Solar on a small TT

[eflyersteve]

I'm looking at a small travel trailer (starcraft satellite 17rb) which is only about 20ft long. Roof is composite one piece without much of a flat area. One thing that I absolutely want on my next RV is solar. I would prefer this be roof mounted if possible with enough battery to dry camp and run lights, water pump, TV, stereo, charge phones and laptop and occasionally run the microwave. The small size of the trailer would seem to bring some challenges because there isn't much area for gathering solar. This may require me to use some carry-out portable panels that I feel are less than ideal (theft mainly).

So my question - is there an ideal minimum roof area on an RV to provide enough room for the required solar panels to accomplish what I want? I'm not restricted to such a small travel trailer if I need to go larger to get enough solar I will, but was curious if someone had already considered this and what conclusions were drawn?

Thanks!

[BFL13]

"Of course this has everything to do with solar when that solar is the means of recharging a high capacity battery bank capable of powering high draw devices. Good grief, one is useless without the other."

Nope. Running a microwave at 140 amps for 5 minutes uses 11.7AH. Peanuts!

Replacing that with solar (add 10% of course ) 11.7 + 1.2 = 12.9AH would take however long at whatever amps of solar. The thing being how much other stuff was done at high or low amps that ate AH that day?

My point is that the actual high amp draw for a short time is not much out of your daily usage. So how much solar you have has nothing to do with it. The big picture daily AH usage does matter for how much solar you need if you expect to replace those AH daily.

[pianotuna]

A run everything system

48 volts with 27 kwh of storage and 2000 watts of high voltage panels combined with a 4000 watt hybrid inverter/charger

A run most things system (or everything but the roof air)

12 volts with 6 kwh of storage and 600 watts of high voltage panels combined with a 3000 watt hybrid inverter/charger

A weekend warrior system

12 volts with 6 kwh of storage and 300 watts (enough to do an equalization) of high voltage panels combined with a 3000 watt hybrid inverter/charger

A maintenance only system

12 volts with 3 kwh of storage and 100 watts of high voltage panels with a 300 watt inverter for convenience charging of low load devices such as cell phones and the like.

[SoundGuy]

rjxj wrote:
You were probably on the low energy use side of things until you mentioned microwave.

SoundGuy wrote:
It's interesting how often folks will come up with a shopping list of small draw items they want to power with battery / solar but then almost as an afterthought throw in a high draw appliance such as a microwave oven and think nothing of it. :R That tells me they haven't thought this through thoroughly, not realizing what a game changer any high draw device represents. Some solar aficiondos willing to throw their wallet at a project like this wouldn't agree but I see solar as most practical for those willing to actively manage their power consumption and restrict their usage to low draw devices.

BFL13 wrote:
Nope. High draw items are a matter of inverter size and battery capacity. Nothing to do with solar. Solar is just another way to recharge the batteries.

Of course this has everything to do with solar when that solar is the means of recharging a high capacity battery bank capable of powering high draw devices. Good grief, one is useless without the other. :S

[BFL13]

SoundGuy wrote:

rjxj wrote:
You were probably on the low energy use side of things until you mentioned microwave.

It's interesting how often folks will come up with a shopping list of small draw items they want to power with battery / solar but then almost as an afterthought throw in a high draw appliance such as a microwave oven and think nothing of it. :R That tells me they haven't thought this through thoroughly, not realizing what a game changer any high draw device represents. Some solar aficiondos willing to throw their wallet at a project like this wouldn't agree but I see solar as most practical for those willing to actively manage their power consumption and restrict their usage to low draw devices.

Nope. High draw items are a matter of inverter size and battery capacity. Nothing to do with solar. Solar is just another way to recharge the batteries.

Actually since the weather keeps changing so sometimes you need to run the gen and a charger, solar should be viewed as just a way to extend the time between generator/charger sessions.

All people are really talking about is how much solar will get you how much time between gen sessions.

Unfortunately, that can easily lead to extended periods of incomplete recharges daily, thus sulfation of the batteries. Can't win them all!

[Shadow_Catcher]

We have a single 185W high voltage panel that requires an MPPT controller to handle the 70V no load. What this does for us is you get usable current even when shaded. We have a large teardrop and the system powers TV/DVD stereo/XM radio an Dometic CF50 refigerator lights fans etc.

[rexlion]

If theft really concerns you, perhaps you can mount some panels onto the roof of your tow vehicle. Just a thought.

I have a portable 70W panel that I move around and angle to catch the sun.

[Lwiddis]

"This may require me to use some carry-out portable panels that I feel are less than ideal (theft mainly)." IMO you will get tired of set up and take down of portable panels. And I'm not a fan flexible panels for heat and cupping reasons.

Most RV solar companies sell multiple sizes of rigid panels. 100 watt panels are not required. WindyNation for instance has 30 watt panels at 16x27 inches and 60 watt panels at 25x26 inches. Other companies have other sizes. Something will fit with enough watts to recharge your batteries.

