Hey Everyone,I previously asked a question regarding installing a 120v only fridge and the solar/battery/inverter system to support it.I spent almost 7 years full time in my last RV and look back at how much benefit I could have obtained from a 500-1000 watt solar install.Unfortunately solar was too expensive at that time.I am currently working to equip my latest rig for travels to Mexico. I was going gangbusters with my planning for solar when it became clear to me that I won't be doing nearly the amount of dry camping in Mexico that I did traveling the US.My solar system questions were well answered and I came to the conclusion that I would need to install a larger system than I had originally considered if I wanted to support my electric needs.Given that I will not be doing the boondocking that I would if I was traveling in the US I am wondering if the solar benefit is going to be worth the cost?If I have shore power every night would I be better served to run my generator when I am without shore power? Solar system, batteries & inverter would cost me close to $2000. I can buy a lot of generator fuel & maintenance for $2000.I like the idea of the solar setup but it is costly and adds an additional level of complexity to my electrical system. "The more parts in the system, the more there is to break"Mexico travelers: What do you think??

Hi,I'm not a Mexico traveler--but there are reports from those who do so, and they often end up using their solar systems when there is shore power.Voltage, both too high and too low, is an issue. I think reliable power 24/7 is also an issue.I'm in the planning stages for phase 3 of my solar system where I will bump up to 1500 watts from the 256 I have now.I found a key component just today--which is a charge controller that can handle 120 amps at 12 volts. It has the advantages of being relatively cheap, and made in USA. Before I was going to have to gang two charge controllers together which was going to cost at least $1100. Now I can do it for $179.00From my point of view, solar is the nearest thing to a free lunch that I'm every likely to find.

Best 2300dollars I ever spent was on my SOLAR. One happy camper

Yo PT... Which controller did you get? And sheesh... If you won't share ;) buy another and send me one... I'll gladly send you the money....

Yes, do the solar thing. While you are at it, install a decent PSW inverter, 2000 Watts minimum. And take along a 40 Amp or better portable battery charger that you can plug into shore power directly.Often shorepower at Mexican RV parks is less than adequate, sometime dangerously low, or high, or both, depending on time of day.The reason for the other charger is that it is unlikely to be damaged by poor line voltage yet will give some charge to the batteries. If you have lots and lots of panels and never camp under trees or other shaded places you could skip the charger, but it is a good backup if you need to charge and can't or don't want to use your generator. When we are camped with shorepower in Mexico we usually leave the inverter enabled. Our inverter (Xantrex Prosine 2.0) will cut power to the coach if incoming AC is out of spec. Leaving the inverter enabled means the TV doesn't switch off in the middle of something "important" :) We disable the invert function at bedtime and when we are out.We have often found sites where in shorepower is unusable; open ground or hot/neutral reversed. In these cases the portable battery charger can be put into play if the usage exceeds the solar charging.

Unless prices have really plummeted recently, $2000 isn't even close to what it's going to cost you if you're going to run a refrigerator and all the other stuff in a 36' 5er. one of the things that you need is enough battery capacity to last overnight. I could do some blue-sky calcs if you send me some specifics via PM

To solar or not to solar? That is the question....

37 Replies

PNW_Steve
Explorer
Aug 21, 2014
pianotuna wrote:
Hi Steve,

The inverter needs to be sized at 125% of the maximum. I can see no reason to not use the 2k pro watt since there is little difference in price between it and the next smaller model. It is a "throw away" unit so it is better to oversize than run a smaller unit on the edge of maximum.

Since it is a trailer, I would run the roof air for the last two hours of travel. I hate the heat.

I am with you on the heat. I spent 7 summers in the middle of the Mohave Desert. Fortunately the A/C in my 29' will drop the temp from 90F to mid 70s in about the time it takes me to make camp.

I ran the numbers on the scenario above except 25% duty cycle instead of 33%. Estimated run current goes from 1.08A (120v) to 1.39A. I wish I had access to actual locked rotor current and run current. That would give me more confidence in sizing the inverter.
pianotuna
Nomad III
Aug 21, 2014
Hi Steve,

The inverter needs to be sized at 125% of the maximum. I can see no reason to not use the 2k pro watt since there is little difference in price between it and the next smaller model. It is a "throw away" unit so it is better to oversize than run a smaller unit on the edge of maximum.

Since it is a trailer, I would run the roof air for the last two hours of travel. I hate the heat.
PNW_Steve
Explorer
Aug 21, 2014
pianotuna wrote:
Hi,

I think your duty cycle on the fridge is too high. But it is better to err at too high than too low.

You may find yourself running the generator a lot more than expected in Mexico because the power grid is unreliable.

Why would you not run the roof air while traveling? Does the dash air "cover" the rest of the RV?

