Trying to figure out how to solar power an embedded device

I have an Arndale octa board which itself needs 5V 3A power supply. Then I have four (4x) DC 5V motors and a 5V servo, and a number of other peripheals. So I think 5V 5A is safe to assume?

I want to power all of this with Solar, which if there’s not enough light I will switch to a backup battery (that the solar also charges, during idle time)

I tried doing some research but I’m just so confused. I know I will need like 12 or 24V rechargable battery and a buck regulator, perhaps a board that regulates between solar/battery and such, and solar panels. But I am really in over my head trying to figure out the pieces. Can someone please help point me to some good products on the site to do what I want?

I would power the devices from the batteries at all times, that way the solar charger will feed in to them when there is sunlight and you wont have to rapidly switch between solar and battery for things like clouds.

Sounds like you are using lead acid batteries so there are many self contained solar charging devices to keep cars from dieing while sitting for long periods. They have charge regulators built in so it keeps things simple.

All that being said 25 watts is a LOT for a self contained system running continuously for very long.


3A is maximum nominal current for board; you need to know average current for your use (include servos and so on).
Let’s suppose it’s 2A, so you need 2 Ah @5Volt.
Using battery (solar powered) you need to use 12V or 24V (more probably 12 V). Then you need to know efficiency of PSU at your average output curent.
Using 90% efficiency PSU (5Vout@2A), you need 920mA@12V.
Keep in mind nominal capacity of battery is half of real capacity, connected to solar controller (for extending battery lifetime), so you need 48Ah battery capacity for every day of autonomy.
Then (depending on weather) select panel power to charge battery with current depending on hours of sun every day.

Solar panels charge need the following equipments:

1, solar panels, responsible for photoelectric conversion;

2, LCD controller, timely transformation of current output and input, effectively protect the battery overcharge discharge;

3, inverter, dc and the mains switch, load electrical equipment;

4, storage battery, responsible for energy storage.

let me share the Current voltage conversion formula:

Current I and voltage V, R, W, power frequency F

W = W = I squared R V = IR V squared voltage divided by resistance power voltage/current = R = * current * time

it is only for your reference.

in general, the voltage= resistance / current.
In this range is acceptable

hope it will be useful for you.

Dearest,Have you found the best solution for no answer with long time?

as you know, our company often need to buy from abroad, maybe it can also be useful for you if you needed to buy some electronics components from oversea.

Have you find the optimal solution for this problem before, You can refer to the calculation method of current resistance just like i told you in previous answer.

By the way, is recommended for you if you need to buyer some electronics component, we often use it for purchasing with our company.