Solar panels for powering an extended time-lapse photo shoot

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wonderspark

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Wannabe Geek

#100420 11-Apr-2012 12:36

Hello, all! This looks like an awesome forum full of smart people.

I'm doing a three-plus month time-lapse of a building being constructed in hot, sunny Texas. There is a company called Harbortronics just up the road from me in Colorado that sells a kit for just such a purpose, but it comes with a small 5 watt solar panel. The kit includes the camera, camera housing, intervalometer, solar panel, battery, charger, converter and pretty much everything needed to set up and go. They also customize the kit if needed.

In my research, I've discovered that some have had issues with getting enough power from that small solar panel to keep the battery charged enough to last for months at a time, so I was considering adding a second solar panel in parallel that is 100 watts, and much larger. I could probably get these guys to implement the second panel, but I thought I'd see if anyone here had tips or advice from experience in such projects.

My idea is to use the standard 5W panel as built with the kit, facing east at 45 degrees tilted to capture morning sunshine, and install the second 100W panel tilted facing west to capture the afternoon sun. The 45 degree tilts would be to minimize the risk of hail damage, and to gather sunshine longer in the day on both ends. The reason for the larger panel facing west would be to charge the battery more after the camera has been running all morning, thus being drained further, so that it hopefully gets fully charged by sunset, ready to go the next morning.

I'm curious about any issues with overcharging, or anything else I haven't thought of, as I've never built or modified any sort of kit like this before. The shoot is scheduled to start around mid to late May, so I have a bit of time to buy, build and test before heading down to Texas for the job.

Any tips, advice or other help would be greatly appreciated! Thank you all in advance.

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#607800 11-Apr-2012 12:55

Why would the company sell a kit that isn't capable of doing the job it's designed for? Texas as a reputation as being a pretty sunny place, doesn't it? How many photos will you be taking a day? Does it have a rechargeable battery built in?

Cameras really don't use much power. I photograph weddings with Nikon cameras, two LiIon cells will take around 6000 photos before they need charging.

You might be better off just charging the battery at night occasionally. Alternately have two batteries built in, occasionally charge one so the other keeps powering everything while it's off being charged.

Bee

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#607803 11-Apr-2012 13:00

interesting...
Maybe the problem is the camera and camera battery that they are using? Can you change either one of those in this kit?

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wonderspark

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Wannabe Geek

#607805 11-Apr-2012 13:01

Well, the kit is designed to work well within 100 shots per day, and up to about 500 in good sun they say... if the shots are just quick exposures. In such a case, the system will last months. However, I plan to shoot over 1000 shots per day, and expose longer than just say 1/125 second by using a neutral density filter and closing down the aperture as much as possible. I'm looking at probably up to ten second exposures every 30 seconds, which drains the battery much more.

Someone who bought the kit was shooting 30 second exposures every fifteen minutes for 13 hours a day, and said the battery was drained (solar panel unable to keep up the recharge) after only a few days. This has to last over three months, and I can only gain access to the roof weekly, but would like to only go up to dump the SD card and check on it every two weeks.

timmmay

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#607812 11-Apr-2012 13:15

Why do you need so many photos, what will you use them for? They're all going to be be near identical. It sounds like it's a bit of solution looking for a problem.

I'd probably just connect it to a huge sealed lead acid battery, or similar, and charge it every two weeks. If you're shooting that much you may need to change the card more often too.

wonderspark

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#607820 11-Apr-2012 13:36

The final product is a video, so smooth action is key.

I did an identical building project for them last year, and the problem is that it's not a normal building. It's a mobile data center that takes weeks to prep, and then suddenly it flies together very quickly with cranes and such. For the earlier prep periods, I can get away with fewer images, but when they bring in the trucks and cranes, the whole thing is assembled in a matter of hours, and that's the part they like the best. The action was pretty fluid and appropriate at 36 seconds per image last year, but looked better at one every 12 seconds when the action kicked up during assembly. I figure this year, I'll compensate by running longer exposures every 30 seconds instead of 1/125 second exposures every 36 seconds like before. The blurring should look pretty nice... better than a quick snap every 12 seconds.

The catch is that they have almost no advanced warning when the parts are going together, since they come from another site across town, and I live in another state. I won't be able to fly to Texas and change the image rate in time ahead of when the action gets going, so it has to be always going full speed when the parts are close to being ready to assemble. If it was just a standard building, I would be able to take a shot every so many minutes and it would look great, but this job is somewhat unique, both in my distance from the site and the sudden unannounced change in pace that occurs.

