Best Vmp for use with SolarBoost 2000E

Hi all,

I am new to solar and am about to begin installation of a system on my small vintage 1976 Boler trailer. I have purchased two AE-80HE (high efficiency) panels from AEE Solar and a BlueSky SolarBoost 2000E MPPT charge controller. This will be used to maintain a 12V/240 amp/hour battery bank consisting of two 6-volt golfcart batteries in series.

I purchased the panels based on a combination of their smaller physical size and the fact that AEE advertises they can produce a Vmp of 17.6 volts.

This Vmp of 17.6 seems important to me as the BlueSky 2000E literature states:

["The effect PV panel design has on performance is that panels with a maximum power voltage (Vmp) of 17 volts or greater will tend to produce more boost, whereas PV panels with Vmp less than 17 volts will tend to produce less boost"

"To obtain good charge performance a rule of thumb is to not attach a PV module of less than 16.5V to charge a 12V battery. PV modules with higher Vmp in the range of 17.5V-18.5V will provide improved MPPT and battery charge performance."


The specs for the panel were listed as follows in AEE literature:

Imp 4.55
Vmp 17.6
Isc 4.89
Voc 21.4

However: the specs listed on the back of the actual panels are

Imp 4.8
Vmp 16.7
Isc 5.43
Voc 21.1

I have asked AEE head office in the USA and they are looking into the discrepancy. (It may be a typo error or I may have received the wrong panel design)


I have also received the following from an AEE rep here in Canada

"This being said, he (kevinhenrycalgary) is incorrect about more power being delivered through MPPT with a higher Vmp.

It is the amps that charge the battery, so higher current will yield higher power delivered to the batteries.

In fact, with MPPT, the only thing that matters is the power output of the module.

So, the new specs yield 80.16 watts, while the old specs yield 80.08 watts.



My question is this:

What is the proper train of thought in regards to Vmp and MPPT in conjunction with the SolarBoost 2000E controller?

My system is small and my power consumption tends to be minimal so good MPPT performance may never be an issue. However, for optimal performance, should I hold out for the panels with the higher Vmp?

Thank you for your help

K. Johnston
Calgary, Alberta, Canada
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Comments

  • icarusicarus Posts: 5,070Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E

    My hunch is, and Niel and Bill will correct me, but I don't think it is going to make much difference with the system you describe. Since the Vmp of both panels is the same, the controller will handle that voltage and convert it based on the battery voltage. I think that BlueSky is suggesting that you would get maximum MPPT advantage with a bit higher Vmp but the marginal difference in your small system would almost be too small to measure.

    Tony

    PS. The panel specs you list convert to almost identical wattage output. The one has higher voltage/lower amperage, the other the reverse. In the net/net, the higher the voltage the more "headroom" the controller has to use to convert MPPT efficiency.
  • WindsunWindsun Posts: 1,164Solar Expert admin
    Re: Best Vmp for use with SolarBoost 2000E
    "The effect PV panel design has on performance is that panels with a maximum power voltage (Vmp) of 17 volts or greater will tend to produce more boost, whereas PV panels with Vmp less than 17 volts will tend to produce less boost"

    "This being said, he (kevinhenrycalgary) is incorrect about more power being delivered through MPPT with a higher Vmp.

    Actually both of those statements are true.

    If your panel voltage is over 17 volts or so, you will get a bigger boost from that panel as opposed to say a 16.5 volt panel.

    However, that does NOT mean you will get any more power to your batteries if both panels are rated at the same wattage.

    What it means is that you lose more if you do NOT have an MPPT controller with the high voltage panel.
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E

    Tony is correct. And your AEE contact is correct--but possibly wrong too...

    The Solar Charge converter will simply maximize the solar panel output following the formula Pmax=Vmp*Imp and the battery output will be Pbatt=Vbatt*Ibatt (less some 5-10% or so power loss)--so absolute voltage and current do matter.

    However, Solar panel voltage must be in a range the charge controller can use... Obviously, too high, the controller is ruined. Too low, the charge controller cannot pass solar panel energy to the battery.

