Another Charge controller choice thread

Seven
Seven Solar Expert Posts: 292 ✭✭
Very new guy here, but this thread was what I was looking for. I am also considering the morningstar controller mentioned here. I have 4 75 watt panels, and I was told that the max output measured from them was 17amps. They are older, used, panels, and I plan on adding 4 similar panels, or start adding some 100-125 watt ones to my system. I have four of the Trojan golf cart batteries(6v) and a few 12v deep cycles. With this limited info, can you tell me if the morningstar is a good choice? I plan on running one room of my house off of solar, and slowly expanding. For right now I want to run things in my garage on solar. Some lights, a small tv, fans, hopefully soon, the fridge.

I am at the experimenting stage at the moment. I have a couple panels hooked up to two of the 12v on a little wagon that I can move around. Mostly they just power some DC radios and occasionally some lights when we lose power. From reading here, I am interested in the Morningstar 300w pure sine inverter. My inverters are currently the cheap modified sine ones that I wouldn't hook a computer or an AC radio to.

Again, very new, limited info, probably no more that 1000 watts total in the near future , more like 600 total, for a while. Any help is appreciated. I have seen this site several times in the last few months and although the info is initially overwhelming, I am starting to get the basics. I am about 20minutes from the guy in the sticky with the 8K system.
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Comments

  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Sorry, I thought I would just add to the other thread so a bunch of e same info wouldn't have to be retold. Thanks for the move though.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    I have moved this to your own thread from here:

    Charge controller choice.

    In general (I find), it keeps things a bit more sane if we talk about your questions/eventual configuration in its own thread.

    So, feel free to ask your questions here and we can talk about configurations that meet your needs.

    Regarding solar panel charge controllers--There are two major types... PWM (Pulse With Modulation) and MPPT (Maximum Power Point Tracking).

    PWM controllers have been around for a long time and are pretty much bullet proof. A lot less expensive than MPPT and use less power to operate. Typically very good for 0-200 watt systems.

    MPPT controllers are DC Switching Power Supplies. Very good for larger installations and for setups where the solar panels are a "long distance" from the battery bank. Also, they support temperature extremes better (very hot and very cold weather). MPPT controllers have the ability to take high(er) voltage / low(er) current series connected arrays and efficiently step down the voltage for charging the battery bank (lower voltage, higher higher current). Basically the DC equivalent of an AC transformer. Typically very good solution for 400 watt or larger arrays (although, they can be very useful down to 200 watt arrays-just not cheap).

    Here are a couple of quick Charge Controller FAQ's:

    All About Charge Controllers
    Read this page about power tracking controllers

    Morning Star makes great line of charge controllers.

    On of the big limitations with solar PV systems--Is they are fairly difficult to expand over time cost effectively. Any expansion greater than 2:1 is probably not going to work out well. If you go beyond the 2:1 sizing--you probably will need to replace major portions of your system (higher voltage inverter, second/new charge controller, new battery bank, etc.).

    It is generally better to measure and understand your loads and needs (emergency power, off-grid, portable solar, etc.) and design a system that meets those needs.

    Morningstar Solar Charge Controllers

    A 200-300 watt system as a educational tool is very nice to build and operate. But, they will not usually supply that much off-grid power...

    For example, a 275 watt Off Grid system with AC output. Assume 0.52 end to end system efficiency, and 4+ hours of sun (9 month of the year operation for many people--in sunnier areas, you may get 5-6+ hours per day of "full noontime equivalent sun" in summer):
    • 275 watts * 0.52 efficiency * 4 hours of sun = 572 Watt*Hours per day
    Say you have a small laptop computer (30 watts) + 26 watts of CFL bulbs... That will operate:
    • 572 Watt*Hours / (30+26) Watts = 10.2 hours per day typical maximum
    The recommended battery size for such a system assuming 1-3 days of "no-sun" backup, 12 volt battery bank, 85% efficient inverter and a maximum of 50% discharge (for longer battery life):
    • 572 Watt*Hours * 1/12 volt bank * 1/0.85 efficient inverter * 1 day of no sun * 1/0.50 max battery discharge = 112 AH @ 12 volt battery bank
    • 572 Watt*Hours * 1/12 volt bank * 1/0.85 efficient inverter * 3 day of no sun * 1/0.50 max battery discharge = 336 AH @ 12 volt battery bank
    Anyway--some of the basics and their Rules of Thumb... Of course there is a lot more details depending on what you need / wish to discuss.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Leper,

    Not a problem--I am assuming you have a lot of questions about what you would like to do for your installation...

