· Get a Cloudy Nights T-Shirt · Submit a Review / Article Click here if you are having trouble logging into the forums Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> Observatories Previous   Index   Next   Threaded   Pages: 1 | 2 | (show all) Hilmi Carpal Tunnel Reged: 03/07/10 Loc: Muscat, Sultanate of Oman Experience with solar powered observatories       #5197689 - 04/30/12 03:11 AM Edit   Reply   Quote Quick Reply   I just payed my down payment for the observatory yesterday. One week to fabricate the panels, then it will be installed at home. I was trying to get the power sorted out and decided I would rather not pull another mains cable to the observatory as the power supply in my neighborhood is very shoddy. So I am going to go solar for my power supply. I will not be ordering from the US as I suspect solar panels are delicate and I do not want to risk having them handled in shipping and arriving defective. Last Thursday I drove over to Dragon Mall in Dubai (all things Chinese for those with a smaller wallet and can live without warranties) and they had a variety of solar power equipment suppliers. I don't trust the sales men will be that useful considering the language barriers so I want your advice on how to set up such a system. I am guessing that a solar panel gets hooked up to some kind of charger that will trickle charge a battery or set of batteries that will then be used to operate everything else via a distribution panel. I have no clue what rating solar panel to get (I assume they are rated in watts?) I do live in an extremely sunny area that only gets cloudy when I buy gadgets. Any components I missed? Does the system need some kind of surge protection? which way should the panels face? I was thinking that I would tilt the panel slightly to the south since I am at 23 degrees North. Is there any calculation as to optimal installation angle? So many questions... and no clue where to start. I will be heading to Dubai for some training next week Monday and I would like to take advantage of that time to make my purchase. Post Extras:       roscoe curmudgeon Reged: 02/04/09 Loc: NW Mass, inches from VT Re: Experience with solar powered observatories [Re: Hilmi]       #5197807 - 04/30/12 07:56 AM Edit   Reply   Quote Quick Reply   Hilmi, A small - 1x2 feet or less - panel will keep an auto battery topped up fine for use running drives on your mount, some LED lighting, and the like.... you will need a charge controller that monitors the battery voltage and keeps from overcharging it. You won't need any sort of surge protector. With the amount of sun you have, all you need to do is aim the panel mostly south, and mostly at the noonday sun. Your battery (an older auto battery will work fine) might off-gas a bit while charging, consider keeping it outside your obs, and in a little shelter to keep the sun off it, because being black, it'll get quite hot otherwise. Use thick wire - number 12 - to connect everything. You might want to do a little on-line research on basic battery charging circuits to work out some details, but if you're not running a lot of gear for a long period every night, you don't need to get involved in bigger panels or deep-cycle batteries. Russ Post Extras:       Hilmi Carpal Tunnel Reged: 03/07/10 Loc: Muscat, Sultanate of Oman Re: Experience with solar powered observatories [Re: roscoe]       #5197823 - 04/30/12 08:14 AM Edit   Reply   Quote Quick Reply   Russ, Thanks for the tips. I plan to run the following -Core i7 laptop -Cooled CCD camera -Canon 7d -Meade DSI -Losmandy G11 with G2 -Motorized focuser -filter wheel -In the future some dew heaters for imaging in the summer when it is easy to reach the dew point -lighting -Dehumidifier -To charge my robot vac to keep the floor dust free. -Occasionally I might run a little fan to keep me cool when it gets very hot. on my wish list - 0.5 ton air-conditioning unit. I don't see how i can run this off a battery so it remains on the wish list Post Extras:       Mirzam Post Laureate Reged: 04/01/08 Loc: Lovettsville, VA Re: Experience with solar powered observatories [Re: roscoe]       #5197840 - 04/30/12 08:24 AM Edit   Reply   Quote Quick Reply   Well the big question is how much current draw? The system has to be sized properly to work. If you just want to power a mount, a light, a small cooling fan, maybe a laptop, you need a relatively small number of amp hours daily--lets say 10, but you should try to work out the numbers yourself. 