Hi, first post on forum. I purchased the DFRobot DFR0580 Solar power manager with the view of using it as a 5V supply for a Raspberry Pi 3B with a camera attached.
I am using the above with a 20W solar panel (18V) and a 12 4.5A SLA battery.
What started out as a reasonable project as far as getting power to the Pi and wifi access has become a bit problematic.
I had connected the DFR0580 with default settings as delivered.The Pi has 5V and was working happily and my little Motioneyeos camera was purring away during the day.Initially I would pack up the project as I didn’t have a weatherproof case. Once I had the case ,I left it outside and I would see in the morning if there was any motion detected.There was activity until just before midnight,then in the morning I opened the case and there was no power to the Pi. When I unplugged the Pi power lead and reconnected ,it restarted and worked again until around midnight. I started by disconnecting the Pi fan but didn’t notice a great deal of difference,maybe another hour of working.Next I tried the MPPT switch on and I couldn’t see much difference only with the charging time .Lastly I turned the other USB power and the 5V and 12V medium power off and got it working until around 4AM based on last event detected. Once again I unplug the Pi and reconnect the DFR0580 and it comes back to life.
Am I doing something wrong and is this module just not suitable for this particular Pi application.
Thanks in advance everyone.
Hi Andrew,
Welcome to the forum 
It’s not immediately obvious what is causing the Pi to shut down during the night as the issue may be a spike in demand that isn’t being met causing it to shut down, or it might simply be going flat in the middle of the night then recharging somewhat before you check it in the morning.
Do you have a back of the napkin figure as to how much current you think your Pi 3 and camera are using both at peak demand, and as a continuous average load?
The official Pi 3 power supply is rated at 12.5W so if we assume your 20W panel is getting full power for 8 hours each day (it won’t) then your panel supplies 160Wh but your power supply consumes 300Wh. This is a massive approximation but it does seem like simply running out of charge is the most likely scenario until we can confirm some more details about your power draw.
Hi Spookee,
Thanks for replying. Off to a bad start today. I disconnected the Pi and brought in inside the house to have a look a couple of things.Looks like the camera is dead so Pi not booting up. I will have a look tomorrow.
I might look at a bigger battery and see how long the Pi lasts and get back to you.
In the meantime,are there many Pi users with solar powered projects here?
Hi Andrew
Have you done that yet ?? That is the starting point. That will give you the figure you will use over 24hr. That won’t change so then you have to supply that, remembering you will only have effective sun for about 6hr max.
For instance suppose your set up uses 10W, that is 240W over 24hr. Your solar charging system has to provide this 240W in 6hr plus a correction for charging efficiency (probably about 85%. That equates to 80W divided by 85 multiplied by 100 = 94W. That is assuming full sun for the full 6hr.
These numbers are only arbitrary but outline the general calculations you need for your system. If they are anywhere near close your charging system is severely undercooked. You need to allow a bit of head room as well to allow for days that are not optimum.
THERE ARE NO SHORTCUTS FOR THIS. The amount of Watts has to add up or you will be sliding backwards. By the way your battery has to have enough grunt to run the system for probably up to 18hr with no or little sun.
Cheers Bob
Hi Bob,
I agree with your math here but I think some of your numbers may have the wrong units. Some of your Watts are actually Watt-hours, possibly this was caused by an autocorrect gone rogue.
For anyone who is confused, Watts are a measure of power that are being drawn continuously at a given point in time. Watt-hours are a measure of total energy capacity, how long the capacity lasts depends on the power being drawn from it.
The video I’ve linked below is brief and covers it well.
Hi Trent
OK. If the system requires 10W then that is10W if used for 1 hour = 10Whr. That to me is a total of 240W in 24 hr. This has to be replenished in say 6hr of useable sunlight (unless you track the sun). Once again to me that equates to 80W for 6hr for a total of 240W plus an allowance for efficiencies as mentioned.
You could put the suffix “hr” to the “240W” and still get the same result, that is 10W for 24hr = 240Whr.
So if the system in question is using anything like 10W the charging is not nearly enough. Even 5W which is only 1A @ 5V would be 120/6 = 20. Then (20/85) * 100 = 23.5. Pretty much border line for the 20W panel. All this for 1A @ 5V.
The only solution then I think is to ascertain just what the load is and then double the minimum requirement. If it was me in the above 1A @ 5V example I would go for a 40W panel as a minimum, but I do tend to leave some head room.
Then there is the battery size. The Amphr size would have to be something like 20 times the current requirement. Convert to watts to do this calculation.
Cheers Bob
PS: By the way. The auto correct here drives me nuts sometimes. It thinks it knows more about what I want to say than I do. Sometimes puts in the wrong word completely and with my kind of keyboard expertise I can’t watch the screen and keyboard at the same time so a lengthy read is called for prior to posting.
It’s been a few months since I posted. I managed to get a Pi Zero 2 W kit and use the existing solar panel,battery and manager. I’m pleased to say it all works now.Much lower power consumption.Very happy with the outcome.Thanks everyone for your replies.
