Details of installation

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cptdondo
cptdondo Solar Expert Posts: 103 ✭✭✭
in Solar Beginners Corner #1
I'm trying to put together a shopping list for a 270W RV install.

Panels (2 in parallel):
http://store.solar-electric.com/kyso130wa12v.html

Charge Controller:
http://store.solar-electric.com/sb2000.html

I picked this one because it has an integral display. I have a question about the temp sensor. How important is it?

Here's my issues with the temp sensor:

I have 2 battery banks; one consists of a single 12V deep cycle battery, and the other consists of 2 T-145 batteries. I have a Blue Sea 3-way switch where I can select bank I, II, I+II, and disconnect.

I can get the solar charger to charge as per the switch setting, or to charge only 1 bank. If I charge only 1 bank, it would be the 2 T-145 batteries. In that case, I can install the temp sensor on the T-145s. I think charging just the T-145s makes more sense than charging the single 12V.

Also, I prewired the rig for solar; I have 6ga wire and a dual shielded twisted pair running from the battery compartment to the control center. I don't want to try and run any more wire (it's a huge undertaking, requiring removal and reinstallation of several cabinets). Can I splice the temp sensor wire into my twisted pair cable?

Nest, since I have wire pre-run, and the panels use the new M4 connectors, how do I connect all this?

I'm thinking of getting enough pre-made M4 cable to do the rooftop to controler installation, cutting off one end to mate with the screw terminals on the controller, and then going to the batteries.

Lastly, the batteries can charge from the on-board 45A 3 stage charger or the engine alternator. Now I will be adding the solar charger. Any potential conflicts? Do I need to install any sort of auto-switch to cut the solar cahrger out if I am also running the on-board charger or the alternator?
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  • rafaelito
    rafaelito Registered Users Posts: 7 ✭
    #2
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    Re: Details of installation

    I have installed the same 2 Kyocera panels on my RV, but with an Outback FM 60 controller and VFX 2812M (the "M" is necessary for RV installation) inverter, networked to MATE controller with FlexNET DC monitor. Cabin battery consists of Lifeline 210 A/hr AGM with temp sensor attached. Temp sensor is critical due to temp swings in RV application. Charge requirements shift dramatically in cold or hot weather. If you garage your RV in 70F conditions, it would not be as critical, since that is the default used by most battery manufacturers.

    I use a Battery Tender for the 2 starter batteries when stored, with isolator that allows the AGM to charge from the alternator when running.

    I looked at the Blue Sky just briefly and Googled it. The downside is that it draws it's power from the battery as designed and will not reboot if the battery goes dead. It has no provision to disconnect power if the battery charge drops to a level that may damage the battery.

    There are other controllers that may work better for your application. Have you checked out http://store.solar-electric.com/motr45ampmps.html Best of luck with your installation. It is a lot of fun stringing wires!
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #3
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    Re: Details of installation

    Some quick comment:
    cptdondo wrote: »
    I have a question about the temp sensor. How important is it?

    Here's my issues with the temp sensor:

    I have 2 battery banks; one consists of a single 12V deep cycle battery, and the other consists of 2 T-145 batteries. I have a Blue Sea 3-way switch where I can select bank I, II, I+II, and disconnect.

    I can get the solar charger to charge as per the switch setting, or to charge only 1 bank. If I charge only 1 bank, it would be the 2 T-145 batteries. In that case, I can install the temp sensor on the T-145s. I think charging just the T-145s makes more sense than charging the single 12V.

    I would just put the RBTS on the T-145 bank... Are the batteries in the same space, or is one in the engine compartment (vehicle battery)? If in two different locations--then any temperature compensation becomes an issue (the RBTS and the Controller are not in the same space as the battery being charged--so no accurate temperature measurements).

    For random charging of the lone 12 volt vehicle battery--I would not worry about RBTS. Becomes more of an issue with long term charging at high temperatures and especially with sealed/AGM type batteries which do not respond well to over charging.
    Also, I prewired the rig for solar; I have 6ga wire and a dual shielded twisted pair running from the battery compartment to the control center. I don't want to try and run any more wire (it's a huge undertaking, requiring removal and reinstallation of several cabinets). Can I splice the temp sensor wire into my twisted pair cable?

    For clarification--what is the 6 awg cable intended for?
    Nest, since I have wire pre-run, and the panels use the new M4 connectors, how do I connect all this?

    I'm thinking of getting enough pre-made M4 cable to do the rooftop to controller installation, cutting off one end to mate with the screw terminals on the controller, and then going to the batteries.

