Controller help

krabidkrabid Registered Users Posts: 15
Hi,
I'm new to the Solar Power world as well as this forum. I'm interested in installing a system on my RV. Thinking of starting with a simple system of 130W to 160W and controller. I want to be able to expand the system in the furure should I need to. Maybe add more panels, batteries and a hard wired inverted at a later date. I now have 2 100ah 12V batteries.

Now to the question I have. Which type controller should I go with, a MPPT or a PWM? Is there a perticulare brand and model I should be looking at? I also want one with a remote indicator panel or should I be looking at a seperate volt/amp hour monitor?

Thanks for any sugestions

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    The question that is always asked (not just by you)--is how to start small and grow into a large system.

    The simple answer is you cannot (or at least; cannot cost effectively).

    The first problem is batteries age and if you attempt to add more batteries in parallel--the new batteries will tend to age quicker until they die, very roughly, around the age of the original batteries in the system.

    Second problem is that charge controllers tend to be either smaller units (under 200-400 watts) or larger units (400 watts or more). As you size up the system, you are generally going to have to toss (sell, give away, or keep for a small system) the original controller as you increase the size of your system (you can parallel smaller and larger controllers together on one battery bank--so, you can keep the smaller one--however, you now have several controllers to monitor and program for proper operation--and making sure they don't clash--like trying to equalize your battery bank on different days).

    Third issue is as you increase the size of your system, typically your power usage goes up. And as your power goes up, so does your current. I sort of recommend that people try and stay around a 100 amps maximum battery current... Larger currents require larger batteries, heavier cabling, and larger (more expensive) fuses/breakers.

    That would mean a 12 volt inverter would be ~1,200 watts max., 24 volt system 2,400 watts max., and a 48 volt system for anything larger.

    So--if you start with a small (12 volt bank), you will probably have to move up to a higher voltage bank (more batteries) and higher voltage inverters as you scale up.

    And... Large devices (charge controllers, inverters) are not really great for small systems... The larger devices typically have more standby and operational losses--so smaller controllers and inverters are typically more efficient at the lower loads that one would expect for a small system).

    Solar panels can be salvaged and moved from your smaller system to a larger system (and they are one of the most costly components of your system). However, when matching solar panels to solar charge controllers, you have to match the Vmp and/or Imp with other panels. If you purchase smaller panels (less than 100 watts)--typically, they are very difficult to "match/share" on a single charge controller with larger solar panels that you may purchase later (>100 watts). Larger solar panels tend to be more cost effective ($$$/watt) and easier to install and maintain (few large panels, with few electrical connections; vs a huge number of small panels and lots of connections).

    Lastly, while charge controllers (and now inverters) are becoming quite smart (even computer interfaces where you can read their power logs)... My 2 cents recommendation is to look for a Battery Monitor to be the "fuel gauge" of your battery. Other than using a hydrometer and measuring specific gravity (messy, can contaminate battery, not possible with sealed batteries)--there is no other real-time type device that can tell you at any time (under load, charging, or just resting) what the current state of charge your battery is at... If you have an expensive set of batteries--a battery monitor will probably pay for itself the first time you don't accidentally under or overcharge your battery bank.

    In the end, you really need to define the use of your off-grid system first and then size it to your needs.

    And, many people do start with a small system so they can learn (relatively cheaply) the ins and outs of off grid power. But there is a cost to that learning.

    I am sorry, I probably did not answer your question in the way that you wish--but, in the end, knowing about your application (power requirements, where it is--roughly-located, other local conditions; temperature, shading, battery type, how far will the panels be from the battery shed, electrical loads, etc.) will help us give you a more exact answer to meet your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Thanks for the info

    I filled out one of those appliance consumption work sheets and I figured my usage per day is about 40 ah. The system is to be added to a 2009 30' Wolf Pack TT Toy Hauler by Forest River. There will be 2 adults staying in it from Fri to Sunday most every week thru the summer months. About half the week ends dry camping and the other half on shore power. I now have 2 Interstate SRM29 deep cycle batteries which are 100ah each. We are located and plan on camping most all the time in Northeastern NY and if Quebec ever opens their ATV trails to side X side buggys we will be going up there a bit. I would say the temp should be 75 to 85 most the summer. The batteries are on the front of the RV and the panels would be about center the roof to be able to run cables down the frige vent as they recomend. So I woud guess about 20' to 25' panel to battery. When I say grow in size I figure start with 1 130w to 160w panel and if need be add 1 or 2 more of the same size panel.

