Community Forums

PJStough · 08-18-2016, 08:07 AM

Quote:

Originally Posted by glennwest

this is being done. Using lithium batteries and mini splits. The mini splits use an inverter compressor. Very low power. Research them before writing them off. Your math is off also. Both run on 1 15 amp breaker.

As I said before, if you have enough solar panels, and enough batteries, you can do most anything. I am talking practicality. The 11,200 mini split unit I looked at took 8.4 amps @ 120 volts. If there are mini splits that take less, they are no doubt, smaller air conditioners.

Also, where is my math wrong, so I can correct it?

MtnTrek · 08-18-2016, 02:46 PM

Back to OP:
Really your biggest benefit of solar power is to provide some level of convenience off-grid. To simply expect to circumvent $0.12 per KWH with a bunch of expensive equipment would not be the best investment. But everyone is different.

Be well.

Jeff6146 · 02-14-2018, 06:45 PM

Quote:

Originally Posted by okcnewbie

I triple dog dare you to try and replace $250 worth of electricity with solar.

At .12 per/Kwh that's about 64Kwh per day. Not gonna happen.

It's not the AC inefficiency you need to worry about it's the tin can.

that is very doable. i have a 44 foot with 2 big A/C. i just need to figure out my KW a day so i know what to i get.

Jeff6146 · 02-14-2018, 06:47 PM

you should be able to get a nice system for about $4500. it will pay for itself

Searching_Ut · 02-14-2018, 07:24 PM

If you’ll be forest service campground or similar where power isn’t available, and you can get by without air conditioning then solar is a great option. I put a thousand watts on my roof, flat mounted, 4 6 volt GC batteries, 2000 watt pure sine inverter, solar controllers, battery monitor, fuses, transfer switches etc. for right about $2,500 dollars. Of course I did all the work myself. This system allows short use of the wife’s hair dryer, drip filter coffee pot in the morning, Cpap through the night, normal light usage, minimal microwave usage, and several hours of satellite tv on most days even with some partial shading, afternoon thunderstorms etc. When we’re not being frugal, our normal battery drawdown is somewhere between 140 and 180 amp hours a day. Keep in mind, battery drawdown would be higher but for the solar supplementing our power needs during parts of the day when it’s not producing enough to support demand, let alone support demand and charge batteries.

On the other hand, if we need air conditioning, our rig requires both 15k ac units to be used if it’s much over 85 to 90, depending on how much if any shading we have on the trailer. There isn’t anywhere near enough space on the roof to support that sort of demand.

vsheetz · 02-14-2018, 09:19 PM

RV Solar can't be cost justified by ROI, etc. Its a convienence - reduces generator run time thus reducing noise and vubration. Residential grid tied can be cost justifued - if installation conditions are right.

I have 1500w on the RV. 2nd coach with solar. Dry camp quite a bit - typically in the deserts of the southwest. Residence has 28 250w panels grid tied - negative annual electric bill for four years since installed.

bddadles · 02-15-2018, 07:35 AM

I'm just going to throw my 2 cents in here and I'm pretty sure some won't agree but here goes.
We started full timing 9 years ago. We had big plans to cover the country and boon dock sometimes. It did not take long to determine that we did not like to boon dock for longer than a rally in the desert and our Honda handled that well. We never carried through on the install past the panels and the equipment to run them. In effect I have a $2200 battery charger and will not do solar on anything else in the future.
Be very sure what you are going to do and why. It definitely did not pay for us.

Brad

MisterT · 02-15-2018, 08:08 AM

agreed... and I think that there are many variables to whether 'solar' is really a cost effective purchase, or whether it's just a 'feel good' purchase.

what I mean is that, unlike 'permanent' solar for your home, where the panels are tilted and fully open to the sun at all hours, RV solar is NOT. Unless you are parked in full sun all day long everyday of your travels, solar is never going to reach it's 'potential' for monetary 'savings' that you might expect.

It WILL provide for less generator run time, but even THAT is suspect, as the generator will have some specific run times REGARDLESS of whether you have solar, or not. Running air conditioning will require the generator.
After the sun is past it's point of providing any real power, the generator will ultimately still be used to 'top off' the batteries for the night time hours, and probably also used in the a.m. hours prior to the sun being high enough to be effective.

Obviously, summer months are the time for solar, as winter months aren't going to have the same hours of sunlight due to it's shorter days and lower height in the atmosphere, with even more tilt needed.

Solar also only serves one main purpose, which is sometimes lost in the conversation for those contemplating adding it for the first time - battery charging...

Fewer batteries/battery size/hours = less benefits, since once the batteries are fully charged, the solar input provides no further benefit, until needed again. Having 20amps of incoming solar is great, in the middle of the day, unless your batteries are already full, then the power is lost.