    Basically, the solar panel voltage must be greater than Vbatt-charging+controller drop.

    Vbatt-charging would be ~14.5 volts during normal charging, and controller voltage drop is around 1-2 volts (plus, you will have some voltage drop in the wiring too).

    Also, for flooded cell lead acid batteries, you will need to charge them at a higher voltage every few weeks or so--called "equalization"... That voltage can be around 15-15.5 volts.

    So, just from a conservative point of few, the solar charge controller (which can only drop voltage, not increase it):

    Vmp >= 15.5v + 2v = 17.5 volts to equalize
    Vmp >= 14.5v + 2v = 16.5 volts for normal charging

    And then you get into the ugly details.

    Batteries require higher voltage to charge if they are cold, and lower voltages if they are warm (~77F is "spec. temp.").

    And, solar panel Vmp (and Voc--open circuit) vary with temperature. When the panels are cold, they output higher votlages, and when the panels are hot, they output lower voltage.

    So, if you have cold batteries, on a hot, sunny, windless day, your Vmp of the panels may not be able to output enough voltage to poroperly charge/equalize your batteries.

    If the Vmp is correct for your panels, then the Vmp=16.7volts is getting very close to putting you in the gray zone where you have the "energy" of the panel, but not enough voltage to push current into the batteries. Remember solar panels get hot under full sun (black object under glass). And even on a 80F day, it is possible for your 16.7v panel to drop down to ~14 volts Vmp if mounted flat to the roof (poor cooling) on a windless day.

    So, your questions to ask:
    • What is the Vdrop requirement of the BlueSky controller
    • What is Vmp for your panel
    • What is the Voltage Temp Coeff - Vtoc (something like -0.0824 V/°C)
    • What are the Vbatt-charge voltages for your battery bank
    • What are the temperatures of your batteries
    • What are the temperature of your solar installation
    • Will there be airflow around the panels (i.e., tilted up / raised up from roof for better ventilation)
    -Bill

    By the way, Vmp is a "fuzzy voltage"--the panel will output higher voltage, but at less current--so the system may still charge--it just won't do it with Imp*Vmp--V will be a bit higher, and Imp will be much lower--so P=V*I into the battery bank will be lower too.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Thanks for the replies guys. You are fast.

    I didn't think it would make much difference in the big scheme of things as my battery will probably be 90% full most of the time.

    Last years power consumption averaged out to about 10% of battery capacity per day with conservative usage. I would go 3 days and then crank up the generator and recharge via a Xantrex Truecharge 20 amp charger. I have since changed all interior lighting from 1156 bulbs to LED's. so consumption may drop depending on usage this year.

    I should not be lacking for power with the combination of the modules and the charger/generator.

    As I need something to do this weekend I may begin the installation before hearing back from AEE.

    On another note, what is the proper procedure for wiring the PV system in with my existing Xantrex charger and Xantrex XBM battery monitor?


    Would it be charge controller positive to battery post positive with an inline fuse at the battery and charge controller negative to the charge side of the XBM's shunt or can they even be hooked together?

    Thanks again
    K. Johnston
    Calgary, Alberta
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Thanks Bill,

    You've caused me to change my mind again. I was originally thinking along those lines from the information I had gathered with my limited grasp of the subject.

    I will now wait to hear from AEE and will "rough-in" the wiring this weekend.

    AEE has a warehouse here in town so it may just be a matter of exchanging the panels if the others are in stock.

    K. Johnston
    Calgary,Alberta
  • hillbillyhillbilly Posts: 334Solar Expert ✭✭✭✭✭✭
    Re: Best Vmp for use with SolarBoost 2000E

    Kevin,
    One thing to note is that the whole "boost" from your Charge Controller tends to be inversely related to how full your batteries are. In other words, if they are up around 90% full (SOC), you wont see much if any boost at all. Where the real boost comes from is the controllers ability to convert "excess" voltage into higher current output in amps, in other words when the batteries are lower and the panels are producing a higher voltage (keeping them cooler will help in this regard).
    As far as wiring with your monitor, that shouldn't be a problem... I'd recommend getting the wiring diagram from Xantrex though (I haven't used that monitor, but with my Trimetric, it's just complicated enough that you really want to have a visual aid in order to not confuse where each wire goes).
    Good Luck
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E

    You are welcome "K".