I have some 128GB SDXC cards that should handle the images just fine for two weeks at a time before dumping and formatting the cards.

timmmay

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#607835 11-Apr-2012 13:55

I'd be careful with long exposures, that's definitely something I'd want to test pretty thoroughly before I bet the house on it. You might end up with a huge blurry mess if it doesn't work quite right. Even 1 second exposures are long, 1/125th or that region would be safer.

An extra solar panel is probably practical, given there's not really any other power source available, other than a large regular battery.

nate

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#607896 11-Apr-2012 15:15

What about using some alternate hardware like this?

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wonderspark

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Wannabe Geek

#608411 12-Apr-2012 18:46

Here's an example of what the last project looked like: Dell / Bing Maps time-lapse
That was done with an image every 36 seconds, except the day when the crane was in use, where I bumped up to an image every 12 seconds. That was something like 70,000 images. When the angles change, it's real-time video from GoPro cameras that is sped up. They really like the cloud smoothness and all that, which you won't get with an image every 10-15 minutes. I want to keep the action smooth, while being able to leave the camera unattended for two weeks at a time, or at least one week. I'm hoping I can pull it off with a second 100W solar panel, shots every 30 seconds and 128GB SDXC cards.

timmmay

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#608454 12-Apr-2012 20:29

That's pretty cool :)

Zeon

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#621272 7-May-2012 21:18

To be honest just get a bunch of lead acid batteries and hook them up. Even one should easily last 2 weeks. No worries with adding something in parallel as long as its the same voltage and the system can handle the extra current.

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wonderspark

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Wannabe Geek

#649549 2-Jul-2012 13:23

Thought I'd follow up on this.

I spoke at length with the engineer of the kit. At first, he said the 100W panel would be fine, but after more discussion, we came to decide it might actually supply too much power to the batteries, and settled on a 20W solar panel in place of the 5W solar panel, and a dual battery pack instead of a single battery for the solar panel to charge, giving a deeper "bucket" of power for the system to use. When the battery voltage reaches 10.1V, it switches to solar charging, and when it hits 11.1V, it switches off... at least I think those are the voltage points it switches at. Anyway, it's been running now for a couple months, taking one shot per minute, 930 shots a day every day from 6am to 9:30pm, and storing the images on the 128GB SDXC cards.

During testing, the camera (a Canon T3) would occasionally lock up, and stop shooting partially through the day. The solution was to set the external intervalometer to cycle the power off and on after each shot, which clears the lockup. I've noticed that sometimes the camera still misses a shot here and there. The longest gap I've found was six minutes between shots. It's puzzling, but I blame the Canon T3, and the company that sells the kit has offered to replace the camera, hoping it will resolve the issue completely. I've been a Nikon guy since 1994, and my two D7000 cameras have shot right around 100,000 shots without ever locking up when shooting time-lapse sequences using the built-in intervalometer. Maybe it's just a bad unit, or firmware... not sure.

Anyway, one thing that seems to be doing very well is the solar charging system. I measured 19.1VDC coming off the solar panel during overcast skies. For curiosity's sake, I measured indoors with ambient light in the room from the windows (indirect sunlight) and got something like 2.4 volts. I forgot to measure it in direct sunlight, though. I'll have to do that on my next trip down to Austin every two weeks. It's been taking shots through the rain and sun, so I'm pretty happy with it.

Short version: It's working almost perfectly... good enough at least!

timmmay

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#649552 2-Jul-2012 13:28

Good to hear, thanks for the follow up :)

Jaxson

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#649566 2-Jul-2012 13:53

I would have thought that with some of those shots (hanging off cranes etc where the actions not very long anyway) that you could have gotten away with shooting straight video and speeding it up?

Looks very cool, good presentation and choice of viewing angles too. Well done.

wonderspark

10 posts

Wannabe Geek

#649580 2-Jul-2012 14:07

Thanks guys.

The problem with these projects is that I get little to no advance notice of when they do major work. The current project has so far only had a fence erected and the pavement ripped up and that's it, for example. I have to shoot a lot since it's 1000 miles away and they don't give me enough advanced warning.

dontpanic42

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#650694 4-Jul-2012 15:29

I just spotted this time-lapse kit. Thought it might be of some interest to the OP.
http://www.tindie.com/GeoNomad/gopro-time-lapse-and-control-board/

Just an FYI. :)

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