Solar harvesting into supercapacitors

This is a 0.8x0.6 inch board with AEM10941 solar harvesting IC charging supercapacitors

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The AEMSUCA is a 0.8x0.6 inch board for the AEM10941 Solar Harvesting IC from E-peas. It efficiently converts solar panel energy into supercapacitor charge, it even works with indoor light. It features 3.3V and 1.8V regulated outputs that are enabled when the supercapacitor has sufficient charge, and a low voltage warning that informs the user of impending shutdown when the supercapacitor runs low. It easily integrates in other projects because of the castelllated via's, and when soldered onto 0.1' pitch header it fits in a bread board. I am selling this board on Tindie. This project is related to and

I designed it because I took part in the HackadayPrize2018 Power Harvesting challenge with a 1x1 inch Tiny Solar Energy Module and found a lot of interest in selling it. However since most projects have different power demands and people want to choose their own solar panel, I decided to remove the onboard solar cells. In addition I wanted a variant of the board that could charge a supercapacitor. 

This board is special because it integrates maximum power tracking, supercapacitor charging and two regulates outputs in a tiny and easy to integrate board. There's is no other board with so little passive components.

Ideal for indoor applications

The AEM10941 harvesting IC is very suitable for indoor applications because it has an ultra low power startup. The boost converter starts at a very low 380 mV input voltage and 3 uW input power. The IC gets most power out of the solar cells by doing MPPT maximum power point tracking every 5 seconds.


  • PCB 2 layers (0.8 x 0.6 inch)
  • solar input voltage 50mV to 5V
  • ultra low power startup 380mV/3uW
  • solar input current max 110mA
  • MPPT every 5 secs, MPPT set to 70% (adjustable)
  • Storage element: you need to connect two supercapacitors
  • 3.3V/80mA and 1.8V/20mA regulated outputs that are enabled when the supercapacitor voltage has exceeded 3.92V (enabled theshold) and not fallen below 3.60V (disable threshold)
  • 3.3V status output pin that warns the host MCU if supercapacitor voltage drops below 3.60V and 600ms before shutting down the regulated outputs.

Q&A about supercapacitors

  • AEMSUCA R3 makes your battery life longer

    Jasper Sikken12/26/2020 at 20:17 0 comments

    In revision 2 the PCBA was pre-configured to output 3.3V and 1.8V on the HV and LV outputs and these levels could not be adjusted. Now in Revision 3 you can lower the HV output to 2.5V using a solder jumper. When R4 is placed the HV output is 3.3V. When R3 is placed the HV output is 2.5V

    In my board R3 and R4 define CFG[0] is 1 or 0, see the table below (from E-peas AEM10941 datasheet)

    If your processor can run on 2.5V then you can run the supercapacitors down to 2.8V instead of 3.6V. This is a big battery lifetime  increase for your application.

  • I compared AEM10941 to BQ25570

    Jasper Sikken04/22/2020 at 13:57 1 comment

    I compared AEM10941 to BQ25570 and it shows that AEM10941 is the best for solar. 

    For thermal I would choose BQ25570 

  • Is my supercapacitor really so leaky? I have tested it.

    Jasper Sikken02/10/2019 at 15:28 0 comments

    The low leakage AVX 10F 2.7V supercapacitor that I used was specified to have 30uA max leakage current, and that worried me because low power applications can have 20uA average current. Is my supercapacitor really so leaky? 

    I have tested 3 different supercapacitors. One is from the well known brand AVX and two others are brandless supercapacitors from Aliexpress. 

    After keeping the capacitors at a charged high voltage for 24 hours I simply measured voltage decay every day with a cheap multimeter and calculated i_leak=c[F]*(u_yesterday[V]-u_today[V])/t[s]

    The tested supercapacitors

    1. AVX SCCT20B106PRB 10F 2.7V, specified to have 30uA at 72hrs
    2. Pixiuonline J469Y 1F 2.7V from Aliexpress
    3. ZHIPU CXHP series 1F 2.7V from Aliexpress, specified to have 8uA at 72hrs

    And the result is put in this chart

    Supercapacitor leakage current over days

    Supercapacitor leakage current over days
    • Interestingly the low leakage 10F AVX supercapacitor had a lower leakage than the 1F supercapacitors from aliexpress, while I expected larger leakage for larger supercapacitors. So it seems that the AVX is really low leakage.
    • the leakage after 72hrs is below 1uA for all supercapacitors which is much lower than expected (30uA for the AVX and 8uA for one of the others). Apparently the max leakage in the datasheet is much higher than actual leakage. Maybe because it is specified at the full temperature range and I tested at 25 degrees.
    • the leakage in the first 24hrs is much higher than after 72hrs but still less than 10uA for all supercapacitors

    I conclude that my tested supercapacitors have a leakage current (1uA/72hrs) much lower than many low power applications

  • I have created a video for AEMSUCA

    Jasper Sikken10/28/2018 at 14:33 0 comments

  • Batch of 50 have arrived and they work

    Jasper Sikken10/22/2018 at 20:51 0 comments

    The batch of 50 arrived. They were assembled by Elecrow and shipped in Saturday. So it took 3 days for shipping! 