    My question was the type of controller, MPPT or PWM? Or do you think I should go with the 3 panel right off the bat? Was hopeing to start out in the neighborhood of about $1000. If I go with the Battery monitor I can save a bit on the controller as not needing one with the remote gauge.

    Am I any wheres near on the right bath or totally wrong?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Controller help

    much of that i think would depend on what you want in the system in the future. sometimes if you have enough knowledge of the subject and a good idea of what will be down the road the expansion can take place. many times compromises will be had to do this like a larger mppt controller operating on one pv for now may not be very efficient or in your case keeping a charge on the batteries until you get the rest of your system together as batteries are an item it's not wise to add later on. an ac charger could fill that void if only applied to the bulk stage of charge for these are unregulated chargers. a regulated one will be an expense that you may or may not want as you may prefer to watch the cheap charger does not exceed the bulk stage and apply the $ difference you would've paid on a good multie stage charger towards more solar stuff.
    the bottom line is if you know what you're doing you can do it with some compromises, but the fact that you're asking us says you don't know enough. keep working it out over and over again on paper and in your head. know where you are and where you're going with it. the requirements of the future are what need addressed and what components in what order are needed to reach that goal. it is alot of research on component abilities factored to the costs and affordability by you over time. the fact that you now have 2 100ah batteries have already set a max for the system unless you buy more now and make a temporary means of maintaining them until other components are purchased. that puts a rush on the time factor for the batteries won't wait many years for the rest of the system to come together unless you stick with the 2 batteries you have now and sacrifice these 2 batteries when the rest of the system needs to come together meaning some items as you pay for them may sit idle for some time.
    it's alot of whatifs and we can't say what the best or only way would be for you.:confused:
  • hillbillyhillbilly Solar Expert Posts: 334 ✭✭
    Re: Controller help

    Hi there,
    I'm taking a bit of a guess at what you mean, so pardon if I am off an any or all of this...

    First of all I would respectfully disagree slightly with what Bill said about not being able to start small and grow a system. I say slightly because each of his specific points are very true, in regards to efficiency and cost issues with larger controllers and inverters on a small system and batteries NOT being a modular component of the system. There are however some choices that CAN be made that will make some system growth much more realistic.
    For example, you have two batteries (12V?) now, so you can't easily change your battery reserve, but you could change system voltage if you buy a charge controller that will allow you to do so. That would mean switching inverters (if you will start off with one). The benefit of this is that you could say run your wires with the idea that you could later add another panel or so and go up to 24V without having to run another set of wires. You could also figure on upsizing the whole system whenever you need to replace the batteries (or possibly other components).
    A few more system specifics would be helpful, I know that you think that you're asking a simple question, but as with most PV system choices... the answer depends.
    A really general rule of thumb is that for small systems, MPPT is not really worth the extra money (ie, spend the extra $ on a bigger PV panel). That said there are certainly some times where they can be very helpful, especially in the cases where you can use it as a voltage step down converter (say wire two or three panels in series, and run smaller wire from the PV to the controller). If you think that you might grow the system later, I would certainly look at the specs of the Morningstar MPPT controller, as well as their Prostar controller (can be set up for 12V or 24V). There are certainly smaller charge controllers out there that would be cheaper, but if you end up needing to just replace them later anyways, might as well start with one that will leave you some room to grow.
    When you say a 40 amp daily load, I would say that overall... very roughly (with 6 hours of "peak solar hours") you'd need about a 120-130 pv watts just to cover the loads, not taking battery charging into consideration.... on the battery side of the equation, you have 200ah batteries to charge, and it is a good idea to have a 5%-10% minimum charging capability (that would equate to roughly at least 200watts of PV). You could probably get away with a bit less than that amount, if you have a good ac/dc battery charger that will give them a FULL complete charging on a regular basis.
    So again there are some big variables still to pin down on your needs and your desires for the system, and for how you might be looking to expand.
    Either way, I would reiterate the ideas of oversizing your wiring for any potential future expansion, and size the charge controller to handle that increase. Often the easiest way to do both of those things is to up the system voltage, so keep that in mind.
    Good luck, I think you're not far off track all in all...
  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    I am sorry--I was running out of time and missed the "RV" part of the discussion...

