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Old 10-18-2016, 12:32 PM   #1
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Solar Controllers?? (and more)

I recently got a Forest River 2306. We are planning on going to various national parks without any hookups. As such, we're going to add a solar/inverter setup to maintain the comforts of home.

My frame of reference is my parents' TT. It has about 375W of solar, a PWM controller, and a modified sine (my dad keeps saying half-sine), 2000W inverter. Also, two L16 Trojan batteries. Finally, a Yamaha 2400 inverter generator. The setup worked great. Never gave batteries a thought, had plenty of power, and run the generator when we needed AC but didn't have shore power.

I've been researching a more modern version of this setup. I've pretty much decided on a 2000W AIMS, true sine inverter with the remote display. Amazon reviews are acceptable to me.

Also, either Renogy or NewPowa panels. Probably 150W times 3 for a total of 450W. Which panel depends on what size(s) I need for my roof space. With 3 panels, it isn't *too* many penetrations in my roof and it somewhat protects against shading.

The batteries, I'll match what he has with the Trojans.

The generator, I'll probably match the Yamaha. It's quiet and I *know* it runs the 13,500 BTU AC just fine, which we both have.

Hopefully you've made it to this point. Now the dilema.......the solar controller. I'll go through some specifics (for my own and hopefully to help someone else down the road) below. However, in general, I'm not even sure what size controller I need. 30A is a common size, and 450W of solar at 12V exceeds 30A. However, I've seen articles reference wattage/amperage and back-calculated voltage. They are using 19.2V to calculate. Well, which is it? I know the "12V" panel is nominal. I've seen people talk about 18V, and articles that are evidently using 19.2. I also know that the max current is when sun is at 100% and batteries are at 0%. Obviously that shouldn't "ever" be happening. I'm sure I could run 31.5A through a 30A controller (if it's not junk), but there's no point in *intentionally* under-sizing components). Gotta love how panels are in watts and controllers are in amps. C'mon, make the sizing easier. So anyway..... I'm assuming I should just pony up and get an MPPT controller, and it should be more than 30A. Both are up for debate.

Prices are amazon. Might be able to do a little better, but prices should be relative.....

Blue sky - 30A/400W (so too small, unless I lessen my panels) for $259.
40A for $410. Good reputation, I think. Probably too expensive for 450W. No remote display.

Renogy Tracer - 40A controller, $188. Same brand as panels I"m considering, if that matters. Not sure about display. Amazon shows people buying it with some other brand display.

Morningstar - 45A, $420. Great reputation, I think. Too spendy for me.

Victron Blue Solar - several options (30A for $226). 50A for $327. Also has a "bluetooth dongle" for $50, which takes care of my remote display desire(s). Victron aso has "color control GX monitor", which doesn't seem like it's out yet. It's an awesome display, but $435 for it ALONE. So, that isn't happening.

Finally, an AIMS 60A for $470. Same brand as the inverter I'm likely going with, if that matters. No remote display, as far as I know. Has LAN, but to use it I'd need to get a USB network card for my stick-PC (media center) and run software. High geek factor, but arg.

What I do recall about using my parents' camper is that I never paid attention to the solar. It displayed voltage, I suppose, but honestly, I didn't pay it any attention. So, maybe my remote display (or worse, mounting the controller where I can see it) is mostly useless. A controller to monitor current usage would be cool, but again, after one "gets used to things", it'd be ignored, I believe.

Super long post to basically say (like many others) MPPT or not?
Any super amazing MPPT controllers for a great price out there?
What size controller do I even need?

I'm probably leaning Victron with bluetooth dongle for name/price/display.
Perhaps in combination with the battery monitor, I dunno...
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Old 10-26-2016, 07:31 PM   #2
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Do your batteries in series not parallel,- thinner wire. Your controller will change all that to amps required anyway. Look into Xantrex/schneider C40 controller. Its 129$ will do 40 amps, and 150v max input , it is pwm. you can setup different voltages for different battery banks-24/12v.
If you are not living in it i wouldnt bother with mppt. Your 450w will be more than enough to recharge batteries. Read reviews on Xantrex c40 on amazon. They arw workhorses that never fail, battery settings are fully customizable for charging modes.
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Old 10-26-2016, 07:42 PM   #3
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6 years later, 24/7 on. Runs all soffit lights in the house and xmas lights - Aims
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Old 10-26-2016, 07:54 PM   #4
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OK...let's slow down here. (1) You cannot wire your panels in series if you use PWM controllers as they cannot use the higher voltages. (2) You don't want to wire them in series anyway as you will lose virtually all output if even a small area of one panel gets shaded, and I mean a really small area. (2) 150 watt panels will only put out a little more than 8 amps each...into a short circuit, which never happens, and normally operate around 6 amps each, so 3 panels generally never even get to more than 20 amps.

