Solar panel/cell info

[alain-chuzel]

I disagree that the “better looking gaps” is a consequence of the Aptera 45 degree rotation. Both other cars have cells, in some areas, that are intentionally “misaligned” so that more active cell area results which increases panel efficiency. Aptera chose the opposite approach. For cosmetic purposes, they intentionally aligned (with much wider gaps) and rotated cells at the expense of panel efficiency.

You might be interested in the following video.

[llewellyn-evans]

Each cell generates the same power for the same area. A cell of half the area will generate half the current. A panel will supply the same current as the weakest cell. Having any cell that is half the size of the others will cut the current by half.

Solar nerds, please correct me if I am wrong.

• This reply was modified 2 years, 4 months ago by  Llewellyn Evans.
• This reply was modified 1 year, 9 months ago by  Gabriel Kemeny.
• This reply was modified 1 year, 7 months ago by  Gabriel Kemeny.

[alain-chuzel]

Solar nerd reporting for duty!

Generally quite correct but two “fixes” immediately come to mind:

1. Two of the the nominally half size triangle shaped cells could simply be electrically paralleled before connecting in series to full size cells.

2. The nominally half size triangle shaped cells could simply be series-ed to each other and paralleled to an equivalent voltage full cell string.

Both of the above techniques are used, on occasion, with solar race car arrays. I know because I’ve designed and built modules using these very techniques (although not with triangles!).

[Stuppie]

Since I am a total dummy on these kind of technical matters but still very curious, how and when( I mean does it also do a feedback during driving or only during parking?) does the Aptera feed solar energy from the panels, back into the batteries…

[alain-chuzel]

While I can’t say with 100% certainty that this will be the case with Aptera, in solar car racing, the solar array, battery bank and wheel motor(s) are, effectively, all electrically in parallel. What that means is that any energy coming from the solar array can go either to the batteries or to the motor(s) or shared by both. When at a stop light, of course the motor(s) aren’t consuming any energy so, in this case all the solar is going to the batteries unless they happen to be fully charged. If at any time the motor needs more energy than the array can provide, the difference is made up for by the batteries.

[993cc]

I remember this question being asked on some forum with a person from Aptera taking questions, and the answer was that the panels would contribute charge while driving, and while charging at level 1 or II, but not while DC fast charging.

[charles-lewis]

The batteries are charged either from the connection to a charger or from the solar panels. Those are two independent circuits that work together as needed. The solar charging should work while the car is being driven. Its would not solar charge as fast as driving would drain the battery. It should appear as better range during the daytime because of the solar power.

That is a generic description of solar charging. If Aptera has a different implementation please post a correction.

[john-k-whaley]

What is the advantage of having all available Solar panels on the Aptera

[Stuppie]

700 Wh of absolutely free energy on a sunny day…………resulting in another 40 miles of free distance…

[john-larocque]

The panels are rated for 700W; provided the 100Wh/mile and 40 mi/day of solar range figures are accurate, that’s _4000Wh_ of energy per day in ideal conditions.

[alain-chuzel]

Here’s another way to do the math.

Aptera with “Full Solar” = 700 watts of power at “peak sun” (claimed)

Aptera energy consumption = 100 watt-hour per mile (claimed)

Tucson, Arizona which gets an average of 5.36 “peak sun-hours” per day on a HORIZONTAL surface. (This is an average over a year)

0.7 KWatts peak power x 5.36 peak sun-hours per day divided by 0.100 KWatt-hours per mile of energy consumption = 37.52 miles per day (average over a year)

[KayleighVenne]

Hi John and all! Great responses in here. The benefit of having all solar panels would allow you to maximize the amount of solar power for the vehicle!