    Regarding wiring everything together... Generally, think of the battery as the "center" of the system, and everything else is "hung" off of it.

    So the "+" point and the "-" common connection points should have a striaght, large wire (or copper bus bar), short and well protected against metal to metal contacts (short circuit possibilities) to the battery as possible. If there is voltage drop anywhere, it costs you power and makes it more difficult to fully and quickly charge the battery.

    You may have a large fuse from the battery to the "+" bus bar/common connection point (for safety). And, in any case, you should have 1 fuse or circuit breaker for each branch that goes off of your common "+" point. This is to protect your wiring from melting if there is a short anywhere else in the positive run from the fuse to the AC charger, Solar Charger, interior lights, fan, radio, etc...

    There should be no fuses in the negative path.

    The battery can supply amazing amounts of current and you need the fuses/breakers to prevent cooking the "smaller" wires that go throughout your trailer.

    Typically, the best wiring for your chargers is to use the recommended wiring practices to the common "+" and "-" connections for the battery.

    I would not recommend, for example, using the same wiring from the AC Charger and the Solar Charger to the battery--the higher current from both chargers running will increase the voltage drop along the wiring--raising the "apparent" battery voltage (Vbatt+Vwire-drop) and fool the controllers into thinking the battery is charged higher than it really is.

    Also, if your controllers support it, get a remote battery temperature sensor. This can get you another 5-10% more charge in your battery...

    It may not sound like much, but typically (for example). You charge your batter to 90% (controller error), discharge another 10% per day in normal usage, and in 1.5 days you are at 75% state of charge--if you discharge below this point for more than a few hours (usually less than one day), the sulfates will begin to harden in the flooded cell lead acid battery and cause its early life failure (or you have to run the generator every day or so to bring the battery back up).

    If you charge the battery to 100%, then you now have 2.5 days of useful power before you need to run the genset (for bad weather, parked under trees).

    Undercharging is probably the #1 killing of batteries (#2 is probably overcharging). We all go through a set or two of batteries before we get the hang of it.

    Read through our host's website/store (NAWS)... They have posted many little FAQs around in the major sections (batteries, inverters, charge controllers, etc.) that do a very good job of answering many of these questions in detail.

    -Bill

    And to add to what "hillbilly" said... Your charge controller will only output Pmax when the battery is ~less than 90-80% full). Once the battery is over 80-90% full, the controller cuts back on the charging current. Another reason that having an accurate battery temperature sensor helps ensure a quick charge and good use of your $$$ you paid for your $olar panel$ and batterie$.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Hi Bill,

    My present AC charge system is set up as follows. Xantrex TrueCharge 20 with temperature probe installed and equalization capabilities. Monitoring is performed with a Xantrex XBM Monitor. (Presently the batteries/charger are in my basement and I plug in every week to keep them charged and equalize when required.)

    The trailer wiring is configured as follows:

    I have 6 gauge stranded wire running from AC charger positive to battery positive with inline fuse close to battery.

    I have 6 gauge stranded running from AC charger negative to the charge side of the XBM shunt.

    I have 1/0 stranded welding cable running from the battery side of shunt to the battery negative post.

    My plan is to run 10 gauge stranded wire from each PV panel through a common entrance on top of the trailer. This run should be less than 5 feet.

    The two positives will then be combined in a power distribution block, inside the trailer, and a short (12 inch)10 gauge lead will be fed to positive "PV in" on the controller.

    The negatives leads will be attached on a separate distribution block in a similar fashion.

    The output cables from the controller will be short 10 gauge leads (12 inches) connected to a 15 foot run of 4 gauge stranded welding cable.