My vote is wire them in parallel, use a PWM controller and I prefer the Bogart SC2030, which cooperates with the Trimetric monitor to produce a really nice integrated system. Even offers battery equalization capability and the panels have the voltage to do it.

Trojans are great as well. Wire size need only be 10 Ga down to the controller, or 10 to 8 Ga from a combiner box and then to the controller. There is plenty of voltage available and the 2030 uses remote sense, so it will get the battery voltage to where it needs to be with reasonable cables (#6?).

At these sizes, MPPT doesn't add enough. With a 5000 watt home installation, it allows panels to be wired in series to reduce the size of cabling to the controller.
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Old 10-26-2016, 07:56 PM   #5
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Renogy's 150 watt panels are rated at 8.38 amps output. That's just a little over 25 amps for 450 watts of panels. Any of those 30 amp controllers would work. As you mentioned you will rarely ever be able to get the full output from each panel so you should be good with a 30 amp charge controller.
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Old 10-27-2016, 01:09 AM   #6
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What Scott said

MPPT does voltage conversion which comes into play with series wired panels. You wire panels in series to A) increase voltage and B) reduce current in the down feed wires. This means you can run smaller wires from the panels and lose less power. UNFORTUNATELY... it also means if just one little square cell is shaded you lose output from the whole string of panels.

SO you usually want to wire panels in parallel as much as possible. Many panels are putting out a voltage which is not much higher than battery charge voltage. So dropping the voltage by turning power on/off (which is what a PWM controller does) is not turning off very much and thus not losing much.

And IF you put your controller close to the battery you run the higher panel voltage down the longest wires. Which is good because you can afford to lose a bit of voltage there without much cost in power (the PWM controller just turns off a bit less and on a bit more).

As to the controller size, well from a reliability perspective it is always better to run less power through a controller capable of higher power. So to some extent you can think of excess controller capability as insurance against failure. Cost will keep you from going silly there but 20A coming down into a 30A controller is not unreasonable margin. It is also true that if you have some extra capacity in the controller you can add panel capacity if you need to scale up in the future. I think I put in a 20A controller with my 100W panel with the thought I can add another 100W panel without changing the controller.

And one last comment on monitoring. In a best case you want to track both the goes innas and the goes outas. This is how you can tell if your solar production is keeping up with your consumption. So you need a meter that tracks over time for you. The Trimetric does this, for a price. I run a much cheaper meter, a Bayite, but it only tracks the goes outtas. I think I could put in a second Bayite to track goes innas but two meters would seem silly to the non-nerds.
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Old 10-27-2016, 05:25 AM   #7
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I was reading this thread and it sounds very educational for me. I understand that aeblank was the one asking for help hear, maybe I can get some help also?


OK, here is me, I'm running 2 15k ac units in a 36 ft 5th wheel. hot water heater, washer/drier, 3 electric heaters, all dc lighting, microwave, complete entertainment system and computer system, several small appliances, air compressor and portable welder.


looking into getting a 6.5kw onan lp generator and a complete solar system.


correct me if I am wrong please, the parts as they connect to each other, what do you think I will need?
- solar panels size___________ how many___________
-hook into a wiring hub then one pair of wires feed
-controller size__________type________model___________amps____ _____volts
-battery pack size_______how many_____
-inverter size________model________make__________
-is there an auto switchover that can automatically change from shore power to generator or solar?
-RV power supply. is there a remote that can be used from the control center inside the RV, to monitor and / or adjust solar activity and is there a monitor that can monitor the individual batteries in the battery pack?


hopefully this is the proper order starting from the roof and working my way down. if not please correct me. almost forgot, the current RV battery, should it get incorporated into the solar system or leave it alone?


any help would be greatly appreciated, if I do this alone I just know I will over kill this project.