10 amp hours can be collected by a 50 watt 12v solar panel with 5 hours of illumination. Set the angle to your latitude (23 degrees) and face due south unless there is some sort of shading issue. Place the panels so that there is no shading at all or they will not work! You need a charge controller to regulate the charge level. These are simple devices, not too expensive and absolutely required or your battery will be ruined in short order. I would recommend using a deep cycle battery. If you plan to use 10 amp hours daily, I'd look for a battery around 40-50 amp-hours. This way it will not be deeply discharged and will last a long time. At this point you have a 12volt system in which you can connect stuff directly to the battery terminals (through a fused 12v plug). If you want 120 volts you need an inverter. If you plan to run a computer on 120 v you need a sine wave inverter. Inverters are not 100% efficient so if you plan on a lot of inverter use I would up-size the rest of your system somewhat. I've been using a 75w panel, 70 amp-hour battery, and inverter for 4 years without problems. No dew heaters. If you want to run a lot of dew heaters your power requirements will be much greater. In this case it may be more cost efficient to simply charge your separate dew heater battery in the house and then bring it out on nights when dew is expected. JimC Post Extras:       Mirzam Post Laureate Reged: 04/01/08 Loc: Lovettsville, VA Re: Experience with solar powered observatories [Re: Mirzam]       #5197846 - 04/30/12 08:27 AM Edit   Reply   Quote Quick Reply   A dehumidifier is just as bad as a air conditioner in terms of current draw. No way will you be able to do this using solar power without a lot of expense. Based on the rest of your list you probably need about 2x the system size that I described earlier. (But check the numbers yourself). JimC Post Extras:       frolinmod Pooh-Bah Reged: 08/06/10 Re: Experience with solar powered observatories [Re: Mirzam]       #5198291 - 04/30/12 01:27 PM Edit   Reply   Quote Quick Reply   Gosh Hilmi, there's a ton of information on this subject available online. You just need to get on the Google and start searching for it. Then you can tell us! Post Extras:       roscoe curmudgeon Reged: 02/04/09 Loc: NW Mass, inches from VT Re: Experience with solar powered observatories [Re: frolinmod]       #5198317 - 04/30/12 01:43 PM Edit   Reply   Quote Quick Reply   Hilmi, I agree with Mizram.......right up to the word 'dehumidifier' we were fine...... and I agree that with all the other stuff, you might want to get a little more panel and perhaps a deep-cycle battery......but with the dehumidifier, any dew/dampness you get at night with the roof open will get cooked out next day, so I wouldn't worry about it. I'm in a far damper climate, and don't use one. Russ Post Extras:       Hilmi Carpal Tunnel Reged: 03/07/10 Loc: Muscat, Sultanate of Oman Re: Experience with solar powered observatories [Re: roscoe]       #5198414 - 04/30/12 02:47 PM Edit   Reply   Quote Quick Reply   Russ, I'm less than 1 mile from the sea. It gets very very humid, 69% humidity with temperatures in the range of 45 C can make all your rubber components turn to goop. I would rather try and keep things a little dry inside to preserve the life of my rubber components. I used to repair ATM machines, and the rubber rollers used to turn into a gummy sticky substance after some time. Frolinmod, I'm one of those people who like interactive learning with the ability to ask specific questions and ask for clarification. Google doesn't help in such circumstances. Post Extras:       StarmanDan Post Laureate Reged: 08/27/07 Loc: Deep in the heart of Texas Re: Experience with solar powered observatories [Re: Hilmi]       #5198637 - 04/30/12 04:52 PM Edit   Reply   Quote Quick Reply   Haven't heard anyone mention you might need an inverter for stuff that requires AC power. Be sure to get one big enough for everything you plan to plug into it. These are rated in watts so just add up the watt ratings of all the AC stuff (laptop, dehumidifier, robot vac) and add a little more to give you some breathing room. Of course you will need more battery power too. Post Extras:       JAT Observatory NOT a Wimp Reged: 02/20/05 Loc: In the Primordial Soup Re: Experience with solar powered observatories [Re: StarmanDan]       #5198820 - 04/30/12 06:41 PM Edit   Reply   Quote Quick Reply   My observatory started life as solar powered. It has a 3000 watt inverter in it. While it now has mains power the observatory is capable of being completely solar powered except for the A/C and dehumidifier units. The solar system is used during power outages. Post Extras:       JMW scholastic sledgehammer Reged: 02/11/07 Loc: Nevada Re: Experience with solar powered observatories [Re: JAT Observatory]       #5199301 - 04/30/12 11:16 PM Edit   Reply   Quote Quick Reply   I have an cargo trailer I use for astronomy camping. I run a mount, 2 