    One 4 gauge cable goes to battery positive with inline fuse at the battery and one 4 gauge cable to the charge side of the shunt.

    I opted for the larger 4 gauge as I wanted the option to remove the panels from the trailer and place them in the sun if I am parked in the shade. This may never happen but, the option will be there. (If I do find the need to remove the panels I will fashion the proper sized cables for the total length of the run)

    I also did order the temperature probe for the SolarBoost 2000E and it will be attached to battery negative post.

    If I understand correctly, would this setup conform to your statement?:

    I would not recommend, for example, using the same wiring from the AC Charger and the Solar Charger to the battery--the higher current from both chargers running will increase the voltage drop along the wiring--raising the "apparent" battery voltage (Vbatt+Vwire-drop) and fool the controllers into thinking the battery is charged higher than it really is.

    Thanks again

    Kevin
    Calgary, Alberta
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Here is a youtube link to my Boler trailer project.

    http://ca.youtube.com/watch?v=NH9HITYmtSY


    Note that some of the battery wiring has since been upsized as I switched from a 10 amp AC charger to a 20 amp charger.

    Thanks again for the help.

    Kevin
    Calgary, Alberta
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E

    As I read your post--yes, you have it "right"... You did not say the sizes of the fuses, but, ideally, they should follow the requirements for NEC--or other organization (wire gauge, insulation, where it runs, all affect fuse ratings).

    Normally, you will never have another branch connection between the "-" battery post and the "batt" side of the shunt. You want the XBM to see "all charging and discharging" current through the shunt. Just like you discribe (I have not looked at your video yet).

    Also, for wiring that may be exposed to sun---it needs to be UV rated. Normal insulation will quickly fail.

    It is probably too late now--but if you have two panels (~200 watts max for 12 volt batteries)... Wiring them in series and using the Morning Start MPPT controller (which has a higher Voc rating than the BlueSky ~70 VDC vs ~30 VDC for the BlueSky--as always, read the manuals before buying/installing anything) would be an excellent (if expen$ive) fit:

    wind-sun_2037_2375254Morningstar SunSaver MPPT Solar Charge Controller

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    If the weather holds out I'm going to install my AEE panels on the trailer this weekend. The best answer I've been able to get from AEE is that the specs printed on the back of the panel (see my original post)are correct and the specs in their catalogue and online data sheets are incorrect.

    The Bluesky controller arrived yesterday but I didn't even open it as I've taken Bills" suggestion to swap it for the Morningstar MPPT and wiring the panels in series instead of parallel.

    This will mean cutting fewer holes in my trailer as I can mount the Morningstar inside a closet and I can use smaller diameter wire for my extension run if I wish to remotely mount the panels in the sun while the trailer is parked in the shade.
    As well, it will provide me with the float charge for my batteries.

    I did pre-wire the trailer last weekend with a 15 foot run of 4 gauge that will go from the controller to the battery. I realize this is overkill for the panels in series but I may leave it in place as the work is completed and the cable was free.

    Questions:

    1: Will having the 4 gauge wire from controller to battery be an advantage, allowing me to use a longer run of smaller 10 gauge from controller to panels (for a remote setup) or do I still have to figure the overall distance from panel to controller to battery to determine wire size?

    If I only need to be concerned about the distance from panels to controller then I calculate I can use a wire run of 37 ft. using 10 ga., (assuming a maximum 10amp output from my solar configuration in real-world use.)


    2: Should I ground the panel frames to my trailer frame?


    Thank you
    Kevin Johnston
    Calgary, Alberta
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E
    I did pre-wire the trailer last weekend with a 15 foot run of 4 gauge that will go from the controller to the battery. I realize this is overkill for the panels in series but I may leave it in place as the work is completed and the cable was free.
    Usually, you are better off placing the controller as close to the battery as possible. This gives you the lowest voltage drop and the most accurate battery voltage reading possible from the controller (plus your Remote Battery Temperature Sensor wiring is shorter too--you got that too? Right? Pretty much 100% required with this controller).

