Solar-When do you start - RV-Dreams Community Forum

blijil · RV-Dreams Family Member

Solar-When do you start

simonsrf · RV-Dreams Family Member

Larry,

We are gearing up for fulltiming by Oct. 1, 2006. Our goal is to be able to boondock as much as possible. We bought 4 solar panels, 6-golf cart batteries, an inverter etc. etc. Yes, we have started, but would not have been able to do this without the fine service and help we got from these people in Eugene OR. They were teriffic. If you are looking for solar, these people know their stuff and they do such a beautiful job with the wiring runs.

The site below is also a good education tool for anyone interested in knowing more about solar energy.

http://www.amsolar.com/

Robbie and Alice Simons

Jack Mayer · RV-Dreams Family Member

Only you can decide when to make the investment. It is really a lifestyle decision. It is hard to make "back" the investment in a proper solar setup.

Take a look at our website - there is extensive info on solar and RV electrical there.

BTW, LOTS of fulltimers boondock. We do - for months at a time....

Doncat · RV-Dreams Family Member

Hey Larry, I use a CPAP also. Do you run your air condition when dry camping? While out for the weekend recently, I had to run our AC constantly. Can you run an AC using deep cycle batteries and an inverter? I imagine they don't last long. Thanks for the info on how many amps the CPAP draws, I was wondering how to determine that.

Howie DoDat · RV-Dreams Community Member

I have been following another blog and he (George) has quite a bit of information on how he has set up his solar panels, etc.

http://vagabonders-supreme.net/blog/blog.html

Yes, I know Howard, how can I get anything done at work while I'm reading all these web sites. I'm just very efficient when I do work.

blijil · RV-Dreams Family Member

Domcat

AC and anything that produces heat like irons, blow dryers, coffee pots, toasters, refrigerator, hot water heater, and microwave ovens are inefficient for a reasonable number of batteries (6 or less). Of course AC is about double the load of a microwave so you are right, it wouldn't last long. I picked up a clamp on Amp meter from Sears which will do DC and AC amps and even though its accuracy is only about +- 10% at the less than 100 amp readings it is very useful in determining actual loads especially when using an inverter.

Good luck with the CPAP. It took some time but I believe we have a good handle on running the CPAP on an inverter successfully. Just watch you battery charge to make sure you have sufficient capacity for the night.

Larry

bjoyce · RV-Dreams Family Member

If you look at most RVs you will find that there is space for 3 to 6 solar panels on the roof where they will not be shaded. If you want to get good solar power in the winter you need to be able to tilt some of those panels to get higher output. We have four 100 watt panels and we can tilt three. In winter the rule of thumb is you get about the equivalent of five hours of full sun a day, so we can get up to 2000 watt-hours of solar power a day or two kilo-watt hours of power from the sun. In Yuma, AZ's inflated price for electricity that is 32 cents a day at 16 cents a kilo-watt hour and most places are cheaper. Each panel is about $500 so it will take over 6,000 days of boondocking to pay for just the panels in electrical usage alone. Of course campgrounds cost much more than 32 cents a day, but I just wanted to point out how truely small the amount of electricity you get from solar panels is. For many it is enough, some can get by with one or two panels, but they adjust their lifestyle to match. You don't run air conditioners on batteries charged with solar panels, it will take 15 panels in full sun just to keep up.

Now there is hope, you have to adjust your life to living on less electricity if that is your desire. You run everything on propane you can, like your fridge, hot water heater, and heat. Open windows and use low power usage fans instead of air conditioning. It is best to get radiant propane heat, ceramic or catalytic, to not use battery power for the furnace fan. You have to be somewhere where the sun is shining and the temparatures are comfortable, like the SW in the winter. Try to have things to cook that do not require using electricity. Get a flat panel TV or better yet, don't watch it. Use the computer sparingly. Unplug everything with a stand by load, like cell phone chargers, TVs, CPAPs (we have one), etc., when not needed. If you can do it right you will only have to run a generator when the weather forces it, but you still might have to spend more money to have enough solar, enough batteries, and all the pieces like a really good inverter/charger, radiant heater(s), fans, awnings, even things like solar ovens.

blijil · RV-Dreams Family Member

After much research and more than a little rationalization we bit the bullet and ordered a system with two AMSOLAR 100 watt panels to start with. We just thought we needed to learn a little about what we need before we add any more panels. The next adventure is installation. We needed something to do while our daughter is finishing High School. Thanks for the input.