    You are probably staying at 12 volts for now. And many of the "nicer" controllers are switchable between 12 and 24 volt output...

    If you choose PWM--then you will need to do panels in pairs... A pair of 12 volt panels in parallel which will give you a nice input for a PWM running a 12 volt bank. Or run the pair in series for 24 volts (really Vmp=17 volts, 2x17=34 volts or so) for a 24 volt bank.

    With a MPPT type controller, you can wire the panels for "Vmp=34 volts" in series and run either a 12 volt or 24 volt battery bank very nicely (you can also wire them in parallel for a 12 volt bank--not a big issue either way--each has its small advantages for your application).

    If you have a long run from the panels to the controller/battery bank--then using a MPPT type controller and higher voltage on the PV panel run (example 24 series panels to 12 volt battery bank) will give you lower voltage drop/power losses (save money on copper, or with lots of copper, less losses. Higher PV voltage is slightly less efficient at the controller--so not a huge difference in your case).

    If you want to keep the costs down... A good quality PWM controller will work very well too. An MPPT controller may give you 10% to 30% improvement during winter camping (cold weather--and it will probably be closer to 10-15% improvement in power increase over PWM in the cold).

    However, you can see that installing tilt mounts for your panels optimized for summer/winter conditions will give you much more improvement in power collection than adding an MPPT controller alone would.

    A good MPPT type controller for your installation would be the MorningStar MPPT controller (12 or 24 volt battery bank support). ~200 watt maximum (12 volt configuration); ~400 watt maximum (24 volt configuration).

    Other PWM controllers will work fine too (MorningStar makes a wide range of controllers). I would suggest which ever controller you purchase has a Remote Battery Temperature Sensor--Absolutely needed for the MorningStar MPPT controller for proper battery charging. You can also find AC battery chargers with RBTS too (recommended).

    Other MPPT controllers (Xantex and Outback) tend to be larger units (>400 watts of solar panels) to make sense--so they are not really recommended for your smaller application.

    If you are looking for 40 AH per day in North Eastern New York or 40 AH * 12 volts = 480 WH or 0.48 kWH per day--Using the PV Watts website... Pick Massena NY, use 1 kW of solar panels (easy to scale), pick a derating factor of 0.52 (battery and AC inverter losses), and assume the panels are either mounted tilted at 45 degrees or or flat at zero degree tilt (in summer months, tilting the panels is not as important, and don't know if you plan in pivoting panels or not).
    Month Tilt at ~45 degrees
    Solar Radiation (kWh/m2/day)
    AC Energy (kWh per month)
    Energy Value ($ at $0.145 per kWhr)

    1 3.13 53 7.69
    2 4.28 64 9.28
    3 4.97 81 11.75
    4 5.12 76 11.02
    5 5.02 74 10.73
    6 5.55 76 11.02
    7 5.55 78 11.31
    8 5.23 73 10.59
    9 4.44 63 9.13
    10 3.67 55 7.98
    11 2.44 36 5.22
    12 2.32 37 5.37
    ===========================================
    Year 4.31 avg sun 766 kWhr per year $111.07

    Month Tilt at ~0.0 degrees
    Solar Radiation (kWh/m2/day)
    AC Energy (kWh per month)
    Energy Value ($ at $0.145 per kWhr)