  • Testrig for AEMSUCA is ready

    Jasper Sikken10/21/2018 at 12:46 0 comments

    I created a test rig for AEMSUCA because this Monday evening I expect to receive the batch of 50 from Elecrow, China.

    The way it works. The AEMSUCA is pushed between the diagonal 0.1" header pins to make electrical contact. Then 1.5V from the AA alkaline battery is applied to the solar input pins and the LEDs connected to the 3.3V and 1.8V outputs turn on when the circuit fully works. This tests all functionality of theboard except for the status output.

  • Video for the HackadayPrize final

    Jasper Sikken10/20/2018 at 14:22 0 comments

    For the HackadayPrize 2018 I designed a Tiny Solar Energy Module. It is cool because it can harvest enough energy from indoor light to power simple BLE or LoRa applications. I am selling two boards on Tinde for $24.90. One stores it's energy into a Li-ion battery, EAMLION, and the other stores it into a pair of supercapacitors, AEMSUCA. This is really cool because now you can make applications that runs forever from indoor light without a battery!

    Tiny Solar Energy Module project on

    AEMLION project on

    AEMSUCA project on

    AEMLION is sold on Tindie  for $24.90

    AEMSUCA is sold on Tndie for $24.90

  • This batteryless BLE temperature humidity sensor runs forever on indoor light

    Jasper Sikken10/17/2018 at 19:20 0 comments

    I have built an AEMSUCA (solar harvesting into supercapacitors board) and two 2.7V/10F supercapacitors into this $12 BLE temperature humidity sensor and connected a 70x70mm 4V/100mA solar panel. I modified he AAA battery compartment to fit the supercapacitors. I have removed the internal 3.3V boost converter and powered the BLE device with the AEMSUCA 3.3V output directly. Finally I placed it all on a 3D printed wall mounted back plate. 

    Some time ago I have tested the battery charge current with this 70x70mm solar panel and found 280uA at 500 lux. Since this BLE temperature humidity sensor uses ~50uA on average I believe the application can be powered from indoor light even at 150 lux for 10 hours a day. It runs uninterrupted since Sept 26th 2018. 

    On my Android phone I have installed the Mijia Temp app to collects BLE advertisement sensor data. I love the app because it works well and it does not require acces to call log contacts, camera, and files on my phone like the official Xiaomi Mijia app.

    I am going to sell the AEMSUCA on Tindie in a few weeks. Currently a batch of 50 is being produced at Elecrow in China.  

    Besides the AEMSUCA I have also created the AEMLION, it's almost the same board but it stores it's energy into a Li-Ion battery. I am selling AEMLION on Tindie

  • 50 PCB assemblies are still not assembled

    Jasper Sikken09/30/2018 at 19:19 0 comments

    On Sept 18th I haved ordered 50x PCB assemblies from Elecrow and have shipped AEM01941 ICs using DHL to the assembler Elecrow in China for assembly of 50x AEMSUCA. The parcel is still on it's way to Elecrow. DHL track and trace did not give any update after Sept 19th, so I am a bit worried. I have asked support from DHL. 

  • Three designs with the AEM10941

    Jasper Sikken09/23/2018 at 11:34 0 comments

    In May/June I have designed the 1x1 inch Tiny Solar Energy Module to take part in the HackadayPrize2018 Power Harvesting challenge and won! And then I received a lot of interested in selling it. However since most projects have different power demands and people want to choose their own solar panel, I decided to remove the onboard solar cells and make two even tinier designs derived from the TSEM. They are both 0.8x0.6 inch small. The first is the AEMLION which is charging a Li-ion battery and the second is the AEMSUCA which charges a pair of supercapacitors. 

    I will be selling the AEMLION and AEMSUCA on Tindie for $24.90. At the moment ELecrow is working on 50 assemblies of each.

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lvogt127 wrote 02/14/2023 at 19:05 point

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Jasper Sikken wrote 02/14/2023 at 20:56 point


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