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Old 07-27-2012, 07:44 PM   #1
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Battery/Solar Power

I know there's a lot of dicussion about this but it seems to get very technical and I'm pretty much looking for a simple explanation if y'all could. My question is, if I were to have two marine batteries hooked up in parallel (not those T6? batteries) and hooked a 3000W power inverter to those batteries, would I be able to supply power to the trailer? Also could I keep those batteries charged with a solar panel say around 145W?

Thanks,
DC
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Old 07-28-2012, 11:04 AM   #2
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I don't have the experience some of these guys do, but I don't believe solar needs to be as technical as what some people try to make it. Not having that experience, I won't try to answer your question, because I don't want to confuse anyone and mostly, the answer to your last question is, it depends...

You may have seen it already, but if you haven't, I highly recommend The RV Battery Charging Puzzle « HandyBob's Blog for simplicity in understanding the RV solar system. He has the education, the background and he actually boondocks with solar (no generator) and has done so for seven years. In other words, he not one of these academics that argue technicalities from the ivory tower. I believe if you study and understand what he has on his site, you'll be able to design the system that works for you.
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Old 07-28-2012, 11:39 AM   #3
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I suggest you go to www.windsun.com and do some research. Windsun has been in the business for over 30 years and they are very helpful. Also toll free 800-383-0195.
Setting up a system needs to be evaluated on an individual bases, depending on requirments, but I can tell you that a single 145 watt panel will not do much.
As an example I have 2-12volt 245AH batteries giving me a total rating of 400 AH and 3-205 watt panels.
A good set up should (arguably) have about 150 watt of solar for each 100 watts of storage capacity.
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Old 07-28-2012, 11:42 AM   #4
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There are two choices when you buy solar panels DC and AC output. Seimens makes a high voltage panel that has an integrated micro inverter, the advantage is these panels are not affected by shade like the common DC panel. The wiring is also a much smaller gauge as the output is 120 vac.

http://www.civicsolar.com/product/au...tt-solar-panel

This is a site that describes an instance of this technology.
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Old 07-28-2012, 12:26 PM   #5
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Quote:
Originally Posted by Alan24601
There are two choices when you buy solar panels DC and AC output. Seimens makes a high voltage panel that has an integrated micro inverter, the advantage is these panels are not affected by shade like the common DC panel. The wiring is also a much smaller gauge as the output is 120 vac.

http://www.civicsolar.com/product/au...tt-solar-panel

This is a site that describes an instance of this technology.
I can't see this being helpful in an RV where your batteries are DC unless you're planning on by-passing those entirely. The batteries need DC to charge them and require 3-stage charging profile. Far better to get a regular panel with a good charger.
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Old 07-28-2012, 12:29 PM   #6
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The simple answer is yes. The useful answer is far more involved. The two batteries will not be a very big storage source for a 3000w inverter. At full output the inverter would kill those two batteries in a matter of minutes. A 145w solar panel is not much of a source of energy to supply a 3000w inverter. I have a 2000w inverter-6-6v AGM house batteries and 800w of solar. A fine system when the sun shines but when its cloudy and/or rainy the solar output is very little.

Solar is great but before you invest in solar get a generator. It will always provide power something solar will not necessarily do. Generator first then solar.

Jim
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Old 07-28-2012, 12:36 PM   #7
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Quote:
Originally Posted by dcarver
I know there's a lot of dicussion about this but it seems to get very technical and I'm pretty much looking for a simple explanation if y'all could. My question is, if I were to have two marine batteries hooked up in parallel (not those T6? batteries) and hooked a 3000W power inverter to those batteries, would I be able to supply power to the trailer? Also could I keep those batteries charged with a solar panel say around 145W?

