Thanks for that! I'm running 170 watts of poly and 100 watts of mono. Although there is really not that much difference in size, on my roof, the smaller poly did make it easier to find a spot for it. Size does matter in tight quarters. A difference multiplied by many panels can mean stuffing one more in an area or not. Of course given you observations about the two different types, with the poly as the clear performer, changes the calculus.
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- Thread starter StarEcho
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Oops, I'm not sure I see the combiner to connect the two panels together. One of the great things about MC4 connectors it's so simple to combine two panels, all you need is this Y connector:
http://www.amazon.com/Renogy-Branch-Connectors-Solar-connector/dp/B00BCWRB48/
Bob
http://www.amazon.com/Renogy-Branch-Connectors-Solar-connector/dp/B00BCWRB48/
Bob
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Jim in Denver, thanks for that very good info!! i'd never heard that before about mono and poly but I'll bear it in mind.
It's always good to get direct user feedback like that.
Bob
It's always good to get direct user feedback like that.
Bob
jimindenver
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I am glad it helps someone. As always, take anything with a grain of salt and apply to YOUR situation.
I am just that weird guy you'll see with panels in his driveway, a bunch of meters and a note book. My next side by side will be to see how well my $100 dollar MPPT controller fairs against a respectable controller made in China. People always assume that just because something is more expensive that it is better, we shall see. Then will be a series of test with the new controller to see what produces the most amps, running at high voltage in series or lower voltage in parallel. I'm betting that the conversion from high to low will produce less than low to low. I'd love to get a pair of 12v panels to run against my 24v panels but until I sell more off, I get the stink eye from Honey every time I mention it.
I am just that weird guy you'll see with panels in his driveway, a bunch of meters and a note book. My next side by side will be to see how well my $100 dollar MPPT controller fairs against a respectable controller made in China. People always assume that just because something is more expensive that it is better, we shall see. Then will be a series of test with the new controller to see what produces the most amps, running at high voltage in series or lower voltage in parallel. I'm betting that the conversion from high to low will produce less than low to low. I'd love to get a pair of 12v panels to run against my 24v panels but until I sell more off, I get the stink eye from Honey every time I mention it.
StarEcho
Well-known member
Ah well Jim, I just sent in my order with Amazon for the monos. I had also read that it didn't really make much difference, but I'm not going to stress about it even if it does.
The whole thing is almost giving me an ulcer.... feeling like if you don't make the right decision the world will end! LOL So I finally just had to put the order in without dithering anymore between this and that. I ended up with the Renogy 100 W monos x2 so 200W total and the renogy pwm charge controller with LCD readout and temp sensor, some cable, connecters, etc. Anything else I'll get at RTR.
Unfortunately for me, what with the holidays, the guy who is doing the welding on my trailer, for propane tanks and bumper rack can't work on it until the 6th or 7th, so I won't be able to get to RTR for the start. But I'll be there as soon after my trailer is ready as I can. Definitely by that Sat.
Hopefully I can find something to barter with. I can do websites and maybe some basic computer skills teaching wise. I could bring my sewing machine if someone wants curtains sewed?
Anyway, thanks again for all who responded. These types of threads also help those down the road who might be looking for this same type of info.
The whole thing is almost giving me an ulcer.... feeling like if you don't make the right decision the world will end! LOL So I finally just had to put the order in without dithering anymore between this and that. I ended up with the Renogy 100 W monos x2 so 200W total and the renogy pwm charge controller with LCD readout and temp sensor, some cable, connecters, etc. Anything else I'll get at RTR.
Unfortunately for me, what with the holidays, the guy who is doing the welding on my trailer, for propane tanks and bumper rack can't work on it until the 6th or 7th, so I won't be able to get to RTR for the start. But I'll be there as soon after my trailer is ready as I can. Definitely by that Sat.
Hopefully I can find something to barter with. I can do websites and maybe some basic computer skills teaching wise. I could bring my sewing machine if someone wants curtains sewed?
Anyway, thanks again for all who responded. These types of threads also help those down the road who might be looking for this same type of info.
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Jim, you gotta watch out for that stink-eye!! We all know the ONE ultimate truth, "If mama ain't happy ....!"
Bob
Bob
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Cyndi, I think you did real good! That's a good solid system for a great price and it should serve you well!