Thank you
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Old 10-27-2016, 09:56 AM   #8
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2014 Sierra...

That is a pretty big question and there are a lot of ways to look at it. First off, get that generator as no solar system is going to serve your needs without a generator, especially to run those AC units and provide electric hot water for more than an hour since those AC units will draw way too much for a reasonable inverter and battery setup.

That aside, solar will give you a lot and should shorten your generator run times when not using electricity for the AC and hot water.

- solar panels size: 150 watt (12 volt) how many: at least 2, but 3 or 4 would be better
-hook into a wiring hub on the roof then one pair of #8 or #6 running down to the controller if you use PWM and panels in parallel (best for shading)
-Bogart controller type PWM model SC2030 30 amps 18 volts
-battery pack size: 6 volt deep cycle how many: 4 or 6 if you have $$ and room
-inverter size 3000/6000 model: Xantrex make: Freedom SW 3000

the Freedom inverter will provide two 30 amp outputs and automatically switch to shore power or generator when present. It will also charge your battery bank at 150 amps when external AC is present.

Now, there are a lot of variations (panels, number of panels, controllers and inverter/chargers. The inverter chargers are pretty pricey the Freedom is around $1,700 bucks on its own.

You seem to be a high power guy, but a nice 2 or 3 panel system with a 70 amp Progressive Dynamics converter (you already might have that), a 2000 watt Xantrex Prowatt inverter, a 15 amp Xantrex transfer switch, 4 batteries (6 or 12 volt but I prefer 6 volt Trojans), a Bogart SC 2030 and a Bogart Trimetric (shows you everything about the batteries and the solar solution inside the RV) would do for most "off grid" RV experiences.(Don't forget that generator!)

This is what I have (I added the solar and the Trimetric) Georgetown did the rest with their residential reefer package.

I am sure that others will respond with their favorites as there are a ton of possibilities, but I like Xantrex, PD and the Bogart stuff as it works together and gives me total control as well as idiot proof operation.

I did a lot of research as well as spending some time in the solar energy world. Some of the stuff (Xantrex, Progressive Dynamics and 4 deep cycles came with the rig) I added a second Xantrex and the rest is what I chose for performance after significant research.

What I like about the Bogart stuff is you look at the Trimetric, it tells you how much power you have in the bank, how much solar, generator and converter (in my case alternator as well) are giving you and you act accordingly.
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Old 10-27-2016, 11:43 AM   #9
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Quote:
Originally Posted by 2014 sierra View Post
...OK, here is me, I'm running 2 15k ac units in a 36 ft 5th wheel. hot water heater, washer/drier, 3 electric heaters, all dc lighting, microwave, complete entertainment system and computer system, several small appliances, air compressor and portable welder.

looking into getting a 6.5kw onan lp generator and a complete solar system.
I think the first thing you need to do is refine your definition. You have some large electrical loads there which will be very difficult, maybe impossible, and very expensive to address with solar. I think you understand that so you have the generator. The generator will more capably handle the AC units, washer/dryer, electric heaters, air compressor, and *portable welder*!

So you must have a generator making the question: what do you want solar to do?
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Old 10-27-2016, 12:00 PM   #10
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Originally Posted by PSU Turf View Post
Renogy's 150 watt panels are rated at 8.38 amps output. That's just a little over 25 amps for 450 watts of panels. Any of those 30 amp controllers would work. As you mentioned you will rarely ever be able to get the full output from each panel so you should be good with a 30 amp charge controller.
This continues to confuse me. 8.38A and 150W is at nearly 18V. So the panels are "nominally" 12V but actually 18V? I've gotten a reply from one of the charge controller places that used 12V to calculate the amperage. While I don't doubt the output is nearly never at full capacity, it's foolish to intentionally under-size any components, either.

So which voltage should I be using for sizing?
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Old 10-27-2016, 12:26 PM   #11
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Talking

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I think the first thing you need to do is refine your definition. You have some large electrical loads there which will be very difficult, maybe impossible, and very expensive to address with solar.
I'll second this. I think you need 2 basic plans. Consider the solar as "roughing it". So, no AC, no electric hot water. You can size your generator for that. While technically possible, you'd need a support truck to haul the panels and batteries. Also, why not propane hot water?