For example, the average American drives 29 miles per day. Even though the longest range Aptera can drive for about 1,000 miles between charges, the reality is that most of our driving is 30 miles or less. For Aptera, 30 miles consumes about 3 kWh of electricity. Now, let’s say your commute is 15 miles each way, let’s assume it’s dark when you’re driving to and from work. While parked at the office on a sunny day, your Aptera could put back in about 4.4 kWh which is far more than what you’ll use that day. You’ll arrive home with more charge than when you left with. That’s how it works, it’s as simple as that. With full solar, Aptera’s integrated solar package provides up to 40 miles free driving miles per day. Making Aptera the first vehicle that won’t need to fuel up for most daily driving. Park Aptera in the sun and come back to your vehicle with more range than when you left it — giving you the freedom to go without having to plug in. Harnessing the power of the sun!

If you choose the basic solar package, all will still function adequately, just with fewer panels. For example, you can reserve the 1000 mile range battery with the basic solar package and you will just have fewer panels, and therefore, less energy captured from the sun. In that event, you could store up to 1000 miles from an electric charge of the battery and about 16 additional miles from the basic solar package a day (depending on where you live). One could charge their Aptera up to 1040 miles for the day, 1000 from the battery pack, and 40 from the panels.

Happy Friday everyone!

[hayden-rank]

From what I understand, photovoltaic cells work by taking energy from the sun and using it to knock the electrons off a substance with a low ionization energy (such as silicon) to create an electrical current. Although there is an extremely large number of electrons contained within every cell, the cell will stop working after every single electron has been knocked off. How long do Aptera’s cells last? And have we found a way to fix this problem? Most solar panels last around 25 years before being depleted of electrons and, while this is more than enough for a lifespan of a vehicle, I am curious nonetheless. Thank you to whoever can provide an answer.

[alain-chuzel]

Your understanding of how photovoltaic cells work is not quite correct. I just did a quick search on YouTube for “how do solar cells work” and found the following 5 minute video that I would like to recommend you watch. Rest assured, there are no electrons lost or harmed in the process!

Strictly speaking, the CELLS Aptera is likely using can last a very, very long time. Many, many decades. What won’t likely last as long are the materials used to, ironically, protect the solar cells. I’m speaking primarily of the encapsulation. It will “degrade” over time by exposure to mother nature. The degradation usually manifest’s itself in the form of “darkening” and even “hardening” of the encapsulants.

I’m happy to discuss further if you’d like!

[Fran]

Solar Panels do not “lose” electrons. The electrons are knocked loose by the high energy photon, that’s true, but once loose they travel the completed circuit back to the panel as a low energy electron, and back into the matrix. How long do solar panels last. I purchased (used) some of the first solar panel built. They were used for a research project and then stored for decades. They still worked when I bought them and they still worked when I sold the property I installed them on. I would guess that solar panels will last similar to how Lithium ion batteries last. They will get less effective over time but still work at a lower output. So technically the last until you break them.

[hayden-rank]

Ahh it is great to know that the electrons are reused! I assumed they worked something like an alkaline battery. So my new understanding is this, the cells are made of a metal with a very low ionization energy. The electrons are knocked out of orbit and and form an electrical that does work. The electrons then return to a silicon atom and the process repeats. Is this correct?

[john-malcom]

Thanks Alain. A good basic video for those not familiar with the operation of solar cells. Is it correct that the efficiency of silicon cells maxes out in the low 20s percent and the cells selected by Aptera are at the higher end of that efficiency?

[Tam]

Even low end monocrystalline based panels offer a 10year/80% output warranty. Higher end panels can offer 25 year/80+%. The real timeline will be encapsulation/physical damage here. The cells will work for a long time, if they are kept dry. I suspect expoxy coating UV damage and impacts/rocks/hail will drive the lifespan.

[alain-chuzel]

No worries John. I invite you to check out the following Wikipedia page regarding the maxing out of single junction silicon solar cells:

https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limit

Regarding Aptera’s cells, they are still the “champions” in terms of what single junction silicon are available today. They are generally available up to about 25.4% (at Standard Test Condtions (STC).

