Ditch Generator - Go Solar?

[WrigleysBraveWin]

We have a 1994 - 23' Brave with 4,000 watt Generator, which we hate to run, so had a thought about removing Generator and install additional batteries, maybe lithium entire system, and go solar .... 

Yea it would be pricey but our budget for a RV was way more than we spent on this Classic, we almost made the dumb goof of buying a new or slightly used 25' Itascia so we are under budget and have money to invest in this Classic, that we just love .....

We have enough room on roof for maybe a 150 to 200 watt system and figure between charging batteries when plugged in and driving along with the sun and the fact both wife and I are old time tent campers we figure we can ditch the generator and will be just fine .....

Has anyone have any experience with this type of conversion?

[MotorPro]

With only 150 to 200 watts of solar you not be able to boondock for very long.

[WrigleysBraveWin]

With only 150 to 200 watts of solar you not be able to boondock for very long.

We only had D Cell Batteries when we tent camped and stayed out 3-7 days .... Understand the 150-200 watts won't run our mini house full time but we wouldn't stay camping long if noise from generator was running either ....

Just an idea we are exploring, anyone have any experience with setting up or who should we go see?

[legomybago]

The father-in-law installed a 200w solar panel with a charge controller, probably a 300 dollar kit?? Anyway, he runs two 6v house bats. He can go out to the desert and dry camp and never turn the genny on for over a week easy. And he watches movies at night sometimes too. He changed all the light fixtures over to LED. Fridge runs on propane. Only uses the gas furnace in the mornings if needed to take the edge off. Boils coffee. Listens to XM radio at night...

[Rickf1985]

I would add the solar but I would keep the generator. A 200 watt system is seldom ever going to give 200 watts, lucky to see 120 most of the time. Considering you are in the north you never see the direct angle of the sun needed for full charge. and in the spring and fall it is even less. Those ratings are under absolute ideal conditions at probably close to the equator. Then if you run into three or four days of clouds you are flat on batteries and it will take a solid 12 hours to charge them. You will still need a generator somewhere along the line. Remember, you WERE tent campers, if you still wanted to camp like that you would still be in a tent. You got this RV for the extra comforts.

[tmsnyder]

Depends on what you need to run.  If you are thinking about running A/C, then no, 200W is not going to do it.  Running LED lights inside, the water pump, and a fan or two, maybe a 200W system would be fine.


I hear you, I too hate running the generator.  Try for the solar solution but get the generator running and leave it in place just in case. It'll probably cost you 0.02 mpg extra fuel to drag it along but if you need it, it's priceless.

[MotorPro]

We only had D Cell Batteries when we tent camped and stayed out 3-7 days .... Understand the 150-200 watts won't run our mini house full time but we wouldn't stay camping long if noise from generator was running either ....

Just an idea we are exploring, anyone have any experience with setting up or who should we go see?

i was speaking from personal experience. I had a 200 watt Renogy system.By the way I would recommend Renogy,good prices and quality products. I quickly found out that it could not keep ahead of normal electrical use. If you need to run a propane heater at night the solar will not fully recharge the batteries before the next night unless you use no electricity at all during the day. It did allow me run the generator less time (1 or 2 hours a day)but not eliminate it. I added 3 more 100 panels and an mppt controller and a third battery. I am now good unless I get a few rainy days in a row. I really suggest that unless you are really comfortable with basically tent camping in your rv keep the generator for backup.

[MotorPro]

If you can only add 200 watts on your roof you can add a a few portable panels. They can be aimed at the sun and are thus more efficient then the roof panels. Together they will give you a good system.

[legomybago]

Good info Ralph

You should put together a "simple" 200amp solar kit that you would recommend for people to buy? I like the idea of gluing the panels to the roof, that's pretty cool.

[Rickf1985]

I am thinking he meant 200 watt kit. :)rotflmao :)rotflmao

[legomybago]

yes I meant watts!  D:oH!

[WrigleysBraveWin]

The father-in-law installed a 200w solar panel with a charge controller, probably a 300 dollar kit?? Anyway, he runs two 6v house bats. He can go out to the desert and dry camp and never turn the genny on for over a week easy. And he watches movies at night sometimes too. He changed all the light fixtures over to LED. Fridge runs on propane. Only uses the gas furnace in the mornings if needed to take the edge off. Boils coffee. Listens to XM radio at night...

That sounds like us, even when we hooked up to power we only ran microwave once and no ac but we do have fridge on but we could switch that to propane ....

Anyways we are new to RV Vacations and will stay with the generator for now but next spring / summer we may make switch - both wife and I dislike generator and for sure our Pup and Cat dislike as well ..... But we want to start thinking, learn and plan well in advance of install ....

