Solar requirements for a single PTZ camera

[advarp 0]

Hi there,

 

I would need to design a solar system for one PTZ camera and *perhaps* a Nanostation. (Perhaps, because I *seem* (there was no rain) to have signal to the camera from the original Nanostation AP without the need for another Nanostation near it.)

 

The PTZ camera is a small, no fuss (ie cheap) Dericam model (see EBay). This is not a high security application but rather the ability for me to see what goes on on that area occasionally - including passing cows - lol without the need to go and download images of a hunting cam (I know they now have mob phone capabilities too but still).

 

Using a powerpoint plug-in power meter (mains adapter) it seems the camera draws only 4.2 Watts at 240AC. Not sure how much it draws when it Pans Zooms etc but let's say 10W max - but this will be for short periods during a day (and not at all some days). The plugpack is only 12V 0.75A.

 

Now - I can see all kinds of solar panels - 80W to 200-W or higher. I have no idea what I need power-wise and also what components - panel, MPPT controller, SLA battery....? I do not want to spend a lot of money and if the cam is offline sometimes (due to eg SLA batt being flat) thats Ok

 

The NanoStation wants 24V (12W I am told) and the camera uses 12V. What would I need for a camera only, and what woudl I need for cam + station? Budget stuff only...Eg I have a solar opener for the gate and very happy with it, it makes do with a 12V 9Ah SLA and a 20Watt panel and runs the actuator, remote and even a SIM card relay. In that location I will have good sun as there is a 110KV line nearby so no trees. Can you suggest a package of some sort, even sourced off EBay?

 

Many thanks

[ronp 0]

You really need to measure the 12VDC amperage of the camera and the 24VDC amperage of the nanostation. Measuring the amperage draw of the AC transformer/power supply is misleading because it’s losing power as heat in stepping down the voltage. Find a friend with a VOM (Volt-Ohm-milliammeter) to measure it for you.

 

Few things to consider:

 

1. The battery. You’ll need deep discharge battery. These are typically called “marine” batteries because they are commonly used on boats. They have an Amp-hour (not a CCA - Cold Cranking Amps) rating. The more Amp-hours a battery provides, the more it costs. Amp-hours are just that, they're how many Amps for how many hours you get out of the battery. A 100Ah battery will give you 10 Amps for 10 hours or 5 Amps for 20 hours. However, that’s to a completely dead battery and you never want to do that because it will damage it. Typically you want to only discharge to 50% so a 100Ah battery will really only yield 50Ah.

 

2. The solar panels. Solar panels are rated in Watts. However, that Wattage output is under ideal (clear blue sky, bright sunny) conditions. You can usually expect only 50% of that rating under normal conditions. Also, you only get usable light for at most 8 hours per day. If you had an 80W panel that only output 40W and it operated for 8 hours you’d have 320 (40* Watt-hours of energy.

 

3. Now it’s simple math. Watts = Amps * Volts. Amps = Watts / Volts.

 

4. Let’s say your camera drew 10Watts at 12Volts. That’s 10W / 12V = 0.8 Amps. You have a 12V battery that’s rated at 50Ah (25Ah at 50% discharge). That battery would provide you with 25Ah / 0.8A = 31 hours of use - enough for over a day. In 24 hours, your camera will use 24h * 0.8A = 19Ah of energy or 19Ah * 12Volts = 228 Watt-hours. To recharge that battery in 8 hours of daylight you need to put 228 Watts back into it. A 60Watt panel really only outputs 30Watts. 8h * 30W = 240W. That’s greater than the 228Watts used by the camera so you should be good with a little extra for inefficiency, charger, etc.

 

5. Plug in your actual numbers to see exactly what you need.

 

I’ve personally used the Morningstar PWM charge controllers and have had good luck with them. They’re typically rated in Amps. Just remember Watts = Amps * Voltage to figure out what size charge controller you need for the size of solar panel you have.

 

Ron

[Kawboy12R 0]

And then plan for a week of cloudy weather and see how the numbers pan out in the winter with poor battery performance and maybe some snow covering the panel. Oversize your panel and add additional batteries depending on how important it is for the camera to keep functioning in poor weather.

[hardwired 0]

If you are going to use the Nanostations, their power consumption is between 5.5 (Nanostation Loco series), and 8 watts (standard Nanostation M2/M5). http://dl.ubnt.com/datasheets/nanostationm/nsm_ds_web.pdf

 

The Nanostations will run fine at 12 volts, and that's probably a better choice. With a 24 Volt system, if the voltage goes even to 25 Volts (which it will while charging), the Nanostations will be damaged. 24 Volts is the absolute upper limit, the power supplies they provide are well regulated to not rise over 24 Volts.

 

I just put together a Nanostation and IP camera combination using this unit- http://tyconpower.com/products/remotepro_systems/rpst1212-100-85.html

 

Possibly slightly oversized, but that site cannot afford downtime.