Thanks,
DC
For a solar installation you need panels, the right size wiring and a good 3-stage charger. The charger is essential since that will convert whatever power you're getting from the solar panels into the right version for your batteries to charge properly. All this stuff will be on the 'input' side of your batteries (going to charge them). On the 'output' side you'd have the inverter. It inverts your DC battery output to an AC current. The inverter is not necessarily critical. Depends whether you need AC or not in your coach. Lights will function on DC, computers Typically use AC (although you can buy DC chargers for computers too!). We have a 2000 watts inverter which is fine for us. You really won't need more than that.

As for size, 145w is a bit small. I'd recommend going somewhat bigger. There are folks who do fine with about twice that. Our system is 600w (six 100w panels) and that works for us, but we are on the Internet most of the day.

handybob's site is a good start for understanding the system. I also have a series on my blog here
http://wheelingit.wordpress.com/2010...overy-process/
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Old 07-28-2012, 01:05 PM   #8
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I'd encourage using a great deal of discretion if going to a site for information that also sells solar. A forum that is hosted by a solar dealer may require some discernment as well.

Handybob recommends a battery monitor as the first component of an RV solar system and, along with understanding battery charging, I believe it is a reasonable and logical first step.

From his site:

"BATTERY MONITORS: The RV industry has really let us down. First of all, you can’t believe the little “idiot light” panel that came in your rig. That thing is very optimistic and tells you the batteries are full at 13.4 volts, when they are actually nowhere near it (14.4 volts). It works by looking at the voltage present on the wiring, which will be much higher than the battery voltage while charging & much lower than the battery voltage when running loads. If it says your batteries are “full” while you are charging, you could be anywhere from 40% to fully charged. People that run their generator until the idiot light says “full” are only getting their batteries up to about 40 or 50%. They start their evening at the point my system would get down to after a week of rainy days. Last, if the monitor says your batteries are “fair” when you are not running anything, they are DEAD. So, how can you tell if your batteries are really getting fully charged? The most accurate way is to test the battery electrolyte with a hydrometer. A hydrometer with a tube float inside it like the $5 one from an automotive store works just fine. This is messy and not very convenient, but if you want to know for sure this is what you have to do. The easy (but not as accurate) way is to buy a cheap little volt meter and measure at any point in your rig (12 volt outlet, light or fuse panel) after the batteries have been resting for over an hour. Both charging and loading will cause false readings. A resting, full battery will test at about 12.7 volts. A resting, dead battery will test at 11.8 volts. Yes, that dead battery will still provide some power, but you are destroying it by letting it get that low. That magic 50% level that most folks say you should stay above for good battery life is about 12.2 volts. Campers generally don’t get decent life out of their batteries because they run them down too low and don’t keep them charged up, causing sulfating and stratification. My first set of RV batteries lasted less than two years."


To make a good decision about your solar, you're going to have to know what your power demands are. A battery monitor will help you know if you're batteries are being charged to full (most systems do not, apparently) and when they are discharged (12.2 volts).


As for your application, it still depends. It depends on the condition of your batteries, how well they are charged, the size of the wire and length of the wire run from the panel to the batteries, your panel, the placement of your panel, how much power you will be using...
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Old 07-28-2012, 01:11 PM   #9
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Quote:
Originally Posted by dcarver View Post
I know there's a lot of dicussion about this but it seems to get very technical and I'm pretty much looking for a simple explanation if y'all could. My question is, if I were to have two marine batteries hooked up in parallel (not those T6? batteries) and hooked a 3000W power inverter to those batteries, would I be able to supply power to the trailer? Also could I keep those batteries charged with a solar panel say around 145W?

Thanks,
DC
How big of batteries?

Whats your actual daily usage?

Whats your daily hours of sun?

How many of those hours is the sun actually charging the batts?

Short answer based on what you have given: NO.. you will not run a 3000W inverter all day with 2 12v batts and 145W solar panel... not even close.
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Old 07-28-2012, 06:45 PM   #10
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Thanks everyone for the advice! I have not yet looked at handy bob's website but I will shortly. What I'm hearing is that the setup in my head is not going to work like I want so with y'alls and handybob's advice I'll get it done.
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Old 07-30-2012, 08:58 AM   #11
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Originally Posted by retmotor View Post
I'd encourage using a great deal of discretion if going to a site for information that also sells solar. A forum that is hosted by a solar dealer may require some discernment as well.