    You can always through "more copper" at the problem--it will not hurt anything... As long as you use the required fuse (near the battery) from the MS MPPT Controller Manual.
    Questions:

    1: Will having the 4 gauge wire from controller to battery be an advantage, allowing me to use a longer run of smaller 10 gauge from controller to panels (for a remote setup) or do I still have to figure the overall distance from panel to controller to battery to determine wire size?
    It does not hurt to use the voltage drop calculator to confirm that your voltage drops add up to less than ~3% (most people aim for under 2%).

    As above, the voltage drop from the controller to the battery is a more serious issue (because the current is higher, and the error created for the controller monitoring the battery voltage), where as the voltage drop from the panels to the controller (PWM) is nothing more than a waste of power only (no "functional/battery charging" issues).
    If I only need to be concerned about the distance from panels to controller then I calculate I can use a wire run of 37 ft. using 10 ga., (assuming a maximum 10amp output from my solar configuration in real-world use.)
    Remember the wiring calculator is the "total wire length"... So if your one-way run is 37 feet--then the two way run is 2x37=72'

    For "portable" wiring, I would suggest a 12 or 10 awg extension cord... Is both oil and sun resistant and highly flexible.

    In theory, you can leave the ends on the cord and attach a standard 120 VAC plug to your solar panels--that way the extension cord can serve double duty... The problem is if somebody tries to "help you" and ends up plugging the solar panels into a 120 VAC powered outlet--not a good thing.

    Some folks will use a non-standard AC outlet (like a twist lock 120/240 VAC) so that it is still polarized, but cannot be plugged into the nearest "wrong" outlet. And the Twist Locks are frequently cheaper than the dedicated DC connectors.

    One issue with twist locks--If you pull away with the trailer, you will drag the panels behind you... A simple push connector should pull apart before the panels are damaged. You might make a sort "pig tail" adapter from twist lock to extension cord--and make sure you open the twist lock connection every time you put the panels away.
    2: Should I ground the panel frames to my trailer frame?
    Yes... This is for lightning protection. Ideally, use Stainless Hardware for the Aluminum connections (to reduce corrosion potential).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    I will see if I have the space to move the controller closer and I did get the temperature sensor.



    I was forgetting about the total wire length. So to clarify, the total wire length includes the length of the positive run PLUS the length of the negative run? I also used a calculation based on a 12 volt nominal wire chart. I should be using calculations based on 24 volts since I am wired in series, correct?

    I may replace the 4 gauge. I have other Boler friends that can use it for their battery cables.


    The extension cord idea is a good one


    And I will ground the panels to my trailer frame

    Thanks again for the advice. It has been a big help and my head doesn't hurt so much anymore.
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E
    I was forgetting about the total wire length. So to clarify, the total wire length includes the length of the positive run PLUS the length of the negative run?
    You are correct.
    I also used a calculation based on a 12 volt nominal wire chart. I should be using calculations based on 24 volts since I am wired in series, correct?
    Voltage drop is based on current flow... So, if you have the current correct, 12 vs 24 volts does not affect the voltage drop. I.e.;

    Volt drop = I*R = Current through wire * Resistance of entire wire run

    For the percentage of voltage drop calculation, yes, dividing by 12 or 24 will change the results:

    1 volt drop/12 volt circuit = 0.083 = 8.3% system voltage drop
    1 volt drop/24 volt circuit = 0.0417 = 4.2% system voltage drop
    1 volt drop/120 volt circuit = 0.0083 = 0.83% system drop (i.e., 120 VAC circuit)

    And since Power=Voltage*Current... If you double the voltage (like you are doing here by placing two 12 volt solar panels in series--and therefor reducing the current flow in your solar panel to controller by 1/2), you only need 1/2 the amount of current to pass the current--which also helps reduce voltage drop.

    To see how much it improves, another power equation:

    Power= V*I = V^2 / R = I^2 * R

    So, if you (in the above example) cut I (current) by 1/2 (and keep resistance the same)--- (1/2)^2=1/4 --- and you reduce the losses (also called "I squared R" loss) is reduced by a factor of 4.

