zozidalom
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Power with solar energy

Thu Jun 02, 2016 1:39 pm

Hi!

I am only a beginner with theis Raspberry PI I have a Raspberre B model. My question is: Can I power my Rasphberr 24/7 with this solar panel and a 5000mAh power bank? http://www.ebay.com/itm/5V-800mA-4W-Sol ... SwstxVCQFA

B.Goode
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Re: Power with solar energy

Thu Jun 02, 2016 2:10 pm

Seems unlikely to me. If you can get the battery pack charged up it wiil run the RPi for no more than 5 or 6 hrs. So for the remaining 18 hrs of the day you will be dependent on the panel, whose characteristics are on the low side, to both run the RPi and have enough left over to recharge the battery for the next 6 hrs...

zozidalom
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Re: Power with solar energy

Thu Jun 02, 2016 2:13 pm

Thank you for your answer. Do you have any suggestions, with solar panel i should use?

zozidalom
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Re: Power with solar energy

Thu Jun 02, 2016 2:14 pm

B.Goode wrote:Seems unlikely to me. If you can get the battery pack charged up it wiil run the RPi for no more than 5 or 6 hrs. So for the remaining 18 hrs of the day you will be dependent on the panel, whose characteristics are on the low side, to both run the RPi and have enough left over to recharge the battery for the next 6 hrs...
Thank you for your answer. Do you have any suggestions, with solar panel i should use?

B.Goode
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Location: UK

Re: Power with solar energy

Thu Jun 02, 2016 2:34 pm

zozidalom wrote:Thank you for your answer. Do you have any suggestions, with solar panel i should use?
No.

But unless you have short nights and long reliably sunny days I suggest you factor in a battery pack with a greater run-time.

mfa298
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Re: Power with solar energy

Thu Jun 02, 2016 2:48 pm

zozidalom wrote:Thank you for your answer. Do you have any suggestions, with solar panel i should use?
First off you need to determine how much power your Pi needs to run for a day. Assuming 5V 1A (safe value for a Pi1) that's 5W and 12 hour for strong sunlight.

To run during darkness (12 hours) you'll need a 12Ah (1A * 12h) battery (assuming it's a 5V cell). If that rating is for cells running at 3.3V you'll need 18Ah (12* (5/3.3) ) of battery capacity.

To charge that during the day you'll need enough power to run the Pi totally (5W) and enough to charge the battery (if it's a 12 hour charge that'll be a bit over 5W). So you'll need a 10W panel.

This all assumes everything is 100% efficient (they're not), and you have strong sunlight for 12 hours every day (chances are you wont). So you'll need to add some buffer to those values. You'll need to adjust those values (most likely up) and then add on a generous margin to cover efficiency losses, less sunny days, etc.

zozidalom
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Re: Power with solar energy

Thu Jun 02, 2016 3:12 pm

mfa298 wrote:
zozidalom wrote:Thank you for your answer. Do you have any suggestions, with solar panel i should use?
First off you need to determine how much power your Pi needs to run for a day. Assuming 5V 1A (safe value for a Pi1) that's 5W and 12 hour for strong sunlight.

To run during darkness (12 hours) you'll need a 12Ah (1A * 12h) battery (assuming it's a 5V cell). If that rating is for cells running at 3.3V you'll need 18Ah (12* (5/3.3) ) of battery capacity.

To charge that during the day you'll need enough power to run the Pi totally (5W) and enough to charge the battery (if it's a 12 hour charge that'll be a bit over 5W). So you'll need a 10W panel.

This all assumes everything is 100% efficient (they're not), and you have strong sunlight for 12 hours every day (chances are you wont). So you'll need to add some buffer to those values. You'll need to adjust those values (most likely up) and then add on a generous margin to cover efficiency losses, less sunny days, etc.
Thank you for the answer! So I will need 1 10W panel or 2 5W panels and at least 12000mAh bettery right?

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RaTTuS
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Re: Power with solar energy

Thu Jun 02, 2016 3:14 pm

over engineer
100W panel and a battery as big as you can get
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lpsw
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Re: Power with solar energy

Thu Jun 02, 2016 4:49 pm

I have two 100W panels and two 100 AH 12V batteries (Trojan SCS150s) feeding a 5V USB power adapter, which feeds a Pi A+ with Pi camera, PIR, and DHT22, in central Maine (USA). Not a lot of sun. It holds it's own - barely.