Handybob recommends a battery monitor as the first component of an RV solar system and, along with understanding battery charging, I believe it is a reasonable and logical first step.

From his site:

"BATTERY MONITORS: The RV industry has really let us down. First of all, you can’t believe the little “idiot light” panel that came in your rig. That thing is very optimistic and tells you the batteries are full at 13.4 volts, when they are actually nowhere near it (14.4 volts). It works by looking at the voltage present on the wiring, which will be much higher than the battery voltage while charging & much lower than the battery voltage when running loads. If it says your batteries are “full” while you are charging, you could be anywhere from 40% to fully charged. People that run their generator until the idiot light says “full” are only getting their batteries up to about 40 or 50%. They start their evening at the point my system would get down to after a week of rainy days. Last, if the monitor says your batteries are “fair” when you are not running anything, they are DEAD. So, how can you tell if your batteries are really getting fully charged? The most accurate way is to test the battery electrolyte with a hydrometer. A hydrometer with a tube float inside it like the $5 one from an automotive store works just fine. This is messy and not very convenient, but if you want to know for sure this is what you have to do. The easy (but not as accurate) way is to buy a cheap little volt meter and measure at any point in your rig (12 volt outlet, light or fuse panel) after the batteries have been resting for over an hour. Both charging and loading will cause false readings. A resting, full battery will test at about 12.7 volts. A resting, dead battery will test at 11.8 volts. Yes, that dead battery will still provide some power, but you are destroying it by letting it get that low. That magic 50% level that most folks say you should stay above for good battery life is about 12.2 volts. Campers generally don’t get decent life out of their batteries because they run them down too low and don’t keep them charged up, causing sulfating and stratification. My first set of RV batteries lasted less than two years."


To make a good decision about your solar, you're going to have to know what your power demands are. A battery monitor will help you know if you're batteries are being charged to full (most systems do not, apparently) and when they are discharged (12.2 volts).


As for your application, it still depends. It depends on the condition of your batteries, how well they are charged, the size of the wire and length of the wire run from the panel to the batteries, your panel, the placement of your panel, how much power you will be using...
I believe you mis-spoke in the first paragraph. Why would one not got to experts in the field with over 30 years of experience? Thats paramount to advising one to avoid an rv dealership when requesting information on a coach.
There is no obligation to purchase from them or participate in the forum.
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Old 07-30-2012, 08:00 PM   #12
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I believe you mis-spoke in the first paragraph. Why would one not got to experts in the field with over 30 years of experience? Thats paramount to advising one to avoid an rv dealership when requesting information on a coach.
There is no obligation to purchase from them or participate in the forum.
Nope, I did not mis-speak. I said what I meant. If someone is selling something and also providing information on it, that's a classic conflict of interest. They're in the business to make money to feed their family, make their house payment, whatever motivates them -- it doesn't really matter -- a salesman's priority is almost always going to be to make money. If a manufacturer is offering a sales promotion on "product A" and it's a money maker for the sales people, that's what product they're going to sell you. If there's a product they know is better but they don't carry it, do you really think they will recommend that product or do you think they will sell you something they carry?

I have years more experience in the field of life experience than these people have sales experience, so why would you not my word at face value considering my vast experience?

Trouble yourself to read through handybob's site paying attention to his experience with solar dealers and installers. If you do this I believe you'll understand why I said what I said. Also, I reiterate, handybob has been off-grid for seven years without a generator and his system works. He's even been using power tools to build a cabin; said tools powered by his RV solar system. On forums, I've seen non-solicited references from people who have gone to the "experts" to buy and install their solar systems that didn't work. The "experts" sold them more panels, more batteries, the newest controller, etc. and they still had systems that didn't work.