    1 1.68 24 3.48
    2 2.64 37 5.37
    3 3.77 60 8.70
    4 4.72 70 10.15
    5 5.31 79 11.46
    6 6.19 87 12.62
    7 6.01 86 12.47
    8 5.06 71 10.29
    9 3.75 52 7.54
    10 2.53 36 5.22
    11 1.55 20 2.90
    12 1.31 17 2.46
    ==========================================
    Year 3.72 avg sun 639 kWhr per yr $92.66

    So, you can see during the summer you average around 70-80 kWhrs per month. Or, divide by 30 days per month:

    70 kWhrs per month / 30 days per month = 2.33 kWhrs per day (per 1kW of solar panel per day)
    80 kWhrs / 30 = 2.67 kWhrs per day (per 1kW of solar panels per day)

    Your needs 0.48 kWHrs per day on panels mounted at 45 degrees for summer in Northern New York:

    0.48 kWhrs per day / 2.33 kWhrs per day * 1,000 watts of panels = 206 watts of solar panels

    Or if mounted flat for summer:

    0.48 kWhrs per day / 2.67 kWhrs per day * 1,000 watts of panels = 180 watts of solar panels

    So, depending on how you mount your panels, and exactly which months you are wanting power--you are pretty close to "break even" with your planned 130 watts of panel...

    The above is a pretty conservative calculation... I don't want to "oversell" a system's performance--makes for unhappy users (not that I get any money either way--Niel and I volunteer here for Spam control--WindSun is the Admin/NAWS contact here).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Thanks for all the info and help with this.

    My plans are to mount flat on the roof. Camp April thru Sept.

    Looks like I should start out with 2 130W panels hooked parallel. Go with a MPPT controller that can be switched between 12V and 24V input with 12V output. Large enough for up to 4 panels, 2 banks of 24V, 35 amp. That would give me the flexabilty to grow should I see a need in the future.

    How am I doing? All this math is puttin my head into a spin :blush: . Been bout 40 years since I did all this figuring and my sponge doesn't wook as well as it once did ;) .
  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    Watch very carefully which Solar Charge controller and which solar panels you choose. Especially with MPPT type controllers.

    Most Solar Charge Controllers are limited by their output current... A small MorningStar MPPT has a limit of 15 amps or 200 watts total of panels at 12 volts; and 400 watt panel limit on a 24 volt batter bank.

    The larger MPPT solar charge controllers are limited to 60-80 amps (depending on vendor and model).

    Also, the solar panel input voltage must never exceed the controller's maximum input voltage (75 volts for the MorningStar MPPT, and 140-150 volts for many of the other larger MPPT controllers).

    Your configuration is a bit large for the Morning Star--so you will have to go with next $ize up of controller (60+ amp).

    Also, you are looking at using panels that are >100 watts. These are good panels and, usually, very cost effective to purchase and mount (vs smaller panels)... However, watch very closely the Vmp, Imp, and Voc ratings of the panels.

    Smaller panels (<100 watts) are typically designed around "12, 24, 48 volt battery systems". And so their panels have Vmp~17-18 volts.

    The larger panels (>100 watts) are typically designed for Grid Tied Inverter systems and have Vmp voltages >> 17 volts... That means, when you put several panels in series, their Vmp and Voc maximum voltages can exceed the controller's maximum limits (and damage them--outside of warranty coverage).

    Not usually a big issue--but something to watch out for as you figure out the configuration of your array (such as two panels in series vs 4+ panels in series).

    There is one issue with high Vmp panels and 48 volt battery banks... With some high Vmp panels, it is not possible use them to charge 48 volt battery banks (one panel Vmp is not high enough Vmp, two panels in series is higher than the Voc maximum of the controller). Not typically an issue for your system if you stay with 24 volts maximum.

