"Finally I assume that indoor light is available for 10 hours a day. 44mA * 1/100th * 75% * 95% * 0.72V/4.12V * 10 hrs =  0.55 mAh is harvested every day. So an application must have an average current less than 0.55mAh/24h = 23uA, that's enough for a simple Bluetooth Low Energy beacon or a very simple LoRa application. "

I am interested in testing that limit. The IxSolar series is sold as large as 4"x8" on Digikey: 

https://www.digikey.com/en/products/filter/solar-cells/514?s=N4IgjCBcpgnAHLKoDGUBmBDANgZwKYA0IA9lANogAMIAusQA4AuUIAykwE4CWAdgOYgAvsQC0AFmQg0kLHiKkKIAEwBmAKzx1dRi0ghhIlUtwlsmTgAIU%2BbHh0gAbFO4ATVqLBUIu1iGJMAJ4M%2BKyuuGhCQkA

If I used monocrystalline, SM262K10L 5.71W 1.02A 5.58V 1.09A 8.661"" L x 4.961""

I am assuming I could get about 832uA continuously from that. 

Edit: I understand 5.58V is too much for the input voltage- which is why I am looking into a lower voltage in parallel: https://youtu.be/LDzxifG7VeA?t=584

Other panels that appear to be efficient include:

https://www.powerfilmsolar.com/products/electronic-component-solar-panels/indoor-light-series/ll200-2-4-75 at 200 Lux: Power: 0.289mW  3.70 x 2.87 (in)

Operating Voltage: 1.6V

Current: 0.181mA

Average Voc: 2.4V 94.0 x 73.0 (mm) / 3.70 x 2.87 (in)

They also have a design tool, which lets me select number of cells, length and voltages: https://www.powerfilmsolar.com/custom-solutions/custom-solar-panel-design-tool/

I'm not sure which ones are more efficient for indoors, including Amorton AM1816CA, and not focusing on cost at the moment. E-peas mentions up to 7 solar cells in one of their kits, but I would like to know if AEM10941 has any limitations to maximum size of panels- I am looking into designing a microcontroller with integrated solar power manager - Sparkfun offers it as an option: https://alc.sparkfun.com/designer/but requiring 10W panels. 

I am not sure if theirs is designed for indoor lighting since I don't know if requires a minimum amount of light to "cold-start" their power manager. Therefore, with an AEM10941, it could jump start trickle charging at a very slow rate, but fast enough to power the Apollo3 microcontroller (this is best in class, excluding the 3uA/mhz Apollo4, set to be released later this year. 

Theoretically, I could design four 4x8" panels that would fit around a 17" laptop keyboard with an Ambiq Apollo3 microcontroller that runs continuously, and not on sleep on "less than 1mA": https://www.sparkfun.com/products/15444 and produce 3.3mA.

"operates less than 5mW at full operation)" https://www.sparkfun.com/products/15442 (Features Tab)

Powering the an e-ink or reflective monitor might be more difficult but it is bistable and only uses power on refresh. Therefore if it uses less than 2mA the board could be powered entirely from a ceiling light.  This is a 4.4" http://www.koe.j-display.com/index.php?option=product&task=showpage&cur=1&id=251# that uses 5mW if backlight off. I would like to try it with 2.7" https://www.j-display.com/english/product/reflective.html but I think more panels could power a larger screen.

You seem to understand my calculations to estimate the amount of daily harvested energy. The AEM10941 input voltage range is max 5V. You need to make sure that the open circuit voltage does not exceed 5V. That often means you need to select 4V or less NOMINAL voltage. Either you put 1 or more 4V solar panels in parallel or put a few lower voltage cells in series. Note that a partial shade on a series string causes the whole string to malfunction. Also note that AEM10941 efficiency drops with solar panel voltage below 1V. So a tradeoff is to select about 2.0V nominal voltage and if you want mor epower you add more in parallel

Thank you, I plan to try my kit soon. I ordered a dev-basic with BQ25570 but will order the AEM10941 after I gain more practice: https://www.powerfilmsolar.com/products/development-kits/solar-development-kit

Very Very cool...Love the energy harvesting chips...
Such a cool design!
Maybe even a slim cellphone battery mount for the back

Chech this out.

https://hackaday.io/project/159139/log/150347-nicely-integrated-application

I am working on two designs using the AEM10941 without the onboard solar cells. One charges the a Li-Ion battery and the other charges a pair of super capacitors.

https://hackaday.io/project/160376-solar-harvesting-into-li-ion-battery

https://hackaday.io/project/160470-solar-harvesting-into-supercapacitor

I have ordered the PCB from Elecrow and soon I will test them

This solar panel - perfect for small devices. I use with LTC3105 (one voltage)

http://akb77.com/g/files/media/image/CT7/solar-2.jpg

Low current but charge small supercap.

now THAT is a tiny booster circuit 

I see AEM10941 datasheet. Looks interesting. Can't find samples but possible buy some chips.