See you soon!
Bob
See you soon!
Bob
I went with poly, they do better in the heat, mono would be better for colder weather and either would be fine if you're using them on a rooftop. Poly panels take up more space for the same watts so mono is also good if you're tight on roof space. Neither is right or wrong and only marginally better for any specific application.
And Cindi, you did fine, you can adjust your system as you go and you're able to figure out your needs along the way. The only word of warning I'm going to offer is the LCD display on your controller is going to be about as precise as using a lawnmower to cut your hair, it will do the job but you don't want to trust it with the health of your batteries as draining them too low repeatedly can cut their life from say 1,000 cycles with a 40% drain to only a couple hundred cycles with a 70% drain.
http://www.solar-electric.com/trtmb...rqGZcWFaoHMNiIs89W7kLTZ2HuWJhPj8jKBoC7ufw_wcB
This is a great next investment to give you some peace of mind.
Good luck and enjoy!
And Cindi, you did fine, you can adjust your system as you go and you're able to figure out your needs along the way. The only word of warning I'm going to offer is the LCD display on your controller is going to be about as precise as using a lawnmower to cut your hair, it will do the job but you don't want to trust it with the health of your batteries as draining them too low repeatedly can cut their life from say 1,000 cycles with a 40% drain to only a couple hundred cycles with a 70% drain.
http://www.solar-electric.com/trtmb...rqGZcWFaoHMNiIs89W7kLTZ2HuWJhPj8jKBoC7ufw_wcB
This is a great next investment to give you some peace of mind.
Good luck and enjoy!
BigT
Well-known member
This is an excellent thread with some great information! Every time I read something like this I learn something new and get at least a few questions answered.
Example: It sounds like I won't need an MPPT CC if I'm running less than 400W of panels. That's good to know as I'm having a heck of a time figuring out which controller to get.
Lots of good information here.
Example: It sounds like I won't need an MPPT CC if I'm running less than 400W of panels. That's good to know as I'm having a heck of a time figuring out which controller to get.
Lots of good information here.
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I disagree, every solar system should have an MPPT controller unless you are so broke you can't afford it.
Bob
Bob
SternWake
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I think the 400 watt threshold is more about bang for the buck. It is cheaper to get another panel and a PWM solar controller and get the same amperage as less panel wattage and an Mppt controller.
With limited roof space on some applications, perhaps most on this forum, the option of more solar and a cheaper PWM controller is not always prudent.
The MPPT preprogrammed algorithm's efficacy varies among different manufacturers, and the MPPT is not always more effective than PWM. Sometimes they are equal, or the PWM even gets the Nod.
The MPPT conversion is most beneficial at lower states of battery charge, and cooler panel temperatures. If your baking in the sun and don't wake upto batteries 12.2 or lower then the added amps MPPT might deliver, might not even be a factor.
The ability to use higher voltage panels with MPPT, also has benefits to consider.
While I understand 'cheap' is in the name of this forum, it appears that many people( not pointing any fingers here) are finding the cheapest possible products, and then hoping they are adequate and get a green light.
I am not immune to this. I've shot myself in the foot too many times by doing this. Doing it right the first time, is so much cheaper than doing it correctly the second time.
Be suspicious when you find a great deal, and take all marketing claims with a large grain of salt. Marketers and politicians are trained liars who just want your money.
There is a difference between being frugal and being cheap. It is just too many cheap people consider themselves frugal and wise, and often these are the most vocal.
With limited roof space on some applications, perhaps most on this forum, the option of more solar and a cheaper PWM controller is not always prudent.
The MPPT preprogrammed algorithm's efficacy varies among different manufacturers, and the MPPT is not always more effective than PWM. Sometimes they are equal, or the PWM even gets the Nod.
The MPPT conversion is most beneficial at lower states of battery charge, and cooler panel temperatures. If your baking in the sun and don't wake upto batteries 12.2 or lower then the added amps MPPT might deliver, might not even be a factor.
The ability to use higher voltage panels with MPPT, also has benefits to consider.
While I understand 'cheap' is in the name of this forum, it appears that many people( not pointing any fingers here) are finding the cheapest possible products, and then hoping they are adequate and get a green light.
I am not immune to this. I've shot myself in the foot too many times by doing this. Doing it right the first time, is so much cheaper than doing it correctly the second time.