    Usually less confusion when we talk about one person's system per thread instead of mixing up between several.

    If you have questions specifically about the original thread--you can still ask them there. Or ask them here so you we can direct the answers towards your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Another Charge controller choice thread

    Avoid mixing batteries of different sizes and ages as they don't "play well" together.

    http://www.batteryfaq.org/

    http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Thanks for the replies.

    I have read the links posted. Some of them several times. It won't take me long to get my head wrapped around the math parts.

    As far as mixing batteries, I will probably do two systems to keep that from happening. I am split right now with half and half. We get weekly deliveries from Interstate at my work, and the driver always keeps his eye open for Blem and Econo batteries for me. It is hard to beat a group31 deep cycle for $29.99. Same with the Trojan 6v.

    Like I said before, I have looked at this site for some time, trying to learn. A wealth of info here. My FIL has used solar as his only source for a while in the past, so I try to take info from him and confirm it here.

    As to my original question, Is there any reason I shouldn't get the Morningstar?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    MorningStar makes a wide range of charge controllers--So there still are choices to be made...

    Normally, it is better to define your power requirements, design the system (array watts, battery capacity, inverter sizing), then review specific components to meet your needs of cost and effectiveness for your needs.

    Charge controllers run from a few amps to over 80 amps. You have a choice of battery bank 12/24/48 volt (typically). And there is the whole MPPT vs PWM design choice.

    Morning Star has some very nice cutting edge MPPT charge controllers (efficiency and EtherNet on one model). But they are not cheap (most charge controllers are not cheap--if well designed).

    For low end and high end MPPT (and PWM)--Morning Star is hard to beat.

    There is a mid-range 30 amp 12/24 volt MPPT charge controller from Rogue which is a very nice--bullet proof controller with good reviews here to think about too.

    Without the paper design and physical requirements worked out--It is very difficult to say that one company is the ideal choice for a charge controller.

    For the most part, designing your system will be a series of balancing acts and trade-offs. Too large of charge controller can waste energy with a too small array as well as cost an arm and a leg.

    If you decide to increase the output power of your system later--you may have to change to a higher voltage inverter (24/48 vs 12 volt). Now you have to look at rewiring/increasing the size of the battery bank, does the existing charge controller support the new voltage, can the solar array be required/increased to support the new voltage/power requirements, etc...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    I see the confusion. My original post was in another thread that was already talking about the morningstar Prostar 30. I like the efficiency of the rogue, and it looks like it can take 12 or 24 input. That is good for my planned future upgrades. It is a good bit more money, but it looks a good bit better. I have seen that rogue in signatures here. Thanks for the input.
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Side question. I have seen projects that people have built a box for outside of a window that brings in heat. Is that called thermal heating? I want to build one but I am having a hard time finding it.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Here is one page with some DIY heater examples.

    And there is:

    Build It Solar DIY Projects website and their Space Heating page.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Thanks. The flat window one was the exact one I remembered.
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Alright, I have done more research, I have tried to get a long term plan, and I have done some serious considerations to what I want in the form of expandability.

    You are absolutely correct. The slow and steady build is filled with unnecessary upgrades and equipment replacements.

    My original thought was to get a small system functional, do a lot of testing and experimenting, and start adding equipment to get it to a larger system. I was wrong. The $300 inverter (and charge controller) become useless when I surpass the 30a range. I have also noticed that I would be better off using the 24v panels instead of the 12v ones. Buying a panel every month, or every other month will quickly bring the need of bigger wiring,controller,inverter, basically everything. The battery links I was provided say to keep like batteries as well as ones that are very close in age, extreme cases of just 6months. That blows my plan all to hell. The only way I can grow my solar like I planned to would be to have multiple systems. I get the benefit of redundancy, but I get the PITA of keeping track of several systems at the same time.

    I don't know what to do. The battery question is the killer. I could build my setup in 1kw strings. 5x 200w panels/controller/charger/wiring/etc. Several circuits that could have the panels combined later, but that would leave me still needing a big main charger and inverter and a bunch of leftover smaller ones. The batteries would be of different ages that would be far enough apart that it would bring the overall system down.

