Charge controller for small 200W 12V system

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Small Cabin Forum / Off-Grid Living / Charge controller for small 200W 12V system


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3bhlives Member	# Posted: 24 May 2016 11:20am Reply Finally picked up a couple 100W 12V solar panels for my off grid system. Currently have a Xantrex 1000W inverter/charger and 4-6V golf cart batteries running in parallel/series (12V). Charging the batteries with a generator. The $1M question is MPPT or PWM CC? I've been able to keep my costs down so far, and would like to keep it that way. Not sure if a MPPT is needed for such a small system. I've narrowed my choices down to (in no particular order): - Coleman 30A PWM - Xantrex C35 PWM - EPSolar 3210A MPPT Any recommendations or suggestions would be appreciated. Also, reading in other strings, it was suggested that the EPSolar (Tracer) was actually a PWM and not a MPPT?? Thank you

NorthRick Member	# Posted: 24 May 2016 02:12pm Reply The further apart the panel's voltage is from what you need to charge a 12v nominal battery bank (14ish volts), the less efficient PWM is going to be. Morningstar Sunsaver is a smaller MPPT controller that is supposed to be good. I've heard that some of the cheap controllers that claim to be MPPT are not.

3bhlives Member	# Posted: 24 May 2016 02:25pm Reply Thank you. My panels will be about 16 ft from my controller, then another 4 ft to the batteries. I'll take a look at the Morningstar Sunsaver. Cheers

NorthRick Member	# Posted: 24 May 2016 03:48pm Reply Ah, I didn't mean further apart physically. I meant the difference in voltage. Find the specifications for your panels and look for the Voc value. For what is commonly called "12volt" or "battery" panels, the Voc will be 21 volts or so. For "grid tie" solar panels the Voc will be higher, 40 volts give or take. Say your batteries are charging at 14.5 volts, with the battery panels and a PWM controller, roughly 70% of the available power from the panels will get to the batteries. With a grid tie panel, only about 35% of the panel power makes it to the battery. You can leave a lot of power up on the roof with a PWM controller.

offgridjunkie Member	# Posted: 24 May 2016 04:04pm - Edited by: offgridjunkie Reply I use this one on my system URL-(210 Watts of solar, 100 Amps of Battery). My panel is 24 volt and my battery is 12 volt. This is great as I get better efficiency. The Morning Star MPPT is also a good one but I wanted to be able to expand my panels. The Morning Star is only 15 amps so I would have been stuck at 200 Watts of panel.

3bhlives Member	# Posted: 24 May 2016 04:55pm Reply NorthRick: Sorry about that: solar newbie. This is all I could find on the panels: 100W Solar Panel Specifications: Maximum power: up to 100 watts of solar power Amperage: 5.8 amps Maximum power point voltage: 17.1V They are the Coleman 100W solar panels; however I'm not sure who the actual manufacturer is. offgridjunkie: Thank you. One of my options is the EPSolar 3210A MPPT http://www.epsolarpv.com/en/index.php/Product/pro_content/id/654/am_id/136 (Tracer A series). This would be the 30A version of what you have I believe. I have that same thoughts as you; start with 200W but have the ability to expand if necessary. Thanks for all your help. The three CC's that I selected are readily available where I am and all at ~ the same cost. The plan was to connect the panels in parallel so I don't have to step down the voltage too much and keep everything at 12V. Cheers

creeky Member	# Posted: 24 May 2016 05:47pm Reply 3b, A lot of us have found it's better to have one big panel rather than more smaller panels. The bigger panels are usually better made. And are often much cheaper. .45 to .80/w vs the small panels at 1 to 1.40 a w. You know. .50 a w for 400 watts starts to add up. Suddenly you've paid for that mppt controller with panel savings. Of course if you run higher voltage at the panels you also save money on wiring. Lower amps means thinner wire. For charger controllers have a look at Victron. On Amazon the 15amp mppt is 100 bucks. They have many others. And great pricing. Victron is one of the oldest and most respected names in solar. The quality control is the best. Morningstar has a new ProStar MPPT. These guys sell more solar controllers than anyone. And the EPSolar "BN" series looks like a morningstar knock off. This is probably a very good choice.