Be suspicious when you find a great deal, and take all marketing claims with a large grain of salt. Marketers and politicians are trained liars who just want your money.
There is a difference between being frugal and being cheap. It is just too many cheap people consider themselves frugal and wise, and often these are the most vocal.
BigT
Well-known member
SternWake said:
Yeah, I've done that a few too many times myself and I'm trying very hard to change that bad habit. With that in mind, I'm trying to compromise and get something in the "middle". Not too expensive but not too cheap. Problem is, every time I think I'm getting a great answer to my dilemma, another trusted and knowlegable member chimes in with exactly the opposite advise. :s
Ugh! Sometimes I think I'll never get this done!
So far I'd put a Grape Solar 160W panel, 25' of AWG-10 LC4 cable, a 6-way fuse box and Shoreline Marine battery box/power station on my Amazon shopping cart. Now I'm just tying to figure out which CC to get and what else I need.
I've got a line on a 91Ah Northstar NSB 27F AGM battery for just $150 (usually $340). I'm just not sure if it's the right battery or not.
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There is no doubt in my mind that MPPT is better, but if you can't afford it or it paralyzes you, then just get a PWM, no big deal. The best can easily be the enemy of good enough. If good enough will do, get it.
However, because you don't have room to add another panel, my inclination would be to get the MPPT and get the maximum out of that one panel.
If you don't want to spend the money for Blue Sky or other premium brand, get the best Renolgy MPPT you can afford.
Bob
However, because you don't have room to add another panel, my inclination would be to get the MPPT and get the maximum out of that one panel.
If you don't want to spend the money for Blue Sky or other premium brand, get the best Renolgy MPPT you can afford.
Bob
BigT
Well-known member
Thanks, Bob, I'm looking around for a suitable MPPT CC. Price isn't a giant barrier, I'd just like to keep it around $150-$200 if possible.
AuricTech
Well-known member
At that price range, BigT, you'll probably do better with a high-end PWM charge controller. While there are good MPPT charge controllers in that price range, the ones I've found won't let you set the charging parameters (such as absorption voltage) to match the battery manufacturer's recommendation without spending another $180 or so on additional equipment.
If you plan to install a good battery monitor (i.e., a Bogart Engineering TriMetric), you might want to consider the matching Bogart Engineering SC-2030 charge controller. It's a PWM charge controller that is specifically designed to work "in tandem with the new TM-2030 TriMetric battery monitor." In other words, the battery-monitoring "brain" tells the charge controller how best to recharge the battery bank.
Of course, if you plan to use "grid-tie" PV panels (which generally have higher voltages than nominal 12V panels, and are usually less expensive per rated Watt), as opposed to nominal 12V PV panels, then you'll obviously need an MPPT charge controller. Many folks go this route, when the cost savings from using grid-tie PV panels outweigh the cost premium from using an MPPT charge controller. Don't forget to factor in the cost of wiring your PV panels to your charge controller; higher-voltage grid-tie PV panels (which, as noted above, require an MPPT charge controller for a 12V battery bank) can use thinner-gauge wiring without unacceptable voltage loss. Thinner-gauge wiring obviously costs less per foot than does thicker-gauge wiring.
The bottom line is that, for best results, you need to construct an entire PV system, with all of the components (PV panels, charge controller, inverter [if you need 110VAC power], battery monitor [not strictly necessary, but quite useful], wiring and battery bank) designed to work together to support a specific load requirement. The smaller the system, the more intricate the balancing act becomes between the various factors. The larger the system, the easier it is to use a "brute force" approach to creating a reasonably-balanced system. The limited rooftop space on any vehicle dwelling means that such PV systems will, by necessity, be on the small side.
If you plan to install a good battery monitor (i.e., a Bogart Engineering TriMetric), you might want to consider the matching Bogart Engineering SC-2030 charge controller. It's a PWM charge controller that is specifically designed to work "in tandem with the new TM-2030 TriMetric battery monitor." In other words, the battery-monitoring "brain" tells the charge controller how best to recharge the battery bank.
