I’ve been working on some solar powered sensor installations which include the purple air along with some other sensors running off of a raspberry pi. My guess is that a 20 watt solar panel and 20 amp hour battery and solar controller should be sufficient to run the purple air unit by itself continuously(assuming decent sunlight), but need to test out. This bookmark details some basic parts used to setup the solar mount, battery(a smaller 10 watt and 10 amp hour setup, would need a larger enclosure for larger 20 amp hour battery), controller and enclosure and can provide more details if needed.
I have 2 solar powered PM sensors that I have operated for a year without an issues. I put the solar controller in a plastic lunch box and put is some moisture absorbing material to make sure it was always dry
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Nice and thanks for the pic! What are the specs on the solar panel wattage and rechargeable battery size and type per unit? Looks like a 4x4 inch post, what’s the mount from the post to the solar panel like? Thanks
The battery I am using is if a 12 V, 7.5AH battery, I have never had the problem of it running out ( but then I leave in Louisiana and its sunny most of the time) the solar panel is a 30W and the connection to the 4x4 pole is as in the attachment. I just got it on amazon. so far it is working well.
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Interesting setup. I would like to do something like this but I live in the Chicago area so probably less sun especially in the winter. Do you have any idea how it would work in the winter?
From what I read online, solar works at 10 to 25% on cloudy as compared to sunny days, so depending on the larger average number of consecutive cloudy days you would need to size up the solar panel to collect equally more and/or the rechargeable battery to buffer more collected energy. I think the purple air consumes on average about 1 watt(more power consumption details watt https://community.purpleair.com/t/q-how-much-power-does-a-purpleair-sensor-draw-and-how-much-bandwidth-data-does-it-use/847 ) Bigger panels provide faster charging and the possibility to ‘power through’ longer consecutive cloudy days or less drain on the battery, while a bigger battery can provide an energy buffer/time to draw from, but will eventually power off if not enough average energy coming in to recharge. There are national maps for ‘home’ solar power considerations https://www.nrel.gov/gis/solar-resource-maps.html and data by location for average number of cloudy days, but haven’t found much with ‘consecutive cloudy days’ which is the dependent factor the energy sizing is designed around, so end up experimenting to see what works most of the time.
If wanted to power through less frequent or rare consecutive cloud cover events of several weeks, then I might guess a 80 to 100 watt solar panel(at 25% giving the equivalent of a 20 watt panel) with 20 ampHour battery might work, but just a guess.
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also, 100 watt solar panels can get up to 6 amps in current output, the solar charge controller I reference in my documents I think is rated to 10 amps and can manage this amperage between the 12 volt battery and load, but keep the maximum power equipment limits in mind if upsizing the panels.
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I have never used a solar panel on a small device before and have limited knowledge. But I am hoping one of you can provide a detailed description of the items purchased and detailed description of how you have connected them to the PurpleAir. Consider this a description for a dummy.
The need for connected power and the 100 foot wireless range are limitations. The wireless range I can fix with an outdoor access point.
Thanks
Steven
Hey Steven,
I recently put together the below document, trying to break down the parts that I’ve found useful, the main components are the solar charge controller, the solar panel, the battery and the load(the purple air monitor) and wiring things together. The solar charge controller specified I prefer due to its readouts for the battery voltage and solar and load currents so you get an idea of how your system is holding up and its 2 5volt USB ports so you can plug the referenced USB to microUSB cable into the purple air(or other similar 1 watt type device).
If you have further questions, let me know and I can try to reference some more details in the document so its generally useful to others.
Thanks