    Am I right in my thinking.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Pretty much... Off-Grid solar just does not lend itself well to being expanded in a cost effective manner.

    So, this comes back to what it is you are trying to accomplish... If it is to save money from paying for utility power (and future cost increases), Off Grid solar power is going to continue to cost ~5-10x utility power (on a $$/kWH cost basis) for the foreseeable future.

    If this is for emergency/backup power--There are some alternatives. Get a hybrid inverter+battery bank large enough to support your emergency needs and add a fuel powered backup genset. That will last for a few years very nicely... Then add solar panels+charge controller(s) as funds permit.

    Or, if this is the save money--go with a Grid Tied solar. Depending on how much solar power you need (hopefully, your utility company supports net metered/GT connected solar)--you can add panels fairly cost effectively in 3kW chunks. With micro inverters, you can even add them in smaller steps (although, building permits, utility approval, possible electrician chargers can make small additions uneconomic). And add a genset+transfer switch for emergency power (use natural gas, if available, for longer term outage support, etc...).

    In the end, putting money into conservation (lots of insulation, double pane windows, Energy Star Appliances, reducing usage with laptop vs desktop computers, heat pumps for space heating and hot water if all electric home, etc.) is usually a much better investment of your time and money vs going with solar RE.

    After you have done all of the conservation possible, then look at your solar RE options... Since you may be using 1/2 the power you used to use, now your solar RE power requirements are ~1/2 too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    My goal.

    Long term I plan on living in a place that is off grid. Completely. Building a place on a piece of land that my family can live in. This is probably 5-6 years off. The house will be built with every power/money saving thing I can do. Super insulated, efficient materials/windows/etc. I have been researching where and how, for several years. I have family that have already been living this way. They have had limits that I do not want to have. I want more power than they use. Deciding on using a radio or having a light to read by at night is not a position I want to be in. I want a more normal life than that.

    That being said, I am starting on the solar system now. It will be on the house we are in. This gives me the time to build the system, figure out the maintenance requirements, and get me used to the system. Trying to do this now, gives me the time I am going to need to get the basics down before the relocation. If I have a functional system, with components I am used to, it will be much easier when the move comes. I can relocate the system and basically just put it back up the way it was. That is a little over simplified due to actual locations and setup areas, but you get the idea.

    The difference of a systems ability in the 40year old house we are in vs the smaller high efficiency it will someday be placed on will make it seem twice as powerful. Things like the grid tie inverter won't be used in the future, but that is ok.

    What will my requirements be in the future? I don't know. As we are slowly reducing our power usage now, we will be better off after the move. Low power lights, appliances, computers, and other things are being added as possible. Reducing consumption, and adding solar now, makes the transition easier.

    I hope this is an adequate answer. I do not have specific numbers now or for the future. It is my current thinking that an 8K system with the appropriate bank will be plenty. Until my thinking changes, that is the goal that I have.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Where are you planning on building your home? Lots of sun? Will you need A/C or cooling system of some sort?

    An 8 kWatt (I am assuming 8kW vs $8,000 system) is pretty good sized... Assuming full solar on 4 hours a day of full sun (about 9 months of the year for many places):
    • 8 kWatt solar panels * 0.52 system eff * 4 hours of sun per day = 16.64 kWH per day
    • 16.64 kWH per day * 30 days = 499 kWH per month
    An 8kW off grid system is not cheap--probably somewhere in the $80,000-$160,000 system cost...

    If you were typing about a $8,000 system cost... You are probably looking at a 400-800 watt system:
    • 0.8 kW * 0.52 * 4 hours of sun = 1.664 kWH per day
    • 1.664 kWH per day * 30 days per month = 13 kWH month
    Both systems are doable. People have built 8kW off-grid system (but be prepared for new batteries every 7-15 years, new electronics every 10-15 years plus possible repairs, etc. vs a 400-800 Watt off-grid system for a small cabin with some lights and a computer+sat modem)--Obviously, the type of lifestyle you wish to live will be the governing factor...

    In the "olden days" when solar panels used to cost $10 per Watt (vs the $1-$4 per Watt today)--A good rule of thumb for a "close to normal" off grid home was around 100 kWH per month power budget (lights, pumps, computer, washing machine, etc.)...