laptops, DC fridge, fan, small 12 volt evaporative cooler, LED lights. I have a pair of 6 volt batteries that give me 220 amp-hours. I have 240 watts of solar feeding an MPPT solar charge controller that puts in about 15 amps back into the batteries during full sun. I live in Nevada and our solar energy is abundant. My fridge, fans, laptops are often on in the daytime so not all of my solar output is available to recharge my batteries but I figure I can put back about 100 amp-hours during the peak summer months when I use it the most. It has done fine on 4 night star parties. You need to figure your worst case overnight amp-hour power draw down. Buy a pair or multiple pairs of 6 volt deep cycle batteries that give you twice your maximum overnight load. Your batteries will last much longer if you don't draw them down over 50%. Buy enough solar watts so you can recharge your batteries on the shortest days of the year. Buy a charge controller that is MPPT to have the top effectiveness on delivering the amps into your batteries. PWM controllers just use pulse width modulation to toss the extra voltage away so the panel output can match the charging cycle. MPPT controllers lower the voltage and increase the amperage to match the required voltage at the battery terminals. Size the charge controller to match the watts of your solar array. A good MPPT charge controller can take a set of 12 or 24 volt panels in series as a 36 or 48 volt input to the controller and still put the proper voltage for a 12 volt battery set. This can allow you do use smaller wires at higher voltage between the panels and the controller. It will be helpful to use a some kind of load monitoring and solar output monitoring. Some of the better charge controllers allow the attachment of metering that show accumulative amp-hours, amps, volts, peak amps, max and min volts. A good charge controller will have a 3 stage charge cycle that will not boil off your batteries so you just need to periodically add distilled water. Post Extras:       frolinmod Pooh-Bah Reged: 08/06/10 Re: Experience with solar powered observatories [Re: JMW]       #5199426 - 05/01/12 12:34 AM Edit   Reply   Quote Quick Reply   220 watts. That's cool. JMW, you're getting about 7 hours of sun a day and taking about two days to recharge a pair of golf cart batteries, is that correct? How many solar panels are you using and how large are they? Post Extras:       Chris Erickson Carpal Tunnel Reged: 05/08/06 Loc: Waikoloa Village, Hawaii Re: Experience with solar powered observatories [Re: frolinmod]       #5199501 - 05/01/12 01:57 AM Edit   Reply   Quote Quick Reply   Considering the desire for an A/C unit or a dehumidifier, I would reconsider using commercial power with a Transtector and/or an isolation transformer. http://www.protectiongroup.com/Surge/AC-Protectors/Type/AC-Panel-Surge-Protectors Significantly cheaper than an off-grid photovoltaic system big enough to do everything you want. Post Extras:       JMW scholastic sledgehammer Reged: 02/11/07 Loc: Nevada Re: Experience with solar powered observatories [Re: Chris Erickson]       #5199518 - 05/01/12 02:31 AM Edit   Reply   Quote Quick Reply   I have 240 watts of solar, 3 x 80 watts in series feeding through a SunSaver MPPT 15 amp charge controller. I have a pair of 6 volt Trojan 220 amp-hour batteries to give me a 12 volt system at 220 amp-hours. I fit all 3 solar panels on the roof of my 5x8 cargo trailer with enough of a gap for a pop up fantastic fan vent. In June-July I am getting 9-10 hours of productive solar. My first couple of years with the trailer I had a 130 amp-hour battery and 2 80 watt panels with a PWM controller. When I bought the DC fridge I needed more capacity so I sold my 130 amp-hour battery to another member of our club and bought the bigger pair. I had enough room on the roof for 1 more panel, so I bought the 3rd panel to match the others and replaced the controller with the MPPT version. If I was going to do it again I would probably just buy one 24 volt 240 watt panel and keep the rest the same. Panels have come down a lot in price. The limitation now is the MPPT controller. They get big and expensive when you go from the SunSaver 15 MPPT to a 30-40 amp version. I just looked at SolarBlvd and they have a Sharp 230 watt 24 volt panel at their site for $253. I paid almost $400 each when I first bought my 80 watt panels 4 years ago. 80 watt panels are about $100 each now. Post Extras:       JMW scholastic sledgehammer Reged: 02/11/07 Loc: Nevada Re: Experience with solar powered observatories [Re: JMW]       #5199524 - 05/01/12 02:45 AM Edit   Reply   Quote Quick Reply   Solar is the best win when there is no reasonable way to bring commercial power to your