    You probably already knew this--but I always type too much. :p

    -Bill "Its for the Children" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Just an update.

    I've left the 35 ft run (2 way total length) of 4 gauge that will go from controller to battery. The trailer is too small to mount the controller closer to the battery.

    The run from the modules to the controller will be about 15 ft (2 way total length) of 10 gauge. when the panels are mounted on top of the trailer.

    I finally found the link to download the software and was then able to open the voltage drop calculator.

    I punched in the following figures.

    24 volt array (2 panels in series)

    4.8 panel amps

    using a 15 foot run of 10 ga. from array to controller.


    plus a 35 ft run of 4 ga. from controller to battery.

    The results were as follows:

    Voltage drop from array to controller is 0.3%
    Voltage drop from array to battery is 0.99%


    If the panels are remotely mounted I can add a 35 ft. (one way length) of 12 AWG extension cord to this and the values will be.

    Voltage drop from array to controller is 2.53%
    Voltage drop from array to battery is 3.23%


    I think I am using the calculator correctly and punching in the right figures but please correct me if my thought process has gone off on a tangent.

    The Morningstar MPPT probably won't arrive until next weekend so won't be able to tie everything together for the "real-world" test until then.
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E

    Looks good... I get slightly different numbers--but I may have misunderstood your exact setup or you changed the ambient voltage (copper resistance goes up with an increase in temperature).

    You did "zero out" the current for array #2 in the spread sheet (has a "throwaway number" in array #1 and #2 to get you started).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Here is what the install is looking like so far.

    I will eventually complete a video and will post the link.


    http://flickr.com/photos/76boler/3263762091/in/set-72157613488933155/
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Just received the Sunsaver MPPT today,after returning the SB2000E, and will hook it up this week.

    I have some questions regarding the load control function as I am a bit "fuzzy" on its' operation.

    Does it function by feeding power back from the battery or is it simply diverting any excess power being produced by the panels that is not being used to charge the batteries?


    Presently the battery positive is connected directly to a fuseblock which feeds all the appliances and lights in my trailer. Can I continue to power my trailer this way, bypassing the load control?

    Can I add a second fuse panel to the load control and run a few small appliances from there as well?
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E

    Are you asking about (from the installation/user manual):
    The primary purpose of the load control function is to
    disconnect system loads when the battery has discharged
    to a low state of charge and reconnect system loads when
    the battery is sufficiently recharged. System loads may be
    lights, pumps, motors, DC appliances, and other electronic
    devices. The total current draw of all loads must not exceed
    the SS-MPPT 15 Amp maximum load rating.

    Basically, if the battery goes dead, the LVD (low voltage disconnect) turns off any attached loads until the solar panels have recharged the battery bank somewhat... Note that the LVD has a 15 amp maximum current limit--so most people don't even use it. And don't attach any heavy loads (like an inverter). They will just blow the internal switch.

    The LVD does not divert any extra power or anything fancy. It just turns off the loads before they can run the battery dead. It would be the same if you just turn off your loads when the battery is being over discharged. LVD's are not very accurate and generally are a last resort to prevent running a battery dead.

    I am not sure what you are saying about your fuse block... Each positive wire leaving the battery bus/common point should have its own fuse that protects the wire in case of shorts (or one fuse protecting several wires if the loads are small enough).

    And yes, you can run your entire system without attaching to the LVD. Or, you can attach a few small loads (lighting and such through fuse block if needed) to the LVD if you want.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Thanks Bill. You have answered my questions.

    I will keep my master fuse panel as is and only run one small fan from the load control. The Sunsaver is installed inside a closed closet so I thought the 0.1 amp fan would help in keeping it cool.

    In the attached photo:

    The 10 ga. solar input wires have not yet been installed.

    The 8 gauge wire leads to the battery have not yet been attached to the Mppt.

    The fuseblock is attached to the Load +

    The Load - (neg) is attached to the ground busbar.

