Solar musing - Page 2

gabe · 08-28-2012, 08:48 PM

I have just returned from a two-week trip to Kelowna and area. I bought a 40 Watt, 2.7 amp. solar panel on sale at Canadian Tire for $150 before I left home. I do also have a Honda 1000 which I also brought with me. I was curious to see how well the Solar Panel would do in topping up the battery (one 12 volt) and replacing the juice used the night before. What I found was that this panel was able to keep the battery topped up but not quite to the top. So, after about a week, I had to run the generator for a few hours to bring the battery back to full capacity. So the net result was that I only had to run the generator twice in the two-week span. This was a huge improvement for me, as on previous trips I had to run the genny every morning to top up the battery. I store the Solar Panel in a box under the bed along with chairs etc. It is quite heavy, but I still think it is well worth the money I paid and of course it is completely silent.

Vermilye · 08-29-2012, 07:55 AM

I have the factory installed solar option - 95 watt panel & controller from Go Power, a pair of 6v batteries, and all LED lighting. This summer I spent 12 days in a row off grid in Leadville, CO - used the furnace since mornings were in the low 30°F. I have a 1000 watt inverter I use to make a pot of coffee each morning, and a laptop that draws 9 amps @ 12v I run for an hour or two. The solar system usually had the batteries back to 100% by 11:00AM. As long as I don't need the air conditioner, I suspect I could run as long as I wanted on the system...

BCnomad · 08-29-2012, 12:54 PM

Another talking point (and please correct me if I'm wrong, I'm only passing along what others have said),

do the larger units give you a buffer against cloudy days and the subsequent percentage drop in wattage output? So if a guy needed, say 25watts for sure, and he camped in mostly tree shade or (west coast) cloud cover, the safe bet would be a 75+watt unit?

dave macrae · 08-29-2012, 04:52 PM

I would say that some over kill on the solar panel is a great idea, as you say not every day or location will be a godd solar charging day, the worst thats going to happen with a larger panel than you mathmaticaly need is your batteries will be topped up earlier in the day, for example recently we were in waterton and our site didn't get sun untill well after lunch and the sun set over the mountians quite early, so we only really got a 2-3 hours of good sun but with a 80 watt panel the batteries still got topped up each day, where as when we are in good sun area they are topped up well before noon.

digger57 · 08-30-2012, 07:51 AM

Jon what kind of inverter are you using. I just had solar panels installed last week and I am trying to figure out which inverter to buy.

cpaharley2008 · 08-30-2012, 08:11 AM

You do realize that inverters are somewhat inefficient. You are converting 12v to 120v and you lose a lot of battery juice. Coffee can be made on a gas stove. In addition almost all computers are 12v as are most new tv's. So rather than convert 12v to 120v and then convert back to 12v, find the correct 12v adapter for your needs. It will use less battery juice.

digger57 · 08-30-2012, 09:01 AM

I do make my coffee on the stove,tastes better than electric drip makers. The inverter is so I can use a toaster and to charge my computer in the trailer and anything else I might need when boondocking.

Vermilye · 08-30-2012, 11:10 AM

Quote:

Originally Posted by digger57

Jon what kind of inverter are you using. I just had solar panels installed last week and I am trying to figure out which inverter to buy.

I have a ProWatt SW1000 sine wave inverter. While the sine wave inverters are more expensive & I don't need it to make coffee, there are some devices that are not happy when supplied by the choppy MSW inverters, including my camera battery charger.

As to making coffee, I do prefer drip, and since I haven't had any problems with recharging my batteries from the solar system, I'll stick with the inefficient inverter. I do use direct 12V power supplies for both my computer & my iPod dock...

dave macrae · 08-30-2012, 11:50 AM

You don't need to make coffee

? what is this world coming to

Jim Bennett · 08-30-2012, 01:12 PM

Quote:

Originally Posted by Dmac

You don't need to make coffee

? what is this world coming to

You don't need to make coffee? Well then, you don't need to go camping either, you don't have to visit loved ones, or you don't have to ever enjoy life.