site. It is also great for mobile installations. There are plenty of people in Nevada using solar that are completely off the grid and too far and costly to attempt to bring a utility line to their site. My goal was not to have to use a generator at a star party. I run a small vacuum cleaner and blender off of a quality 2000 watt inverter but I try to do it earlier in the day so the sun has plenty of time to top of my batteries. If you want to run and air conditioner, microwave or a dehumidifier I think you will find it requires a huge investment in solar panels, charge controllers, batteries and inverter to sustain a 110 volt A/C appliance for any amount of time. Watts = Volt x Amps. It takes a lot of Amps when the volts are only 12. Most RVers use the solar to maintain the batteries and the 12 volt loads and kick on the generator for the time when the want the microwave or air conditioning. I can't stand listening to a generator run for hours. Solar gives you the quiet you desire when you want to relax. Your neighbors will appreciate the quiet also. Post Extras:       Hilmi Carpal Tunnel Reged: 03/07/10 Loc: Muscat, Sultanate of Oman Re: Experience with solar powered observatories [Re: JMW]       #5199785 - 05/01/12 09:45 AM Edit   Reply   Quote Quick Reply   The AC unit was just wishful thinking, I think that if I can run a small dehumidifier like this one, I would not necessarily need an AC unit. If I can keep the place dry, I figure I will have less chance of the rubber parts going all sticky and pasty. Also, my robot vacuum cleaner shouldn't be much a of a problem, after all, it is a battery operated unit. Remember, I live in the land of extreme sunshine, and my panels will get little obstruction. Mains power will probably cost me more due to the cost of labor as I don't trust myself to do it safely. The Solar powered system, I figure I can install that myself Post Extras:       Alex McConahay Carpal Tunnel Reged: 08/11/08 Loc: Moreno Valley, CA Re: Experience with solar powered observatories [Re: Hilmi]       #5200067 - 05/01/12 12:36 PM Edit   Reply   Quote Quick Reply   One concept I think needs attention.....many things we plug into the wall appears to need 110 (220 in other places) "mains" power. But, in fact they do not. What we plug into the wall is a converter that steps it back down to 12 or 19 volts. My camera, mount, focuser all run on twelve (they really use 14 if they can get it) and my computer at 19. When you put in an inverter to boost the 12-14 coming off the battery to 110 or 220, you are using more power than you get out. THen you lose a bit of it when you go back to 12-14 to actually power your observing tools. (Don't believe me--put your hand on one of the "bugs" doing the inverting or converting. Inverters and converters both give off heat--this heat is wasted energy.) Point is--Be careful to use the inverter only when needed to actually power something needing mains type power. Do not use it for things that really need 12, 14, or 19 volt power. Alex Post Extras:       frolinmod Pooh-Bah Reged: 08/06/10 Re: Experience with solar powered observatories [Re: Alex McConahay]       #5200588 - 05/01/12 05:59 PM Edit   Reply   Quote Quick Reply   My Dell laptop power supply brick delivers 19VDC, but the actual laptop actually only requires 12VDC and even operates directly off 12VDC when the auto adapter is used. The auto adapter is just a wire, fuse and cigar plug with no converter! Nice... Oh, and then there is my Paramount. Most people would plug the supplied 110/220VAC to 48VDC power supply brick into an inverter. With the inverter that's about 85%*85% = 72% efficient (or worse). I instead use a direct 12VDC TO 48VDC converter that is 96% efficient. Huge power savings. Post Extras:       Alex McConahay Carpal Tunnel Reged: 08/11/08 Loc: Moreno Valley, CA Re: Experience with solar powered observatories [Re: frolinmod]       #5200767 - 05/01/12 07:50 PM Edit   Reply   Quote Quick Reply   Is that serious about your laptop.....is there more to it than that. And is that true of all laptops? Alex Post Extras:       JAT Observatory NOT a Wimp Reged: 02/20/05 Loc: In the Primordial Soup Re: Experience with solar powered observatories [Re: Alex McConahay]       #5200867 - 05/01/12 08:59 PM Edit   Reply   Quote Quick Reply   It's not true of all laptops. My work Dell has a similar setup except you remove the 120 volt cord from power brick and connect the 12 volt DC auto plug on the side of power brick. My netbook is powered by 12 volts. Post Extras:       Pages: 1 | 2 | (show all) Previous   Index   Next   Threaded   Extra information 3 registered and 9 anonymous users are browsing this forum. 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