Solar help

[Travis]

Maybe some of you can help me a little bit. About the only thing I know about solar panels are they are shiny. I saw this, and was wondering if it would be sufficient to keep a charge, and run some minor appliances. What is good and what needs to be different? Is this too much/big for a tear? Any help would be appreciated.
Thanks.

Nominal Peak Power [Pmax] +/- 3% 60 Watt
Maximum Power Voltage [Vmp] 18V
Maximum Power Current [Imp] 3.34A
Short-Circuit Current [Isc] 3.63A
Open-Circuit Voltage [Voc] 22.5V
Optimized Cell Efficiency 16.8%
Limits
Operating Temperature -40C to 85C
Maximum System Voltage 715VDC
Temperature & Coefficients
NOCT 48C +/-2C
Current Temperature Coefficient 0.06 +/-0.01
Voltage Temperature Coefficient - (78 +/- 10)
Power Temperature Coefficient -(0.5 +/- 0.05)
Additional Data
Number of Cell & Type of Connection 24, Serial Connection
Dimension Length: 800 mm
Width: 550 mm
Height: 35mm
Weight 5.5 Kg
Guaranteed Power Output 15 Years: 90% of its nominal power rating
25 Years: 80% of its nominal power rating
Warranty Period 5 Years Limited Manufacturer Warranty

Replacement of Defective parts. Labor excluded.

[dreadcptflint]

Travis,

Hopefully, I can help you a little bit. If the numbers hold true then it may work for you. I am going to have to say may because I don't know some vital information.

1. What is the draw? When you say minor appliance, it can be a big difference. For example there is a huge difference between a LED light and an Air Conditioning Unit.

2. Are you going to run panel to a battery bank and charge it up or are you going to skip the battery all together? You can have a fairly large battery bank and run off that for a very long time.

3. How are you going to mount the panel? Are you going to move it with the sun or keep it flat on the roof of your trailer? Do you like to park in the shade? Are you going to use a MPPT charge controller? These all affect how well you panel works and charges a battery.

4. Do you know anyone who has this brand of panel and what do they think? Some look good on paper but are not so good in reality.

I hope that helps.

Matt

[wannabefree]

I'm no solar expert but am considering adding a panel to our tear. I do know a bit about electricity, though.

For battery charging, you normally size the charger at about 1/10 the capacity of the battery. So if you want to charge a 40Ah battery, a 4A charger is about right. A lower value will still charge the battery, but it will take longer. A higher value will charge it faster, but at the expense of battery life due to heating and venting.

Lead acid batteries have a coulombic efficiency of about 75%. That means you only get out about 75% of the energy you put in. So to charge that 40Ah battery, you need to put in about 50Ah. So a 4A charger will take roughly 13 hours to recharge that 40Ah battery.

Now, for solar charging, to reproduce that same effect, you would need a 48W panel operating at peak efficiency for 13 hours. But they rarely operate at peak efficiency, even if you have a tracking system that follows the sun. And you rarely get 13 hours of uninterrupted sunlight. So you have to oversize the panels to overcome the inefficiencies. A 60W panel might just barely be sufficient for the 40Ah battery. A bigger battery will require correspondingly larger panels. Of course, we are talking about fully recharging a battery, something you may not need.

I use a 35Ah battery that usually just runs LED lighting and my Fantastic fan. I think I will use an 80W panel to recharge. In the meantime, I recharge off the car if I think we will stop somewhere without shore power or be without AC for more than 2 days. That turns out to be a lot cheaper than a panel, too.

[Travis]

Travis,

Hopefully, I can help you a little bit. If the numbers hold true then it may work for you. I am going to have to say may because I don't know some vital information.

1. What is the draw? When you say minor appliance, it can be a big difference. For example there is a huge difference between a LED light and an Air Conditioning Unit.
I would be running some LED lights, a radio at times, and either an F.Vent or A/C.
2. Are you going to run panel to a battery bank and charge it up or are you going to skip the battery all together? You can have a fairly large battery bank and run off that for a very long time.
Yes I will be using a battery, and mostly using the panel to keep it charged.