    Even today--I still think that works out to be a good compromise between power and capital costs (plus fuel costs for winter)... Assuming $15 per Watt system cost:
    • 100 kWH per month * 1/30 days per month * 1/4 hours of sun per day * 1/0.52 system eff = 1.6 kW = 1,600 Watts of solar panels
    • 1,600 watts * $15 / Watt = $24,000 system cost
    Battery bank sizing, assuming 2 days of no sun (1-3 days of no-sun rule of thumb) and 50% maximum discharge, assuming 85% inverter efficiency and 48 volt battery bank:
    • 100 kWH per month / 30 days per month = 3.33 kWH per day
    • 3,330 WH per day * 2 days of no sun * 1/0.50 max discharge * 1/0.85 inverter derating * 1/48 volt battery bank = 326 AH @ 48 volt battery bank
    Backup generator sizing assuming 10% rate of charge (based on 20 Hour battery AH capacity, 80% charger efficiency and a minimum of 50% of rated genset load):
    • 326 AH bank * 59 volts charging * 1/0.80 charging eff * 1/0.50 generator loading * 0.10 rate of charge = 4,809 Watt Genset Rating
    The charger rating should be around:
    • 326 AH bank * 0.10 rate of charge = ~33 Amp # 48 volt AC charger Rating
    An "appropriate" Inverter Max Rating based on C/8 max continuous and C/2.5 max surge rating of battery bank:
    • 326 AH * 48 volt battery bank * 0.85 inverter eff * 1/8 continuous current = 1,662 watts max continuous AC load (~4 hours maximum)
    • 326 AH * 48 volt battery bank * 0.85 inverter eff * 1/2.5 continuous current = 5,320 watts max surge AC load (~4 hours maximum)
    Most inverters are rated around 2xRated Load = Max Surge, so your "appropriate" inverter size would be around 2.5 to 3 kW or so for the above mythical 100 kWH per Month system configuration...

    Anyway--some numbers to think about... The above are very rough estimates and intended to give you a range for planning your costs/capabilities. I am not in the solar business.

    Until you get a better handle on your actual power needs (and available money)--the above is close enough for you to plan budget vs loads for your future home.

    Hope it helps.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Also, I want to highlight your 5-6 year time-line in a separate post.

    Solar panels should last 20+ years fairly easily (although, you could not prove that with mine so far)--Electronics 10-15 years (perhaps some repairs at 5+ years) and 7-15 years for a good quality battery bank.

    Looking 6 years out for building a system to support your current home and moving it to your new home--You have already used over 1/2 the expected life for major components (batteries, inverters, charge controller, possibly genset, etc.) to install in your "new home"...

    I would be not be in a hurry to build out a full system now for use in 6 years--These things age, and electronics are advancing so quickly--that 10+ years it will probably be close to impossible to support major repairs on your electronics given the recent history of digital electronics (let alone installing a 6 year old battery bank).

    At best, build out a small system (200-600 watts of solar panels) at 12 volts. Get the nice MorningStar 300 watt inverter + a battery monitor + AC battery charger + inexpensive battery bank and play with that setup. The MorningStar has some really neat power saving features that most small inverters do not.

    Relatively inexpensive, and small enough to move around or even install in an RV (if you camp). It will give you a good life, cheap to repair, and will be useful in the short term too (park/stay in RV/1 room cabin at building site, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,731 ✭✭✭✭✭✭
    Re: Another Charge controller choice thread

    Nice advice Bill ! I would add that once you buy the land things start getting easier and a strategy can be formed. There never really is a one size fits all plan as we are all very different. I am constantly surprised at the different people I have worked with and what they will tolerate living offgrid.

    Bill please close the Pacific storm gate! 27 inches of rain before New Years is way above normal for us!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • dhsola
    dhsola Solar Expert Posts: 38
    Re: Another Charge controller choice thread

    NAWS has a nice discount on a couple of pre-built systems:

    off grid:
    http://www.solar-electric.com/oufxofflsy60.html

    grid tied:
    http://www.solar-electric.com/ougvgrflsy72.html
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Thank you for the complement Dave! :D

    Nice to hear that I am not too far off from somebody that actually makes a living selling and installing off-grid systems in the Sierras.

    Can't say that we have had too much rain in the central SF Bay area... Running about 6" on a 2.89" December average--I guess more of a series of steady rainstorms vs a huge dump in a day or two like we usually get. So--it has not been too bad for us. The big storms have been splitting north and south of us--so shutting my door won't help. :blush:

    0Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Thanks for the replies. I will try to address some of the questions.
    Location...
    NOrth east TX. The two places I have put offers on are from Blue Ridge to Bonham. There is a possible place, just on the other side of the Red River in OK. They are all close together, in Texas distance thinking.