    The small fan + is attached to the fuseblock, which does not yet have a fuse installed. The - for the fan is attached to the ground busbar.

    The light is wired directly into existing wiring and is fused at the master fuse panel.

    If anything looks out of place, let me know.

    Thanks again for the help.
  • BB.BB. Posts: 24,573Super Moderators admin
    Re: Best Vmp for use with SolarBoost 2000E

    I have some comments... Don't take any of them wrong--because I may not know what your final intent is.

    1. If you are worried about heat, place the controller low in the closet so that the heat rises. Right now, you have the controller sitting in the hottest point of the "room". You may want to cut vents in the door for better ventilation. 5% power loss of 200 watts is 10 watts of power--not a huge amount (like two 120 vac night lights). But, things do last longer if kept cool. I would also lower the controller as this keeps your battery to bus bar (the heavy black wires) short too. Not a problem in this installation--but short & heavy controller to battery connections can only help in the long term.
    2. You might want to put some sort of "shield" over the installation if there will be things put in the closet to prevent shorts, blocking of air flow, and melting of items that touch hot surfaces (possibly made hot by shorts or blocked air flow).
    3. Where is your main battery fuse? I see what appear to be bus bars near the controller--but no fusing. assuming your bus bars are the "common connection point" all your wires leading off of them should have a fuse each (your fuse block connected to the positive bus bar would be a good solution).
    4. The fan is a constant load; with solar, reducing power use to the bare minimum will be your mantra--It would be better to not have it at all (or at least use a switch/thermostat to turn it on only when needed).
    5. The fuse block connected to the LVD connection is fine for "small" loads--but having it connected to the main + bus bar for the major loads (or a second fuse block) is best.
    6. You have a white "ground wire" from the LVD ground to the small ground bus. I would not do this... You may end up with a "ground loop" through the controller (basically two ground wires in parallel). It is not needed, and can cause damage when loads are connected. Either connect all of your load returns to the big brass - bus bar, or connect the LVD loads to the LVD ground--not both.
    7. You appear to have two - bus bars in the picture. One really nice big brass one. And a second smaller one with white wires attached. Connect your "small ground bus" wire (goes down in picture?) directly to the big brass - ground bus. Also, make sure that all of the currents from your ground returns that go to the "small ground bus" do not exceed the wire ampacity from the "small ground bus" to "big brass ground bus" connection. (currently your wire appears to be ~14 awg--plan on about 15-20 amp maximum current for safety. Remember voltage drop--so keep small gauge wires short and with low current).
    8. You have no external temperature sensor connected. The external battery sensor is just about mandatory for this charge controller (internal sensor usually undercharges the battery). Especially important as the controller is mounted in a warm closet--makes the undercharging worse.
    Again, just what I see/understand at this point. I know you are not done yet.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Thanks for the suggestions Bill. I'm off to work so I will address the concerns when I'm working on the trailer again.
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: Best Vmp for use with SolarBoost 2000E

    forgive me if i don't go to the beginning of your thread kevin and so i might overlook something, but the pic shows on your heavy wires points labeled as 'to bat +' and 'to bat -'. are these connectors or did you fuse both + and -? pics on this screen show up small as i would need to change my resolution to blow up the images. if they are only connectors, i might suggest you use some fuses or circuit breakers. it is not necessary to put fuses or cbs on both the negative and positive leads just to clarify, but you should have one between the cc and the battery and one from the battery to any load (positive usually chosen for any fusing or cbs). batteries, when shorted, can send hundreds of amps flowing even from a small sized battery through wires not intended to carry that much.
  • mike95490mike95490 Posts: 6,298Solar Expert ✭✭✭✭
    Re: Best Vmp for use with SolarBoost 2000E

    BB covered most of what I would have said. I'll add:

    1) agree with mount controller low, and have hot air vent holes up high. Skip the fan

    2) battery fuse should be at the Battery, to protect as much wire as possible.