Edit: Forgot to mention it's also powering a DS3231 RTC, and a voltage divider circuit (triggered once per hour via transistors, sampled by Python script). Battery voltage, temp, and humidity written to SD card every hour. Also, any motion detected causes 640x480 .jpg written to SD card (maybe 3-4/day).
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davidcoton
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Re: Power with solar energy

Thu Jun 02, 2016 5:48 pm

RaTTuS wrote:over engineer
100W panel and a battery as big as you can get
+1

But it all depends on where you Pi will be, and how much sunlight it gets, and how long the gaps in adequate sunlight last, and what peripherals are connected. To get a proper answer, you need to do your own calculations (roughly as above, but eliminate voltage change problems by working in Wh, not Ah).
  • Work out the Pi's power requirements, preferably by measurement.
  • Find a panel that will generate enough power on average over a low sunlight period (winter, cloudy, etc).
  • Work out your battery size to carry it through when no sunlight is available.
  • Triple the battery size and double the panel size.
  • See if you can actually get parts at an affordable price.
  • Connect it all together.
  • See if it's enough.
I would suggest looking for a 12V battery and panel system, with a suitable high-efficiency 12V to 5V converter. If not 12V, try 24V.
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lpsw
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Re: Power with solar energy

Thu Jun 02, 2016 5:50 pm

+1
on the 24V suggestion. More efficient. When my 12Vs give it up I'll be converting to 24V using 6V golf cart batteries.
Self-education is, I firmly believe, the only kind of education there is - Isaac Asimov

mfa298
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Re: Power with solar energy

Thu Jun 02, 2016 7:23 pm

+1 on 12/24V and over-engineer by a lot.
My numbers above were really bareminimum and assuming everything was perfect (they never are)

12V is probably enough for a Pi (there's enough room to fully discharge the battery with a decent SMPS module). If you wanted to run 12V gear as well I'd definitely move up to 24V with suitable SMPS (I do that for running radio gear off batteries).

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lpsw
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Re: Power with solar energy

Thu Jun 02, 2016 7:51 pm

+1 on SMPS
Self-education is, I firmly believe, the only kind of education there is - Isaac Asimov

mosespi
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Re: Power with solar energy

Thu Jun 02, 2016 8:29 pm

Here is a real world operating example...

http://www.allspectrum.com/mopower/sola ... solar.html

For disclosure, the UPS is my product. Unless you horribly over spec your solar panel or battery, which is a waste mostly, you need a supervisor circuit to properly turn off your Pi when power goes low. You can make the Pi tolerant of power cuts and possible avoid this portion, but you may still need some way to power it back up. The rest of solar Pi is fairly standard stuff.

Regards,
-Moses
Power problems? MoPower UPS for the Pi
http://www.allspectrum.com/mopower/

mfa298
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Re: Power with solar energy

Thu Jun 02, 2016 8:59 pm

zozidalom wrote:
mfa298 wrote:
zozidalom wrote:Thank you for your answer. Do you have any suggestions, with solar panel i should use?
First off you need to determine how much power your Pi needs to run for a day. Assuming 5V 1A (safe value for a Pi1) that's 5W and 12 hour for strong sunlight.

To run during darkness (12 hours) you'll need a 12Ah (1A * 12h) battery (assuming it's a 5V cell). If that rating is for cells running at 3.3V you'll need 18Ah (12* (5/3.3) ) of battery capacity.

To charge that during the day you'll need enough power to run the Pi totally (5W) and enough to charge the battery (if it's a 12 hour charge that'll be a bit over 5W). So you'll need a 10W panel.

This all assumes everything is 100% efficient (they're not), and you have strong sunlight for 12 hours every day (chances are you wont). So you'll need to add some buffer to those values. You'll need to adjust those values (most likely up) and then add on a generous margin to cover efficiency losses, less sunny days, etc.
Thank you for the answer! So I will need 1 10W panel or 2 5W panels and at least 12000mAh bettery right?
Note that I made an awful lot of (probably incorrect) assumptions there, you need to work the numbers for your environment and read all the other comments.

MarkTF
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Joined: Tue Mar 03, 2015 4:59 pm

Re: Power with solar energy

Thu Jun 02, 2016 9:24 pm

There exist any number of calculators for sizing solar power generation and storage systems. Using a good one will probably bring up some issues which you might not have considered. e.g. https://www.batterystuff.com/kb/tools/s ... lator.html

As was mentioned up thread, one needs to get a handle on the average power for the RPi and peripherals as used in their specific application. It's also worth investigating what peripherals can be powered down on the RPi if they are not being used (e.g. HDMI, USB, . . .) to minimize the size of the power system.

geoffr
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Location: Melbourne, VIC

Re: Power with solar energy

Fri Jun 03, 2016 12:31 am

zozidalom wrote:Hi!

I am only a beginner with theis Raspberry PI I have a Raspberre B model. My question is: Can I power my Rasphberr 24/7 with this solar panel and a 5000mAh power bank? http://www.ebay.com/itm/5V-800mA-4W-Sol ... SwstxVCQFA
One thing you haven't added is what the application for your Pi is. While the approach of beefing up your power supply and shutting down in an orderly manner when it is exhausted have been discussed, it may also be worth seeing what you can do to reduce your power draw.
Given that a Pi zero costs about USD 5 (if you can get one) reducing your power draw may be cheaper than increasing your power supply!

Ajex29
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Joined: Fri Mar 09, 2018 7:17 am

Re: Power with solar energy

Fri Mar 09, 2018 7:26 am

Hi, we got 1mw plant - planning to buy siemens Gateway and install & monitoring plant SCADA and Reports etc.. could anyone suggest Raspberry Pi supported for solar plant device like [ Inverte - SCB - Meters...].

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