Aptera Solar panel/cell info (2)

[alain-chuzel]

First, realize that each panel (hood, roof, dash and hatch) will likely act independently of each other. This simply means that any damage to one will have no impact on any other.

“Specifically the question is if one of the solar cells is damaged (impact/malfunction) will it take out the whole sub array (hood/dash/roof/hatch)?”

For the most part the worst case scenario is a single cell becomes an “open circuit”. If that happens, the bypass diode, to the extent there are any, will shunt the current from the rest of the string around the opened portion. The problem is that it’s possible that the resultant voltage loss may reduce the string voltage to below the minimum needed for proper operation of the MPPT.

“As I feel damage to those cells is basically guaranteed if you own the car long enough, and will likely be a pain to fix,….”

Fixing would be difficult but not impossible. Replacement is likely the better option.

I, too, am interested how Aptera has configured the cells…..

[Mike-Mars]

I seem to recall them saying that each solar panel would have a few (2 or 3?) independent zones (probably because of the curve?). Does anyone remember the details from that?

Fixing would be difficult but not impossible. Replacement is likely the better option.

Maybe drilling into the panel from the back and putting in a shunt over the bad cell? Encapsulation would be ruined though, so the panel would probably fail within a year or two.

10 years down the line it might be interesting to see if they have replacement panels available with upgraded (multijunction?) cells.

I wonder what failures they are expecting past the 10 year estimated life of the panel. Is that them just being cautious?

• This reply was modified 1 month, 4 weeks ago by  Michael Marsden.
• This reply was modified 1 month, 4 weeks ago by  Michael Marsden.
• This reply was modified 1 month, 3 weeks ago by  Gabriel Kemeny.

[alain-chuzel]

I seem to recall them saying that each solar panel would have a few (2 or 3?) independent zones (probably because of the curve?). Does anyone remember the details from that?

That is my recollection as well but I have no details.

Maybe drilling into the panel from the back and putting in a shunt over
the bad cell? Encapsulation would be ruined though, so the panel would
probably fail within a year or two.

The drilling/bypass idea is how I would approach it. I’ve done, essentially, the very thing in the middle of the outback at night under a big tent on a 1/4 million dollar array on a solar race car! If done well, I see no reason to expect the encapsulation to be ruined.

10 years down the line it might be interesting to see if they have
replacement panels available with upgraded (multijunction?) cells.

Agreed. I’m thrilled about the possibility of so-called “hybrid” cells. Essentially Perovskite on Silicon. https://www.oxfordpv.com/perovskite-silicon-tandem-cell

I wonder what failures they are expecting past the 10 year estimated life of the panel. Is that them just being cautious?

Based on the panels Aptera has made that I’ve seen/studied, I see interconnect failure as the “weakest link” and delamination as the second weakest. I’m not referring, by the way, to the same delamination as seen on the recent hood panel. Also, I feel Aptera’s current expectation of 10 to 15 year lifespan of the panels is a bit optimistic.

[volin-lecky]

How does damage to any of the solar cells affect the solar charging system?

[Mike-Mars]

Normally there is a bypass diode, so that a shaded or faulty cell will not generate power, but it won’t block the rest of the panel. There are some specific scenarios where the bypass diode won’t help (partially shaded or partially faulty cells where they still generate a little power, for example). Note that the bypass diodes can also fail, although this is less common than shaded cells.

• This reply was modified 1 month, 3 weeks ago by  Michael Marsden.

[alain-chuzel]

Normally there is a bypass diode, so that a shaded or faulty cell will
not generate power, but it won’t block the rest of the panel.

Only true if there is a bypass diode on EVERY cell which is unlikely. It is more likely if a cell is “mismatched”(*) enough, some number of other cells will, indeed, be “blocked” and also not generate power.

There are
some specific scenarios where the bypass diode won’t help (partially
shaded or partially faulty cells where they still generate a little
power, for example).

Strictly speaking, activation of bypass diodes doesn’t depend on the power generating capability of a cell or group of cells, it depends solely on the voltage of what it is connected across. If the voltage goes negative enough due to enough current mismatch, the diode activates. This can and does happen even with partially shaded or partially faulty cells.