    Size...
    8kw not $8k. The baseline I had in my head was about five dollars a watt. That number hasn't changed much in the last two years. If anything, I may be low.

    Equipment life cycles...
    There is not much I am able to do about that. My timeline and fund availability limits what I can do when. Trying to budget for the solar array as well as everything else that is going on, only allows me a certain amount for each project. I understand it is not a good way to go about it. However, not everything will be five years old, in five years from now. I figure that if i start with the panels and then buy the controllers and inverters last that will give the best lifecycle. The experience working with the stuff is important to me. It may be a full year from now before I have the first bank put together and operational. I do not intend to waste anyones time here. I am gathering as much information as I can from all available sources. My FIL has been a wealth of knowledge on theory and basic systems, but I am getting to the point that exceeds his knowledge.

    One size fits all....
    I agree, completely, it doesn't work. Having an operational system in the same basic location will allow me to fine tune the house as well as the final system. If I know exactly what my system will do, it puts me in a better position to know what I have to work with. Batteries are an entire different story. That may be the hard part.

    The small system that I originally posted about, will be built. I may try to go ahead and use 24v stuff so that it won't become completely useless in the future. I think the Rogue is 24 or 12. One of the many things I still have to look into. One possibility would be to do one of the things my FIL did when he was solar only. Have an AC system and a smaller DC system as well. Something we have talked about doing with the panels we are currently using once the next system gets started. HAM radios seem to get more range from a DC system. At least that has been our experience so far.

    Again, thanks for the replies, and the information, and the good attitudes. I understand that I am a noob, and I do not have the numbers required for precise calculations of what I need/want. You guys are a wealth of info. This was one of the first sites I looked at a couple of years ago when I started thinking about solar.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread
    Leper wrote: »
    I do not intend to waste anyones time here. I am gathering as much information as I can from all available sources.

    Not a problem--If I thought people here were just wasting time here, I probably would have stopped posting some 8,000 posts ago. :blush::confused::cry:;)

    Are you thinking $5 per watt of solar panels installed? Or just $5 per Watt for panels on racks, concrete, and wired to combiner boxes?

    They are getting pretty close to $6-$7 per Watt for Grid Tied systems installed--but those battery and off-grid/hybrid inverters/AC chargers/Gensets/etc. are not cheap.

    Obviously, we are not here to design a system for you--but give you enough tools/information/other places to look that you can design (and if you wish) install it your self.

    I am certainly a believer in having funds in the bank for purchases as opposed to taking loans out and paying of in the future. It sure does make life less stressful if you are not living pay check to pay check.

    Good luck!
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    Re: Another Charge controller choice thread
    BB. wrote: »
    Not a problem--If I thought people here were just wasting time here, I probably would have stopped posting some 8,000 posts ago. :blush::confused::cry:;)
    <snip>
    I am certainly a believer in having funds in the bank for purchases as opposed to taking loans out and paying of in the future. It sure does make life less stressful if you are not living pay check to pay check.

    Good luck!
    -Bill

    Man I have to agree with that one, for 25 years I did the credit thing, cars, houses, credit cards .... About 10 years ago I decided that was no way to live, first worked extra hard to pay down the CC, then the mortgage was next, then all the automobile debt. As of 3 years ago we are pretty much debt free, just in time for everyone else to get caught in the financial mess, we have seen friends loose houses, have cars repo'd and stress to make ends meet. Some are in their 50's and had to start from scratch. Some filed bankruptcy and lost lots in the process. Granted we still have credit cards, but when used, they are paid off at the end of the month. We have a mortgage on a rental property but it is cash flow positive and only 5 years from payoff now. We are considering a second rental property, but I hate being a landlord and may consider it only if a service manages the properties. If we do it will be with a large down payment so it to can be cash flow positive.

    One key to getting there is not to live for the moment but make a plan and achieve your goal, small steps are the beginning of a journey.