Larry and Jacki

Tmcblane · RV-Dreams Family Member

200 watts is a great place to start, that gives you about 12 amps an hour in prime conditions. With your past conservation measures you will be doing good. Solar is not getting any cheaper so now is as good as anytime to start. We have 540 watts on our rig and stayed in the desert first of the year for about 7 weeks with another 2 weeks on the california coast without power. We did not really watch what we used. We ran the tv, satellite internet, wife used the hair dryer everyday and so on. Now we did not just leave the internet and such on during the day unless we were using it but when we did use it we did not worry about how long. On average we were using 100-135 amp hours a day and generally recaputured it by 3pm in the afternoon unless we had clouds. Few days was that the problem and if it was a quick 1 hour run of the generator got us caught up.

You want to consider getting a battery meter if you are going to do some serious boondocking. Batteries are life and taking care of them is super important. A volt meter just don't get it.

-- Edited by Tmcblane at 16:32, 2006-11-13

bjoyce · RV-Dreams Family Member

That battery meter is a good idea, we are planning on getting one in a few weeks when we can get to someone competent to install it. You just can't tell off the voltages what is really going on since the voltages are not resting ones.

Tmcblane · RV-Dreams Family Member

Bill the meter really is a must for regular boondocking. It tracks a history of min and max draws and such and will alert you of certain situations. They can be a pain to install, mainly from the point of running the wire if your install point is not close to the batteries. If you have an easy run the connections are simple. Seems to me on the Link 1000 there are 5 wires to connect. Most important is making sure ALL your grounds run thru the meter. Been using mine for 2 years now and love it. Easy to tell what appliances you DON"T want to run off the batteries. :)

blijil · RV-Dreams Family Member

All the stuff arrived just before we took a week in Denver for Thanksgiving with the kids. After returning all the literature was read once again and the planning reviewed. The heavy #8 cable routing was of most concern because it is so stiff. Then two consecutive cold fronts have hit New Mexico and working in the basement etc at 30F and less is not on our list of things to do. Finally about noon yesterday we able to route the heavy cable down from the roof to the controller and from the battery box to the controller. Quite a chore but it looks good except for one or two extra holes in the basement. We always knew that the best time to move a hole was before you drilled it. Now for terminating all of those cables with right terminals and labels. At least most of that is inside. Then we will be ready to mount the panels on the roof if it every warms up.

Larry and Jacki

bjoyce · RV-Dreams Family Member

Our battery meter, a Xantrex TM500A, has been very useful for us to get a good handle on our real 12-volt electricity usage. It is amazing what having real numbers can do. Our estimates, based on expert help, were wrong. Not massively wrong, but wrong enough to lead us astray. Now we have real values on how our charger(s) run and how much load we really have.

I have recently been digging into inverter info and learned some things.

Inverter efficiency is a key for running 120-volt appliances for the least battery drain. Turns out inverters work most efficiently at 30 to 80% of their ratings, so our running something all night, a CPAP with heated humidifier, that uses 20 to 110 watts is very inefficient. Our 2000 watt inverter is wasting 5-6 amps, which adds up overnight. The heated humidifier is required in this case, the CPAP itself can run on 12-volt.

Plus some appliances will use more power on modified sine-wave than pure sine-wave, so watch that. A quote from http://www.solar-electric.com/solar_inverters/inverters_for_solar_electric.htm is "Typically, an electric motor (such as a pump or refrigerator) will use from 15% to 20% more power with a modified sine wave than with a true sine wave.". Since our big inverter is a pure sine-wave model this is not a current problem, but since we are thinking of getting some small modified sine-wave inverters we have to watch what we want plugged into them. Also if you have a modified sine-wave inverter you need to measure the 120-volt amps, watts, and voltage used with an RMS meter or take your measurements only when hooked to shore power or from the generator. RMS monitoring devices like a Good Governor or Watts-Up cost much more than the non-RMS devices like a $15 voltage meter or a Kill-A-Watt. You can buy a lot of generator fuel for the price differences.

blijil · RV-Dreams Family Member

Thanks for the info. We have been using two small inverters to meet most of our needs and even though we have the battery capacity we aren't convinced that the microwave, toaster, electric coffee maker are worth the price of a larger inverter. The little 140 watt does a great job on the cpap (no heater), occasional chargers, and even the laptop. Our 400 watt inverter does the TV, DVD, vacuum cleaner, small kitchen appliances as needed. We have wired the 400 watt into the grid with a switch that removes the converter from the grid at the same time. An efficient inverter still uses 10-15% more power than it produces. In this case smaller is better. We would guess that as we have more power available we will use more but at the moment we are so conservative in use that a power monitoring system isn't really necesary. It might be needed next year though.

Installation of the wiring for the system is going nicely. A couple of troublesome moments which were overcome with some rethinking. Can anyone say "I cut off twice and it's still too short?" Hopefully the panels will go on the roof on the next nice day.

Larry and Jacki

bjoyce · RV-Dreams Family Member

Larry and Jacki: Good point on the little inverters. Anything above 150 watts needs to be hard-wired to the batteries and fused properly since cigarette lighter plugs are only rated for 150 watts maximum.

Big inverters can be really nice in some instances so you can run the large appliances. We stop for lunch on the road and run the microwave off the inverter and by the time we leave the batteries are back up from the solar panels. We run the toaster in the morning during quiet hours and catch back up with the generator if we have to. There have been a couple times I have run power tools off the inverter.

You also mentioned a converter. A friend has a converter with charge wizard and rewired his fifth wheel so he could power the converter from an extension cord while leaving the RV off the grid. The converter is not hooked to shore power or battery except with a plug since he has a 3000 watt inverter/charger. He uses the converter in two instances: 1) when he can only pull 4-8 amps out of the extension cord. He can still run the microwave and most everything else off the big inverter, but with the converter able to put 50AMPs into the batteries he can recover it well. 2) When the power is lousy. In this case the converter still charges everything well and he isolates the RV from the bad power.

-- Edited by bjoyce at 20:28, 2006-12-07

blijil · RV-Dreams Family Member

Hm! Someone always has another good idea that turns into a project. A seperately wired converter/charger seems to have some real benefits especially if the system is already wired with a large inverter/charger system. Thanks for the tip.

Well the wire is in, routed, and terminated. We just have a few places to clamp to provide sufficient strain relief. On the next warm day the panels go to the roof. It seems that this body gets sore easily when it climbs around in the basement, the roof, and stretches deep into the back of the battery compartment.

The satisfaction of a job well done makes it worth the effort.

Larry and Jacki

blijil · RV-Dreams Family Member

The whole system is in and operating. Strange but putting the panels on the roof was the easiest thing to do. The AM Solar equipment works as advertised. Thank you all for some good advice. As mentioned by others mid-December is not the time of the year you have the best solar insolation but we still get about 60% at noon hear in sunny New Mexico. Now we are in the learning stage again.

Guess that means we are past the starting point on Solar.

Larry and Jacki

Tmcblane · RV-Dreams Family Member

Larry, did you mount the panel so it can be tilted? That can make quite a difference in the winter months. Not necessary but if you want to maximize the system it works well. Tilting should bump it up to about 80-90 %.

blijil · RV-Dreams Family Member

We did mount them so that they can be tilted but we are currently parked in a poor location to take advantage of that. Hopefully next time we park we can try that out. For the present they are keeping the batteries topped. We have electric.

Larry and Jacki

Tmcblane · RV-Dreams Family Member

Larry, at least they can be tilted! That will come in handy. Some friends of ours were just boondocking at Imperial dam outside of Yuma and they sent me a picture of a rig there that had 33 panels mounted on it! Seems like a little overkill but they are certainly supplied.

blijil · RV-Dreams Family Member

We are a bit more modest with 2 100 watt panels to start with and room for two more. We hope to get 40 to 60 amp hours during the spring and fall. Don't expect quite that much in the winter but we don't dry camp as much then. As always we seem to be able to use everything we get so we will see how things work out. This should reduce the work on the generator and get the batteries topped off more often.

Have a nice Christmas and New year. We will be in Austin for Christmas and Albuquerque the week after New Years eve.

Larry and Jacki

bjoyce · RV-Dreams Family Member

Hopefully you configured the solar controller to charge the type of batteries you have. You really need it to give sufficient voltage to top off the batteries or you will not be getting everything you paid for. The controller defaults are rarely right. It sounds like you used heavy wires, there is no reason to throw away power just to use smaller wires. You want every amphour you can get.

blijil · RV-Dreams Family Member

Well after a 1300 mile round trip to Austin, the panels are still on the roof and everything is working properly.

Larry

bjoyce · RV-Dreams Family Member

I was just at a rally where there were a lot of people with solar including some new solar installs. The world of solar is not staying static, so us with installations that are just two years old are somewhat out of date. The new trick is the newest MPPT controllers (Solar Boost 3024i and Outback Energy MX60 are the ones I have specs for) can handle higher input voltages and still charge your 12volt batteries. The Solar Boost can handle 56 volts input and the Outback Energy can handle 72 volts. I need to find out the numbers for the Heliotrope HPV-30.
Why is this significant? It lets you wire your solar panels in series and therefore you get some real advantages:
1) Higher voltage means less loss through the same wiring, .5volt of loss from 16.5volts is more significant than .5 volt of loss from 33volts.
2) You can use those old 33-cell panels wired in series and get the voltage to top off your batteries, which was not true in the past
3) Partial shading won't take the panels completely out since the voltages add.
4) You can mix voltages on panels, so you can series connect 33, 36 and 44 cell panels as long as the total voltage is kept under the controllers numbers. I would keep a safety margin here, especially if you are heading to the north in winter where your panels will put out more voltage at -30 degrees than speced.

