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Alternative to microinverters

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cegue:
Hi, I want to start a personal project for my small countryside house. However, the lack of a similar product in the market is making me doubt its feasibility.

The house is surrounded by trees, so shading is always present during the day. There’s no way to improve this by changing the panels’ layout. Thus, a parallel connection is necessary, and a friend suggested using microinverters. This is fine, but I already have an inverter and still want to use it. So, this idea came to mind:

Why not create an isolated DC-DC converter to be placed on the back of each solar panel? The output of each converter would be >320V DC, and then the main inverter would transform it to 230V AC.

Why doesn’t this product exist on the market? They would be cheaper and less complex than microinverters

Edit:
Similar to this product
https://www.ti.com/lit/ug/tidu404/tidu404.pdf

Siwastaja:

--- Quote from: cegue on September 02, 2024, 01:04:19 pm ---Thus, a parallel connection is necessary,
--- End quote ---

Wat???


--- Quote ---Why not create an isolated DC-DC converter to be placed on the back of each solar panel?

--- End quote ---

There already exists something much better: non-isolated DC-DC converters to be placed on the back of each panel, then those in series, together generating high enough voltage for the inverter, yet allowing separate MPPT control per each panel. These are called "optimizers" and are widely available.

Microinverters or optimizer based system are both OK for your case.

Marco:
They're called power optimizers, but they are usually used with series connection (and I assume they just bypass under full illumination).

For parallel they would have to be mandatory, with the serial solution they can be optional.

nctnico:
Optimisers are one way, but you can also think about arranging the panels in groups which receive shading together. That is how I organised the system on my roof.

Siwastaja:
Also worth considering:

1) If shading affects most of the panels most of the day, consider not doing the install at all. Only in such case, microinverters/optimizers provide significant advantages over string inverter, but then again the system is more costly and still producing much less than a less obstructed system.

2) If shading, at any point in time, only affects small number of the panels (e.g., significantly less than 50% of panel count), a string inverter could do surprisingly well: partial shading is not as big as a problem as microinverter sales folks say. Panels have bypass diodes: only the production of the shaded panel drops to zero, rest produce fully, this is what microinverter or optimizer sellers want to lie to you about to make their case.

e.g. with 10 panels out of which 2 are shaded, string inverter produces 0.98*(8 * 100% + 2 * 0%)/10 = 78.4% of rated power, while microinverters produce like 0.95*(8*100% + 2*30%) = 81.7% of rated power. Not much of difference even if you had two panels out of ten shaded for the whole day! If you have partial shading for only an hour or so, you already lost your gains in lower efficiency of the micros.

But if the shading affects many panels at the same time, then make sure the rest are capable of exceeding the inverter's minimum MPPT and minimum startup voltages, otherwise exactly what microinverter folks claim will actually happen. If like 5 out of 10 are shaded more than some half and hour or so, consider micros/optimizers or not doing it at all.

If you have enough panels to satisfy two strings of a string inverter, then play the game as nctnico says. Then again if you are only barely able to exceed the minimum MPPT/startup voltages, then not dividing into two strings might be better after all.

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