Sunflower: Solar Power Manager 5V (DFR0559)

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DFRobot is launching a brand new series - Sunflower, focusing on high-efficiency, small power solar energy management for IoT projects and renewable energy applications. … read more

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Do you sell a compatible solar panel for this? All the panels I can find online (5V 10W) already have regulated outputs.

Here’s one, but it looks like Core and Sparkfun are out of stock:

Else here’s some from trusty old ebay:

Hey there, what’s the highest capacity battery I can use with this product? Sunflower: Solar Power Manager 5V | DFRobot DFR0559 | Core Electronics Australia

That depends on the solar panel capacity and how much current you want from the battery.
Theoretically you could connect any capacity, it would just take a long time to charge a high capacity battery (days). Solar panel output can vary greatly during the sunlight hours.

The panels listed by @Oliver33 range from 5.5W to 10W.
(this is under absolute ideal conditions in a lab)

A 20W panel I have is good for around 100 to 200mA charge over a number of daylight hours on a sunny day. It has been tested to output 1.3A under ideal conditions. The panel has fully charged a 400mAH LiPo in a day, larger capacities will take a few days to reach full charge.

So answer: depends on what you want to use it for.

Hello! I have some questions regarding the sunflower solar power manager 5v, Polymer Lithium Ion Battery (LiPo) 3.7V 2000mAh, and the 1 Watt solar panel (Seeed Studio):

  1. I intend to power an Arduino Uno R3 with these three products, is this an appropriate combination?
  2. Is there a port for both the solar panel and the battery with their existing wires on the solar manager?
  3. Is there a pathway for the battery to power the load in the solar manager when the solar panel is not outputting any current?
  4. Would you recommend the LiPo safety bag? If so, would I be able to charge the battery with the solar panel while it is in the bag?

Thank you so much!

I have bought the unit, DFR0559, Solar Power Manager 5v.
I have also bought solar panel Monocrystalline Solar Panel (5V 1A) | DFRobot FIT0601 | Core Electronics Australia
and the panel has USB out.
Can I plug the USB out of the panel directly in the USB in of the DFR0559?


The manufacturer did not intend a Solar Panel to be connected to the USB-IN.
It is for connection of a stable 5V USB supply (or 5.2V).

From the web page, schematic and datasheet.
The Solar Panel has an open circuit voltage of 7.2V.
The LiPo charger on the Sunflower, CN3065, has a VIN specification of 4.4 to 6V.
The voltage from the USB-IN connector passes through a schottky diode, dropping maybe 0.25V.

In reality the Solar Panel will never put out 7.2V when connected to something.
I have these devices and will post again after testing tomorrow when there is full sunlight.

The conclusion is maybe it will be ok but it is not what the manufacturer intended.


Testing today, would have liked bright sunlight, overcast here today.
The USB voltage remained at 5.2V dropping only when there was insufficient light on the panel.
It never went above 5.2V.

The label on the back of the solar panel is confusing and has nothing about the USB output.
I suspect it relates only to the panel.

From this test I would say connection of the solar panel USB to the USB-IN of the Sunflower would work ok, the voltage is within the range the CN3065 allows.


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Thanks Jim,
I’ve tried it and it worked well! Even in partial sun. It did take about two days to charge a new 2600mA cell though.

Great to hear.
Tested mine in bright sunlight, USB from Solar Panel is constant at 5.2V.
It quickly charged a 120mAh LiPo.

Just a word of caution, LiPo’s and other Lithium batteries do not like direct sunlight.
If the battery temperature exceeds 50 degrees C they can explode.
Ensure the battery is well ventilated and out of direct sun.

Not surprising it took a couple of days to charge a 2600mAh.
The CN3065 charge chip can provide up to 1000mA but the limit is the panel and how much sunlight is available.

In my opinion the panel would work well attached to the top of a back pack connected to a phone inside the back pack; in a hiking situation.