This really works well for people who have inadequate wiring and/or panels in their existing installations. They can rewire on the roof to series connections, change controllers to one that can handle the input voltage and gain a lot of solar charging for the effort. If you have four panels, series them in twos, if you have three panels, series them all together.

The Solar Boost "i" panel can also work with a shunt and work as a battery meter, so if you do not already have a battery meter/monitor, you don't have to add one.

RVDude · RV-Dreams Family Member

bjoyce
When you get the Heliotrope data I wonder if you are planning to do a three way compare of it and the Solar Boost and the Outback Energy controllers? That would be a great help. Heliotrope plays the higher voltage game using the AM-100 slightly higher voltage panels, but wiring PV panels in series to drive 50+++ volts would cut down line loss like you said and boost overall system efficiency. I'll be adding some 4 panels to my rig in the summer so any thoughts on the newest controllers would be great!

blijil · RV-Dreams Family Member

Just an update on the Solar experience. We have spent 3 outings ranging from 4-6 days without hookups. We have yet to even think about firing up the generator because the 4 batteries are always completely charged before the day is over. We aren't heavy consumers but we do use about 50 amp hours a day when we watch TV a couple or three hours.

So far we are very satisfied with 2ea 100 watt panels from AM Solar and we have used them in January thru April so far.

Larry and Jacki

Judy the Other · RV-Dreams Family Member

I would encourage anyone thinking of buying a PV system to live like you're off-grid for a while. As panels, inverters, wiring gets expensive it would not be good to sink money into something and then find that you just can't do it. We've seen many systems up for sale because the owners didn't want to conserve or do without certain things. As Jack stated, you shouldn't expect $ payback on your solar system, your best payback comes from conservation.

bootsak · RV-Dreams Community Member

I'm mainly posting to avoid falling into my old lurking habit.

However, this is a topic that I'm trying to learn more about, so I'm taking notes like crazy (suggested links,etc), as well as just trying to absorb all this terrific info. (Maybe I'll just print the whole thing out because I know I'll need to read it and reread it).

We have one solar panel on the roof of our recently acquired '98 Alpenlite 5er- there's no info in manuals and previous owner knows nothing about it. We will just be starting with trying to find out about what we've got and would later like to add more panels so thanks to everyone who is sharing there experience and expertise.

We have so much to learn about our 5er but fortunately have a year before we begin our voyage.

Boots

bjoyce · RV-Dreams Family Member

Bootsak: I suspect that one solar panel is either too small or the wiring or controller are inadequate to get much charging out of it. If it is not mounted at least an inch off the roof to get air under it, it is really not worth carrying. Somewhere there is probably a little box with a red light on it. When the light is lit you are getting a small amount of charging, when not you are getting no charging. The box could be behind the fridge or by the batteries. Unless you can determine you have the rare one panel setup that does something useful, it is best to design your solar setup completely ignoring that panel.

bootsak · RV-Dreams Community Member

Thanks, Bill. The panel is definitely not 1 inch off roof. I will look for the little box but think you're probably right that there's not much happening. You said 'design a setup completely ignoring that panel' - does that mean we wouldn't remove it if it is a dud. Boots

bjoyce · RV-Dreams Family Member

I would only remove the panel if it is in your way or will make it hard to install the solar setup you want. It can be easy to cause roof damage. Good panels are bolted to mounts and have a label on the underside that tells you their specs.

blijil · RV-Dreams Family Member

Well we spent 6 weeks this summer dry camping and we ran the generator for a total of 2 hours with the solar doing the rest providing more electricity than we needed. We even enjoyed a movie or a couple hours of TV each day along with some computer time. Even on some cloudy days the charge was sufficient over several days due to the long summer days.

We are very happy with the set up. We will change to some Golf cart batteries before next summer. The old RV Marine 12 volt batteries have worked well for 3 years+ but are getting a bit long in the tooth. They are starting to require more maintenance and using a bit more water.

Glad to see there are others thinking more about solar.

Larry and Jacki

-- Edited by blijil at 13:24, 2007-08-14

Joezilla · RV-Dreams Community Member

I have a definite newbie question for you Solar power gurus............How does the inverter hook up to the trailer? Once hooked up, are all your 110 volt plugs active? or just a few?

I notice that Howard talks about turning his inverter off. Why is that necessary? Doesn't the solar buildup of electricity stop if the inverter is off?

Too many questions, not enough answers.

Joezilla

DealinDavid · RV-Dreams Community Member

Joezilla, I wired my 1500W inverter through a 30A switch. When the inverter is on I have power on my outlets in the 5er. When connected to shore power, the switch automatically activates and the shore power runs my RV. The inverter draws power when on, so turning it off will save on batteries when sleeping or not using outlets. The solar controller, another piece of equipment necessary for solar power, controls the battery charging. Good battery storage is a must as well, so you probably will need to upgrade them as well.

We went over 2 years using generators, and just upgraded to solar as the summer home is off the power grid. There are lots and lots of great sites on the internet to educate oneself.

RVDude · RV-Dreams Family Member

You are asking the right and tough questions. Unfortunately, they can not be answered with a simple yes/no. As you will see, the answers to all your questions is "it depends!"

So what to do? Here's the quick answer... Come to the RV-Dreams rally and get your questions answered hands on. You'll be able to touch and see and understand many of the factors that go into answering your questions. Really, I am not plugging the Rally, well, maybe I am, but it is a way to get these complex topics addressed. Sort of like our own Howard, after actually seeing how his system was designed and installed he's now a master of it. No way to learn all that from a book/forum...

In your case…

How does the inverter hook up to the trailer? (it depends)
Once hooked up, are all your 110 volt plugs active? (could be, it depends)
or just a few? (could be it depends)

turning his inverter off. Why is that necessary? (again it depends and things like parasitic loads and idle loads all play into it)

Doesn't the solar buildup of electricity stop if the inverter is off? (well, they really don't connect that way, but again, it depends)

I don't mean to de effusive, but these are multi-faceted questions which there are numerous "right" answers!

Hope to see you at the rally!

bjoyce · RV-Dreams Family Member

I think you might already have your answer, which is there is no simple answers with inverters. Inverters come in multiple sizes, most are modified sine wave (which really is "modified square wave") instead of the better pure sine wave (just like the electric company supplies), and some of the big ones have built-in chargers. Small inverters can be hooked to 12 volt plugs, but anything that needs to supply over about 150 watts needs to be wired in since those 12 volt plugs can't handle the load. Wire sizes for larger inverters is very important, it does not take many feet of wire to loose 1 volt if you don't size it right. There are tables and probably internet guides to help with wire sizing.
Our present RV has two inverters, a 2000 watt pure sine wave one with a built-in charger, plus a small 400 watt modified square wave inverter wired into the bedroom for a breathing machine. When the big inverter is on the microwave clock is running, plus it is charging two computers, an electric toothbrush (modified square wave kills these), a couple of cell phones and a set of two way radios. Since it also wastes 2 Amps on its own we save a lot of battery power when it is off since all those other loads it uses 6 to 7 amps of 12 volt just being on. The little one only gets used at night when we dry camp and wastes much less battery power. Most of our outlets are on the big inverter, but not all.
The rule in dry camping is "if you are not using it, turn it off". That applies to lights and inverters. Batteries and solar really don't supply that much power, Howard can safely use 300 Amp-hours of battery power a day but can only recover about half of that with solar on a good day. 300 Amp-hours is 3600 Watt-hours or 3.6 Kilowatt-hours. I am sure that when hooked up to shore power on a meter you normally use more than 3.6 Kilowatt-hours in a day.

Joezilla · RV-Dreams Community Member

RVDude wrote:

You are asking the right and tough questions. Unfortunately, they can not be answered with a simple yes/no. As you will see, the answers to all your questions is "it depends!"

So what to do? Here's the quick answer... Come to the RV-Dreams rally and get your questions answered hands on. You'll be able to touch and see and understand many of the factors that go into answering your questions. Really, I am not plugging the Rally, well, maybe I am, but it is a way to get these complex topics addressed. Sort of like our own Howard, after actually seeing how his system was designed and installed he's now a master of it. No way to learn all that from a book/forum...

In your case…

How does the inverter hook up to the trailer? (it depends)
Once hooked up, are all your 110 volt plugs active? (could be, it depends)
or just a few? (could be it depends)

turning his inverter off. Why is that necessary? (again it depends and things like parasitic loads and idle loads all play into it)

Doesn't the solar buildup of electricity stop if the inverter is off? (well, they really don't connect that way, but again, it depends)

I don't mean to de effusive, but these are multi-faceted questions which there are numerous "right" answers!

