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Author Topic: A little confused about solar! First timer  (Read 1093 times)

misplacedfriday

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A little confused about solar! First timer
« on: January 28, 2017, 08:23:59 AM »
Hello, my name is Mike. I'm new to this forum, and also to RV life! I'm about to buy a brand new, 2017 Gulfstream travel trailer. According to the dealer, this bad boy already has an inverter that will switch DC power to AC power. In fact, she told me everything runs off the 1 deep cycle 12 volt battery which can power everything itself except for the AC (there is no generator on this thing). This is nice and simple, like I like it. She also said that all I need to do for solar is install some panels (and maybe a charge controller?) right to this existing house battery (and maybe install a second battery if I need it?) and voila! Solar power in my RV.

Is it really that simple? All these RV solar install websites are always mentioning buying these expensive inverters along with your solar panels. Is it true that my house battery will already be all set for a solar panel hookup? She also told me that the house battery is being charged also when I'm driving if I have a brake controller installed in my car and ALSO when I'm on shore power at an RV park?! Will this charge two batteries at the same time if I daisy-chain another one in there? This all seems too good to be true!

Thanks for any help. Forum people are the best people.

Gary RV_Wizard

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Re: A little confused about solar! First timer
« Reply #1 on: January 28, 2017, 09:03:49 AM »
Well, superficially it is that simple. The devil is in the details, and (as usual) the sales rep glossed over those.

You can't invert very much power or for very long from just a single battery, so if you were thinking to brew coffee, cook a microwave dinner or watch tv all evening, you are likely to be disappointed. Nor did you mention the size (watts) of that inverter, which may be another limiting factor.

On the plus side, your water heater & furnace will work fine on LP gas, so don't need any 120v electric (they use 12vedc, though). And the interior lighting is all 12v too.

Solar panels, a controller and wiring can be added, but it's probably pointless without adding more batteries.

The real question is how much you expect to use the trailer without access to an electrical hook-up (most RV campsites have them) and for how long.  If more than a brief stop, you are probably going to need at least two batteries (and larger/better ones than the factory supplied) and more likely four of them.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Isaac-1

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Re: A little confused about solar! First timer
« Reply #2 on: January 28, 2017, 09:25:45 AM »
I don't know about your particular install, but you need more information.  First off with a single house battery you are not going to be running much with an inverter, meaning it may be great for plugging in your cell phone charger, maybe a modern flat panel tv that draws 30-40 watts or a notebook computer that draws the same. Think of your house battery as a fuel tank, the smaller / fewer you have the quicker you are going to run out of fuel.  Also you need to know the size of the included inverter as well as what you plan to run, there is a big difference in a 200 watt inverter and a 2,000 watt inverter.  You also need to learn the difference between a modified sine wave inverter and a pure sine way model, as well if you plan to run anything that needs pure sine wave. Lots of stuff don't care (things like computers and TV's with switch mode power supplyes), on the other hand microwaves are one where it can make a difference  as they tend to overheat and burn out when connected to modified sinewave inverter, the question then becomes one of is it worth paying an extra $250 for a pure sine wave inverter to extend the life of a $80 microwave oven (if you have a fancy $500 microwave/convection oven the answer gets easier).  A 200 watt inverter is enough to run many modern low powered items like the phone charger or flat tv mentioned above, what it will not do is let you run your microwave oven that may draw 1,500 watts.  Think of the inverter as the size of your engine, the bigger it is the more load it can pull, but also the more fuel it consumes, in the case of a modern inverter, the only downside to buying one that is too big is inital cost, a 2000 watt inverter powering a 40 watt TV will consume about the same power than a 200 watt inverter under the same load.

Back to that initial sizing, if you have a 1,500 -2,000 watt inverter and a single battery you can use it to power higher electrical draw items, if you run it for a short time, meaning you can use it to warm instant oatmeal in the microwave, but not to cook a turkey.

As to the solar ready / solar prep on many RV's this just means they have ran (an oftern undersized) wire from the roof to the battery bank area for you, if you are lucky they will have put quick connects on the ends of the wires.  You will still need solar panels, mounting brackets, and a charge controller.  Now as to sizing roof top solar as a general rule of thumb you want less than about 250 watts of solar panels per deep cycle battery on the upper end,  and at least 80 watts of panels per battery on the lower end.   There are many cheaper off brand imported panels on the market priced in the $1 per watt ballpark, some are better than others,  they often do not perform as well as the big name panels, meaning a 120 watt fly by night no name import may perform as well as a 100 watt big name panel when used to charge a battery.  (I am not claiming false advertising on watts here, just lack of optimizing the exact output for charging purposes)  Many of these cheaper panels are not built as well either, with thinner and weaker metal frames, which may be an issue with wind loads at highway speeds.