Of course, if you plan to use "grid-tie" PV panels (which generally have higher voltages than nominal 12V panels, and are usually less expensive per rated Watt), as opposed to nominal 12V PV panels, then you'll obviously need an MPPT charge controller. Many folks go this route, when the cost savings from using grid-tie PV panels outweigh the cost premium from using an MPPT charge controller. Don't forget to factor in the cost of wiring your PV panels to your charge controller; higher-voltage grid-tie PV panels (which, as noted above, require an MPPT charge controller for a 12V battery bank) can use thinner-gauge wiring without unacceptable voltage loss. Thinner-gauge wiring obviously costs less per foot than does thicker-gauge wiring.
The bottom line is that, for best results, you need to construct an entire PV system, with all of the components (PV panels, charge controller, inverter [if you need 110VAC power], battery monitor [not strictly necessary, but quite useful], wiring and battery bank) designed to work together to support a specific load requirement. The smaller the system, the more intricate the balancing act becomes between the various factors. The larger the system, the easier it is to use a "brute force" approach to creating a reasonably-balanced system. The limited rooftop space on any vehicle dwelling means that such PV systems will, by necessity, be on the small side.
BigT
Well-known member
Wow, that's a lot of information (Information Overload). I have no idea what the difference is between "grid-tie" and "nominal" panels are.
This is what I'm planning to buy. http://www.amazon.com/gp/product/B00GGCK7IQ/ref=gno_cart_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
My plan (hope) is to connect it via a suitable CC to a single, 12V, 91Ah AGM. The only use I can think of for a converter would be for charging my razor, but for now my plan is only to run my CPAP, 12V fan, and LED lights off it.
I'm starting to think that Bob's "Good Enough" approach really is good enough.
This is what I'm planning to buy. http://www.amazon.com/gp/product/B00GGCK7IQ/ref=gno_cart_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
My plan (hope) is to connect it via a suitable CC to a single, 12V, 91Ah AGM. The only use I can think of for a converter would be for charging my razor, but for now my plan is only to run my CPAP, 12V fan, and LED lights off it.
I'm starting to think that Bob's "Good Enough" approach really is good enough.
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A good solid system installed and used is far better than the supreme-primo system talked about. And the learning curve is steep enough for many people that it really is one or the other.
Bob
Bob
BigT
Well-known member
akrvbob said:
I agree completely Bob, and if I can just figure out what CC to buy, I'll get right on it!
My plan for a new trailer mounted system for next year is the following:
· (2 or 3) 100 -140W quality solar panels (Fab some tilting mounts)
· (1) Trimetric SC-2030 charge controller (30 amp PWM)
· (1) Trimetric TM-2030-RV battery system monitor
· (1) Magnum MM1212 (1200W) or ME2012 (2000W) mod sine wave inverter/charger
· (4) Crown CR-235 6 Volt deep cycle batteries, 235ah each (470ah) with box vented to outside.
Shunt, cables, fuses, disconnects, wall through grommets, etc
Not the least expensive, i know, but i only want to build it once.
· (2 or 3) 100 -140W quality solar panels (Fab some tilting mounts)
· (1) Trimetric SC-2030 charge controller (30 amp PWM)
· (1) Trimetric TM-2030-RV battery system monitor
· (1) Magnum MM1212 (1200W) or ME2012 (2000W) mod sine wave inverter/charger
· (4) Crown CR-235 6 Volt deep cycle batteries, 235ah each (470ah) with box vented to outside.
Shunt, cables, fuses, disconnects, wall through grommets, etc
Not the least expensive, i know, but i only want to build it once.
AuricTech
Well-known member
I have a couple of questions about your planned system, johnny b:
1. Why are you planning to install such a large battery bank? Even if you go with three 140W PV panels, your system will only provide about a 4.75% charging rate:
That's hardly enough to serve as a maintenance charge. Unless you plan to use some other means to keep your battery bank charged, you'll have sick batteries in short order.
2. What are your decision factors behind using a modified-sine-wave inverter/charger? I suggest at least considering the Magnum Energy MMS1212 PSW inverter/charger.
1. Why are you planning to install such a large battery bank? Even if you go with three 140W PV panels, your system will only provide about a 4.75% charging rate:
That's hardly enough to serve as a maintenance charge. Unless you plan to use some other means to keep your battery bank charged, you'll have sick batteries in short order.
2. What are your decision factors behind using a modified-sine-wave inverter/charger? I suggest at least considering the Magnum Energy MMS1212 PSW inverter/charger.