You don't need to make coffee? Sheesh.....are you out of your mind? (though you don't have to have electricity to make good stuff)

Yours truly,
Jim the Coffee Freak

dave macrae · 08-30-2012, 02:30 PM

I am putting a power inverter to mostly to run my little 4 cup coffee maker while on the road, it is much quicker than using the stove. the 4 cup cuisinart coffee maker makes about as good a coffee as you can get from a electric drip machine and only uses 550 watts and is very quick, can pull over and make coffee in about 10 minutes. I will not need a drive thru

Jubal · 08-31-2012, 11:20 AM

I have neen researching RV solar installations. Here are the best sites that explains the best solar applications.
http://www.thewanderman.com/2011/11/...ap-part-1.html
http://www.jackdanmayer.com/rv_electrical_and_solar.htm
http://handybobsolar.wordpress.com/t...ging-puzzle-2/
Jubal

BCnomad · 08-31-2012, 11:25 AM

OT -- A readable article on what IBM is doing to research next generation solar panels:

http://arstechnica.com/science/2012/...-fossil-fuels/

btroxell · 08-31-2012, 02:59 PM

Quote:

Originally Posted by Dmac

... power inverter only uses 550 watts...

DMac, that may not be much power but it is a lot of current that your wires must carry. The 50 amps (550/12 + inefficiencies) must come from your battery, through the power distribution panel to your inverter. To carry this amount of current, you should have at least #8 wire (and possibly #6, depending on the type of wire) which I know my trailer was not wired with.
When you use it for the first time, watch and feel the wires to make sure they don't get too hot.
Good luck and be careful.

Ben

dave macrae · 08-31-2012, 03:26 PM

Thanks, I am using a triplite 1700 watt inverter that i have installed for a few customers in their work vans, I seem to remember we used #2 wire. I will be going directly to the battery and locating the inverter in the lhs front by the converter so the wire run will be short. I can source this inverter locally for a very reasonable price and have good luck with them so far. The guys that i have installed them for are using them much harder than i ever will and they seem to be holding up. the1700 is a running wattage not a start up so it will be plenty for a cup of Jo on the road.

Vermilye · 08-31-2012, 04:46 PM

The wire size needed for an inverter is determined by a couple of factors. There is the standard "look it up in a wire table" for the proper size for length & maximum current draw, but often overlooked is insuring that the wire size is large enough to prevent enough voltage drop to shut down the inverter under heavy demand. The typical 3% drop most wire tables use may be too much for the inverter. Most large inverters will shut down at a pre determined voltage input to prevent killing the battery. You may have plenty of battery left, but if the wire size is too small the voltage drop will shut the inverter down well before there is an overheating problem due to wire size.

For example, Prowatt suggests 1/0 wire size for a 6' run (total length of both wires) for their 1000 watt inverter, much larger than a wire size table would indicate.

digger57 · 08-31-2012, 06:24 PM

Escape put 10 gauge wire in my trailer for the inverter and I was told not to go over 1500 watts. The wires are connected to what looks like relays or circuit breakers. Do these wires now have to be changed.

cpaharley2008 · 08-31-2012, 06:55 PM

Quote:

Originally Posted by digger57

Escape put 10 gauge wire in my trailer for the inverter and I was told not to go over 1500 watts. The wires are connected to what looks like relays or circuit breakers. Do these wires now have to be changed.

Can you post some pictures of your inverter/wiring set up?

digger57 · 08-31-2012, 07:07 PM

I haven't purchased an inverter yet, I just need to make sure the wiring is correct or if I need to change it. I am not sure if the wire is different because of the solar panel install or that doesen't matter. I won't be going more than 1000w with the inverter.

btroxell · 08-31-2012, 09:43 PM

Quote:

Originally Posted by digger57

I won't be going more than 1000w with the inverter.

You will have to run a dedicated circuit, bypassing the Power Distribution Panel (PDP), going directly to the battery (using it's own breaker) as Dmac said he has. A 1000W inverter (about 90% efficient) will draw about 75 amps (1000/12/0.9). My PDP states that it has a maximum of30A DC per circuit. For 'house' wiring, #10 wire is capable of carrying 30A (this does NOT take into consideration of voltage drop) but temperature is the main criteria. If you are going to draw 75A, you will need wire close to the size of your (at least mine) finger.
If you need 1000W, you should look at 120VAC and not 12VDC. Basically, you will draw 10 times the current on DC as you would on AC.

Ben

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