Thanks for information !

I consider selling TSEM for USD24.90 on Tindie. Would you buy it? Why would you buy this module and not another tiny board like this one? https://www.tindie.com/products/onehorse/bq25504-solar-cell-lipo-charger/

Would you prefer a AEM10941 breakout board without the to onboard solar cells?

The nice thing about a board with just the boost converter is that you can tailor the selection of solar cell(s) to match the application. I like the 50 mm Panasonic Amorton AM-5412CAR a-Si cells since they are still small but provide 7 mA per hour in full Sun, meaning about 40 mAH per day on average, enough to power a 2 mA device. But the point is that many user don't want to pay in board size and price for solar cells that might not fit their application.

Hi Kris, I think you're right. The board that I will be selling won't have the solar cells and will be much smaller than this one. 

I have designed a new PCB and ordered from Elecrow. https://hackaday.io/project/160376-aemlion

please make a experiment. put this outside on one year and tell me. it working 24h or not.

nothing more

meybe send data to server or other way check device is working or not.

What do you think that could fail? Solar cells, capacitors, the AEM10941 IC, resistors, or the the external battery?

Uninterrupted functioning could we be checked by monitoring the 3.3V and 1.8V outputs using another device that logs any voltage dips. In my opinion it may be hard to make such device thats works for a year and does not falsely trigger. 

That fabian has zero projects, criticizes many decisions of makers with zero positive feedback and just asks for changes or "do this or that (please)". Wouldn't even pay attention to this troll... 

my english is not good. Solar  is a capricious device.

Rather you would underestimate the size of the panel, but until you do it you will not know. Therefore, do an experiment and you will know if it suits you. Can it work completly offgrid. It is important that it is useful and not just a gadget for nothing. test it. I foud interesting art. meybe help You

https://www.voltaicsystems.com/blog/powering-a-raspberry-pi-from-solar-power/

In PCB revision 2 I added 1.8V regulated output to the TSEM. 

Nice! There are two more solar cells from Ixys with same form factor but higher open circuit voltage available. Have you considered rather using one of them since the booster efficiency would be better there ?

A link is here.

The active cell area decreases a bit with more single cells. Maybe KXOB22-04X3F-ND with 1.8V open circuit voltage is worth trying..?

Great idea, I thought they were not available, but I see them at digikey and conrad.de. I ordered a couple of the 1.5V/15mA cells (KXOB22-04X3F). Now effiecincy goes from about 85% (1V) to 95% (3V). 

In my design I have 2*0.5V*44.6mA=44.6mW solar cells. To get 10% more booster efficiency I could change to 2*1.5V*13.38mA=40.14mW which is 10% less power. So that doesnt make sense. Then I choose for the more economic 0.5V solar cells.

I can't find this chip in shops (Farnell etc). Where did you find it?

I got a few samples from e-peas. I will ask when chips become available at the large distributors.

I dont think they will be available at the large distributors soon. E-pease carefully selected a few distributors. See here. https://e-peas.com/where-to-buy/

@Alexandre LE GALL I learned from e-peas that most of their customers chose for standard configurations that don't require extra pins. I wanted to keep it simple and chose for lipo only (no super capacitor) and use only 3.3V output because that is standard for most MCUs.

The AEM10941 is very interesting compared to the BQ25504 (the energy harvest chip I use in my project) : There are two integrated regulator and a balance feature for dual-cell supercapacitor !

I think you would make an external connection for the cvercharge, overdischarge, charge ready, and the balance pins.

Sorry initially I wrote the incorrect part number. Glad you found it

ah found it. https://e-peas.com/products/energy-harvesting/photovoltaic/aem10941/

cant find this chip. Is the code correct?