I am guessing at the duty cycle based on what I have read. No solid info on this particular model.

Assuming a known daily average consumption of apx 1 kWh daily we will pull the same A/H total daily from our batteries regardless of duty cycle.

Lower duty cycle will mean a higher current draw for a shorter period of time. This will dictate a larger inverter to support the higher start/run current.

As to the roof air: I try not to run it when we are not in the trailer for extended periods. This would include times that we are underway.
Almot
Explorer III
Aug 20, 2014
Turtle-Toad wrote:
Don't know about your system, but mine keeps track of the battery cycles and automatically adds a finishing charge when needed.

Any solar system will automatically add charge whenever battery demands it - if solar panel can provide it, of course.

Generator-based system could do this, but not silently, and not too efficiently. Even on low output it will still make a bit of noise and consume a bit of fuel. This how they are, making noise even at 1A.
Almot
Explorer III
Aug 20, 2014
PNW_Steve wrote:

When I first started looking at solar I expected that I would boondock extensively as I have in the past in the US.

Unfortunately it has been made quite clear to me by folks who have traveled extensively in Mexico recently that boondocking in Mexico is not a good idea except in limited circumstances.

That means I will be spending the majority of my time in parks with hookups.

Your initial post was TAD unclear. Not clear whether you are going to boondock less in both US and Mexico, or boondock less in Mexico, while keeping doing it same as before in the US.

If you will spend most of your time in parks with hookups, then you don't need a big solar. 100W portable system would be enough, to reduce the generator time a little, on those rare occasions when you do drycamp.

A pure "boondocking", i.e. in wilderness or unoccupied land, might not be a good idea in some places in Mexico, but in terms of energy it is no different from doing it on a dry camp. Maybe I was traveling in a different Mexico, because I don't know why "drycamping on the camp" is not a good idea, at least during October through May when you don't need A/C. The biggest - or the only - drawback is that such camps are often noisy, because gringos are trying to live a "North-of-the-border lifestyle" without a NOB power supply, and often - without any solar. Which means - running generators all day long. On the camps where generators use is regulated, it's quiet, and cheap, and - usually - less crowded.

To each its own, of course. You don't need solar if you are on hookups.
pianotuna
Nomad III
Aug 19, 2014
duplicate post
time2roll
Nomad
Aug 19, 2014
PNW_Steve wrote:
If I elect not to install the solar I will be running my generator in the event of power failure or when traveling between parks.
I would still add a 1000 watt inverter for in transit. (for the fridge not the air conditioner) ;)

May also run fridge overnight without the generator if necessary or during an unattended power failure.
reed_cundiff
Explorer
Aug 19, 2014
We had good luck running unreliable power through battery charger (it does not pay a lot of attention to wildly varying voltage) and then running microwave or air conditioner via inverter as has been discussed elsewhere - one German couple burned out just about everything in Yucatan. We lost one micro-wavein Baja and another in Yucatan due to bad power and almost lost an ac unit at a state park in Colorado.
Reed and Elaine
pianotuna
Nomad III
Aug 19, 2014
Hi,

I think your duty cycle on the fridge is too high. But it is better to err at too high than too low.

You may find yourself running the generator a lot more than expected in Mexico because the power grid is unreliable.

Why would you not run the roof air while traveling? Does the dash air "cover" the rest of the RV?
PNW_Steve
Explorer
Aug 19, 2014
PNW_Steve wrote:
My plan was for around 300-400 watts and a 225AH battery bank. After some discussion I realized that I will need 500+ watts of solar and a 300+ AH battery bank.

I found a package with 5-100 watt panels, connectors, wire, mounts and charge controller for less than $800. Battery bank will be 4 - Trojan T105's and battery cables $540.

Inverter choice is still open. I see 2000 watt PSW inverters with decent to very good reviews ranging from $200-$850.

That puts me at $1540-$2190 plus a few bucks for stray hardware.

The fridge that I am looking at (per the "energy guide") consumes 1.08 kWh daily. I cannot find the specific current draw. I can make a good guess that (assuming a 33% duty cycle) that the compressor will run 8 of 24 hours. If so then it will consume .125kWh per hour of compressor run. I=P/E. 1.04amps=125watts/120volts.

1.04 amps @ 120v and an 80% inverter efficiency would yield a 130 AH daily draw on my battery bank.

The question is still: is it worth the time and $$ to save generator run time? Fuel cost for generator run is generally $.75-$1.00 per hour.

From some of the comments above it sounds like supplemental power may be useful even when in a park with hookups. With that factored in I am leaning towards installing solar.

Refresh of proposed solar system install.

Forum Discussion

To solar or not to solar? That is the question....

37 Replies

About Bucket List Trips

Related Content

Another solar question.

Solar questions

solar question

Solar question

Solar Questions