    Our life has been absolutely stress free through all of the bad times. We could cover our nut on unemployment if we had to, we do have good savings back up now and are headed to a comfortable retirement (fingers crossed).
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    http://www.solar-electric.com/kykd210waaop.html
    http://roguepowertech.com/products/mpt3024.htm

    Anything wrong with these? I realize I can only put four of those panels on that controller. At least that is what I think is correct.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Make sure you read the Rogue PDF Manual (very interesting if you are into electronics/details)--There are lots of conditions to account for...

    First, those are Vmp-stc=26.6 volts (Kyocera pdf spec sheet)... And the Rogue is (relatively) a mid-range Voc-cold rated controller (60 VDC max). The Kyocera panels are rated at Voc-stc=33.2 volts--Which means, for this set of panels, you can only put one panel in series maximum (i.e., connect all 4 in parallel) to meet the controller's input requirements. And these panels will only charge a 12 volt battery bank.

    If you want to change to a 24 volt battery bank later--You will not be able to use these 4 panels in series/parallel combination with this controller. 1 panel in series is below the ~Vmp=35 volts required to charge a 24 volt battery bank and 2 in series is >60 volt controller maximum.

    If you are happy with these components on a 12 volt bank--this is a nice choice.

    If you want to go 24/48 volts later with these panels, you would need a different (higher end 150 VDC Voc rated controllers) and can only support 3 of these panels (maximum) in series to charge a 48 volt battery bank (the panel/controller configuration dance can be confusing). 2 series x 2 parallel would charge a 24 volt battery bank on a higher rated input voltage controller.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Poop. I see what you mean. I need a different controller because I would be over 80v


    Alright. I am asking for a suggestion. Assuming a 24v bank. What panels and controller would you recommend. Figure a 10panel string.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    How many watts of solar array do you want?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    Start with 2000+/- 1800 is ok 2250 is ok

    I will be building as I go. Whatever I start with, is what I will try to keep getting. I still plan on making the system off grid.


    BTW.... My daughter roller her truck last night, she is fine, so my first purchase may be delayed a month or so.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Another Charge controller choice thread

    The one question that I haven't seen asked in this thread is why the desire to "go off grid?". In the real world, as compared to grid tie PV, off grid Pv comes at about twice the price per watt, with about 1/2 the net efficiency leaving one with power that is in the range of ~ 4 times as expensive net/net than grid tie solar, (which already comes at a premium over basic grid tie energy exclusive of rebates and tax credits)

    While I encourage self sufficiencies, people often get caught up in the notion that off grid is the only way to do that. Given a choice, grid tie is a (IMHO) a much better utilization of resources. That coupled with strict energy conservation goes much further on a buck than does battery based PV. Factor in battery replacement costs, generator purchase and running costs and it becomes clear, that the grid is a bargain!

    Those that life off grid usually do so because the cost of running the grid to their site is more expensive than building a battery based system, even with it's built in expensive costs.

    Just a thought,

    T
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    A 2kW off-grid system is fairly large--and if you plan to go larger, I would probably start with a 48 volt battery bank right from the get go...

    One of the reasons is that 12/24/48 volt MPPT charge controllers are rated on their output current--For example, assuming 60 amp controller and 0.77 system derating:
    • 14.5 volts charging * 60 amps * 1/0.77 = 1,130 watts of panels
    • 29 volts charging * 60 amps * 1/0.77 = 2,260 watts of panels
    • 58 volts charging * 60 amps * 1/0.77 = 4,520 watts of panels
    The same charge controller can manage 2x-4x the cost effective amount of solar panels at 24 or 48 volts.

    And with higher voltage battery banks, wiring can be 1/2 or 1/4 the amount of copper for the same amount of power and an ability to carry it longer distances (voltage drop is less of a problem with higher voltage systems).

    For a larger system, I would recommend choosing a MPPT type charge controller--not because it can give you ~10% or so more power in cold weather, but because it allows you to run "non-standard" solar panels and higher Vmp-array voltages (upwards of Vmp-array=100 VDC)--You can have longer wire runs between the solar array and the battery bank when operating at these higher voltages.

    As a warning, with the current crop of 150 VDC maximum input voltage MPPT charge controllers--There is a "doughnut hole" of solar panel Vmp range that does not work well with 48 volt battery banks... ~50<Vmp-array<72 volt panels are too low of voltage to charge a 48 volt battery bank when wired in 1 panel per string, and Voc>150 VDC when two panels are wired in series in cold weather.

    Otherwise, this would be the most flexible system for you (assuming a large PV system).