Hope to see you at the rally!

I was trying to ask questions that showed I know nothing about what I was asking about. As such, I do not understand your answers either.

I would love to come to the rally, unfortunately, the wife is still working until June 30th. We'll definitely be there for next year's rally. Hopefully, I'll know enough by then to ask better questions.

Joezilla

bjoyce · RV-Dreams Family Member

Joezilla: Do you already have an inverter or are you just asking in general?

An inverter takes 12 volt battery power and converts it to alternating 120 volt current. The conversion is not 100% efficient which is why boondockers look for 12 volt devices since they will use less battery power. Many big inverters have charger circuits and run in reverse when on shore power to charge your batteries back up. Quality of the 120 volt current coming out depends on the inverter, there are some really lousy $100 1500 watt inverters out there and high quality $200 150 watt ones.

If you already have an inverter you can easily test which outlets are hooked up and if you have a good multi-meter (inductance is best) or battery monitor you can find out how much power it uses. You just disconnect from shore power, turn on the inverter and walk around with something that uses a small amount of electricity trying outlets to see which ones are live. Our power bricks for our desktop computers have lights on them for example.

With a multi-meter set to measure DC amps one person measures the amps drawn at the battery while the other turns on and off various things inside, like lights, inverters and plugging things into the inverter after it is turned on. The person with the multi-meter can see how many amps each device takes and write it down. People who boondock a lot or just like to know install battery monitors that make this testing much easier since the monitor is always hooked up.

If you don't have an inverter you have the chance to learn enough to decide if you need to have any inverters and can decide how many, how big each should be and where they should be installed. Being an informed consumer is always good.

Edit: I missed the part about how does the inverter hook up. The inverter hooks to the batteries somehow either direct connected, through the fuse box, or using a 12 volt cigarette lighter plug. Some have remote switches or panels that you wire to somewhere inside the RV (normally with something like phone wire) to turn them on or off or do other things with the fancier ones. Big inverters with chargers are also hooked to the shore power and are then wired to outlets in the RV. These fancy ones pass the shore power through when shore power exists, otherwise they provide power to the outlets by converting the battery power to 120 volt electric when they are turned on.

-- Edited by bjoyce at 11:59, 2008-05-07

Joezilla · RV-Dreams Community Member

Thanks, Bill for your explanations. That makes it so much clearer. I was wrongly thinking that the inverter was somehow tied into the wiring and the fuse box/switch box.

Joezilla

jcw · RV-Dreams Family Member

Is there any downside to leaving the inverter turned on all the time, even when connected to shore power? My thinking (and this has come in handy more than a couple of times) is that having the inverter enabled provides a constant battery backup system for my power needs. Should the park power go out for some reason (which has happened on several occasions like storms) the power in my rig remains on, protecting my desktop computer from unexpected power outages.

What's the downside to enabling the inverter all the time?

Luvglass · RV-Dreams Family Member

I believe you would quickly burn out your batteries. The inverter would be draining the batteries to make 110 and the charger would be converting 11o to try to recharge the batteries at the same time. Since neither operation is 100% efficient, I think you would relatively quickly drain your batteries below half and ruin them.

Also, I don't believe that a power loss should damage you computer. It's not the way they should be turned off, but not damaging.

I'm not that knowledgeable though, so lets see what the experts have to say.

bjoyce · RV-Dreams Family Member

I suspect you are talking about a big inverter/charger combination instead of small inverters and a converter/charger? Most smaller inverters do not have transfer switches that cleanly switch over and act like a uninterruptable power supply (UPS), while the big (2000 watt and above) inverter/chargers do.
Many leave the inverter on their inverter/charger when on shore power for just the reasons you give. I am sure if you have a modified sine wave inverter you already know if something will not run properly with it and have taken precautions to not have them plugged in when you leave the inverter on. This is not a problem with pure sine wave inverters.
If you leave for long periods and/or your inverter is powering something that takes a large load, like a fridge, you might find your batteries way down if the power goes off. Some retro-fitted inverter/chargers will even power the air conditioner and the batteries will drain fast if the power goes out.
You want some kind of visible indicator that you are running on the inverter if you do this, maybe something plugged into a non-inverter circuit. I know many who did not realize they had tripped a breaker or lost power for hours while home because everything kept running and they had nothing that told them they were on the inverter. Our inverter/charger panel is visible in the main area of our RV so we can notice if the panel is not lit and we are inverting. I know someone else who plugged a emergency flashlight in by their washer/dryer that beeped when the power went out since the washer/dryer was not on the inverter.

jcw · RV-Dreams Family Member

bjoyce wrote:

