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obiwancanoli's avatar
obiwancanoli
Explorer
Mar 30, 2018

Solar Solution Adequate?

Hello, everyone!


Pretty new to the Class A (2017 Newmar Ventana LE) lifestyle, I had the dealer install a 160 Watt Zamp Solar Deluxe kit, with a 30-Amp Controller, anticipating I would have a need and desire to increase capacity. It was important that the Zamp panels make it easy to add a panel or two with simply a plug-in feature, requiring minimal effort to do so at minimal cost (short of self-installation).


While I don't have specific plans to boondock extensively, I also expect I will want to seek hideaways and places absent shore power, so that I may also enjoy the benefit of dry camping for 1-2 weeks at a time, and perhaps longer. After much research, and tapping the experience of the technicians who initially installed the first panel, I've chosen to add two additional 160 Watt panels (for a total of 480 Watts, producing 8.7 Amps each (total 26.1 Amps).


Since the original dealer is 500 miles away, Amazon offers these panels at a much better price than the original dealer, and I'm planning to have a local Zamp dealer install them, which saves me about $400, when compared to having the original dealer sell and install each panel.


Based on the above information, would you conclude that my solution should, under most circumstances, work well for my anticipated needs? If not, what would you recommend?


Thanks for your input and advice - it's much appreciated!


Michael

26 Replies

  • 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.
  • 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?
  • 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.
  • 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."
  • 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.