    Solar panel wise, basically larger panels are usually cheaper on a $$/watt basis. Mono and Poly Crystalline panels are the standard for long life and reasonable pricing (roughly around $3 per watt or so).

    There are now more Thin Film type panels out there--And they are getting down towards ~$1 per watt... Very difficult to ignore that price advantage. But it does come with some issues.

    Roughly, Thin Film panels are 2x the area because they are less efficient at capturing sunlight... So if mounting space is an issue (and the associated rack costs) are an issue, then I would think twice before jumping on these guys. Also--There is not a lot of history out there with Thin Film panels to see how they hold up to weather--It will take 5-10 years before we start seeing the shakeout (although, $1 per watt over 10 years vs $3 per watt over 25 years is almost a wash).

    You can start looking at the MorningStar TriStar 60 Amp MPPT--Efficient and lots of options (Ethernet, Remote Battery Temp Sensor, Remote Battery Voltage Sense, efficient) as a start.

    Morningstar TriStar 60 amp MPPT solar charge controller

    A new controller is just being introduced--The Midnight Solar Classic--Maybe worth a look for you too (should coming out with a Voc=250 volt version too):

    MidNite Solar Classic MPPT Charge Controller

    For an off grid inverter--the Xantrex XW Hybrid inverter is a nice system (can do both off grid and grid tied). Supports 120 VAC and 240 VAC out of the box (no extra parts). Also, includes transfer switches for AC Grid Power and AC Generator, plus an AC input battery charger too. Available in 24 and 48 volt models.

    Xantrex XW Sine Wave Inverter

    For wiring all the pieces together, Midnight Solar also makes some nice "E-panels":

    Midnite Solar E-Panels

    Battery wise--Really the heart of your system. Size the batteries to your needs, then size the hardware around them to keep them "happy" (solar array, DC backup charger, wiring, maximum inverter sizing, etc.).

    Personally, I like to recommend 1 series string of batteries/cells. That means very large AH rated batteries... Which are heavy--so you need to plan on access for fork lift/crane/pallet jack/etc... Many of the larger cells are 6 volt, 4 volt, or even 2 volts per cell.

    If you need/want to parallel strings--Each string needs it own fuse/breaker (to protect wiring/cells against short circuits)--And, again personally, I would recommend 2-3 parallel strings maximum.

    There are people here who are very happy to parallel more than three strings and satisfied with the results--so take my opinion with a grain of salt.

    Paralleling Battery banks


    The above are all more towards the higher end in price/functionality--What you choose is purely your choice (I am not in the solar business in any way)--But they give you a good idea of what is out there and the various options... Look at the less expensive units too and see what you will need for your installation.

    -Bill

    And, I am glad to hear your daughter is OK--my first kid is getting close to the whole driving thing. :cry:
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Seven
    Seven Solar Expert Posts: 292 ✭✭
    Re: Another Charge controller choice thread

    It looks like I will have to do some more learning. I know I am taking up a good bit of time. What I have learned previously did not go into running parallel panels. Nor did I ever envision running a 48v bank. It makes sense, but I need to figure it out more. I need to figure out what batteries to run in the 48v setup, what panels will give me enough amps to keep them alive, and what charger I can get that will handle more power in the future while at the same time no being too big to put unneccesary draw on the system. I need to go back and re-learn what I though I already learned. I missed some simple stuff it seems.

    Thanks to all that have replied, especially you Bill. You have a wealth of knowledge on the subject.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Another Charge controller choice thread

    Leper,

    Aw--don't worry--You are helping to get my post count up. :roll::p;)

    And, I hope I am helping to fill in your knowledge as opposed to confusing you or making you think did not understand the stuff the first time through.

    Working with complex power systems (with solar PV is)--can be very daunting and it is very easy to get lost in the details--plus I make mistakes too (this is not cut and paste from a text book--every post freshly typed for your satisfaction :D).

    If it helps, think of the battery as the central point and each load/charger only interacts with the battery bank (roughly true--the battery sets the voltage fairly near 48 volts regardless of load / charging currents). So just pay attention to the Solar Charge controller when working on it. Then when installing the inverter--just pay attention to how it works with the battery bank.

    When you start programming set points (charging voltage on the solar controller, vs charging points for the Hybrid inverter/charger and sell voltage for grid tied operation)--It does get complex again... But that is for another day.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset