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Solar Panels
#21
ped Wrote:Keep in mind if she has a big battery bank an MPPT is virtually useless. They do not work unless you're in the bulk charge phase.


I don't know where you got that peice of misinformation, but it's not true.  MPPT lets you use higher voltage panels, (sometimes cheaper) and in all cases converts the excess voltage to more amps to charge with.  The only time it's not useful is when your panels can put out more amps that you are using and the batteries will accept.  The only time that happened to me so far is a few hours durring the middle of the day, the rest of the time MPPT lets me get more charging from fewer panels.

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#22

Quote:I don't know where you got that peice of misinformation, but it's not true.  MPPT lets you use higher voltage panels, (sometimes cheaper) and in all cases converts the excess voltage to more amps to charge with.  The only time it's not useful is when your panels can put out more amps that you are using and the batteries will accept.  The only time that happened to me so far is a few hours durring the middle of the day, the rest of the time MPPT lets me get more charging from fewer panels.

Okay, but are you only using 6% per day of you batteries? That's exactly what I said. She'd rarely if ever get that large of a bank drawn down enough for them to accept it in any significant way.

First, it's just common knowledge that MPPT boost goes down as the battery voltage goes up. So even if you have a design that attempts to boost in the 1st and 2nd stage, at 185W-17.7v, the gain is extremely minute. In the milliamp range for her particular conditions. Second, as you said there is a point when the batteries cannot accept more current. Hence 3-stage charging. You can only give them a steady, high current charge when their capacity is below about 80%. That's why 3-stage chargers have the boost mode where it puts in the max current the charger is capable of then goes into the second stage of tappered charge. Third, I got it from the manual.

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What most people see in cool comfortable temperatures with typical battery conditions is a charge current increase of between 10 – 25%. Cooler temperatures and highly discharged batteries can produce increases in excess of 30%. Customers in cold climates have reported charge current increases in excess of 40%. What this means is that current increase tends to be greatest when it is needed most; in cooler conditions when days are short, sun is low on the horizon, and batteries may be more highly discharged. In conditions where extra power is not available (highly charged battery and hot PV modules) a Solar Boost charge controller will perform as a conventional PWM type controller.

Now since she wants to go with AGM's she can set the absorbtion mode to a higher bank voltage. Say 90%. But to do that you have to buy a really good charge controller. So she'll spend something like $250-300 on a Morningstar to get, again, 1 or 2 amps IF she ever gets her bank below the absorbtion stage. Which with 4 batteries and such a small amp load would be next to never. We're talking a 30 amp daily load on a 500 amp battery bank here with easily double the average panel wattage needed.

What would be much more valuble is a tilting mount.

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MPPT BOOST CONTROLLERS (maximum power point tracking);  Yes, they do work, assuming that you run your batteries down low enough, which you will hardly ever do if your system is set up right.  My system runs in the top 15% of its range 95% of the time.  The magic boost kicks in when the batteries are low and will accept more amps at a lower voltage.  There is little or no boost at higher voltages.  Also, the manufacturers will tell you that you can overload their controllers and they will limit the power and protect themselves.  If you look at the meter on one of these, it will show boost even when it is at set point volts where the manufacturerâ€Âs specs say there is no boost, so just what is it doing; boosting or shutting the power off?  It canâ€Ât be doing both at the same time!   I have proven that these controllers play games with the input amps shown.  If you take one out and replace it with a good non MPPT controller when the batteries are near full, you will see that the input amps change, while the output stays nearly the same.  I have done this more than once.  I even got one of the RV Solar dealers to do this and boy did he get upset, red in the face & started yelling at me, something I am sure he would deny now that he is on the boost band wagon.  I tested the input & output of one of the best ones available with my Amprobe and when I multiplied the numbers to get watts, I found that the controller was losing about 10% in its electronics.  It was definitely boosting the amps while lowering the volts, but that unit was advertised to be more than 98% efficient, not 90% as I measured.  If you carefully read the reports on these controllers, you will realize that the magazines never do comparison testing side by side with other brands and independent metering.  They simply report what the meter on the charge controller shows as if it is gospel.  The whole story is suspect and when you look around on the discussion forums; people have backed off from those huge claims and are now being more realistic.  Of course there is another new manufacturer who is making up to 40% boost claims, but where he found this energy that nobody knows about is not explained.  There are those who donâ€Ât believe in MPPT at all, but they are in a small minority.  My background was in the lighting business, where certified independent test reports were the norm, so that is what I expect to see.  There doesnâ€Ât seem to be any such thing in the solar business.   Iâ€Âm just not convinced that these controllers are worth two or three times as much money.  I know, the small two stage units donâ€Ât cost that much, but they donâ€Ât work.  I have replaced several of them with non-boosting three stage units and the systems had more power afterward, not less.  The “experts” donâ€Ât want to believe this, but the people that I have done this for would tell you the truth.  Buy a three stage boost unit if you can afford it, just donâ€Ât expect any ”25% or more” extra power and do not overload it so that it shuts your power off.  Just read the directions.  Somewhere around 5 or 10 % average daily increase is more like it and you are going to get that much extra by running big wires.  Last, donâ€Ât completely believe the latest “trick” about fixing voltage drop problems in a system by running 24V down from the roof in small wires and then transforming down to 12V in the controller.  All transformers (including electronic ones) have an efficiency loss and even the MPPT circuitry is not 100% efficient.  You gain by running 24V & then lose by running it through a transformer.  Last, the boost comes from using excess volts put out by the solar panels and turning it into amps.  If you donâ€Ât install great big wires so that voltage is actually getting to the controller, then you are wasting the extra money spent on the MPPT controller.  Morningstar is recommending that you design for only a 2% loss, panels to the controller and that means even bigger wires when using MPPT.  The older recommendation (that the solar “professionals” have mostly ignored) was 3%.  The dealers who tell you that MPPT will make up for the voltage loss in the wiring are lying to you.  Without the voltage, MPPT cannot work.  You can use higher voltage, lower amperage panels and get a bit more power with MPPT.  This does work because at a higher voltage, you will have less voltage drop before the controller.  However, 100 watt panels put out a max of 100 watts.  When the company makes outrageous boost claims, they are talking about boosting the amps from panels that put out lower amps than other standard voltage panels, not the watts.  They use this as a marketing tool.  You need to do some serious comparison shopping before you decide if their system is worth the price.  You need to compare other systems using standard voltage panels and big enough wires for watts per dollar into the batteries.  I have seen my meter showing 340 watts for short periods of time from my ten year old 345 watts of panels on cool mornings with my PWM Morningstar Tristar that is not MPPT.  I know that MPPT would give me a bit more, but I donâ€Ât believe it to be worth the $250 increase in price to get another 10 or 15% at most (maybe 40 watts), when at 2010 prices that would buy a whole solar panel.  However, on my future house I will be using an MPPT Tristar and running high voltage down from the roof.  I have calculated my voltage drop at 1% using only #6 wires on a 1200 watt system.  A 10% boost there would be 120 watts.  That is worth the money, especially when you look at the reduced wiring cost.  Who does not understand MPPT?  (Just a little barb aimed at those who will know who they are.)

