Emon TH - solar charging

In my EmonTH I use rechargeable batteries - If I wanted to add a small solar panel to recharge them would it be as simple as
connecting the solar panel to the same connections as the batteries?
Would I need an additional diode to prevent the reverse charging (ie powering the solar panel.)?
Any ideas welcome!

1 Like

My dream become true if we will think about replacement of LTC3525ESC6 and XC6206P with LTC3106. Then it can be easy to do:

  1. Powering from USB
  2. Powering from solar panel
  3. Backup powering from battery
  4. Charging battery from USB
  5. Charging battery from solar panel.

See Figure 14 http://cds.linear.com/docs/en/datasheet/3106f.pdf


@glyn.hudson wdyt?

emonTH can be easily powered by a small solar panel the power requirements are very low. You will need a LiPo rechargeable battery and a solar PV charge controller. Either build you own charge controller or buy one ready built from Adafruit e.g.

However, since the emonTH V2 can last for a few years on a couple of AA’s, maybe it’s not worth the extra cost…

Hi Glyn,
I’m using rechargeable batteries - but unlike “normal” batteries they seem to run down far quicker.
I don’t really like using the battery & then bin them - hence the rechargeable ones.
Not really a cost type thing more a waste of a battery type reservation. Given the nature of the emon project
throwing away batteries; given the resources used to make them seems to go against the flow.
I like Sergii’s idea - i have no idea on the cost implications though.
I do look at the little rechargeable garden lights with their solar panel and I can’t see any complexity in them.

just mentioning garden lights use nic/cad battery they have a long charge cycle but need to be completely discharged, to maintain charge time as these battery develop a charge memory. the longest commercial cheap lithium battery would be lifepo battery fully discharge is + 2000 cycle. ( twice that of normal lion) , but if you over size the battery by 100% so it only goes down to +50% of DOD the lifecycle should be is 5000 - 7000 cycles (13- 20 years)

Hi David,

Yes, you’d better to have an additional diode to prevent the reverse charging, or you should have one solar charge controller to connect the mini solar panel.