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!

[eflyersteve]

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.

Awesome information! I really appreciate it.

[pianotuna]

Hi,

It was an Alberta Provincial Park. They did have another spot, but it was down at the bottom of the hill. There was no cell phone signal to feed my addiction to the wobbly wide web--and no nice view as there was up top. It was the last site available, and I was tired. It was a "one night stand".

rexlion wrote:

pianotuna wrote:
X2 (except getting up early)

Just think how fun it is to have to break camp to go buy propane for a fixed tank! Then you get back and some numbskull has set up in your spot. (The campground host sided with the newcomer btw, in spite of the paid sticker on the post).

Sheesh! Did the host find you another campsite, since you'd already paid for the next night? I'd have raised holy heck and contacted whoever supervises that Bozo. Who ever imagined that one might have to inform a camp host whenever one leaves the CG to sightsee, run to town, or whatever?

[brulaz]

pianotuna wrote:
Hi brulaz,

At 6000 watts of storage there may be four 12 volt jars--so I'd jump to 48 volts. My gut feeling is that there are more devices at 48 volts than at 24.

IIRC 2oldman went from 12 to 24, and found it less than pleasing so has jumped to 48 volts.
...

Was never exactly sure why 2Oldman went up to 48V, but since he was upgrading pretty much everything, including his batteries to LiFePO4, it made sense. You can double your system wattage but still use the existing wiring by doubling the system Voltage.

And with more cars going to 48V start/stop systems, I suspect that 48V will be the wave of the future in solar systems.

But when I converted, the 24V stuff was cheaper and more was available. All the way from little things like USB port converters that can work on anything from 12V to 32V, upto 12-24V solar chargers and inverters.

But there were some other practical reasons that were more important to me:
- 4 relatively new GC2s and no room for more unless I completely replaced them with AGMs or a LiFePO4 battery bank inside the trailer. Because of the $$ that was not going to happen.
- Three 72 cell panels (690W) currently wired in parallel and no room for another 72 cell panel AFAIK on the roof. My MPPT only goes up to 100V, so I couldn't rewire all three in series.
- the Kisae 24V 2000W inverter was being sold off at a discount.

But yes, starting from scratch with a high powered system, 48V would be the way to go.

[BFL13]

If you go 24v batts, be sure the solar panels are 72 cell. ie, one 24 or two 36 cell 12s in series.

I ran a test with a 60 cell 24 on 24 and it got the batts to 30v and that was as high as they would go. Fine for regular charging at 14.8 equivalent of 29.6 but no good for any kind of over-charge conditioning.

I suppose the same would be true with 48 on 48s.

[time2roll]

For the op I would stick with 12 volts.

[pianotuna]

Hi brulaz,

At 6000 watts of storage there may be four 12 volt jars--so I'd jump to 48 volts. My gut feeling is that there are more devices at 48 volts than at 24.

IIRC 2oldman went from 12 to 24, and found it less than pleasing so has jumped to 48 volts.

I believe time2roll stayed with 12 volts--but has 600 watts of solar. His generator lives at home now.

brulaz wrote:

pianotuna wrote:

...
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
...

If a person had >2000W loads, I would go up to 24V and perhaps specify AGM batts.

Under load the 24V will halve the %V drop of batteries, wire and connectors, and AGMs tend to drop less V than FLA in the first place.

Even with our 2000W inverter and <2000W loads, 24V has been very helpful.

[rexlion]

pianotuna wrote:

Just think how fun it is to have to break camp to go buy propane for a fixed tank! Then you get back and some numbskull has set up in your spot. (The campground host sided with the newcomer btw, in spite of the paid sticker on the post).

Sheesh! Did the host find you another campsite, since you'd already paid for the next night? I'd have raised holy heck and contacted whoever supervises that Bozo. Who ever imagined that one might have to inform a camp host whenever one leaves the CG to sightsee, run to town, or whatever?

[brulaz]

pianotuna wrote:

...
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
...

If a person had >2000W loads, I would go up to 24V and perhaps specify AGM batts.

Under load the 24V will halve the %V drop of batteries, wire and connectors, and AGMs tend to drop less V than FLA in the first place.

Even with our 2000W inverter and <2000W loads, 24V has been very helpful.