I suspect you are talking about a big inverter/charger combination instead of small inverters and a converter/charger? Most smaller inverters do not have transfer switches that cleanly switch over and act like a uninterruptable power supply (UPS), while the big (2000 watt and above) inverter/chargers do.
Many leave the inverter on their inverter/charger when on shore power for just the reasons you give. I am sure if you have a modified sine wave inverter you already know if something will not run properly with it and have taken precautions to not have them plugged in when you leave the inverter on. This is not a problem with pure sine wave inverters.
If you leave for long periods and/or your inverter is powering something that takes a large load, like a fridge, you might find your batteries way down if the power goes off. Some retro-fitted inverter/chargers will even power the air conditioner and the batteries will drain fast if the power goes out.
You want some kind of visible indicator that you are running on the inverter if you do this, maybe something plugged into a non-inverter circuit. I know many who did not realize they had tripped a breaker or lost power for hours while home because everything kept running and they had nothing that told them they were on the inverter. Our inverter/charger panel is visible in the main area of our RV so we can notice if the panel is not lit and we are inverting. I know someone else who plugged a emergency flashlight in by their washer/dryer that beeped when the power went out since the washer/dryer was not on the inverter.

Yep, I'm talking about one of those 2000 watt Xantrex inverters with the transfer switch and a pure sine wave output.

You have a point about not recognizing when a failover may have happened. I guess I'd have to notice the battery level dropping. As far as I know, I don't have any outlets that aren't serviced by the inverter. I also do not have an auto-start generator setup, so if I missed the clue that the batteries were being depleted, the first thing I'd notice is the loss of power in the rig when the inverter quit converting.

With the automatic transfer switch, though, at least when the park power returned it would automatically switch back over.

But, it seems like you are saying that, as long as I retain shore power, there's no problem leaving the inverter enabled, just in case I do happen to lose shore power.

-- Edited by jcw on Tuesday 25th of August 2009 10:18:34 AM

bjoyce · RV-Dreams Family Member

jcw: You are 99% safe doing what you are doing, but just be aware it is not 100%. We leave our pure sine wave inverter on all the time unless we are boondocking.

dextercath96 · RV-Dreams Community Member

blijil wrote:

Ok someone had to get the discussion rolling. We have dry camped for a week at a time without even a generator. Four standard marine RV batteries would do it with a lot of conservation. I use a cpap and on the inverter it demands about 24 amp hours a night so we use 200 amp hours in about 5- 6 days even if we are real careful. We drycamped almost 6 weeks straight this summer with the help of a Honda 1000 to charge the batteries each day. It took almost 2 hours of generator time a day to recharge and do chores like housecleaning pumping water etc. It seems to me with maintenance and fuel costs even with this very small and very efficient generator (about a gallon of gas a week) it might be wise to invest in a couple of solar panels (about 240 watts) and cut the generator time to rainy days and supplemental uses like a lot of TV. We camp all summer but won't be full time for another 2 years (retired but daughter still in high school).

So when should we add the solar panels? Now and learn the ropes or wait until we are full time and they would be more cost effective?

I'm wondering how many fulltimers dry camp at all now that I ask the question.

Thanks,

Larry

Larry and Jacki - Retired but not on the road yet.

Yes I agree. Solar power generator must use in camping because it is ideally to have electricity in your camping site. I always carry my solar power generator when we are having our hiking and camping.

danielhenry31 · RV-Dreams Community Member

You will find if you look at the RVs that there is room for 3-6 solar panels on the roof if they are not shaded. If you want to get a good solar energy in winter must be able to tilt the pot to get some more production. We have four 100 watt panels and tilt three.I can only say how very small amount of electricity from solar panels. For many, simply, some people can get along with one or two panels, It is not necessary to run air conditioning systems and battery charged by solar panels.

Sailbad · RV-Dreams Community Member

This discussion has been going on for a while. Being the topic is boondocking as well as solar, I thought I'd jump in.

Before you purchase solar there are several things that need to be considered. First and foremost is how much power are you using. That requires an energy audit. You need to know how much energy each of the appliances including the "phantom" draws actually consume.

To be successful, your battery capacity should be rated at least 200% of your consumption. As an example, let's say you consume 100amps a day. Your battery capacity needs to be 200amps. It damages batteries to be drawn down past 50%.

That's a bare minimum. It would be better for the batteries if your capacity was 400amps and you only use 25% or 100amps.

The second thing to be considered is what method of recharging the batteries are you going to use. Do you want to recharge just using a generator? Do you want to recharge just using solar? Or do you want to use a combination? If you are using a generator, how long will it have to run to accomplish the charge you desire. If you desire to add solar panels, how many and of what output do you want to accomplish the recharging.

