Small Solar Power system

[riptides]

I'd like a complete "small" solar power system to provide ample juice for two lights (manual control), a motion detector light and a heater in a water trough.

The system will be mounted on a roof and all components except the wiring and panels will be housed out of the weather.

My issue seems to be that of watts. I think the heater is the issue, because it draws so much. At this point, I don't need it full time and would probably opt for a day on battery backup.

Recommendations or advise, welcome. Thanks!

 

[newbury]

C'mon - you know better -
Give us some specs
Where? Northern Virginia? Alaska" Hawaii?
To what temp? just above freezing?
What size is the trough and will it be insulated?
Can we assume LED lights or do you want the lights to provide heat?
Will the batteries be mounted on the roof?

 

[John_Mc]

The lights are easy, especially if you use LEDs to minimize the draw. Is the motion detector light for you, or for whatever is using the trough? If it's for you, figuring out how to keep what is using the trough from triggering it will minimize battery drain. What size heater are you thinking of running? That could easily turn your "small" solar system into a larger one.

I assume the heater in the trough is just for freeze protection. Anything you can do to insulate your trough to slow heat loss will help cut down on the size of the system you need (a bucket or tank lends itself better to insulating than a shallow open trough).

If you have a day on battery backup, is 3 days without sun going to cause problems for whatever is using the water trough, or do you have other means of dealing with that?

It's hard to size the system with all of the variable (including how much sun you get in your area - I'm aware of calculators which will give you average annual solar estimates for your area - PVWatts is one. However, "average annual" won't help you, since wintertime output is much less than average. I but don't know if those resources will show seasonal solar expectations - it's been several years since I've used it.)

 

[riptides]

Northern Virginia. Climate, Jan-Mar (20 degrees to 50, average).

Inside LEDs (manual switch only) no more than 40 watts.

Outside LED (flood light, motion detector) no more than 90 watts.

Water trough (deep tank) looks to be no more than 1500 watts.

Panels on top, all components including batteries on inside. Probably right under panels. No more than 3 feet distance.

I have other means of getting water to area, if needed. So a day or so on battery backup is fine.

 

[Diggin It]

The trough heater is the issue. How big? How much surface area? How much Sun do you normally get? How much loss is there due to shade from trees, buildings, terrain, etc.?

There are solar pool heaters that lay out on the ground and circulate the water through them via a small pump. If you get enough Sun and temperatures don't too bitter cold, that may be an option.

 

[Diggin It]

Inside LEDs (manual switch only) no more than 40 watts.

Outside LED (flood light, motion detector) no more than 90 watts.

Those don't need to be anywhere near that. Outside LED floods can be 10 watts unless you want to light a huge area.

 

[riptides]

The water trough sits in the sun for 3/4 of the day. 4 foot surface area to it. Depth is at least feet. Heater is at the bottom, will look into solar pool heater with pump. Good idea.

 

[Jchonline]

As you can see there is a great deal of detail needed to make solar work. You need to figure out how much power you will draw (max power) in a 24h period. Then you back this into a battery and solar system to support it based on your location. Take the heater out of the equation and it will be much easier.

 

[riptides]

Those don't need to be anywhere near that. Outside LED floods can be 10 watts unless you want to light a huge area.

Ok. TIA. Fairly large area (need to see what we are walking into), can experiment with lighting watts, not a problem.

 

[Deerherd]

Instead of a heater, get a large aquarium/small pond bubbler that will draw no more than 15-25 watts.