Optimizer

[bcroe]

There have mentions of the "optimizer", but no details. My impression is, it takes a string partly disabled
by things like shade or snow, and boosts its apparent output voltage to match other strings. It would operate
the string at its present MPPT, converting its voltage/current to a higher voltage (but same power less
conversion losses) matching other string voltages. The string would operate at the current of the unshaded
cells, bypassing the shaded cells. The boosted voltage would be at a reduced current, but put the unshaded
cells back into full production.

Is that close or not? Where is more stuff on optimizers? I'm thinking I have a string or 2 that could benefit
from such equipment at some times of day. Maybe build one. Bruce Roe

[GridGrants]

You're on the right track. SolarEdge gives the best short description I have seen:

"The SolarEdge power optimizer is a DC/DC converter which is connected by installers to each PV module or embedded by module manufacturers, replacing the traditional solar junction box. The SolarEdge power optimizers increase energy output from PV systems by constantly tracking the maximum power point (MPPT) of each module individually. Furthermore, the power optimizers monitor the performance of each module and communicate performance data to the SolarEdge monitoring portal for enhanced, cost-effective module-level maintenance. Each power optimizer is equipped with the unique SafeDC™ feature which automatically shuts down modules' DC voltage whenever the inverter or grid power is shut down.

The MPPT per module allows for flexible installation design with multiple orientations, tilts and module types in the same string. When working with SolarEdge Inverters, SolarEdge power optimizers automatically maintain a fixed string voltage, allowing installers even greater flexibility with longer strings and strings of different lengths in order to design optimal PV systems.

http://www.solaredge.us/groups/us/powerbox-power-optimizer

Tigo Energy has another popular optimizer they call a "maximize":

http://www.tigoenergy.com/why-tigo

The info at those two links will give you a good lesson on optimizers.

[bcroe]

You're on the right track. SolarEdge gives the best short description I have seen:

"The SolarEdge power optimizer is a DC/DC converter which is connected by installers to each PV module or embedded by module manufacturers, replacing the traditional solar junction box. The SolarEdge power optimizers increase energy output from PV systems by constantly tracking the maximum power point (MPPT) of each module individually. Furthermore, the power optimizers monitor the performance of each module and communicate performance data to the SolarEdge monitoring portal for enhanced, cost-effective module-level maintenance. Each power optimizer is equipped with the unique SafeDC™ feature which automatically shuts down modules' DC voltage whenever the inverter or grid power is shut down.

The MPPT per module allows for flexible installation design with multiple orientations, tilts and module types in the same string. When working with SolarEdge Inverters, SolarEdge power optimizers automatically maintain a fixed string voltage, allowing installers even greater flexibility with longer strings and strings of different lengths in order to design optimal PV systems.

http://www.solaredge.us/groups/us/powerbox-power-optimizer

Tigo Energy has another popular optimizer they call a "maximize":

http://www.tigoenergy.com/why-tigo

The info at those two links will give you a good lesson on optimizers.

So Solar Edge adjusts all modules MPPT to a standard bus voltage, like 75VDC?
Sort of like a "converter per module", but DC output. I think the outputs are
paralleled, too bad the picture shows them in series.

That sounds OK for a wild mix of panels. But not what I need, described in the
first post. Guess I'll need to build my own, at the 360V 8A (3 KW) level. And
call it a ....... Bruce Roe

[inetdog]

So Solar Edge adjusts all modules MPPT to a standard bus voltage, like 75VDC?
Sort of like a "converter per module", but DC output. I think the outputs are
paralleled, too bad the picture shows them in series.

That sounds OK for a wild mix of panels. But not what I need, described in the
first post. Guess I'll need to build my own, at the 360V 8A (3 KW) level. And
call it a ....... Bruce Roe

If you put the optimizers in parallel, there would be no need for them most of the time. They are designed to produce the optimum current from all modules when placed in a series string.
And since the string will be driving an MPPT device, the optimizers have to react to the changing current draw from the GTI or CC rather than just put out a constant voltage or constant current.
It is a complex task.

If the optimizers produced a constant voltage output, then you would indeed want to put them in parallel. But that is not what they do.

[bcroe]

Interaction

If you put the optimizers in parallel, there would be no need for them most of the time. They are designed to produce the optimum current from all modules when placed in a series string.
And since the string will be driving an MPPT device, the optimizers have to react to the changing current draw from the GTI or CC rather than just put out a constant voltage or constant current.
It is a complex task.

If the optimizers produced a constant voltage output, then you would indeed want to put them in parallel. But that is not what they do.

OK, they are in series. Apparently each "panel manager" optimizer looks at the string current, and
raises its own voltage till using all of its panel power. Other strings may fix the the total voltage, so
other optimizers in the same string will note their reduced voltage, and raise their current for their
panel MPPT power. The first will note the increased current & lower its voltage a bit. Eventually all
will adjust to a combined MPPT, till something changes again. And the GTI is also doing its own MPPT
search.

It sounds like a very complex interaction, unless there is a communication system & overall control.
Great potential for the whole thing going into a grand oscillation, something I have seen a few times
in my career. Bruce Roe