These questions need to be answered before you purchase solar.

I have a Trimetric 2020 battery monitor. It tells me two important values that I am interested in. One is the current voltage of my batteries. The second is how many amps I have consumed. It will also tell you how much draw each item in your rig uses. I installed the Trimetric several months before I installed my solar panels. When it is set up, it is more fun to watch than television.

I am a fulltimer and normally boondock almost full time. I do not enjoy RV parks.

As an example of the system that works. I will use mine.

My 5er is a 30amp system.

I consume between 100amps to 140amps in a 24 hour period. I have a Magnum 2012 (2000 watt) inverter wired in line. It is supported by a battery bank of AGM batteries rated at 670amps. I have and use all the appliances you would find in a normal house except a washer and dryer. I normally run the refer and water heater on propane. If I am home, my sat dish, TV and computer run almost all day.

I elected to install solar. I have 4 Kyocera 135 watt panels wired series/parallel that are permanently mounted flat on my roof. They produce 24 volts to a Morningstar 3024iL that reduces the voltage to a maximum 14.4 volts and restricts the amps to a maximum of 28.6amps.

As you can see from the above, normally I have no problems replacing the energy I use each day. If I had a few days of heavy cloud cover, I do carry a Yamaha generator as a back up. The Magnum does have a 100amp charger built in.

I have not had the cover off the generator or turned on the Magnum charger since I installed the panels last March.

My only restrictions are water capacity and food.

My advise to anyone considering solar is to become well informed on the subject. Panels, controllers, and batteries are not all that are important. Wire sizes are also very important. Too small a wire between the panels and the controller as well as too small a wire from the controller and the batteries can choke the system and you will not get the voltage or the amps you paid for at the batteries.

sonicsix · RV-Dreams Family Member

We have 270 watts of solar on our camper and are very thankful to have it. Our 2 Kyocera 135-watt panels keep our four 6v golf cart batteries charged quite easily. We have a 300-watt Pure Sine Wave inverter to run the TV, satellite receiver, DVD player,, charge cell phones, charge our 18v drill batteries, charge our vast array of NiMH batteries for flashlights, etc...

We do not conserve but we do turn things off when not using them. We do not run the A/C or the microwave but do use everything else in the camper and we have never run out of power. In the past month we have camped 24 days with no hookups and the worst part was going to get more water and dumping the holding tanks. Power was never an issue as there was always plenty of it. Our batteries were brought to full almost every day, the only time they didn't was the 4 days that it rained and the sun never came out. But even with overcast skies, the panels did remarkably well.

A full write-up on our solar install can be seen at http://rvroadtrip.us/library/solar_install.asp

Jerry n' Cynthia

-- Edited by sonicsix on Wednesday 7th of July 2010 07:20:10 AM

mick22 · RV-Dreams Community Member

I think the new led tvs would work better than plasma or lcd tvs. The cost to set the solar system up is getting lower every year but it will still take years to get your money out of the system.

Just make sure to find the most efficient things you need to run and use the generator for anything that uses too much electricity.

blijil · RV-Dreams Family Member

Wow, time goes by fast when you are having fun. We just spent 6 weeks dry camping around Granby Lake in Northern Colorado. We love our solar but the Honda 1000 comes in handy when we watch too much TV or it is too cloudy. The combination of solar with a small generator make life almost too easy for the dry camper. We could have stayed longer but the mornings were getting below freezing and the water was to be turned off soon. Hauling water many miles is not fun!

Just a note that we were with friends who have solar but were not having fun. Two reasons for their problems. They did not realize that 12 volt marine RV batteries typically cannot be discharged below 55% without a significant reduction in the battery life. Typically an over discharge (below 12 volts) reduces the life (charge carrying capacity) of the battery by almost 2.5%. So by the time there are 40 discharges or so you can't hold enough charge to do any good.

We replaced the totally shot interstate RV marine batteries with Golf Cart 6 Volt batteries which can handle up to 10 times more deep discharges as the 12 volt marine RV batteries. Life was getting better for our friends.

Then we did an energy audit and found a lot of stuff needlessly left on which contributed to their power drain problems. Well they are working on the conservation end but at least now the understant the problems with deep discharging their batteries and pay much more attention to their battery status. Sometimes the generator must go on just to keep the deep discharge from happening.

Of course you can use batteries less sensitive to the problems of the cheaper lead acid batteries but they cost a lot and they weigh a lot so again with the trade offs.

Just thought the experience and diagnosis may be helpful to some.

Happy boondocking.

Larry and Jacki