    Configuring solar panels to charge controllers/battery banks is a non-trivial task. Read the manuals and supporting website closely and ask questions as you get close to your final choices (before your buy).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Thanks, your info is just what I've been looking for. The specs I need to look for and in the language I understand. I find on the net there is over wellming info and a lot of it is in language way over my head. I've read so much info on solar in the last 3 weeks to make my head spin and eyes bleed. Reminds me of when I started working with computers.

    Another question. When hooking panels in series and paralell does it work the same as batteries? 2 100W / 12V paralell = 200W 12V and 2 100W series = 100W 24V?

    Thanks again you have been very helpful
    Ken
    BB. wrote: »
    No need to quote the previous post in whole unless you are trying to answer/ask questions--I won't change anything on you--other than my spelling and grammar. --Bill B. ;)
  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    You are very welcome Ken,

    We all try to help.

    Regarding:
    krabid wrote: »
    Another question. When hooking panels in series and parallel does it work the same as batteries?

    2x 100W / 12V parallel = 200W 12V

    and

    2x 100W series = 100W 24V?
    NO: still equals 200 Watts--see below

    -edit above for clarity and correct statement

    Remember the Watts (Power) equation is:

    Power (Watts) = V*I = Volts * Current

    When you "add" two panels in series--the voltage "adds", and the current remains the same.

    When you "add" two panels in parallel--the current "adds", and the voltage remains the same.

    Solar panels are really similar to batteries in a flashlight or car/truck/boat battery systems.

    For your truck, you add a second battery in parallel to get more current for your starter or accessories.

    For a boat with a 24 or 36 volt battery bank--you add two or three "12 volt batteries" in series to get your 24 or 36 volts needed to run the boat...

    Power wise, adding a pair of panels (aka solar batteries) in parallel or in series does not affect the total power. For example--say we have a pair of solar panels rated at Vmp=17 volts, and Imp=8 amps:

    Power solar panel = V*I = 17 volts * 8 amps = 136 watts per panel

    Add two panels in series:

    Power-series = (17 volts + 17 volts) * 8 amps = 272 watts @ Vmp=34 volts and Imp=8 amps

    Add two panels in parallel:

    Power-parallel = 17 volts * (8 amps + 8 amps) = 272 watts @ Vmp=17 volts and Imp=16 amps

    You end up with the same power--just one is 272 watts at 34 volts (series--higher voltage/lower current) vs the other set at 272 watts at 17 volts (parallel--lower voltage/higher current)

    Make sense?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    That is the info I needed.

    Thanks so much you have been a GREAT help. Now I have some thing to work with. I'm sure I'll have more questions down the road but at least now I can start my research into what I need.

    Thanks Again
    Ken
    BB. wrote: »
    No need to quote entire previous post... -Bill B.
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    I have a preliminary selection of parts put together for a system. Can I run it by you to see what you think of my selection? Can I name the products on here that I have chosen? No dealers, just manufacturers.

    Ken
  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    Sure, not a problem. Even links to other dealers that have useful information/products which are not available at NAWS are OK too.

    We just try to limit obvious free advertising (AKA "spamming"). I don't think I have ever done anything other than a gentle post or PM to a new poster that was posting multiple links (regarding perfectly OK discussions/questions) to competitors' sites for products that NAWS also sold (I left the old links behind--we are not religious about the issue).

    We all would prefer you to be happy with your system than to quibble over the small stuff in life. Ask away! :cool:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    OK, Thanks, Here is what I come up with.

    1 Kyocera KD135GX-LP panel (to start with and go upto max of 3 panels hooked parallel)-- 17.7 Vmp , 7.63A Impp , 135W Pmax

    Blue Sky SB2512iX controller -- 35VDC max

    Battery Temp sensor for SB2512iX

    Trimetic TM2020 monitor

    100A shunt for monitor

    Flat roof mount for panel

    Also I know all the hardware as in wire and fuses with holders

    Whats you opinion on what I have put together?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Controller help

    i'm sure none of us would have a problem with what you propose as long as it will cover your needs now and in the future. know that the 2512 will not accept higher pv voltages making any series pv arrangements or 24v pvs in the future to be out of the question. it will not allow for higher battery bank voltages if you were to have need of that. it will also be limited to outputting that 25a max. you most likely will need more pv to charge those 2 batteries, but if you are planning any expansion of that battery capacity the controller will need to be able to meet your needs with higher levels of current to charge the battery bank with and not just more pvs. all of this in addition to my previous comments apply.
    if after knowing you will need more pv with knowing what the limitations of that controller are and it still meets your needs all around, i say thumbs up.:D
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    My other choice is a Xantrex C40. Might be more expandable, just thought that going with a MPPT was a bit better.

