How many solar watts should I get?

Thank you everyone for the input. But.....dont misunderstand my intentions or goals. Its not to NEVER start the generator as there are some things I'll need that will only run when the generator is on, like A/C. I'm OK with that too but would rather only run it on necessary occasions if possible.

And its not like I'm running out of power but that I'd like to help the batteries.....as long as its affordable. Sure $500 would get me lots of watts but I can also run my gen for a long time on $500 of fuel. Crude analogy.....but just simple fact. If I can get away with a smaller portable solar unit that supplies "X" amount of electricity for whatever I'd like to offset, then thats the most convenient route for me. Permanently mounting is not going to work since parking in the sun is NOT an option unless there simple is no other place to park. And at that, I'd be looking somewhere else since dry camping in the direct summer heat of the sun is no fun. Who wants to run their gen all day just to stay cool. Even plugged in to shore power, depending on how hot it is, that can still sometimes be unbearable.

So back to the point, I guess I need to know how much usage I'm currently using to understand what size panel I need. So in saying that you guys made me think and I Googled RV calculators and came up with one calculator said that with the minimal usage we use, I could get away with 100 watts panel. With the few articles I've seen about easy lightweight 50 watt panels being a benefit, I just thought I'd ask you professionals.

One thing is clear - 50W is almost nothing. There is no exact answer to "How many watts?", but I'll try.

To live generator-free, you may need anywhere from 200W to 700W, flat panel. A little less with tilted panel. A lot depends on your habits. Not "needs" but habits. You don't "need" a 120V toaster and coffee-maker, from nutritional POV. Even if coffee is an addiction issue, there is an instant coffee and gas stove. Same goes for microwave, though eliminating this requires more learning.

You asked how to "calculate" your 12V draw. This spreadsheet I find useful in sizing a solar system. Note that it has "refrigerator" in both "Fantom loads" (LP frig) and DC loads (if you have 12V COMPRESSOR frig). Fan and some other items might be repeated as well, so make sure you check only one if you have one. Put zero where you don't have the load listed.

Also note that spreadsheet includes battery bank as well, because you do need enough batteries to last through some rainy spell until sun shines again.

The spreadsheet opens on Instructions page. If you haven't used Excel before - there are tabs at the bottom that say "RV Load Calculation" or "Battery sizing" etc. Don't remember, but I think they assumed a flat panel, no tilt.

Measuring the actual draw may or may not be better than using spreadsheets like this - you need to know the pattern of use, some loads draw different depending on task, and random measurement can be incorrect.

Kits like the one from Solar Blvd, VS procuring separate parts: buy a kit if this is easier. It usually includes a panel, controller, cables and brackets. At least 1 item you won't need at all (like brackets), and few other you might want to replace (like cables). I would buy all parts separately.

As to portable systems... 2oldam said it already. When it is big enough to provide enough energy, it becomes a pain to assemble-dissemble-load-unload every time you move or leave the camp. Unless you are many hours away from other fellow humans, you don't want to leave it outside.

KATOOM wrote:
The lightweight portable solar panels seem like a good idea since I like to park the TH in shade and having the ability to move the panels into the sun would be good. .. I'm not sure how much 50 watts will do.

Portable panel kits are attractive to the novice because they seem affordable and easy. The reality is they are underpowered and expensive.

I recommend at least 300w to really accomplish anything, and not portable. You'll get very weary of lugging panels in and out of the RV, and storing them. Put them on the roof and be done with it.

Sorry, but you'll have to just park in the sun.

If you want to gain a couple of days boondocking, you do not need enough to power your rig every day for a month. You say you are getting two days now, and I suspect that a 50 watt setup would double that, since you will be charging for four days to gain the two. The experts can tell you how many Ampere Hours per day that a fifty watt setup will provide.

If your idea is to never run your generator and use even more electricity than you currently are, then you will need the suggested systems.

KATOOM wrote:
How do I calculate my 12 amp/hours usage? Generally we're very frugal with energy usage but the most solar offset I can afford would be great.

You can get yourself a clamp-on DC amp meter (I have a permanently installed amp-hour meter, Victron BMV-600). You can turn on various devices and measure how much amp draw there is from the batteries. Then you can figure out how long you'll use that device. That will give you the total amp-hour draw per day. For example, my dinette lights draw 1.98A. I use them about 3 hrs per night so total amp-hours is 5.94A.

IMO a minimum would be 150 watts, and I would opt for 200 or more.
I have 210 and would like more.

How do I calculate my 12 amp/hours usage? Generally we're very frugal with energy usage but the most solar offset I can afford would be great.

I think you are better in the 200w zone.

200w, $460 shipped

A 50 watt panel will not do much more than keep your batteries up when you are not using them. While a 95 watt panel in full sun will keep up with my usage in a small 17' trailer with LED lighting & the usual loads (including making a pot of drip coffee each morning), most systems start out at a couple of hundred watts.

To determine how much solar you need, you should do a usage survey. Keep track of how many 12V amp/hours you use over a typical day for a week or so. The average daily usage is what you are going to have to replace if you want to depend solely on solar. Since the panel(s) will rarely put out their rated wattage, and you will have cloudy days, and of course, dark nights, you will need more solar wattage than your average use. You will also need enough battery to cover the times your solar system is not meeting your demand.