    3) Relocate your light, so it shines on the parts, not your face. Do you have a monitor lamp outside the closet that would indicate the inside light is ON?

    4) agree with battery temp sensor (BTS) Needed
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E
    niel wrote: »
    forgive me if i don't go to the beginning of your thread kevin and so i might overlook something, but the pic shows on your heavy wires points labeled as 'to bat +' and 'to bat -'. are these connectors or did you fuse both + and -? pics on this screen show up small as i would need to change my resolution to blow up the images. if they are only connectors, i might suggest you use some fuses or circuit breakers. it is not necessary to put fuses or cbs on both the negative and positive leads just to clarify, but you should have one between the cc and the battery and one from the battery to any load (positive usually chosen for any fusing or cbs). batteries, when shorted, can send hundreds of amps flowing even from a small sized battery through wires not intended to carry that much.

    They are connectors. The positive line is fused at the battery.

    The battery positive feeds inside the trailer to a 30 amp circuit breaker and then to a fuse panel. All loads are individually fused.
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E
    mike90045 wrote: »
    BB covered most of what I would have said. I'll add:

    1) agree with mount controller low, and have hot air vent holes up high. Skip the fan

    2) battery fuse should be at the Battery, to protect as much wire as possible.

    3) Relocate your light, so it shines on the parts, not your face. Do you have a monitor lamp outside the closet that would indicate the inside light is ON?


    4) agree with battery temp sensor (BTS) Needed



    I will see if the controller can be tucked away somewhere lower and closer.

    Positive line is fused at battery.

    Light is a temporary fix.

    BTS is sitting on my coffee table, waiting for installation
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    [QUOTE=BB.;26769

    1. I would also lower the controller
    2. You might want to put some sort of "shield" over the installation
    3. Where is your main battery fuse?
    4. The fan is a constant load;
    5. The fuse block connected to the LVD connection is fine for "small" loads--but having it connected to the main + bus bar for the major loads (or a second fuse block) is best.
    6. You have a white "ground wire" from the LVD ground to the small ground bus. I would not do this... You may end up with a "ground loop" through the controller (basically two ground wires in parallel). It is not needed, and can cause damage when loads are connected. Either connect all of your load returns to the big brass - bus bar, or connect the LVD loads to the LVD ground--not both.
    7. Connect your "small ground bus" wire (goes down in picture?) directly to the big brass - ground bus.
    8. You have no external temperature sensor connected.

    -Bill[/QUOTE]

    I think I have found a spot in my electrical enclosure that is much lower and closer to the battery, where the controller will fit. I did a test fit and it has the required clearances. I may however have to purchase the remote meter for easier monitoring OR my existing XBM Monitor may provide me will all the monitoring information I may need.

    The new location is under my front bench seat and is dedicated to electrical only. No loose things flying around to create shorts.

    The positive line is fused at the battery.

    I will get rid of the fan.

    I will not use the Load Control and will run everything through the main fuse panel.

    Once I get my grounds connected I will draw a schematic and pass it by you.

    I have the BTS ready for installation.

    Should be working on the install this weekend. My thanks to all for the suggestions.

    Kevin Johnston
    Calgary
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Here is the new location for the Sunsaver MPPT

    http://www.youtube.com/watch?v=bP6pDkpe1-o
  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: Best Vmp for use with SolarBoost 2000E

    that looks good, but i would be concerned about the wire flexing near the controller connecting point from flipping the controller up and down which in time could weaken and break it.
  • kevinhenrycalgarykevinhenrycalgary Posts: 33Solar Expert
    Re: Best Vmp for use with SolarBoost 2000E

    Thanks Niel. I will have to keep an eye on it. I've used the fine strand 8 ga. and pre-bent the wires. Hopefully I won't be down there flipping it around too much. It will be hooked up with a Xantrex XBM monitor and this should tell me how it is performing.

    I may purchase the remote monitor so that it can supply me with the self-diagnostics and give me the temperature at the controller.

    Looks like it will be sunny and below freezing today so, if I complete the wiring, I should be able to give it a test run.
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