    Do the PWM controllers have to be the same voltage input as output? I can't see me every wanting to up my battery voltage on the RV because that would involve way too many other changes in the RV from 12V to 24V. At this time I also can't see needing any more that 3 of those panels. My thoughts are to start with one panel and chances are go to 2 with the second next summer and if need be the third. We don't use a lot of energy to camp because we are outside most all the time other than shower and sleep.

    If nothing else you folks got my brain a workin :D Haven't done this much figurin and research in many many years :blush:

    Thanks
    Ken
    niel wrote: »
    i'm sure none of use would have a problem with what you propose as long as it will cover your needs now and in the future. know that the 2512 will not accept higher pv voltages making any series pv arrangements or 24v pvs in the future to be out of the question. it will not allow for higher battery bank voltages if you were to have need of that. it will also be limited to outputting that 25a max. you most likely will need more pv to charge those 2 batteries, but if you are planning any expansion of that battery capacity the controller will need to be able to meet your needs with higher levels of current.
    if after knowing you will need more pv and what the limitations of that controller are and it still meets your needs all around, i say thumbs up.:D
  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    Either should work well for you needs (best bang for the buck).

    If you are into "options"--take a look at their onboard display and possible remote display and what data they provide to you...

    In the end, other than for simple debugging using the controller data/display--you will probably use the Trimetric for understanding the "health" (state of charge) of your battery bank.

    For AC power--you might look at the MorningStar 300 watt TSW inverter--it is pretty nice for your scale of application and allows you to have some 120 VAC creature comforts (drills, dvd, etc.) without being stuck with DC. Of course, the more power you use--the more you need to collect/store.

    -Bill

    PS: Krabid; You don't need to copy the previous post when replying--unless you want to quote a specific passage.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Controller help

    the c40 does have more current and voltage abilities, but it will not downconvert pv voltages like some mppt controllers will, so this means that any excessive voltages over the base voltage desired will be wasted. no lost current recovery either from being straight pwm.
    i'm glad you are thinking as it means you are solving your needs mentally first as it should be. if one does not think things through mistakes are made that you may regret later on. some here like to refer to this as ready, fire, aim and the analogy is sound on this parable.
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    I was thinking of going with a remote display and that is why I chose the Trimetric. Would the one that are optional with the controllers better way to go (more info?)?

    By the time I get this up and running I'm going to need an inverter to run the blender ;) frozen mixed drink :D

    I have a Coleman 800W/1600W already that I can use till the time I decide to go hard wired unit.

    I just came across another controller the Solar Boost 50 by RV Power Products. Have to do some reading on it.

    Ken

    BB. wrote: »
    Either should work well for you needs (best bang for the buck).

    If you are into "options"--take a look at their onboard display and possible remote display and what data they provide to you...

    In the end, other than for simple debugging using the controller data/display--you will probably use the Trimetric for understanding the "health" (state of charge) of your battery bank.

    For AC power--you might look at the MorningStar 300 watt TSW inverter--it is pretty nice for your scale of application and allows you to have some 120 VAC creature comforts (drills, dvd, etc.) without being stuck with DC. Of course, the more power you use--the more you need to collect/store.

    -Bill

    PS: Krabid; You don't need to copy the previous post when replying--unless you want to quote a specific passage.
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Guess I better keep looking for a MPPT that better suits my needs. I just came across the Solar Boost 50 that I have to read up on once my eye sight gets back to normal. Every thing gettin blurry after all this reading.