[pianotuna]

Hi,

You may be a candidate for semi flexible panels that could be permanently attached to the roof.

Beware any shading.

[SoundGuy]

rjxj wrote:
You were probably on the low energy use side of things until you mentioned microwave.

It's interesting how often folks will come up with a shopping list of small draw items they want to power with battery / solar but then almost as an afterthought throw in a high draw appliance such as a microwave oven and think nothing of it. :R That tells me they haven't thought this through thoroughly, not realizing what a game changer any high draw device represents. Some solar aficiondos willing to throw their wallet at a project like this wouldn't agree but I see solar as most practical for those willing to actively manage their power consumption and restrict their usage to low draw devices.

[vermilye]

I don't know what your roof space looks like, but I had an Escape 17B that came with an optional 95 watt panel mounted across the back end of the roof. I added a 100 watt panel to the front. The combination worked well combined with a pair of 232 amp hour 6V batteries during the summer months, but during the low angle winter sun I found I needed to add a portable panel (a 160 watt) to keep up with my usage. All 12V panels wired in parallel through a Blue Skies Sun Charger 30 PWM controller.

Using a 1000 watt pure sine wave inverter, I typically make a pot of coffee in the morning (6 amp hours), sometimes toast (9 amp hours), do a bunch of photo editing on a power hungry laptop (5 - 10 amp hours). I have a 600 watt microwave that uses 1.5 amp hours per minute that I sometimes use for dinner, although my primary cooking is on a propane grill/stove. This is on top of the normal uses. I average 30 - 40 amp hours per day.

[DrewE]

eflyersteve wrote:

Microwave use is not an important requirement compared to all the other things I would like to be able to run, so optionally I can just plan to cook with propane instead in trips without shore power.

I think that makes a whole lot of sense. Propane is much much more energy dense than lead-acid batteries, though of course cannot be "recharged" using solar power.

A crock pot often works nicely with solar power. Just take care to investigate the power requirement; a normal traditional crock pot uses a pretty low wattage element, maybe a couple hundred watts, but there are also dual-use ones that can be fryers and have a much larger element. You would want the first kind, of course.

[azrving]

eflyersteve wrote:
Thanks for the replies everyone! I was thinking I would shoot for 400 watts minimum of solar. More curious how easy it is to get 400 watts on such a small roof. Probably isn't easy based on the size of panels. I was looking at 250-280 watt panels which are larger than the 100 watt panels (of course), but it actually might be easier to fit smaller, lower output panels on a small roof so this gives me some ideas.

I'll see if I can get on the roof of one and see what available areas I have. If needed, I could always try and install as much rooftop and then make up the rest with a portable setup that I would deploy in the mornings and stow before heading out. Second concern will be where to store batteries. I'll likely start with lead but move to a self-built lithium battery eventually.

Microwave use is not an important requirement compared to all the other things I would like to be able to run, so optionally I can just plan to cook with propane instead in trips without shore power.

Yes, 24 volt panels have fantastic prices but 12 volts will often fit the footprint better. Look at panel dimensions then cut out some cardboard shapes and go up and see what fits. As mentioned look for potential shading issues. I can tilt in either direction but of course try to place the awing to the south. Consider where you will places a combiner box if you use pwm and where you will send the cable down. Frig vent, stack or roof termination.

[eflyersteve]

Thanks for the replies everyone! I was thinking I would shoot for 400 watts minimum of solar. More curious how easy it is to get 400 watts on such a small roof. Probably isn't easy based on the size of panels. I was looking at 250-280 watt panels which are larger than the 100 watt panels (of course), but it actually might be easier to fit smaller, lower output panels on a small roof so this gives me some ideas.

I'll see if I can get on the roof of one and see what available areas I have. If needed, I could always try and install as much rooftop and then make up the rest with a portable setup that I would deploy in the mornings and stow before heading out. Second concern will be where to store batteries. I'll likely start with lead but move to a self-built lithium battery eventually.

Microwave use is not an important requirement compared to all the other things I would like to be able to run, so optionally I can just plan to cook with propane instead in trips without shore power.

[clarkster]

I am a huge fan of solar power......it's FREE after the initial costs are paid.

But.......solar requires sunshine to work.
If you like a nice, cool shady spot.....the output will disappoint.

You cannot easily move the trailer around to get some sun with a rooftop, but with a 15' cable from a portable panel, finding a sunny spot becomes less of a challenge.

A typical 100W solar panel is 47" long by 21" wide.

[time2roll]

Microwave generally requires 2000 watts sine wave inverter and 4+ batteries and then 400+ watts solar. You might get by on less but it will have compromises.

Otherwise it is just about fitting panels on the roof while minimizing shadow issues from vents, A/C, antenna etc. 200 to 300 watts should serve well with two batteries for off-grid camping.

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