Let me compare 3 Solar panels I own, that I have bought over the last 10 years or so for various small stand alone remote solar applications.  Just focusing on the metal frame that holds it the panel together.  The big name panel uses a fairly thick E channel aluminum extruded frame which is anodized for extended outdoor life, import panel a (Newpowa brand bought last year) uses  common U channel all the way around and is about half as thick as the brand name panel, import panel b (no name eco something that was $10 less than the Newpowa also bought last year) uses U channel on the sides only and L channel on the ends allowing for much more flex.
2002 Safari Trek 2830

Alfa38User

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Re: A little confused about solar! First timer
« Reply #3 on: January 28, 2017, 09:33:03 AM »
No, it is not that simple!!! Add to that AC, a microwave, the entertainment system. With only one battery, a large inverter will eat it up very quickly if used a lot without being plugged in. Remember the 50% rule for these so-called "deep discharge" batteries, they should not be discharged more than 50% before charging again. Most travel trailers use a CONverter which charges the battery(ies) and supplies additional 12V power when plugged in, supplementing the batteries, although some can have INVerters which double as battery chargers, most don't. But regardless, you have to be plugged in to charge the batteries if you don't have a very robust solar system!!!! You would have to know the make and model of said INVerter unit to understand exactly what is proposed.

Solar with an inverter is a nice option but not viable with only one battery, it will require a much bigger battery bank, especially with an INVerter in use. The solar system has to be sized correctly for your needs, it is not as simple as slapping a couple of panels on the roof and throwing in a controller. For example: how do you charge the batteries at night or during a several day rainy/cloudy period if it your only source of charging? There are several sites with very good info on this subject, like Handybobsolar.com

Charging while towing down the road? Possible IF the tow vehicle is arranged to do so but not necessarily all are, it may take additional wiring and fusing to set it up initially.

By far the biggest concern for you initially should be the tow vehicle you have. Can it handle the proposed trailer safely? The trailer sales people will often gloss over this by saying "you can pull anything we have on the lot!!" which is might be true for pulling it.... but safely? And stopping it?? What if the trailer brakes fail?? This are the questions you have to answer for yourself and not rely on them. For starters, you need to know the VGWR (not the empty weight) and length of the TRAILER and the payload capacity of your tow vehicle etc. Plenty of help available here on that subject, just ask if you need help on this sometimes confusing subject....

A lot of good info in the posts above, Isaac-1 and I were typing at the same time!!!!
« Last Edit: January 28, 2017, 10:16:26 AM by Alfa38User »
Stu
Montréal, Canada 🍁
Snowbird, Naples Florida
Alfa Gold 38 (2000) 5ver (parked!)

"Of course I talk to myself, sometimes I need expert advise!!!"

misplacedfriday

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Re: A little confused about solar! First timer
« Reply #4 on: January 30, 2017, 04:52:17 PM »
Wow, what a great group on here! This is beyond helpful. I'm starting to wonder if the saleswoman IS referring to a converter, not an inverter. This is a 2017 Gulfstream Amerilite 16BHC so it's not anything fancy by any means. I'll pick it up on Sunday and do some inspecting with a fine-toothed comb to see what's already there before buying anything. Thanks to everyone who responded!

Gary RV_Wizard

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Re: A little confused about solar! First timer
« Reply #5 on: January 30, 2017, 05:45:27 PM »
Don't mean to be insulting, but it would be very unusual for a small, fairly basic travel trailer to include an inverter. Nor is there any inverter listed in the Amerilite brochure, either standard or optional.  I wonder if he was trying to sell you on a dealer-installed option?

http://www.gulfstreamcoach.com/products/light-weight/amerilite/features
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

misplacedfriday

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Re: A little confused about solar! First timer
« Reply #6 on: February 09, 2017, 06:51:43 PM »
Who would you be insulting?

Anyway, yes I haven't found any trace of a power inverter in the trailer. So, either the saleswoman misunderstood me or she was saying anything to get the sale. What's great though, is that EVERYTHING runs off 12vDC except for the outlets. There is even a 12vDC 'cigarette lighter' type slot inside (I have a little inverter to plug into there). My new question is... can I just buy a solar panel and charge controller, and hook it up to my existing deep cycle battery on the trailer? Will it interfere with the shore power charging my battery or the car alternator charging my battery while I'm towing?

 So, ultimately... use my solar panel just for all the 12vDC stuff in my trailer! It still sounds too good to be true, and unbelievably simple. I'd love to save some money and installation time by not buying a big inverter.

Thanks again, group!

AStravelers

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Re: A little confused about solar! First timer
« Reply #7 on: February 10, 2017, 08:19:25 AM »
Who would you be insulting?