    Ken
    niel wrote: »
    the c40 does have more current and voltage abilities, but it will not downconvert pv voltages like some mppt controllers will, so this means that any excessive voltages over the base voltage desired will be wasted. no lost current recovery either from being straight pwm.
    i'm glad you are thinking as it means you are solving your needs mentally first as it should be. if one does not think things through mistakes are made that you may regret later on. some here like to refer to this as ready, fire, aim and the analogy is sound on this parable.
  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    Ken,

    Here is another trailer thread with lots of details (and videos) about installing a small(er) solar RE system.

    Since your requirements may end up being larger--the controller choice in this thread probably does not apply to you.

    However, you can see how others have chosen to resolve their design questions (in this case, using an MPPT controller to allow solar panels to be mounted away from the trailer when their are sun/shade issues at the campsite (trailer in shade to keep cool--panels in sun for power).

    One other caveat. Some MPPT controllers, and magazine reviews, talk about 98+% efficiency... In the real world (where we live)--that is not possible. Many times, this is the result of people using the Charge Controller's own Volt/Amp meters (and GT inverters too)--which surprise--tend to read 5-10% high (and never 10% low :roll: ). Nobody is "unhappy" when "their controller says" that is is performing with perfection.

    Some of the Xantrex controllers are an exception--Solar Guppy (in his RE test lab) shows a couple of the Xantrex units (those that he tested) are 1-2% accurate (as I recall from another thread--not trying to talk for him).

    -Bill

    PS: I watched kevinhenrycalgary's videos instead of the Oscars--more interesting to me. :p
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,020 admin
    Re: Controller help

    Forgot to add--A battery Monitor provides much more useful battery status information than any metered Solar Charge Controller. You are correct (IMHO) to spend the extra money on the Battery Monitor Function. The remote meter for the solar charge controller is less important to manage your battery bank's storage.

    There is at least one solar charge controller that includes a Battery Monitor in its design (I am not an expert in solar RE equipment--just what I have read)--but our host ended up dropping the product line.
    Windsun wrote: »
    Just a heads up - we no longer carry the Apollo stuff for the simple reason that far too much was coming back on warranty.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    From a quick scan of the spec on the Solar Boost, it looks like in might fit my needs.

    Output current rating 50A
    System Voltage 12/24V
    PV max open circuit voltage 57V
    MPPT

    what is "Acceptance voltage adjust range ......13-16V/26-32V" ???
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Controller help

    that would be the charge stage that is reached when it will start to cut back on or regulate the power to the battery to prevent any overcharging or damage to the battery. basically, it will be a voltage regulator preventing the voltage from going any higher than the voltage selected for it and this will cause a gradual decrease of current as the battery continues its charge until it hits a set point and switches to float, assuming it's a 3 stage charger we're talking about. 2 stage types will go from bulk to acceptance and stay there. acceptance is sometimes also referred to as absorb.
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Thanks

    Going to take me a bit of time before I get a handle of the terms and lingo to this solar stuf, but I'm starting to get it.

    Yup, it is a 3 stage charger. Bit more money than I wanted to spend but better spend a bit more now than a lot latter.

    Doesn't seem to be a very popular controller. I see a lot of dealers handle the Blue Sky line but so far only one that I've been to handles the Solar Boost 50. I figure one of 3 things, 1- older/discontinued, 2- new to the market, 3- problem unit

    Ken


    niel wrote: »
    that would be the charge stage that is reached when it will start to cut back on or regulate the power to the battery to prevent any overcharging or damage to the battery. basically, it will be a voltage regulator preventing the voltage from going any higher than the voltage selected for it and this will cause a gradual decrease of current as the battery continues its charge until it hits a set point and switches to float, assuming it's a 3 stage charger we're talking about. 2 stage types will go from bulk to acceptance and stay there. acceptance is sometimes also referred to as absorb.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Controller help

    i have an sb50 and it works ok. its popularity went down when they started asking for more money as you could get an mx60 or some other quality controller with more features for about the same amount or a few dollars more. of course the mx is discontinued now as they've replaced it with the flexmax series. other controllers are now a better bang for the buck.
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Morning guys,

    In my mind I think I have the controller and panels figured out. What you think about this configuration?

    controller - Blue Sky Solar Boost 3024iL

    1 panel - KD135GX-LP to start with and can grow to 2 panels at latter date and have the abilty to go to a 3rd as a buffer should it be needed. If I did my figuring right 1 panel would be border line with me using 40ah per day and 2 should be plenty as long as my usage stays the same.