    Purchasing a Male/Female MC4 cable and cutting it in half for installation is a common practice (i.e., good idea).

    Where are you mounting the charge controller? Ideally, or almost pretty much a requirement, the Solar Charge Controller should be mounted very close to the battery bank +/- bus connection points. You don't want any more than 0.1 volt (12 volt system) or so voltage drop between the charge controller and the battery bank when charging current flows (high voltage drop will have the charge controller cut back on charging current/voltage and lengthen the time to charge your battery bank).

    Yes, the twisted pair cable can be spiced into the end of the RBTS cable to make the run easier. But because the controller should be next to the battery bank, there should be no reason to use the twisted pair wiring (gets back to my question about the 6 awg cable and where is the charge controller being mounted).

    If you are mounting the charge controller in your equipment bay/closet for easy of inspection--It would be a much better idea to move the controller close to the battery bank for the reasons above.

    If you are really into monitoring your battery bank--I would suggest a Battery Monitor (like the Trimetric or Xantrex) and a smaller MPPT charge controller like the MorningStar 15 amp MPPT. Because it has a higher Vpanel input voltage--You can run the two solar panels in series and reduce the voltage drop a bit more (although, with 6 awg cable, you probably don't have a big issue anyway).

    If you still want a panel--Either get the remote panel for the MorningStar or get a MorningStar TS line of MPPT controllers.

    By the way, are you stopping at 260 watts of solar panels, or are you planning on going larger and want to install a larger solar charge controller for future expansion? The TS MPPT 45 amp is a very nice controller. It also has Remote Battery Voltage Sense lines if you need to mount the charge controller some distance from the battery bank (the whole MorningStar TS MPPT/PWM product line has remote voltage sense--I believe).
    Lastly, the batteries can charge from the on-board 45A 3 stage charger or the engine alternator. Now I will be adding the solar charger. Any potential conflicts? Do I need to install any sort of auto-switch to cut the solar charger out if I am also running the on-board charger or the alternator?
    In general, no problem with paralleling different charge controllers...

    In practice, there can be one issue. When equalizing a battery bank, the charging voltage is raised to 15-15.5 volts or so... That is above what most 12 volt automotive appliances expect. There have been reports of some computer 12 volt adapters being burned out by this high voltage (car alternators tend to max out around 14-14.4 volts, and add some voltage drop in the harness to most loads).

    So, if equalizing, I would avoid using car appliances/connecting to your vehicle power system during that period.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • vcallaway
    vcallaway Solar Expert Posts: 157 ✭✭✭✭✭
    #4
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    Re: Details of installation

    Wow, I posted similar questions and only received a non-answer.

    I'm running my wires using this combiner box in the refer vent.

    I was also looking at the bluesky controller, but have not made a decision yet. The price is right but it maxes out at two panels. I would like to expand to 4 down the road. The cost of the morningstar 40amp is just not in my budget though.
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  • rafaelito
    rafaelito Registered Users Posts: 7 ✭
    #5
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    Re: Details of installation

    Vcallaway,
    Your post was in the RV forum which may not be frequented as often by the very helpful people who frequent this forum. I have lurked, but this was my first post. I hope it is helpful...

    Gary
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #6
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    Re: Details of installation

    No--He posted a question about his setup too... I have just answered with some more detail (don't know if it was helpful or not:roll:).

    His question was about PWM and MPPT controllers and keep the costs low--Bryanl answered in general that PWM on a small system is probably more cost effective than MPPT...

    Anyway, did not want anyone to feel that they were left out.

    -Bill :D
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • rafaelito
    rafaelito Registered Users Posts: 7 ✭
    #7
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    Re: Details of installation

    Thank you for the info, Bill. Here are a couple of pictures of my rig and setup. It has been a fun project, but programming was difficult.
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #8
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    Re: Details of installation
    vcallaway wrote: »
    I was also looking at the bluesky controller, but have not made a decision yet. The price is right but it maxes out at two panels. I would like to expand to 4 down the road. The cost of the morningstar 40amp is just not in my budget though.

    You can parallel charge controllers, so if you add two more panels later you can just run them into another Blue Sky.
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  • cptdondo
    cptdondo Solar Expert Posts: 103 ✭✭✭
    #9
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    Re: Details of installation
    BB. wrote: »
    Some quick comment:
    I would just put the RBTS on the T-145 bank... Are the batteries in the same space, or is one in the engine compartment (vehicle battery)? If in two different locations--then any temperature compensation becomes an issue (the RBTS and the Controller are not in the same space as the battery being charged--so no accurate temperature measurements).