Anyway, yes I haven't found any trace of a power inverter in the trailer. So, either the saleswoman misunderstood me or she was saying anything to get the sale. What's great though, is that EVERYTHING runs off 12vDC except for the outlets. There is even a 12vDC 'cigarette lighter' type slot inside (I have a little inverter to plug into there). My new question is... can I just buy a solar panel and charge controller, and hook it up to my existing deep cycle battery on the trailer? Will it interfere with the shore power charging my battery or the car alternator charging my battery while I'm towing?

 So, ultimately... use my solar panel just for all the 12vDC stuff in my trailer! It still sounds too good to be true, and unbelievably simple. I'd love to save some money and installation time by not buying a big inverter.

Thanks again, group!
Yes you can just install a single solar panel to keep your 12V deep cycle battery charged.  You don't really need a solar charge controller either as long as your solar panels output is rated at the typical 17V to 18V.

Also some people don't mount them to the roof.  They just carry them and set them outside, aim it to the sun and have some wires which attach the panel to the battery.

Here is a link to AMSolar.com which has a kit with mouting brackets and most everything you need:  http://amsolar.com/rv-solar-panel-kit/panel-kits  This kit should be able to be shipped via UPS for a fairly nominal amount.   Big solar panels must be shipped via freight companies and the shipping usually runs into the hundreds of dollars.   A few years ago I bought some of these panels from AMSolar and they were shipped via UPS.

You only need the big 1000 to 2000 watt inverter if you want to operate a microwave, electric coffee pot, etc.   But then you really need much more battery.  Also if you go that route, there are more things to consider than needs to be addressed in this topic.

To operate a laptop, or TV you can buy a small 200-400 watt inverter.  It is best to hard wire the inverter to the battery rather than plug it into the 12V outlet.  The 12V outlet won't carry the load of more than a 100 watt inverter. 

If you are interested in learning lots more about RV Electric, batteries & solar here are some links:

http://www.marxrv.com/12volt/12volt.htm
http://www.marxrv.com/12volt/12volta.htm
http://www.jackdanmayer.com/Batteries_and_charging.html
http://www.jackdanmayer.com/rv_electrical_and_solar.htm
« Last Edit: February 10, 2017, 08:21:33 AM by AStravelers »
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

Alfa38User

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Re: A little confused about solar! First timer
« Reply #8 on: February 10, 2017, 08:57:32 AM »
Quote
  It still sounds too good to be true, and unbelievably simple.

That is because it is!!!

You are not likely to find an INVerter. An inverter is connected to the batteries and produces 120V to power certain 120V items such as the entertainment system. You mentioned you already have a small one. What you will find is a CONverter which produces 12V from 120V when plugged in.  It also charges the battery(ies) and helps run the house 12V system. Actually locating the converter may be difficult as it is often skillfully hidden as part and parcel of the main electrical panel especially when the 12V fuses are co-located with the 120V circuit breakers.

To get a decent battery life, remember you should not discharge that "deep discharge" battery to more than 50% of its capacity before recharging. If you have a single battery you are not a good candidate to operate from solar, as you have no 12V (battery) reserve available even for light overnight use, for cloudy, rainy days, where there is shading or partial shading by trees and other roof mounted equipment or days where there is simply not enough sun to get a good solar panel output that is sufficient to bring the batteries to full charge.  It takes a substantial battery bank to provide an adequate reserve and possibly several panels for charging it in order to do that.
« Last Edit: February 10, 2017, 09:34:27 AM by Alfa38User »
Stu
Montréal, Canada 🍁
Snowbird, Naples Florida
Alfa Gold 38 (2000) 5ver (parked!)

"Of course I talk to myself, sometimes I need expert advise!!!"

AStravelers

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Re: A little confused about solar! First timer
« Reply #9 on: February 10, 2017, 09:39:30 AM »
Since the OP has a small trailer I doubt he is talking about using lots of battery power. 

A single battery to just operate the lights and perhaps operate a small LED TV off an 150 watt inverter for a couple of hours a day, a 100 watt or 160 watt solar panel will work just fine to keep the battery charged. 

If there was a day or two of cloudy weather, just don't run the TV and be conservative with the lights.

One killer would be if you had to run the forced air propane furnace a lot. That fan uses lots of battery power.  Especially with cloudy weather when you don't get much solar energy.

Bottom line, it depends on what your wants and desires are as to whether or not a single battery and a 100 watt solar panel will work for you. 

Don't just rely on the opinions given here (mine included).  Go to the links I gave earlier and become educated about batteries, charging and solar.  Once you learn about the topic, each of us can decide just what we need to do have our RV'ing without hooking up to electrical power in campgrounds or RV Parks.

Lots of people like to tell others what they cannot do.  However when you look around there are a lot of people doing just what others have said you cannot do.  And they are very happy doing it.  Just like having a single battery and one solar panel.  It works just fine as long as you know what your usage requirements are. 
Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

 

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