    I looked at the Outback and Xantrex but they are a bit over budget for me. If I go too expencive the wife will pull the plug on me. I don't forsee going as big as they are capable of going to. Trying to keep the price down as low as I can with out hurting my self in the future.

    Ken
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: Controller help

    I'd suggest the MorningStar Sunsaver Mppt ... much better controller

    You can do two KC130's, since your only starting with one panel you can still add one more.

    The Blue Sky model your looking at I tested last year, Mppt tracking stalls when there is large inverter load due to AC ripple ... I wouldn't recommend any of the BlueSky models, very dated technology and low efficiency.

    If you every out grow the 15amp limit of the MorningStar unit, its still cheaper to have a pair of them than getting a large XW/FM unit and no more expensive that the Blue Sky stuff
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Can 2 panels be hooked parallel to the Morningstar MPPT? One panel has a Short Circuit Current of 8.37A. Two would make it 16.74A, wouldn't that be over the limit? Can 2 of those controllers be paralleled? I some say they can but I didn't see that in the specs of the MS MPPT. I do like the price and size if it a lot better than the others.

    Ken

    I'd suggest the MorningStar Sunsaver Mppt ... much better controller

    You can do two KC130's, since your only starting with one panel you can still add one more.

    The Blue Sky model your looking at I tested last year, Mppt tracking stalls when there is large inverter load due to AC ripple ... I wouldn't recommend any of the BlueSky models, very dated technology and low efficiency.

    If you every out grow the 15amp limit of the MorningStar unit, its still cheaper to have a pair of them than getting a large XW/FM unit and no more expensive that the Blue Sky stuff
  • Solar GuppySolar Guppy Solar Expert Posts: 1,973 ✭✭✭
    Re: Controller help

    Since your putting the panels flat on a RV roof, you will never see the peak current, the angle will always be non-optimal, so its your choice, put two in series or two in parallel. Also regardless of how much PV you have in the input, the Output is limited to 15 amps, so at worst, in a rare occurrence that there is more current to harvest, nothing gets damaged by having to much input current

    Having the two KC-130's in series mean you will not need a second pair of wires to the controller and get full use of the Mppt in all weather conditions, remember the PV voltage falls as the panels heat up, a 12V panel to a 12V battery on a hot metal roof may bot even produce enough voltage for a Bulk Charge. The SunSaver is good to 75V input

    You can have as many controllers as you want connected to the battery bank, they have no effect on each other.
  • krabidkrabid Registered Users Posts: 15
    Re: Controller help

    Looks like a good way to go. It will save me a bit of money to get started and I can expand in the future should I see a need. I think going 2 panels will be plenty just was thinking of the third for a buffer should the wife go crazy with the blenders ;)
    Thanks
    Since your putting the panels flat on a RV roof, you will never see the peak current, the angle will always be non-optimal, so its your choice, put two in series or two in parallel. Also regardless of how much PV you have in the input, the Output is limited to 15 amps, so at worst, in a rare occurrence that there is more current to harvest, nothing gets damaged by having to much input current

    Having the two KC-130's in series mean you will not need a second pair of wires to the controller and get full use of the Mppt in all weather conditions, remember the PV voltage falls as the panels heat up, a 12V panel to a 12V battery on a hot metal roof may bot even produce enough voltage for a Bulk Charge. The SunSaver is good to 75V input

    You can have as many controllers as you want connected to the battery bank, they have no effect on each other.
Sign In or Register to comment.