More batteries/solar panels = more cost and more 'time' that solar must really be working, in place of any other power source, to offset that up-front cost.

I own some solar, and view it as a simply way to deploy 'quiet' battery recharging during the day, in order to limit generator time. If I want to use the microwave, at least for several minutes or more, then I'll probably have to use the generator anyway. If I want to run the a/c units, then I'll have to run the generator anyway. etc.

Engineers and Salespeople for solar will certainly explain the benefits of solar. Quiet. 'Free'. Easy, Mobile, etc.

but, the REALITY of RV mobile solar is very different from 'static' benefit calculations that are typical to 'home' type installations. It's easy to transfer those same type of calculations to mobile scenarios, but the real world is very different, and can be different each and every day. Parking in the shade changes things. Not tilting your panels changes things. Your batteries being already 'full' changes things. Being in the North, versus the South, changes things. How often you use your generator changes things. Even just the 'how you use your electricity' changes things.

If your RV is parked in full sun and never moves, it would change things.
If solar was 1/2 the cost to deploy than it is currently, it would change things.
If solar was 1/2 the size it is currently, it would change things.
If batteries where 1/2 the size and 1/2 the costs....

you get the idea. Enjoy! : )

p.s. I'm not against solar, but I'm just a realist. I understand 'calculations' and things like that to qualify solar as an 'investment', but I also understand that the 'real world' doesn't always meet our calculation expectations.

nothermark · 02-15-2018, 08:13 AM

It's hard to believe that the payback period for big solar will be rational for anyone full timing who does not migrate to better places in the really hot weather and is not dry camping a large part of the time. By that I mean less than 10-15 years. The chances of keeping the same MH with the same setup for that long seem low.

MisterT · 02-15-2018, 01:56 PM

OMG!!!!!

https://www.youtube.com/watch?v=gP3dhz6VSg4

you gotta check out this VIDEO and how it perfectly describes the 'crux' between the Solar benefits and the Real world! Watch the whole piece, she does a GREAT job at being both VERY KNOWLEDGEABLE with engineering and calculations, and yet VERY REAL about how 'reality' and solar work!...... wow!

I need more solar panels : /

cruzbill · 02-15-2018, 02:08 PM

The VALUE in having solar, as long as your RV is out parked in the sunshine, is in BATTERY CHARGING. If you can save one set of batteries from going dead, always at the worst moment, by having a nominal (200-400w) solar array, you will be miles ahead. Your batteries will die at the worst possible moment without being (almost) constantly charged.

Solar is a no-hands-on, no reminders needed battery charger. To be without is simply asking for dead batteries.
Those who can plug into shore power, go ahead and flame away.

Where I store my MH there is no power available, and, to keep the MH stored out of the damaging sun, under a canopy, means my 100w solar panel cannot keep my 4x6v batteries charged. So I have to run the 10k generator 1x or 2x/mo to keep them charged. Not efficient, but no choice for me.

C.Martin · 02-15-2018, 02:11 PM

I can isolate my heavy ac loads and Inverter/dc loads...so I did some calculations. If I run my DC off of Solar instead of shore power...at today’s kWhr rates...it would take me over 20 years to pay off our solar install. Of course, utility prices will definitely go up in price during the next 20 years...so, it was never meant to be an accurate computation.

For me...Solar wasn’t about getting cheap electricity. It was about having self sufficiency. It frees me from having to find a power cord whenever we stop...or having to run the generator. As you may well know...letting your batteries drain to a very low state of charge shortens thier life. Keeping the batteries charged...wherever was my number one goal. Then I decided...should we need to park somewhere without power for a few days...maybe a hurricane evacuation, a breakdown, an unexpected stop...or family emergency. Now...instead of coming back to spoiled food in the refrigerator...the Solar will keep the batteries charging each day, Inverter running and residential fridge happy. When we retire...I hope to do a fair amount of off grid camping out west. The Solar will just be a serious leg up...keeping us from having to fire up the generator and let it run for hours. We’ll still need to do a good Absorbtion Charge on Generator...(if we haven’t gone to Lithium in the next 6 1/2 years...)

Jeff6146 · 02-15-2018, 04:12 PM

ok question, why is it everyone is running 100KW panels when there are 350KW panels for a RV off grid package?

cruzbill · 02-15-2018, 04:18 PM

A 350 watt panel is gonna be pretty big and the voltage (48) is optimized for home systems, not RV battery charging systems. Pick the right size panel for the roof space, factoring in shading from A/C covers and roof vents/skylights. I think the more common panel for RV use these days is about 200w, still can be a large panel. On my 21' TT, I have room for 4x100w panels and no need to go larger as I only have 2x 12v batteries.