ClimberKev Member	# Posted: 24 May 2016 06:06pm Reply I just upgraded to the EPSolar 3210A MPPT early this spring. I haven't done any in-depth analysis other than it seems to keep my batteries at a higher voltage then my old Phocos PWM controller. I really like the digital display and programmable load options. I also use a Xantrex 1000W inverter with four panels around 240 watts.

3bhlives Member	# Posted: 24 May 2016 06:34pm Reply creeky: Thanks for the advise. I was originally considering a 260W panel, but the dimensions of the panel was getting pretty hard to transport; my cabin is 7 hrs away. Got a great deal on the 2-100W panels. Checked out the Victron. Looks good, but can't seem to purchase from Canada (Amazon.ca sucks). ClimberKev: Thanks for the information. May I ask where you purchased and for how much$. Cheers

skootamattaschmidty Member	# Posted: 24 May 2016 08:10pm Reply I recently bought the Morningstar sunsaver mppt controller through Amazon. It is 15 amp. I have 180 total watts with the Coleman solar panels. ( two 40 and one 100 watt) I just temporarily set the 100 panel out inthe sun and hooked all 180'watts to the charge controller, then the battery when I was up last week. I had previously used the cheap Pwm controller that came with the two 40 watt panels I bought through Canadian Tire. Although I have no real empirical data to present based on my limited usage, I am very impressed with the Morningstar. When I was getting full sun, my inverter was showing that my battery was at 14.6 volts by early morning. I never saw these kind of numbers previously. Again this was just a temporary set up till I decide where best to mount the 100 watt panel ( the two 40 watt panels are installed on a post previously.) I am not sure if I am just getting more power because of the extra panel or if the Morningstar is making more of a difference. When I go back up I hope to monitor things more closely to better measure my results. I realize there are probably better panels out there but I have been able to buy these on sale at Canadian Tire and use my Canadian Tire money to ultimately get them free. The Morningstar seems very solid, easy to use and has a 5 year warranty. There are also options to attach a remote temperature sensor as well as the ability to plug into a computer to monitor things.

Bret Member	# Posted: 26 May 2016 08:35am Reply A question for offgridjunkie. Would you mind sharing your set up? I also have 24 volt panels and would like to use a 12volt battery system. Half the number of 6volts batts in series and more selection of inverters. I have three 195 watt 24volt panels and only need about 1000 max. watt hours per day. Great conversation. Bret

ClimberKev Member	# Posted: 26 May 2016 10:24am Reply I picked it up on Ebay back in March for about $103. It looks like it's going for around $122 now from the same supplier. Shipping took a long time via "slow boat" from China. I see it's on Amazon for around $125

ILFE Member	# Posted: 26 May 2016 12:44pm - Edited by: ILFE Reply Quoting: 3bhlives Currently have a Xantrex 1000W inverter/charger and 4-6V golf cart batteries running in parallel/series (12V). Charging the batteries with a generator. I don't know what rating your batteries are. But, for the sake of argument, let's say they are 230 AH each. Four, in series-parallel, would be 460 AH at 12vdc worth of batteries that you want to charge with 200 watts of panels. To even get a 5% charge rate* on those batteries, using panels, you would need 435 watts. Personally, a 10% charge rate* is what you should be shooting for, for panel charging. In that case, you are looking at over 850 watts of panels to charge them. *This is using a formula assuming a 77% rating (77% of the total rated power output) of the panels. You may want to use that inverter / charger for a while, until you can purchase some more panels. At the time you go with a solar array to charge them, I would suggest a quality MPPT controller over a PWM controller, any day.