So then what's solar?
For me, it's LIGHT use of the microwave, hair dryer, TV, media center computer (way cool IBM stick computer), charging laptops and the like.
For me, a 2,000w inverter is pretty well overkill, but a 1,000w is probably a bit small. I also want the inverter for the automatic transfer switch and the 3 stage charger (vs. the battery boiler that I assume my camper has now).

My entire system is a "do it once" in combination of "while we're at it". I'm sure I could get by with a few added 12V outlets and a couple cheap inverters. get a new 12V tv, etc. But the convenience of pressing a button and nearly everything works........way cool. I think the inverter I picked will even kick the AC. But not for long. For a couple grand I'll have what I consider to be a premium system for the entire life of the camper.
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Old 10-27-2016, 12:35 PM   #12
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The whole voltage thing is because solar panels generate voltage and then can support current flow. The maximum current is referred to as "short circuit" which practically is of no use in your calculations. 12 volt panels are "nominal" 12 volt but actually generate from 0 to 22.5 volts depending on how hard to load them and how much sunlight they receive. The number you are looking for the the "optimum" current at the "optimum" voltage, which for the Renology 150 watt is 17.9 volts at 8.38 amps...or...magically 105.002 watts. Now, all that being said, this measurement is only good for a brand new panel at 77 degrees F. You lose .5% for every degree OVER 77 (the panel, not the ambient) and you lose 5% of that after 5 years and that loss keeps going. Not a big deal for lifetime loss, but the temperature deal can be pretty big, especially if they are used in southern climates with no air space under the panel, hence the brackets that lift them off the roof for a modicum of air circulation.

Remember this output assumes perfect alignment, so a flat roof mount never gets there and you have other losses. In southern Florida in December, taking everything into consideration (angle, efficiencies, temperatures, sun angle and cloud cover) you might expect to get 387 watt hours per day from that 150 watt panel and in the best month of the year, which in Florida is April or May, you get a little more than 700 watt hours (remember it gets hot in Florida in the summer and panels don't like heat...and then it rains a lot!) In say, Washington DC, you get 320 and 640 respectively in the same months. Taken another way, in December in southern Florida we get almost 10.5 hours of "daylight" and that means that the panel effectively is not 150 watt but on average a 37 watt panel.

So don't take that 150 watt panel and assume 8 or 10 hours of power generation and expect 1,200 watt hours. It won't happen...ever!
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Old 10-27-2016, 12:53 PM   #13
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My vote is wire them in parallel, use a PWM controller and I prefer the Bogart SC2030, which cooperates with the
Yes to the parallel, due to shading. Cabling be damned. If the output is 0 due to shading, I can use 99GA wire.
That said, if I calculate using 12V, a 30A controller isn't enough for my 3x160W panels. At 18V, a 30A charger *is* enough. This goes back to my previous reply. I can get a 30A PWM charger, the same brand as the inverter, for $100.

Quote:
Originally Posted by ScottBrownstein View Post
Trojans are great as well. Wire size need only be 10 Ga down to the controller, or 10 to 8 Ga from a combiner box and then to the controller. There is plenty of voltage available and the 2030 uses remote sense, so it will get the battery voltage to where it needs to be with reasonable cables (#6?).
Good to know. I'm not sure where everything will be located yet. I'll need some beefy cables for the inverter anyway. So I'll be spending some coin on wires.

Quote:
Originally Posted by ScottBrownstein View Post
At these sizes, MPPT doesn't add enough. With a 5000 watt home installation, it allows panels to be wired in series to reduce the size of cabling to the controller.
I can appreciate the cabling discussion. I was leaning that way for two reasons, 1) the efficiency. I read it can be 50% more, but in practice is 20-30% more output. That was pretty appealing. 2) the amperage. So again, this goes back to the first part of this post and/or one of my other replies. WHAT AMPERAGE DO I NEED? Two "votes" for not bothering with MPPT. Good to know.
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Old 10-27-2016, 01:12 PM   #14
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The whole voltage thing is because solar panels generate voltage and then can support current flow. The maximum current is referred to as "short circuit" which practically is of no use in your calculations. 12 volt panels are "nominal" 12 volt but actually generate from 0 to 22.5 volts depending on how hard to load them and how much sunlight they receive. The number you are looking for the the "optimum" current at the "optimum" voltage, which for the Renology 150 watt is 17.9 volts at 8.38 amps...or...magically 105.002 watts. Now, all that being said, this measurement is only good for a brand new panel at 77 degrees F. You lose .5% for every degree OVER 77 (the panel, not the ambient) and you lose 5% of that after 5 years and that loss keeps going. Not a big deal for lifetime loss, but the temperature deal can be pretty big, especially if they are used in southern climates with no air space under the panel, hence the brackets that lift them off the roof for a modicum of air circulation.