• This reply was modified 2 years, 1 month ago by  Alain Chuzel.
• This reply was modified 1 year, 9 months ago by  Gabriel Kemeny.
• This reply was modified 1 year, 7 months ago by  Gabriel Kemeny.

[danny-mattijetz]

When thinking about the solar cell sandwich that was shown in the video, think about a perfect matrix of silicon throughout the whole sandwich. Everything lines us correctly and every possible bonding point is filled. Phosphorus has one more electron than silicon, so when it is added to the top layer, the matrix gets a little out of whack. That extra electron is kind of hung out to dry. The opposite is true of the Boron on the bottom layer of the sandwich. It has one spot that has a mismatched bonding point. The result is a permanent electric field across the sandwich. As electrons are freed, they feel this field and move in whatever direction it points. This causes them to move up to the metal contact points. The electrons do not come from the metal. The metal merely connects the top to the bottom of the sandwich. A freed electron can only move to the original spot by taking the long way around. This makes a full electrical circuit.

An interesting point is that the photons coming from the sun or any other source of light, have to be of the exact wavelength to knock the electrons out of orbit. This is a quantum effect. If the energy of the photon is too much or too little, it does not free the electron. Many of the photons can go right through the sandwich without changing. This is how a multi-junction cell might work. By doping the top and bottom layers of a second sandwich so that it responds to a different wavelength, it can be positioned above or below the first sandwich to absorb those photons. The combined effect creates a more efficient cell than either one by itself.

That last paragraph was just for interest. The Aptera cells are single sandwich cells.

[alain-chuzel]

Great summary Danny!

One comment/question if you don’t mind. I am under the impression that an electron would be freed as long as the incoming photon had AT LEAST (rather than exact) the amount of energy required(?)

[Pragmatic_to_a_Fault]

I read an article that said the newest solar cells can last 25-30 years.

It also states that solar cells have come a long way in the last 20 years

I’m hoping this isn’t like tattoo ink where they said. Guaranteed not to fade for 10 years, even though the ink had been around for about 3 years…( that brand )

Using that logic. If you take care of the solar cells. Wash them, don’t scratch them , don’t let bird poo bake into them , they will probably last 20 years. Wether not they become less efficient over time …. Meh. Who knows

[alain-chuzel]

Solar cell and solar panel (a.k.a. module) are different things. Technically, cells can last a hell of a lot longer than 25-30 years. Top tier solar panels are currently power warranted for 25+ years. It is unlikely Aptera will offer the same kind of warranty because they really can’t assemble and encapsulate them like top tiered solar panels are. It’s the encapsulation that will likely limit their useful life. Yes, take care of them and they’ll likely last well over 10 years though.

BTW, I’ve been in the solar fab industry for over 30 years. The first Silicon cells I worked with were on the order of 15% efficient at Standard Test Conditions (STC) and made by ARCO Solar. Now the best (Maxeon/SunPower) are, at best, 25.4%. Personally, that seems like NOT such a long way. What has, however, come a long way is the reduced price per watt.

[danny-mattijetz]

You bring up a good point, and I will admit that it has been almost 50 years since I studied quantum physics, but I believe the photon must have exactly the right amount of energy or quanta to eject the electron. Photons can still hit atoms and cause them to vibrate. That would result in heat. Another heat loss would be electrons recombining with their newly created hole before moving away from the atom. In recombining, a new photon will be created that will travel in a random direction and probably hit other atoms. That would also result in heat. Despite having said this, I’m not going to insist that I am right on this point. The memory cells fade after 50 years of not firing.

[danny-mattijetz]

You got me thinking, so I decided to do a little search. From the little bit that I read, it would appear that you are right on this point. The quantum amount required to move the electron out of the atom’s orbit and into the conduction band must be met. If the photon had more energy, the difference would go into heat. Many of the photons still pass through the cell and right out the other side. Even solids have a lot of space between atoms.