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#23
Thanks for all the VALUABLE information all. There's a lot for me to learn.  Bob suggested a place in Flagstaff, "Wind and Solar" that does all of this work and would probably be the ideal place for me to go because it's fairly close to me and has an excellent reputation.  I can't tell you all how much I appreciate the time you took to jot down all of this important information!  "Thanks sooo much."     

I'll keep everyone posted after I have the work done, as to what they did to my little cottage on wheels.  Of course, I don't purchase it till the end of March, but I'll still let everyone know what I ended up with for power! 

"Happy Trails."
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#24
I'm pretty enthused now that I know I can disperse camp at times and not have to worry about power!  That is my only concern.  I really don't need to use a microwave.  The Propane is fine.  I don't plan on going to Flagstaff in the winter or Phoenix in the middle of summer!  So I think I'll be fine. 

Thanks again!

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#25
Someone told me I could use my generator if I wanted to use the microwave.  Not sure yet about that...I forgot where I read that.

The only thing I use the microwave for is steaming broccoli.  I can do that on a stove. I don't drink coffee really, but I do like Chai Tea.  I don't mind using propane.  I hear you though, we get used to using certain gadgets.  I'm going to try to keep it as simple as possible.   Simplicity is the best medicine, I know laughter is too, but I added simplicity. 

Have a great evening all...

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#26
Using your generator is probably the best and easiest way to run your microwave... depending on the size of your microwave and generator... A 1KW(1000 watts) generator will work for 650 watt micro, any bigger you should have a bigger generator... just start the generator, plug in an extension cord, and then plug in the micro wave... do your cooking and when done simply stop the generator and unplug all cords... It is best to only have the micro wave connected and running alone off the generator as it draws allot of power, to be safe...
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#27
That's what I thought, but wasn't sure!  "Doh."  lol...  Sorry, I should have mentioned to everyone that I will have a generator!  I'm obviously new at this! 

I can't tell you all how much I appreciate the tips.

Have an awesome day! 

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#28
http://www.youtube.com/watch?v=DjBIKGBzj9E  Here is a video I posted on you tube of the back yard fountain of the house I just sold in Arizona.  It is a hummingbird fountain, or what ever bird would like to use it! 

Have a nice day everyone!
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#29
Corrine, just re-read that you have a 2kw Honda genny... you are so set for a micro and much more... you have all the power ya need to run a small house... Also this is about the best genny on the market with a 1-2 pull start... remember to check and change the oil regularly per the manufactures specs... If the genny is new you must change the oil after the first 10-20 hours of use to rid the genny of any shavings in the 10-20 hour break in period, this is a must do!!! ... Just start it up and let her run... Also stop being timid and afraid of the gear ya have, use it, learn it, and become friends with them, know all of your gear inside and out before adventuring for a easy and stress free fun times...

Corinne Wrote:That's what I thought, but wasn't sure!  "Doh."  lol...  Sorry, I should have mentioned to everyone that I will have a generator!  I'm obviously new at this! 

I can't tell you all how much I appreciate the tips.

Have an awesome day! 
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#30
I'm not timid or afraid of the gear at all,  I just want to get to know it way ahead of time so I'll have a clue when I finally get the Trailer.  lol..  

 I grew up with Carpenters, being a stage tech carpenter myself for years at one time, so I'm familiar with the gear, just not the gear for a Trailer.  But I'm getting used to it by reading all the awesome material provided here.  Plus, they are going to go through the Trailer with a fine tooth comb with me when I buy it, making sure I know how everything works.  They told me to plan on spending at least a good two hours with them so they can go over every detail.  They also fill all the tanks and get the propane ready and everything.  The Trailer will be 'full' when I pull out of the Dealer. 

I've also been researching the Nature Power Solar Panels.  Nice.    There is a 25 year warranty on them.  I'm definitely going to have the two AGM batteries bolted or strapped somehow to the frame so no one can walk off with them.

Have a great day!

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