DC will drop if the line voltage is lower than 240V AC but the solaredge inverters do not do 120V. With StorEdge they get 120V with an autotransformer add on for backup capabilities.

Note that even at 240V AC I have seen the DC much higher than 400V.

New HDWave spec sheet indicates an optional "self-sustaining power outlet" indicated to be 120V and 1500W. I thought you posted a link about this previously but maybe not. Don't know what else it could be but a SMA Secure Power Supply equal, which is why I brought up SMA...

http://www.solaredge.com/sites/default/files/se-hd-wave-single-phase-inverter-datasheet-na.pdf

[foo1bar]

Well I've thought about using the secure power supply like feature to regularly produce daytime power without battery (overspending on inverter capacity). 1500W is the max, so I may or may not want a full out panels serving this.

1500W across 8 modules is only 190W/module.
190W is what I am getting for a peak on my 280W modules today. (less on the ones that are more east or more west oriented)
So you need at least 8 modules if you're going to be close to that 1500W max.
And even then there's not enough power in the morning/evening.
And there's the question of what the efficiency is (ie. will 1600W of DC power in give you 1500W of AC power out? Or do you need 3kW+ of DC power?)

I think in the end what you wind up doing is sizing the DC side based on your grid-tie, and the secure-power-supply feature is a rarely used "nice-to-have-just-in-case" thing.

[ButchDeal]

New HDWave spec sheet indicates an optional "self-sustaining power outlet" indicated to be 120V and 1500W. I thought you posted a link about this previously but maybe not. Don't know what else it could be but a SMA Secure Power Supply equal, which is why I brought up SMA...

http://www.solaredge.com/sites/defau...tasheet-na.pdf

ok I though you were thinking of solaredge optimizers on an SMA. I am with you now.
But I don't know the answers as we don't have any HD waves installed yet.

[adoublee]

I think in the end what you wind up doing is sizing the DC side based on your grid-tie, and the secure-power-supply feature is a rarely used "nice-to-have-just-in-case" thing.

Agree in the typical use - it's a daytime circuit available if utility power is out. I'm referring to using completely off-grid versus other methods of off-grid, but would be niche application for sure.

[foo1bar]

Agree in the typical use - it's a daytime circuit available if utility power is out. I'm referring to using completely off-grid versus other methods of off-grid, but would be niche application for sure.

A normal off-grid system would be a better choice in basically any scenario I'm thinking of where you can't have grid available.

[inetdog]

A normal off-grid system would be a better choice in basically any scenario I'm thinking of where you can't have grid available.

But a Secure Power Supply or equivalent is a lot cheaper to add to a pure GTI system for grid outages than an additional off grid system or use of a hybrid system in the first place.

[foo1bar]

But a Secure Power Supply or equivalent is a lot cheaper to add to a pure GTI system for grid outages than an additional off grid system or use of a hybrid system in the first place.

Right - but if you can't have grid available, then you wouldn't have a GTI system.

adoublee is looking at using a solaredge w/ secure-power-supply instead of an offgrid system for an off-grid application.
And I think off-grid solutions are going to be better for any off-grid situation.