    The batteries are in different spaces; the T-145s are in a storage compartment, the single 12V is stuck behind the back bumper, and the controls are in an interior closet. There's a central electrical "box" that sits about 3' from the T-145s.
    BB. wrote: »
    For clarification--what is the 6 awg cable intended for?

    It's actually 8GA and it's some wire I pulled to wire the solar panels to the controller and to the batteries. I just did the voltage drop calcs, and with 12V panels I can't really use it. :grr
    BB. wrote: »
    Where are you mounting the charge controller? Ideally, or almost pretty much a requirement, the Solar Charge Controller should be mounted very close to the battery bank +/- bus connection points. You don't want any more than 0.1 volt (12 volt system) or so voltage drop between the charge controller and the battery bank when charging current flows (high voltage drop will have the charge controller cut back on charging current/voltage and lengthen the time to charge your battery bank).

    OK, I'll have to move things around. I'll locate the controller in the closet and get a remote panel.
    BB. wrote: »
    By the way, are you stopping at 260 watts of solar panels, or are you planning on going larger and want to install a larger solar charge controller for future expansion? The TS MPPT 45 amp is a very nice controller. It also has Remote Battery Voltage Sense lines if you need to mount the charge controller some distance from the battery bank (the whole MorningStar TS MPPT/PWM product line has remote voltage sense--I believe).

    I have room for 2 panels; that's it, so 260W is about my limit.

    I looked at the Mornginstar 15A controller; it seems that it only handles 200W of panels with 12V batteries, so while it may be OK as my panels will be mounted flat and I live at the 45 parallel, it's cutting it awfully close as far as capacity goes.

    Blue Sky so far is the only one that I've found that makes an affordable (around $300 with all the fixings) MPPT controller in the 20A range. Any other suggestions?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #10
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    Re: Details of installation

    Realistically, most people are going to average a maximum of around 77-80% of panel rated output power unless they are in sub freezing temperatures:
    • 15 amps * 14.5 volts charging * 1/0.80 derating = 272 watts
    So, for a few handful of hours a year, you may be missing on 5% extra power (~15 watts) -- Generally, not really increase in available power that I would lose sleep over.

    However, if you want a larger controller, there is the 30 amp Rogue--But I do not think it has a remote panel meter. If you ever purchased an extra set of panels that you could stake in the ground--you could put them in series (and series your original two panels)--and run a DC extension cord to them for more power (if you boondock for longer periods of time).

    The 8 awg wire from the panels to the charge controller--Take a look at the voltage drop when using the two panels in series--Cuts your voltage drop by 1/2 and also the current by 1/2--You would probably be just fine with a MPPT type charge controller (that can take two or more panels in series).

    The MorningStar TS series with the remote voltage sense would allow you to use longer/lighter gauge wiring to the battery bank--but they probably are too big and expensive for your needs. Better to run new cable and/or mount the controller closer.

    For the second battery--there are 12 volt to 12 volt battery chargers... Perhaps that would be an OK solution (say charging a trolling motor battery).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • cptdondo
    cptdondo Solar Expert Posts: 103 ✭✭✭
    #11
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    Re: Details of installation
    BB. wrote: »
    Realistically, most people are going to average a maximum of around 77-80% of panel rated output power unless they are in sub freezing temperatures:
    • 15 amps * 14.5 volts charging * 1/0.80 derating = 272 watts
    So, for a few handful of hours a year, you may be missing on 5% extra power (~15 watts) -- Generally, not really increase in available power that I would lose sleep over.

    I figure too with the panels mounted flat I lose another 25% or so, so it won't be an issue. And I like the form factor - I am limited in space in the electrical box and that unit would actually fit. It would be under the closet floor, which is why I need a panel of some sort to see what it's doing.
    BB. wrote: »
    For the second battery--there are 12 volt to 12 volt battery chargers... Perhaps that would be an OK solution (say charging a trolling motor battery).

    That may just be overkill; I'll just end up switching banks when I have other power sources to keep it charged.

    Have you had a chance to play with this one yet?

    http://www.blueskyenergyinc.com/products/details/solar_boost_1524ix/

    Thanks for all your help and advice!

    --Yan
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #12
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    Re: Details of installation

    I don't have an off-grid PV system--so I don't get a chance to play with any charge controllers... And I have not read anyone here that has tried one yet.

    Perhaps somebody else here can tell you about them--Or contact a retailer (like our host, NAWS) and see if they have further information.

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