Remember this output assumes perfect alignment, so a flat roof mount never gets there and you have other losses. In southern Florida in December, taking everything into consideration (angle, efficiencies, temperatures, sun angle and cloud cover) you might expect to get 387 watt hours per day from that 150 watt panel and in the best month of the year, which in Florida is April or May, you get a little more than 700 watt hours (remember it gets hot in Florida in the summer and panels don't like heat...and then it rains a lot!) In say, Washington DC, you get 320 and 640 respectively in the same months. Taken another way, in December in southern Florida we get almost 10.5 hours of "daylight" and that means that the panel effectively is not 150 watt but on average a 37 watt panel.

So don't take that 150 watt panel and assume 8 or 10 hours of power generation and expect 1,200 watt hours. It won't happen...ever!

Still absorbing. Good info for sure.

I'm (oddly) not concerned about watt hours. I understand that's the total power being made, etc. The reason I know this is previous experience. My frame of reference (my dad's camper) tells me that 375W of solar, a 30A PWM controller, a 2000W inverter, and 2 Trojans are perfectly acceptable for our use.

I'm just trying to improve on that system where it makes sense. It's several years later, things improve, etc. For instance, if a 160W panel is cheaper per watt than a 100W panel, then why not? If the new controllers give better efficiency, then that seems good too.

So, I'm literally only concerned about the amperage of the panels for sizing the controller. No point in getting (paying for) a controller 2x as big as I need, but to save $100 and under-size it is foolish too.
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Old 10-27-2016, 01:23 PM   #15
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then the best bang for the buck today is a couple of 150 watt panels (really doesn't matter who makes them) a Trimetric, an SC2030 (it will handle 30 amps), a Xantrex Prowatt 600, 1000 or 2000, a ProWatt remote on/off switch and a Prowatt automatic transfer switch. Wire them in parallel with at least 2 deep cycle batteries, 4 would be better. You can wire the inverter to intercept one of the 120 volt breakers that power your outlets and I think that it is best cutting into the breaker that controls the non-gfi outlets. That way, all of the outlets in your RV outside of the kitchen will always work whether connected to shore, running the generator or running the inverter (when you turn it on) and generally this also includes all of your TVs. Personally, the whole purpose of my Xantrex 1000 is so that I can use my computer, charge a phone or watch TV without running a generator.
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Old 10-27-2016, 02:23 PM   #16
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If money is no object...you might want to consider moving from the typical flooded (Trojan) or
gel filled battery to the newer LiFePo storage batteries. Less voltage sag, resistant to partial charge deterioration, 2-3x the life, lighter weight per Ah plus 80% discharge is acceptable. With the types of loads being discussed (welder, air compressor etc) LiFePo will provide a much higher instantaneous current with no damage. I've also "heard" that they are more efficient on the charge side e.g. charge more quickly but I may stand corrected on that attribute. Cost about $1600/200 Ah.
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Old 10-27-2016, 03:09 PM   #17
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Money would have to be no object since that is about 15x the price of flooded batteries! But they do take a charge faster than lead acid...if you have the amps.
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Old 10-27-2016, 04:23 PM   #18
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Well I didn't say it was cheap...(something about men and boys and the price of their toys LOL)

So a quick search provided the following:

Amazon:
Trojan L16H-AC Flooded Lead Acid Deep Cycle Battery 6V 435Ah FAST USA SHIP
by Trojan
Be the first to review this item
Price: $399.95 + $175.00 shipping x2 so $800.00

LiFeMnPO4 Prismatic Battery: 12.8V 200Ah (2560Wh, 10C Rate) - UN38.3 Passed
Conjunction Bar, support 200AVerions 1: ObsoleteVerions 1: Obsolete
Your Price: $1,470.00

So $800.00 vs $2900.00 (to achieve roughly equal Ah capacity)

So 4x+ the cost (however since you can draw down to 80 percent vs 50 percent and the batts last 3x longer so its not really an apples to apples comparison) As I understand using LiFePo you can get away with less capacity than flooded so that should/might cut the costs some. Im budgeting 200Ah at the start and I can always add to it since Ill have the room and weight is less of a consideration (sprinters are very constrained on weight).

