I am creating a weather station with the following sensors: DHT22, BMP280, LM393 Rainfall sensor, Adafruit Anemometer and Wind Direction sensor (Did not choose one as yet). Also, a RYLR998 LoRa module is connected to transmit the data. An Arduino Uno is used. This Arduino Uno must be powered remotely. I need help designing the power source for continuous use. I am thinking to use solar panels to recharge the battery. It is a school project and I need it to be cost effective. The daily power consumption should be (0.53 W×24 hours=12.72 Wh/day). Thanks for the help guys.
- Sounds like you have done some work.
What is your question ?
Need help picking the batteries, solar panels and the charge controller.
The most important step is to put the system together, get it working to your liking, and measure the average current draw during typical use conditions over at least a 24 hour period.
That will be your "energy budget".
The battery is then chosen with sufficient capacity to meet or exceed that average current draw, for the longest period you want the system to run during bad weather. Solar panel output is chosen to recharge the battery, given typical weather conditions at your location and time of year.
Hint: battery capacity is typically measured in mAh (milliAmpere hours), and when divided by the average current draw in mA, gives an estimate of battery lifetime in hours.
Let's see a list of which ones you've considered. Please include links to each.
thank you for the help
can this be used?
That is a good fit for a pair of Lithium 18650's. As far as panels and charger, just google. Just remember, if you have a cloudy day and you didn't double the battery pack they will die, similarly for two cloudy or rainy days. The rule of thumb is to expect 3 days of no sun so you will need 8 batteries total, a BMS and balanced charger otherwise high risk of fire. As to how many solar panels, you need to have enough to fill those batteries in one 4 hour day.
I highly doubt that panel will refill the battery in 4 hrs.
Noted, your help is greatly appreciated.
This one is good
You will need at least 2 of those.
That's true. An overcapacity for the cloudy days, and winter.
Thank you for the assistance.
A couple of panels will benefit your installation since you can have them pointing in different directions, to get more direct sunlight. The optimal is to follow the sun, but that's a lot more complicated, at least at this stage.
@ledsyn Here is a website to help you do the calculations for solar panels. You set Alt and Lat plus angle of panel. Since it's for a garden, just use the worst case during the growing season. Also multiply by 3 or 4 to withstand non sunny days. REMEMBER you can't connect Lithium in parallel without a BMS otherwise you risk fire and explosion.
https://pvwatts.nrel.gov/pvwatts.php
Remember to use a power latch circuit to turn off the Arduino at some fixed time of day then use a RTC to wake it back up in the morning. You can try deep sleep, but total power off is the most savings.
NOTE the popular ZS-042 is NOT a good RTC, in fact it is so flawed you have to cut traces. Get a Chronodot or make your own from a bare DS3231.
Thank you for the help. It is greatly appreciated.
Here are a couple links to power latching circuits. To use the REAL RTC to power on, siply connect the INT pin of the DS3231 where the switch is. Don't forget pull ups/downs. You will need to do a lot of reading.
https://randomnerdtutorials.com/latching-power-switch-circuit-auto-power-off-circuit-esp32-esp8266-arduino/
OR
https://randomnerdtutorials.com/power-saving-latching-circuit/