Solar Solution Adequate?

300 watts is adequate for our dry camping/boondocking with a full recharge by noon or so on most days for our total 240 AH batteries. However, it depends on your electric use, and battery capacity is also an issue. No need to make juice and have no where to put it. Do a liberal calculation of the AHs you use daily dry camping then multiply it by 1.5. That number keys you in to necessary solar watts and battery needs.

What will the climate and shading conditions be at your hideaways? What sort of electrical devices do you intend to use, and for how long? Is your fridge an absorption fridge or a residential fridge? Without information on these things, it's impossible to say much other than "maybe, maybe not."

Without your response, Drew, I would not have know these issues were important, so thank you for noting it...

First, no idea what climate and shading conditions will be, but I completely understand the significance. I would anticipate SEEKING shady areas, but, one never knows when boondocking... Climate objectives are, of course, sunny clear skies, but that's not what will happen, I'm sure, and cloudy days will be in the equation, no doubt.

As for electrical devices, I have a fridge that will function via AC or Propane. Also, have TV, and anticipate SOME usage, but hard to put a finger on that, and recognize that fridge, TV, and especially A/C can be huge draws on power that may not - likely not - be sufficient to run all these for extended periods.

Nevertheless, I'm generally cautious about such use, even in my own home, and am attempting to minimize generator use as much as possible in these circumstances, knowing it likely will be required to some extent.

Hi,

If you have and absorption fridge that runs on propane it is NOT a residential unit.

This series of articles may help you understand solar a bit better:

https://freecampsites.net/adding-solar/

What are you needs. Do you know how much amp-hrs you want to use at night. TV, DVD, lights, Refrig, microwave use? I suggest you not use the refrig or microwave but that is your call. When you camp in hideaways will the sun hit your collectors. Winter fall shorter sun light time and lower angle than summer. Can you adjust the collectors to the best angle to get maximum sun?

As was said, you have an absorption fridge, rather than a residential one, as it can run on propane. That is good in this case; it uses a lot less electricity (since the main energy to run it comes from the propane).

For RVs, 12V electric usage is commonly computed in amp-hours (Ah), an amount of charge transferred by one ampere over the course of one hour. (It's not really a measure of energy per se, but since the voltage is taken to be more or less constant at 12V it is equivalent in practice). An absorption fridge might use an average of 1A when it's running, or 24 Ah per day; some use a good bit less, and probably some more, particularly if they have fans that must run for them to operate. Miscellaneous constant loads like the LP detector and CO detector might use a few Ah per day. Most other things are somewhat under your control--you can decide when and how much to use them.

Incandescent lights are an amp or two per bulb; LED lights a lot lower consumption. A TV probably uses around 2-5A when running, a laptop on average probably about the same (possibly a bit more when the battery is recharging).

Running the air conditioning from solar power in an RV is generally impractical, certainly without having a very large solar and battery setup and perhaps a small air conditioner to boot. A typical RV air conditioner would require somewhere on the order of 100+ amps from the battery bank when running, and they are usually run for extended lengths of time. If you need air conditioning, you need either a shore power connection or a generator.

Microwaves (and other heating appliances, like coffee makers or hair dryers) also use a large amount of power, but limited use may be possible as they often are not used for extended periods of time. You would need a good sized inverter to be able to do that, and a reasonably large battery bank preferably.

The other side of the equation from electric usage is how much power you get from solar. I'm not really an expert here, but I've seen claims from people who are more knowledgable than I here that, as a rule of thumb, you can reasonably expect to get the equivalent of four hours worth of full output per day under good conditions--clear skies, not too far north latitudes, open areas. That would mean maybe 80-90 Ah or so going into the battery. If you're in a shady spot, that could very well be dramatically lower...probably enough to keep up with the fridge, I would guess, but maybe not much else.

You would be very well served to get some decent instrumentation to see how your electric usage and solar charging are fairing. At a minimum, I'd suggest a decent voltmeter and ammeter--and the ammeter ought to read both positive and negative current. The voltmeter gives some idea as to the state of your battery (though it's not the best way to do that), and the ammeter shows how much current is being put in or taken out at the moment. Better, and preferred, is a battery monitor such as a Trimetric unit, which monitors voltage and current constantly and figures out the state of charge of the battery from them.

obiwancanoli wrote:
I have a Residential fridge, but do not know the power consumption details. I can tell you it will function via AC or Propane. Also, have TV, and anticipate SOME usage, but hard to put a finger on that, and recognize that fridge, TV, and especially A/C can be huge draws on power

Resi fridges do not run on propane. No TV draws huge power, but you will need an inverter. Yes, I'm aware of 12v appliances but let's keep it simple.

I didn't see a mention of what your battery bank is. How many amp hours? The usual rule of thumb is 100 watts of solar for every 100 aH of battery capacity.

While I understand that you may not have had enough interest in these areas to have measured usage or put meters on the system to test usage, a simpler question may be whether you have tried camping in the rig for a day or two with the system as it is now. If you find that your batteries are holding a greater than 1/2 or 50% charge after 2 days with the single panel, you know you will extend that with the additional ones. The amount of sun is constantly variable, and panels dont like even partial shade, but if a cloudy day cost you 50% of your possible charge rate, feel good knowing that you are still getting 50% of 24 amps versus 50% of 8 amps.
As to AC, thats a generator issue in almost all cases.

480 watts should work well with modest conservation to back it up.
I recommend converting to LED lighting if you don't have that already.