3bhlives Member	# Posted: 27 May 2016 10:50am Reply Thanks for all your help. After reading more, I've decided to return the two 100W panels and purchase a single 260W panel and the EPSolar MPPT. I'm still deciding whether to purchase the 20A CC (good for the single panel), the 30A (giving a little extra safety factor), or the 40A (so to have the ability to add a second 260W panel in the future). Based on my calculations, a single 260W panel would be sufficient (current loads are ~50 AH/day), but until I try it out, I won't know. I always have the ability to charge my batteries with my generator. My load calculations are based on the following first year of use: 2-6V batteries @ 240 AH (conservative) 3 days of use before needing a charge (50% drain = 120 AH/3 days = 40AH/day). I also purchased an additional 2-6V batteries for added protection. This should give me about 6 days without requiring a charge (a cloudy week). Thoughts?

NorthRick Member	# Posted: 27 May 2016 11:39am - Edited by: NorthRick Reply You haven't said if you plan to have an inverter to provide 120 ac power to your loads. If so, since you are looking at 4 6v batteries now, you might think about wiring them in series to get a 24 volt battery bank. If you do this, get an inverter that works off 24 volts. Why do this? You can get the 30A charge controller and still add a second panel. By going from 12v to 24v at the battery, you halve the number of amps going in and out of the battery bank for the same amount of power. You can use smaller wires too. You will also have all the batteries in series instead of pairs in parallel. This is better from a balanced charge perspective and should lead to a slightly longer life for the battery bank. All four batteries should be the same and, even better, all manufactured at the same time.

creeky Member	# Posted: 27 May 2016 11:44am Reply 3b. The 40 for expansion is probably a good idea. You didn't mention if you've looked at the BN series. But it is much nicer. imho. One thing I found. Once you have power ya kind of get hooked on "just one more thing." My system has grown to 2 kw/panels. And my poor battery pack ... so a bigger battery pack to start is a good idea also. Also the lower discharge will mean the batteries last longer. Most lead acid battery's have a 600 cycle life at 50% dod. So plan accordingly. And I can't wait for my lithium pack this fall. smile. How often are you up there?

ILFE Member	# Posted: 27 May 2016 11:46am - Edited by: ILFE Reply Quoting: NorthRick You haven't said if you plan to have an inverter to provide 120 ac power to your loads. It appears as though he has purchased two more 6v batteries. If I read that right, he's up to six - 6vdc batteries? Quoting: 3bhlives I also purchased an additional 2-6V batteries for added protection. 3bh, you add the voltage of the two batteries in series. You add the amp hours of the two strings in parallel. So, if your batteries are 240ah, you have a total of 480ah with the first four wired series-parallel. I know you are looking at this as though you have ample time for the panel(s) to charge them up. But, you really should charge them as fast as possible, after draining them. Until you have enough panels, which I would focus on buying in the future, rather than more batteries, you will need to use that generator to charge them. Then, let the panel(s) keep them topped off - more or less like a trickle, or maintenance charge.

3bhlives Member	# Posted: 27 May 2016 01:35pm Reply Thanks again guys. I'll try to clarify. As of last year I had: 2-6V batteries Xantrex Freedom HF 1000W - 12V inverter/charger Based on my loads, I had to charge my batteries every 3 days or so. This Spring I purchased another 2-6V batteries (same manufacturer) for a total of 4-6V batteries. I'm not planning to upgrade my inverter to 24V, therefore I'm stuck with 12V. By adding panels, I hope that I will not have to use the generator to charge, but that option is still available if required. Based on my very crude calcs, I believe that 1-260W panel will provide enough charge for my loads. I didn't look at the BN series CC, because there is no local supplier where I am. I like to have the ability to return easier if it doesn't work. The local guy here supplies the A series. Lastly, my cabin in unfortunately 7-8 hours away, so we only get there 2 or 3 separate weeks a year. I know that going solar for such a short time is probably not money well spent, but I got the itch to try it out. Thanks again guys

ILFE Member	# Posted: 27 May 2016 02:19pm Reply Here is another issue that came to mind while reading your latest post. If your batteries are flooded lead acid, they need to be checked, and possibly filled with distilled water, every month. Letting your batteries remain even on a low amp charge over the course of months, without checking them, is not a good thing to do.

3bhlives Member	# Posted: 27 May 2016 02:24pm Reply Thanks ILFE. When we shut down the cabin for the year, I bring the batteries home, check the level (top up if necessary) and keep a trickle charge on them over the winter.