[westend]

I have a 235W panel on a 22' trailer. There is room for a second panel because I don't have roof-top AC. The raised option obviates a lot of concerns about shading.
Yes, microwave usage means more of everything in the general sense but it can be done without too much pain. Right now, I choose to use other options besides microwave or high-draw coffee pot. That may change as my system evolves.

[pianotuna]

BFL13,

Previously a 1987, but now in a 2005 which I purchased in 2009. I do know where to "borrow" power but..that is not ethical so I won't do it.

I was traveling in Alberta at the time of the campground incident. Part of being on holidays for me, is using campgrounds LOL.

Here is the location:

https://www.albertaparks.ca/parks/south/lundbreck-falls/information-facilities/camping/lundbreck-fal...

[BFL13]

PT, I thought you were now one of those "urban campers" who have ancient Class Cs that hang out at the library parking lot and then move to a grocery store parking lot, and then who knows where, every day. They even know where to plug into the XMas light 15 amp receptacle at that community park lamp post unless they get chased away by the By-Law guy in his van.

Campgrounds? You just have to get creative like those other guys. 🙂

[pianotuna]

X2 (except getting up early)

I miss the larger battery bank I used to have.

But I can make a pot of coffee for about 7 amp-hours, about the same for toast and do a soft boiled egg (steamed actually) for about another 9 amp-hours. The heated water is used for washing the dishes.

Just think how fun it is to have to break camp to go buy propane for a fixed tank! Then you get back and some numbskull has set up in your spot. (The campground host sided with the newcomer btw, in spite of the paid sticker on the post).

BFL13 wrote:


OK 🙂

My big thing is I get up early. Way too early to run the gen against campground gen hours. So I want my breakfast now! I want toast in a real toaster (high amp draw) not that horrible bread- burner on the stove- top that sets off the fire alarm and gets the dogs barking like mad, waking up the entire campground, who mostly seem to sleep in till lunch-time. 😞

Then I want coffee. More inverter draw with an electric kettle unless I boil water on the stove. It happens that if there is some solar available later that day, I will use the kettle instead of stove- propane, which I have to go downtown to a gas station that has propane to replace.

I have a big inverter and enough battery bank to run everything I want without waking everybody up at 0-dark thirty. Later that day, if needed, I can run the gen or if it is sunny, let that sunshine take care of things.

People here, who keep saying, "Leave that big stuff for your gen." must be among those who sleep in past when gen hours start.

[CA_Traveler]

Besides panel mounting close to the roof there are raised panel mounting options which can solve your problem. I talked to every owner with raised panels that I could find. Here's one of my panels.

[BFL13]

rjxj wrote:
It isnt that the micro will consume a ton of amp hours, it's that it has a high current draw. Battery, inverter and cable sizes all go up when trying to power something like that.

This is a general statement that told him that his overall system requirements jumps when he powers a micro.

It isnt that the micro will consume a ton of amp hours

He wants solar
If he stays away from high draw items his set up costs are lower
RUN the micro off a generator

Always looking for another pissing contest.

OK 🙂

My big thing is I get up early. Way too early to run the gen against campground gen hours. So I want my breakfast now! I want toast in a real toaster (high amp draw) not that horrible bread- burner on the stove- top that sets off the fire alarm and gets the dogs barking like mad, waking up the entire campground, who mostly seem to sleep in till lunch-time. 😞

Then I want coffee. More inverter draw with an electric kettle unless I boil water on the stove. It happens that if there is some solar available later that day, I will use the kettle instead of stove- propane, which I have to go downtown to a gas station that has propane to replace.

I have a big inverter and enough battery bank to run everything I want without waking everybody up at 0-dark thirty. Later that day, if needed, I can run the gen or if it is sunny, let that sunshine take care of things.

People here, who keep saying, "Leave that big stuff for your gen." must be among those who sleep in past when gen hours start.

[azrving]

It isnt that the micro will consume a ton of amp hours, it's that it has a high current draw. Battery, inverter and cable sizes all go up when trying to power something like that.

This is a general statement that told him that his overall system requirements jumps when he powers a micro.

It isnt that the micro will consume a ton of amp hours

He wants solar
If he stays away from high draw items his set up costs are lower
RUN the micro off a generator

Always looking for another pissing contest.