Folks who (IMHO) pride themselve in quality installations like AMsolar are using LiFePo due to the significant advantages in weight (110 lbs vs 250lbs), size (I cant shoehorn L16H-AC into the battery box), tech specs etc. Im strapped with using the existing battery box in a Sprinter 2401r. While I can squeeze 600 watts of panel on the roof and crowbar in a 2Kw inverter into a storage bin, storing enough current gets to be the main issue. Im sure Im not the only one out there with this issue. So at ~4x the cost, reduced weight and the fact that I can draw them down to 80% capacity and demand higher amps makes them attractive. 5K charge cycles and no partical charge degredation means you wont be spending another $800.00 anytime soon. I wasnt able to find the average life cycle of Trojan batteries but I think its in the 1K charge cycle if they arent abused. Just another option for those looking to solve a problem...
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Old 10-27-2016, 06:01 PM   #19
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So then what's solar?
For me, it's LIGHT use of the microwave, hair dryer, TV, media center computer (way cool IBM stick computer), charging laptops and the like.
For me, a 2,000w inverter is pretty well overkill, but a 1,000w is probably a bit small. I also want the inverter for the automatic transfer switch and the 3 stage charger (vs. the battery boiler that I assume my camper has now).

...I'm (oddly) not concerned about watt hours. I understand that's the total power being made, etc. The reason I know this is previous experience. My frame of reference (my dad's camper) tells me that 375W of solar, a 30A PWM controller, a 2000W inverter, and 2 Trojans are perfectly acceptable for our use.
...
Ok if you are not concerned about watt hours then you need to be concerned with maximum power. My DW really likes her hair dryer. It is rated at 1700W which is only 14A of 120V but 142A of 12V. So you need a 2000W inverter and the ability to feed it 150A (in round numbers). That is some SERIOUS current flow coming out of batteries and going through cables.

Then you need to worry about the amp/watt hours so you can put back what you take out.

No disagreement about transfer switches and a single master inverter being cool. I am in violent agreement on that and can understand wanting those kinds of toys. Myself, I ruled out the the hair dryer and made my solar life a LOT simpler
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Old 10-27-2016, 06:12 PM   #20
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As I understand, solar panels are best modeled as constant current sources. They are rated in watts at their maximum output - close to their rated voltage. Believe most RV panels are about 18 volts. Watts (DC) equals volts times amps, so a 180 watt panel puts out about 10 amps; a 90 watt panel about 5 amps; etc (at ideal conditions).

As these are essentially constant current sources, the 180 watt panel noted above also puts out 10 amps at 12 volts. A PWM controller just pulses the power from the panel to the battery, varying the pulse width based on the battery's state of charge - so the pulses are each 10 amps. As the battery charge comes up, the 10 amp pulses get shorter and shorter - at full charge, pulse on time is essentially zero. At 12 volts into the battery (heavily discharged battery, maximum controller output) with a PWM controller, the 180 watt panel actually only delivers 10 amps times 12 volts, or 120 watts.

A MPPT controller, in contrast, takes the power in from the panel and converts the power to the required battery voltage. Ignoring controller losses (ideal or 100% efficient controller), an MPPT controller with the same 180 watt panel will deliver 180 watts to the battery - with the same heavily discharged battery, at 12 volts out, the (ideal) controller will deliver 15 amps to the battery (12 volts times 15 amps is 180 watts).

Obviously, it should be very rare that a battery is discharged to 12 volts while it is under charge. ~13 volts is more typical. As such the actual difference in current to the battery between the two controller types is less.

Back to your original question, with a PWM controller, current is the output current of the panel array. With an MPPT controller, output current to the battery can be higher than the array's output current (panel array wattage determined).

Hope this helps -
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JLeising
2012 Solera "S"
Calif SF Bay Area
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