I took a good look at our generator, electric box and plugin cord locations today and in my case one simple hole thru roof (don't worry about leaks, 42 years in roofing trade) and you are down inside closet and electric panel is there and just below is the electric cord storage/plug in area and the generator sits just forward of the closet/cord/electric area with another wire from generator running under frame to other side where the two 6 volt batteries are stored along with the car battery ....

In my mind - remove generator and install additional batteries in generator area (inside a locked steel box welded to the generator frame set area and hook up your inverted whatever boxes and hook into system via the same plugs that plug into generator - replace generator with batteries and charge batteries via solar and when RV is driven and when RV is hooked up to shore power ..... Thinking you could store a lot of power in the 24" by 20" area and then upgrade other two batteries that came with Coach and maybe have a four to six battery system that as I said is charged in many different ways ....

My questions include woukd this work, with correct parts and second has anyone done ....

As far as if we can make it without the generator that really is not a question in our minds, we know we can as a lot of time we will be plugged into shore power or only staying a night/maybe two nights and we won't be in cold weather much either and if necessary we will just do without, wouldn't be the first time ....

Will it work (not run ac or that type of work but in theory)
Has anyone done?

[Rickf1985]

I can go two days now just on the two batteries I have without charging. It can be done without too much issue. I would get one of those battery monitors that tells you what is going it and what is going out in addition to the exact charge. That way you know at all times what your state of charge is. I don't know where your generator is but most are at the rear of the coach, if it is back there you would not want to replace a 100 lb. generator with 300lb.s of batteries, especially behind the rear axle. If it is in the front then it is not as much of an issue as long as the load is balanced side to side. You don't want all the batteries and the water tank on the same side. You can see where I am headed here, weight is the big enemy of any RV and you want to spread it out evenly side to side and front to back so the axles are within the limits.

Something else I will mention is batteries are storage devices, just like a water tank. You use a half tank of water you have to replace it. You use 100 amps of battery power you have to replace it. Depending on the charge rate is how long it takes to replace that 100 amps. 120 watts is 10 amps and it would take 10 hours at that charge rate to replace the 100 amps used. Needless to say you will not have ten hours of bright sunshine so you will not get the full charge in one day. This is just an example and the odds of using a hundred amps in pretty slim unless you have several days of heavy clouds and rain. This is where the battery monitor comes in.

[WrigleysBraveWin]

Think wife said it best .... We won't run generator to run ac .... so basically we don't really use generator...

Our power use would be limited to lights, maybe microwave maybe, water pumps, charge electronics and maybe some radio and 19" tv maybe .... so with four batteries we should be able to handle a few days, even with a small solar charger ....

Rick, Comments make sense, got ya .... Rick - How many watts would we be using with limited use of RV led lights, water pumps and say two hours on tv and charging of couple phones / pads ... daily how many watts under that usage?

The generator is located on drivers side under the dining table window and on the inside behind table seat area is the closet with electric panel at bottom of closet and the outside cord storage and circuit plug is under and generator is next to circuit plug but forward towards driver area so every thing lines up and the balance of weight is best case as it's between both wheels

[tmsnyder]

Amps are the rate of use, to figure out the amount of power used you need the duration also. 
For DC:
Watts = Volts * Amps
Watt*Hours is the actual amount of power used, just like in your home the bill is for kw-hr, that's 1000 w-hr. 


A typical walmart deep cycle battery is almost 100 Amp-hours  (100 Amps X Hours).   So 1 amp for 100 hours, or 2 amps for 50 hours, or 10 amps for 10 hours.... you get the picture, that's 100 A-hr.  At 12 V, that's 100A-hr X 12V = 1200 w-hr, or 1.2 kw-hr.


For a 200W solar panel, assume you get 150W out of it for 4 hours a day just to be realistic and not over optimistic about its output.  And maybe that's even being optimistic! 150W x 4 hours = 600w-hr.  At 12V, 600w-hr/12v = 50 A-hr.  So it's like a half a deep cycle battery, kind of.


That's how those calcs work, you can't talk about amps/watts without duration if you're trying to figure out where the power is going, how much you have and how long you can camp.  Amps and watts only determine how big the wire is to carry it and the size invertor you need. 


If you run your microwave (not recommended btw!!) and it's drawing 1200 watts of 120VAC power from your inverter, that's 10A at 120vac.  That's at least 100A at 12vdc from the battery (assuming you used wire as big as your pointer finger to connect it to the battery), divided by the efficiency of your invertor, assume 90% and the current would be 100/0.9=111 Amp.   If you run it for 5 minutes to cook a potato, that's 12v*111a*5m=6660 w-min .  If your PV panels are putting out 150w of power, it will take at least 6660w-min/150w=45 minutes to recharge at 100% efficiency, and nothing is 100% efficient.  So figure on an hour of output from your 200W panel putting out during its limited number of prime sunshine time, which you get maybe 4-5 hours a day, and you're going to use one of those hours to cook a potato!   D:oH!  Not a great use of your $300 PV system.  Better to just boil a pot of water outside in the shade using a 1lb propane stove LOL.