Hi there, I have a question about the USB IN connector. If I plug a constant 5V source into it or if I plug my solar panel (Monocrystalline solar panel has a USB out) into it, the connected devices will operate fine but the charging LED always shows DONE, never CHG. In addition, the connected batteries never seem to charge if the power source comes from USB IN.

Is it correct to say then that to charge the batteries (connected to BAT IN) the power source must come from the SOLAR IN connection?

If that is correct, I will need to cut the end off the USB cable coming from the solar panel and wire it to SOLAR IN. How would I know which two wires to connect to SOLAR IN?

Sorry if the questions are a bit newb :slight_smile:

Many thanks


Hi John
Red +, Black -.
Cheers bob

Thanks Bob :slight_smile:

No. The schematic shows VUSB can be used to charge the battery.
The charge chip CN3065 works with a VIN of 4.4V to 6V.
VUSB is connected through a diode to the CN3065 so VIN will be slightly less than VUSB.

The charging depends on the current drain of whatever is connected. If it is too high the LiPo will not charge as the step up voltage regulator will take all the current. Also VUSB and VSolar must be higher than 4.4V for the charging to work.

In my opinion the CN3065 is not designed to be used the way it is in the Sunflower. I have used the solar panel you linked to successfully to charge a LiPo but very slowly with nothing connected to the USB output. All the testing I did with the Sunflower confirmed it works well to charge a LiPo as long as that is all it is doing via USB or Solar panel input.

Suggest you try without anything connected, if it still does not charge via VUSB then there is something else wrong. The schematic aboves shows there is not much difference between VUSB and VSolar, they both should work.

Hi James
Re that input circuit. with USB connected the gate of M1 will be higher that the source by only the voltage drop across D1 so M1 will be off thus isolating the solar panelled battery will charge vis USB. When USB removed the gate will be grounded via R2 and M1 will be on and solar will be restored as charging source. The charging source can only be solar or USB, never both.
Cheers Bob

If I understand what @John81612 is saying.
With just the USB socket connected the battery is not charging and in my opinion and experience it should. The Solar panel I think @John81612 has is the same as I have. It has a built in 5VDC regulator output via a USB socket. I assume only this is plugged into the USB socket of the Sunflower. I could be wrong.


Thank you both this is very helpful. It is clear now that it should charge from either USB or Solar, and knowing that I will do some additional testing. Just to note, my assumption that it is not charging is purely based on the CHG LED not being lit.

If it ends up being that the load is too high (should not be) I’ll have to come up with a different strategy for charging, perhaps cycling my connected devices off entirely from time-to-time. As suggested, I’ll try with no load at all and confirm.


When testing this stuff. I built a resistive load to drain the LiPo and monitored the voltage. When it got to around 3.7V or so I then connected it to the Sunflower and monitored the voltage as it charged. Note 3.7V is not fully discharged and LiPo’s should never be completely drained as it will shorten their life. (same goes for mobile phones, charge when below 30% to something over 80%).

I had a 6V solar panel and when it and a USB source were connected the USB was ignored.

Suggest connecting just the solar panel to the USB (as the panel is designed for that) and monitoring the battery voltage. If it is around 4.2V it will no longer be charged. The done light should be on.
Also monitor the voltage from the solar panel, without good direct sunlight its output can fall off drastically. It should be around 5V due to the built in voltage regulator, think I measured 5.02V at the best output.

cheers, all the best

Hello All,
Came across this topic of discussion re: DFRobot 5V power manager.

I currently using this board in my backyard project. Using a 6V 240mA solar panel and charge a 3.7v Lipo with it. The USB out is connected to a UNO with DHT and DS18 sensors and send data to IFTTT via TEL0126 every hour.

It was working fine initially (lipo was 4.1v). The lipo was able to survive 12 hrs first use without the solar charging during testing phase (for the sensors and IFTTT). Once I connected the solar panel, things got a bit weird. The lipo initially was around 3.5v, worked for a few hours (2-3 hrs) and dropped dead. Lipo voltage became 2.8v-2.9v.

Any ideas/suggestions? Thanks.