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Electricity Options for Observatory

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#1 anemec

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Posted 07 February 2013 - 03:36 PM

I have a plot of land which would be perfect for an observatory about 300ft from my house. It is approximately 10 feet below the level of the house and would sit on a giant slab of stone. The location is great, but I wonder about getting electricity to it.

My initial thought was to run underground electric to it. I have used a trencher in the past to run extra lines for my aerobic septic system sprinkler heads. But that was for an area which has some dirt instead of all rock. We live in a very rocky portion of NE Oklahoma. The observatory spot has some 50 ft of rock I would have to get through. And it would be tough to do.

I suppose I could put up a telephone pole above the observatory and run electric from my house that way. But I would really like to avoid that if possible.

So I wanted to ask you guys what you thought. First, how important is a constant source of electricity? Do any of you have unpowered observatories? Are there other options other than those two which I am not thinking of?

I know I could always just run an extension cord or use some deep cycle marine batteries. Which might be a decent option. I clearly miss out on the really cool stuff I can do with the observatory - but it is better than nothing.

My main reason for an observatory is so that I can mount my scopes on piers instead of hauling them out from the study every night. I obviously would like electric out there. But am not sold on any of the options as I see them right now.

Oh, I would be using my Tak EM-200 out there as well as my Vixen GPDX and fork mounted LX200 8" plus all the fixings.

#2 rimcrazy

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Posted 07 February 2013 - 03:41 PM

Do you have enough sunlight to use some solar panels to charge some batteries? No trench, no poles, just use DC Power with perhaps a DC to DC converter to run a laptop if it cannot use 12V. Just about everything astronomical can run on 12Vdc.

#3 zawijava

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Posted 07 February 2013 - 04:02 PM

Solar is pretty darn cheap nowadays. My Astro Club's ROR observatory [16'x30'] is/has been solar powered since it was built in 2000/2001. We have both DC current and pure sine wave AC. Yours would be a fairly straight forward and inexpensive system to put together. That's the way I'd go :waytogo:

#4 anemec

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Posted 07 February 2013 - 04:05 PM

That sounds like a good option.

I have mostly unobstructed sunlight. Pretty much 8-12 hours depending on time of year.

Though the two halves of my pitched roof would probably slant southeast and northwest instead of strictly true east and west because of the lay of the land. Which would probably change the amount of powerful sunlight I get. I'm guessing the Southeast one might get the most sunlight.

How much would be "enough" sunlight? Is there a specific solar panel or kit you've used?

#5 zawijava

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Posted 07 February 2013 - 04:53 PM

Adam,

I would suggest pole mounting your panels somewhere within 10' or so of your building as long as they are not in the shadow of the building at any time during the year. This would allow you to tilt your panels for optimum exposure[more critical in Winter]. Then put your battery bank in the observatory. -Tim

That sounds like a good option.

I have mostly unobstructed sunlight. Pretty much 8-12 hours depending on time of year.

Though the two halves of my pitched roof would probably slant southeast and northwest instead of strictly true east and west because of the lay of the land. Which would probably change the amount of powerful sunlight I get. I'm guessing the Southeast one might get the most sunlight.

How much would be "enough" sunlight? Is there a specific solar panel or kit you've used?



#6 anemec

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Posted 07 February 2013 - 05:13 PM

The pole mounting is a good idea.

Is there a good article or forum post which covers some of the details of hooking everything up. I have no experience with solar panels at all. So I don't even know where to start with figuring out which brand to get, how many to purchase, how to install, etc. etc.

#7 Tom and Beth

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Posted 07 February 2013 - 10:01 PM

Here's one of many I have bookmarked.

http://www.homepower...lar-electricity

You would be surprised howmuch those into RVs and living off the grid can help you to plan and design a working Solar System. Like anything else, be leery of snake oil and "over enthusiastic" claims.