I just replaced all the lights in my rv with LED and I measured the amp draw, it took 20 to draw 1A.  That's a lot of light for almost zero current.  But if those were on 4 hours a day, they would draw 4 A-hr of power from the 50 A-hr provided by the 200W solar panel. 


You'll have to go through all the stuff you plan on using and do a similar analysis.  Measure how much current each thing draws and how long it will be on each day. 


The idea of chargers is troubling to me.  If you are using an inverter to make 120VAC from 12VDC, then using a charger to convert back to the electronic's DC charging voltage, then you are doubling up on the inefficiencies of those conversions.   It would be better to get DC chargers and go direct from 12VDC to the DC charge voltage. Measure with an amp-meter to see what kind of juice they are using.  You might be surprised how much power they take, let us know, it might be interesting.


Same with the TV. Depends on what it is.  I could see that being a major power user potentially.  Good luck and let us know how it works out!

[Schmitti]

Hi,
leave the generator as a back-up system where he is - so he can still work in an emergency. I do not know the prices in the US for gel / lithium batteries but I am under the guise now that it is a utopian difference. If you need new batteries, buy the ones suitable for solar, lead-based. It does not get any cheaper and it also takes about 5 years. Calculate times the price for Liithium batteries.
Some of the money saved is invested in a good MPPT charge controller and a little more solar panels. We have 400W on the roof and 330Ah of batteries. So we do not even need sun. A cloudy sky is sufficient to get another 6-8Ah of the charging current. At full lunch in the summer, about 18-20Ah are possible.
Even in the tagelangen Dauerregen, we have it with a little power saving not yet managed to bring the batteries completely to their limit.






Thomas

[strykersd]

Another important factor to keep in mind is if you have a large enough power inverter.  If not, the cost of one large enough to run your microwave will be a few hundred dollars.

[legomybago]

There is a guy in the FMC community who built a system that will run a rooftop AC unit when he drives down the road, all from the battery bank with a fancy Inverter. He runs duel alternators on his Duramax engine. Not cheap to build, and I suppose you would need to be driving to maintain battery juice to run that AC. Not sure though...

[Rickf1985]

Running through an inverter from the vehicle alternator is not that big of a deal since there are some pretty big alternators out there. A stock alternator is usually in the 120-150 amp range so the power is easily available. Wiring the inverter is going to be expensive since it will require large wire plus running the alternator at high load like that will take a toll on the alternator, the belts and the gas mileage. Running a 4,000 watt generator while driving consume a half gallon per hour of gas at the most. It is just not worth all the money and extra maintenance problems to do the alternator bit. A half gallon an hour at 60 MPH is 120 MPG, is it really worth complaining about that little extra gas used? But really this discussion is about stationary use, I still say a Tri-metric battery monitor is the best add on you can get. It will educate you on how much you can use and how much you are actually putting back. Like Ralph said, you can always add a couple remote panels on the ground.

[WrigleysBraveWin]

Appreciate all the thoughts/concerns/pitfalls - making us smarter .....

Lots of opinions but not a single answer to the question:

Can you disconnect generator leads and use those wires for input from solar, verses input from generator!

Everyone needs to forget about talking us into or out of the idea, rather help us understand if applicable or not?

Also understand we would do this until at least summer and this is just the "napkin drawing stage" ..... again ....

Can you disconnect generator leads and use those wires for input from solar, verses input from generator?

[Rickf1985]

No, The input from the generator is 110 volt AC and the input from the solar is probably around 18-20 volts DC on a 200watt system and it has to go to a controller to be stepped down to supply the battery. You cannot run the AC side of the system from the solar.

Picture apples to oranges.

[strykersd]

There is a guy in the FMC community who built a system that will run a rooftop AC unit when he drives down the road, all from the battery bank with a fancy Inverter. He runs duel alternators on his Duramax engine. Not cheap to build, and I suppose you would need to be driving to maintain battery juice to run that AC. Not sure though...

Have a link to his build?  I'm curious

[legomybago]

You can try this link. http://www.fmcowners.com/mbbs22/photos/photo-thumbnails.asp?albumid=127&Page=29&sortdir=asc

His set up:
9200btu AC unit
4000 watt Inverter
580ah battery bank
270amp alternator, runs duel alts on the engine.

[M & J]

Well, there are 2 sets of leads in the genny compartment. The gennys AC out that feeds the AC breaker panel for 120VAC to the coach are the ones Rick is referring to. It may be possible to use those being fed by an inverter to distribute its 120VAC output.
There are also the 12VDC cables used to start the genny fed from a battery. They are also used by the genny when running to charge those same batteries, which many have commented as a reason to keep the genny as an emergency source to recharge the cells. Those can be used to charge the batteries from the charge controller.

[WrigleysBraveWin]

Thanks all that helps a lot.