New challenge for you: Power for remote observation post

Steven Lake

Ok, I've got a new one to toss your way. So far my other projects are either done already, or close to done (Thanks everyone for the help so far! This is fun!), so I'm pretty much settled with all my things. But since discovering solar, I'm finding that it has a lot more applications than I realized. So anywho, here's my my new dilemma. A friend of mine runs a remote weather station that sits in the middle of nowhere and collects data. It's part of a project he's running for a small local college.

Anywho, each unit is powered by a single 12v-9ah AGM battery about the size of a motorcycle battery, but with the blade connectors similar to what you'd find in a UPS. Each week he goes up and swaps out SD cards in each of the units with new ones, and at the same time pulls the current battery and replaces it with a fresh one. He then takes the nearly dead one (I think it's down to like a couple amp hours remaining when he pulls it) and replaces it with a freshly charged battery which he takes back to the lab and recharges.

Now, my question is this. The batteries, according to the label, have a 14v-2amp charging limit, and can be fully recharged in 5-6 hours on average. My thought is this. Instead of him having to swap them every single time he goes up there, and fully deep cycling the batteries multiple times as well, I was figuring that I could recommend a solar power solution instead that would keep the batteries charged, and only require him to replace the batteries when they die (a cheaper solution overall).

So, I did a little math and figured out that I'd need a 40watt solar panel for each site, and a tiny little 12amp 12v charge controller for each site. So essentially about $350 in parts. I'm considering recommending the Kyocera KC40T 43 Watt Solar Panel and the Xantrex 12 Amp, 12 Volt Charge Controller for his setup. Now, the advantage here, at least in my thinking, is that if he has this system, he only needs to drive up to each site once a month (he only changes the sd cards each time he goes up because he's already there, so he may as well), thus saving gas.

So, what do you guys think of this setup? Sorry for asking about so many setups, but I'm finally starting to really get whole hog into the solar arena, but I'm still new in my understanding of all these setups, so I want to be sure I get this right the first time, because mistakes can be costly.

Cariboocoot

Re: New challenge for you: Power for remote observation post

I think we've done this before. For a fellow in Ireland. Remote wildlife observatory; no generators.

Steven Lake wrote: »

So, I did a little math and figured out that I'd need a 40watt solar panel for each site, and a tiny little 12amp 12v charge controller for each site. So essentially about $350 in parts. I'm considering recommending the Kyocera KC40T 43 Watt Solar Panel and the Xantrex 12 Amp, 12 Volt Charge Controller for his setup. Now, the advantage here, at least in my thinking, is that if he has this system, he only needs to drive up to each site once a month (he only changes the sd cards each time he goes up because he's already there, so he may as well), thus saving gas.

Maintaining a battery in a charged state is generally preferable to cycling it, especially if it is going to be left "uncharged" for any length of time.

For that 9 Amp hour battery, 40 watts might actually be bigger than necessary as it can take "up to" 2 Amps (which is no doubt what you calculated from). You probably don't need any more charge controller than this: http://www.solar-electric.com/sg-4.html And possibly something this size for a panel: http://www.solar-electric.com/spm030p.html

Steven Lake

Re: New challenge for you: Power for remote observation post

*bows* Much appreciated, good sir!

BB.

Re: New challenge for you: Power for remote observation post

Pretty much got it...

Peak current from a 40 watt panel may be kind of high though... (2amp*12 volts = 24 watts).

Also, say it uses 7 AH @ 12 volts every week... And you want to run deep into winter with 1 hour of sun per day:

• 14.0 volts * 7 AH per week * 1wk/7days * 1/1 hour of sun * 1/0.90 battery eff * 1/0.77 efficiency = 20.2 watts of solar panels

You can probably get away with 1/2 the solar array... And a smaller charge controller (~2-4 amps).

Get 2x10 watt panels and only put on the second 10 watt panel in winter (less to loose out in the field to damage--could also start now with good weather and see how the plan works out).

And your friend may need to monitor the weather and service the sites after 1 week of bad weather.

Another question is can he leave the sites for 4 weeks at a time (i.e., lost weather date if site gives out at the beginning of the month or vandalism)?

Lastly, I have looked a bit for a "cheap version" of a Battery Monitor that could be installed at each site (quick glance to see if battery was charged or not) and could not quickly find one... One of these would be fine for DC Amp*Hour/Watt*Hour bench top use (but they only run "one direction"--I wonder if the maker would be willing to update firmware for totalizing both + and - current flow?).

Options would include placing a battery monitor only on a weather station at the office and monitoring it (for weather / power collection)--Or logging voltage dips below ~12.0 or 11.5 volts to indicate when a weather station is having electrical power issues (in data card or other indicator).

-Bill

Cariboocoot

Re: New challenge for you: Power for remote observation post

Steven Lake wrote: »

*bows* Much appreciated, good sir!

Well don't take my word for it. There's still the issues of how much insolation the panel will get, and how much power will be drawn from the battery. I'm just thinking it could be "dialed down" a bit - which will save the ever-so-rare $.

niel

Re: New challenge for you: Power for remote observation post

a small maintenance pv couldn't hurt and it could be smaller than the guys state, but he has to go there periodically anyway so why go through the expense of placing solar there?

mike95490

Re: New challenge for you: Power for remote observation post

He will also need a mount for the PV, weather case for the charge controller, and a self-defense system. Skynet is supposed to come on-line tonight, maybe that will be a good one.

mike95490

Re: New challenge for you: Power for remote observation post

Cariboocoot wrote: »

You probably don't need any more charge controller than this: http://www.solar-electric.com/sg-4.html

I don't know if the Sungard is adaptable for AGM/Gel/flooded batteries. Overcharge can destroy as fast as deep deep cycles

Steven Lake

Re: New challenge for you: Power for remote observation post

mike90045: Yeah, the batteries are AGM, so I'm hoping this charge controller does the job handling the charging of them.

niel: Good point. Right now he has to go weekly to change the battery on the unit. So while he's there he swaps out the SD cards since he's already there. The unit itself doesn't fill the card in that time. In fact, it barely fills 1/4 of the card. So my idea is designed to save him some gas by limiting the number of trips he has to make up there to the units.

Part of my inspiration comes from the fact that there are twelve monitoring stations (well, 12 that I *know* of) within a 4 square mile area. The kicker is that they're ~35 miles outside of town in the middle of nowhere. The units themselves are setup in such a way as to create a type of redundancy in his data gathering. He's actually studying micro-climates, so all the nodes are laid out in a grid pattern at quarter mile increments to collect data over an area.

This way he gets maximum info gathering while allowing for the loss of units without adversely affecting his data. In fact, according to what he's told me, he could lose up to 75% of his stations and would still be able to collect usable data. It wouldn't be quite as detailed, but it'd still be usable. So loss of one or two units isn't going to be earth shattering. But maintaining them has proven a bit costly, given the drive and gas involved. Hence my idea of the single PV investment to reduce maintenance visits.

Now if you figure that he's got about a 75 mile round trip (35x2 + 5miles on site) to do each week, plus wear and tear and whatnot, it adds up quickly. But with the system suggested above, the entire upgrade could pay for itself in 3 years, leaving him sitting pretty for the remaining 7 of the project. Or at least that's what I'm shooting for in order to help him make his grant money stretch.