#8 zawijava

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Posted 07 February 2013 - 11:28 PM

Adam,

The very first step in any Solar System [no pun intended] is to determine your usage demands. You want to size your system appropriately so as not to spend more money than you need to(oversize) or not have enough power when you need it(undersized). This is a bit time consuming to do but necessary. Unlike being on the grid where you just hook up and not worry about demands, on Solar it's all about proper sizing based on demand. Lots of online resources for this. I'd also search locally for someone who's knowledgeable about this via their own hands on personal experience. Don't base your needs on the word of a "solar salesman". Learn/know exactly what you need, then go find your best deal on the internet for those items. We were lucky to have a long time Club Member who is a solar engineer. You may have someone just like him in your Club or Community. -Tim

The pole mounting is a good idea.

Is there a good article or forum post which covers some of the details of hooking everything up. I have no experience with solar panels at all. So I don't even know where to start with figuring out which brand to get, how many to purchase, how to install, etc. etc.



#9 anemec

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Posted 07 February 2013 - 11:35 PM

Thanks Tom and Beth and everyone else. Now I am going to show my inexperience in this matter -
How do I go about figuring out what amount of wattage I need, size of batteries, etc.?
I have always just plugged everything into an extension cord from my house so have never needed to consider Wattage and Amps.
I will be running a laptop, three mounts (though only probably one at a time), a dslr, an STL-11000, Dew heaters, and that's probably it for now.

#10 anemec

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Posted 07 February 2013 - 11:42 PM

Zawijava, it looks like you posted while I was writing. Thanks for the advice. I'll look around locally. Though I am not really sure what category of people to contact locally. Electricians?

#11 JJK

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Posted 08 February 2013 - 04:41 AM

Thanks Tom and Beth and everyone else. Now I am going to show my inexperience in this matter -
How do I go about figuring out what amount of wattage I need, size of batteries, etc.?
I have always just plugged everything into an extension cord from my house so have never needed to consider Wattage and Amps.
I will be running a laptop, three mounts (though only probably one at a time), a dslr, an STL-11000, Dew heaters, and that's probably it for now.


Hi Adam,

If you know how to safely use an ammeter at AC line voltages, you can measure the current your system draws now (and thus the power needed). If you don't, then determine the power used by each component (usually provided by the manufacturer). You need to pay particular attention to peak and steady state demands. For example, a mount slewing rapidly to an object will require more power per unit time than it does when tracking. The power supply and wiring has to accomodate the peak demand. You can reduce the peak demand by the mount by not slewing at the top speed.

Will you need power to open/close the observatory?

You also need to assume that there will be cloudy days, which limit how quickly you can recharge your system. What I would do is get heavy duty batteries (perhaps two) and use them to see how long your system can go without recharging (you probably want to continuously monitor the battery voltage and not run them to failure). You can recharge them with an appropriate charger attached to the grid.

Depending on the load, a telescope mount might consume at peaks about 60W to 150W, and less when simply tracking in RA. Some mounts want their own dedicated power supply (to ensure that transient loads caused by the other equipment don't confuse the mount's built-in computers).

With a thermoelectric cooler, the STL11000 is likely power hungry. The manual suggests the power is about 72 W at 12V (but it might be more if they really meant 13.8V). I don't know if this rating includes the filter wheel, but I'd add capacity for that in case you get another camera + CFW someday. You'll need SBIG's 12V power cable (you can the standard power brick, but you'd then need a 12V to 110VAC sine wave generator; the brick and generator waste power).
http://www.exp-astro...perating_man...

A typical laptop computer consumes under 60 W inside a home (I don't know if that changes much in the freezing cold) , and can be minimized by lowering the LCD screen intensity. See the note about turning off the battery charger on the computer. http://www.upenn.edu...powerusage.html
http://tech.groups.y...o/message/26316

Consider the power demand for other amenities including
1) lighting (red and white LEDs),
2) an external guide camera,
3) electric focuser (this demands very little power, as it's used sparingly)

You also should anticipate some future demand and you don't want your batteries being depleted after a single 8-hour session.