I hope I this answers question.
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Old 07-30-2012, 08:59 PM   #13
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Nope, I did not mis-speak. I said what I meant. If someone is selling something and also providing information on it, that's a classic conflict of interest. They're in the business to make money to feed their family, make their house payment, whatever motivates them -- it doesn't really matter -- a salesman's priority is almost always going to be to make money. If a manufacturer is offering a sales promotion on "product A" and it's a money maker for the sales people, that's what product they're going to sell you. If there's a product they know is better but they don't carry it, do you really think they will recommend that product or do you think they will sell you something they carry?

I have years more experience in the field of life experience than these people have sales experience, so why would you not my word at face value considering my vast experience?

Trouble yourself to read through handybob's site paying attention to his experience with solar dealers and installers. If you do this I believe you'll understand why I said what I said. Also, I reiterate, handybob has been off-grid for seven years without a generator and his system works. He's even been using power tools to build a cabin; said tools powered by his RV solar system. On forums, I've seen non-solicited references from people who have gone to the "experts" to buy and install their solar systems that didn't work. The "experts" sold them more panels, more batteries, the newest controller, etc. and they still had systems that didn't work.

I hope I this answers question.
My home solar system and my motorhome were both designed by Windsun. There are reputible dealers that give exelent service and advice.
You and Handy Bob try to lump them all into one basket. He does have some exelent advice but is not the only resource available.
With your vast life experiences I would think there would also be the wisdom to seek out more than one resource when doing research.

PS: I recommended them because they are a reputable company that I have delt with for many years. The coach we have now is the second one they have designed the solar system for as well as the home we built in 1989.
So much for conflict of interest
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Old 07-31-2012, 12:06 AM   #14
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Solar-wise, if you have more extensive solar boondocking experience than a cited reference, you should say so. It'd save a lot of unnecessary discussion. How many panels do have on your RV? How many watts per panel? How many batteries? What's the average life of your batteries? What electrical appliances do you use and for how long? Do you use a generator?

You've assumed I've only sought out one resource. What other resources out there can you recommend that don't sell solar components? I'm interested.

I don't lump any group into one particular category and I fail to see how you came to that conclusion. I do however like to find someone successful in whatever endeavor I am interested in and learn from them. I really don't know that much about solar, but I know of someone who does, who has made mistakes and is willing to use them as examples, who has been doing it well for years, who has unsolicited references and who has put his experiences, good and bad, on the web for educational purposes.

Handybob does not lump all the dealers into one basket either. On his site he names solar dealers which he believes to be reputable. Have you read the information he has on his site? If you have, you may have noticed this: "...I recommend Backwoods Solar and Northern Arizona Wind Sun [windsun.com] as honest suppliers." (I have done research on that site, by the way.) So you've essentially said handybob is a bigot prejudiced against all solar dealers, yet he agrees with you.

While involved in different vocations, handybob and I were both trained in sales. We also both quit because because selling and our morals were at conflict -- and so it goes with sales. Will you ever meet an honest salesman who has your best interest in mind and not the dollar from the sale? I don't know. I've met one that I'm aware of and that was in a very specialized field. One.

If you want to dismiss the conflict of interest, you'll have to present a better argument, because I've been on that side of the fence. It is a conflict of interest. If you actually found someone in sales who gave you the best you could get for the best price you could get and it's a system that actually works independent of other power sources -- congrats, I'm glad to hear it.

If you haven't read my words carefully, you may think I'm arguing against windsun.com. I'm not. I have no personal experience with them and when I do purchase solar components, they are on a short list of possible vendors from whom I may order. What I'm saying is extraordinarily simple. If you're looking for information and you go to a source that also sells what you're interested in, some discretion is in order because in sales, sales people need to sell stuff to keep their jobs and nearly all sales people will sell what makes them the most money.

I apologize for my part in taking this thread off-topic.
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