3. How are you going to mount the panel? Are you going to move it with the sun or keep it flat on the roof of your trailer? Do you like to park in the shade? Are you going to use a MPPT charge controller? These all affect how well you panel works and charges a battery.
I'm thinking of a swivel mount in order to chase the sun around.

4. Do you know anyone who has this brand of panel and what do they think? Some look good on paper but are not so good in reality.
NO

I hope that helps.

Matt

[dreadcptflint]

I would be running some LED lights, a radio at times, and either an F.Vent or A/C.

If you are set on the A/C then you need to get you power from a hook up. There is no way that you will be able to keep up with Energy usuage of a A/C unit. However with a decent deep cycle battery then you should be able to keep up with your usuage. If you think that you are going to run the fan and radio for extended periods then you may wish to step up with a second battery and /or a larger panel.

You might want to check with some of the solar forums to see if the panels that you are concidering are quality. I usually pick the brains at http://www.solarpowerforum.net/forumVB/index.php Unless you have money to burn it is always a wise idea to get multiple opinions.

I am curious to see what you are using for a swivel mount. Do you have any pictures?

[wannabefree]

A good solar resource: http://pvcdrom.pveducation.org/index.html

Simple rule of thumb:
Add up your load watts. Double it. Buy panel accordingly. Pray for sun.

[astrotrailer]

I have a 130 amp hour battery which can support me for multiple days if the sun isn't out. I wanted a solar
system that would totally replace the need for a AC/DC charger, so I went with 160 watts of solar. This gives
me 9.6 amp peak which is close to an ideal amp charging rate for my battery. I went with a couple of Sharp
80 watt panels which I mounted side by side on aluminum angle stock. This fit the open roof area on my
5x8 trailer behind my fantastic fan.

I think you need to decide if you are going to be mostly away from the power grid (remote camping) and for
how long. If you need to only use battery and solar, you should choose the most efficient lighting using LEDs.
It also helps to stay away from 120 volt inverter. If you are powering a laptop, get a 12 DC power supply instead
of using the 120 volt one. I run my LED lights, laptops, astronomy mounts and camera, 1.8 amp propane furnace,
fan and personal swamp cooler using 12 volt power only. I monitor my power draw and charging rate with a couple
of DOC Wattson meters. In the colder season when I use my furnace, I have less solar but the panels have been able
to keep the battery charged.

I only turn on my 1000 watt inverter if I want to run my blender or 6 amp vacuum cleaner. I vacuum early enough
in the day so my panels top off the battery before the sun goes down. The blender only takes about a minute to do
its job so I turn off the inverter as soon as I am done.

Here is my advice.

Pick out the most efficient 12 volt devices you can find to meet your needs. Calculate your usage of each device over a
24 hour period and multiply the hours of use times the amps. This is your 24 hour draw on your battery. Pick a battery
that is at least 4 times the amp hours of your 24 hour draw. This will give you at least 48 hours before you need to
recharge your battery. Size your solar panels to meet the ideal recharge rate for the size of battery you need.
Get a good 3 stage solar charge controller. If your charge rate is under 15 amps, PWM will be fine, but MPPT is
better more efficient for larger systems (300 +watts). You also need to consider where you live and camp and
if you plan to camp in the winter season. There are maps that can give show you the intensity of the sunshine
for the time of year. Southwest will alway do better than the east or midwest. Summer is much better than
winter.

If you always camp in developed campgrounds with 120 power, don't bother with solar.

[bdosborn]

The performance numbers look good. The Vmp at 18V is good for charging a 12V battery and will work with a PWM controller (cheaper) in hot weather. The warranty is a just little weak, especially if it is a crystalline type panel, but acceptable. A 60 watt panel is the the minimum size for a 100 amp-hour battery, which a lot of guys on the forum (myself included, till we sold it) happily run in their tears. Now its just gets down to cost. There's a glut of 60 watt panels on eBay right now that are in the $3-4/watt range so that gives you an idea of what you should pay.

Bruce
P.S. emiller runs a 60w panel on his tear and is happy with it.