Mount 60W to 150W
Camera 80W
Filter wheel 12W ??? (used transiently)
Electric focuser 12 W??? (used transiently)
Laptop computer 60W
LED lighting 12W (used transiently)

A rough estimate for power demand would be about 240W to 330W at 13.8V (i.e., about 0.24 kW to 0.33 kW). If you want to be able to run the observatory for 8 hours/night for three nights without having to recharge the batteries, that'd mean a power demand of about 5.2 kW-hr to 8 kW-hr, which is not trivial. These are rough guesstimates, so if anyone here has actual hands on experience, please correct me.

When going solar, you also need to manage the power going to the batteries (you don't want to overcharge them, and you want the batteries charged optimally; if you have more than one, they will charge at different rates) and ensure that the power in the batteries isn't going back to the solar cells.


Clear Skies,
John

#12 zawijava

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Posted 08 February 2013 - 07:28 AM

Adam,

Invest in one of these and run your equipment through it as a guide to usage[might find it cheaper at another retailer]:

Kill-A-Watt

Also, not all Electricians [household 120V] are experienced with Solar 12v.




Zawijava, it looks like you posted while I was writing. Thanks for the advice. I'll look around locally. Though I am not really sure what category of people to contact locally. Electricians?



#13 anemec

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Posted 08 February 2013 - 08:23 AM

John, that was a great explanation. Thank you for it and the links. And zawijava I just ordered that electricity usage monitor. That is definitely the place to start. Once I figure out my usage in a night then that will determine exactly how big of a system I need to install.

Right now I plan on just building a ROR which I would open and close by hand not with an opener. The area I have picked out would allow for a nice 10' x 14' footprint. So the roof should be fairly manageable as long as I mount it correctly and keep it well oiled.

#14 jazle

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Posted 08 February 2013 - 02:37 PM

Depending on your local codes, you might be able to run underground in steel conduit with as little as 6" of cover.
And if the rock is on the surface, you can cover it with a 2" concrete sidewalk. Check with the building folks there to see what they say.

But just a warning, if you are trying to avoid a building permit, don't run the electrical into the observatory. Just put a plug on a post just outside the observatory and run a cord inside.

#15 JJK

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Posted 08 February 2013 - 04:01 PM

John, that was a great explanation. Thank you for it and the links. And zawijava I just ordered that electricity usage monitor. That is definitely the place to start. Once I figure out my usage in a night then that will determine exactly how big of a system I need to install.

Right now I plan on just building a ROR which I would open and close by hand not with an opener. The area I have picked out would allow for a nice 10' x 14' footprint. So the roof should be fairly manageable as long as I mount it correctly and keep it well oiled.


Please let us know what the electricity usage monitor suggests your equipment requires.

#16 anemec

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Posted 11 February 2013 - 03:34 PM

Jason - thanks this was a great idea. Since I live in the country with no specific codes to speak of I called an electrician I know and he told me following your advice would be fine. It would be safe for the house and not run against any codes. So I think this is the route I will go.

Thanks to everyone for your input. Perhaps I will try solar on another project at some other time.

#17 zawijava

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Posted 11 February 2013 - 04:00 PM

If you've got room on your house breaker panel why not give the Observatory Outlet it's own circuit [breaker] and make it a GFI Breaker. Possibly even put Surge Protection on that circuit if the price is not prohibitive. -Tim

Jason - thanks this was a great idea. Since I live in the country with no specific codes to speak of I called an electrician I know and he told me following your advice would be fine. It would be safe for the house and not run against any codes. So I think this is the route I will go.

Thanks to everyone for your input. Perhaps I will try solar on another project at some other time.



#18 Startraffic

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Posted 12 February 2013 - 12:11 PM

Adam,
Something to consider is adding a UPS in the Obs. That will give you clean uninterrupted power and a reserve for if you should have your GFCI breaker pop. I wouls size that big enough to give you about an hour before mandatory shutdown. That will protect your equipment and any imaging run you're in the middle of.

Clear Dark Skies
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39.138274 -77.168898

#19 Mary B

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Posted 12 February 2013 - 04:49 PM

If you go solar www.solarblvd.com has great panel prices, low as 80 cents a watt. Might be cheaper than a 300 foot run of wire...






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