Bighorn Solar Install

                                                      

The information provided here will touch on several aspects of a solar install.  I will not get into the more technical details of solar and each component of the system.  The component technical details can be found in the manuals provided with each component.  Many sites can be found on the internet with in depth explanations for most any subject relating to solar. Forums can be helpful after sorting out the good information.  Assertions arise constantly about which batteries, panels, charge controllers and installation methods are the best.   The following system is a long proven method for a solar install and does reflect some of my preferred system preferences from past experience.  Each system needs to be designed for the users needs.      

This is my solar system install for our 2015 Bighorn 3570RS.  A little background needs to be shared about this install.  Several components and parts were installed on my previous rig which was some other brand.  I have upgraded my system to accommodate our new Bighorn with a residential frig.

This system is an array of 820 Watts of panels and 672 amps of battery storage.  There are 6 Kyocera panels and 6 Fullriver AGM batteries.  Four of these panels were left over from my previous rig.  A little overkill in the panel area will allow for more efficient charging and allow for different wiring arrangements if I decide to change something.

My solar system consists of:

4    135 Watt Kyocera Panels    (Old)
2    140 Watt Kyocera Panels    (New)
6    Fullriver DC 224 AGM Batteries    (New)
Midnightsolar Classic 150 MPPT Solar Charge Controller    (New)
2000 Watt 30 Amp Xantrex Inverter/Charger    (Old)
Midnightsolar Big Baby Breaker Box    (New)
6 Circuit Sub Panel    (Old)
Trimetric 2020 Battery Monitor    (Old)
Most all cables and other parts are leftover from previous install. 

A Blank Canvas

                                                                 

                      

Panels in Storage

                                                              

My wife has encouraged me to move these panels out of the living room.  They served us well for 5 years and I thought they were not all that bad to look at.  I guess this is where the blank canvas will come in handy.

Panel Layout

                                                                

Final Panel Layout

The first thing I did was to decide where to place the solar panels.  My choice for the final panel layout allows me easier movement on the roof.  I am using lower wattage and lower voltage left over panels.  If I were purchasing all new panels for the install I would probably choose to use higher wattage panels, thus less panels, but larger in size.  With the new MPPT solar charge controller using larger panels with a higher output would be possible.

The idea is to place my panels where they will not be shaded.  Small amounts of shade can knock out a string of panels.  Smaller the roof the less choices we have to work with placing the panels.  There are a lot of things up there that can cause shade.  The air conditioners and that satellite dish can cast a lot of shade.  Cardboard cut to the size of the panels works great to help layout the panel arrangement.  The panels will rise in height off the roof about 3" when using mounting brackets.  This also will help with shade issues.  This is where I have noticed some folks will install panels a lot higher off the roof than I intend to do.  Installing over skylights, vents and air conditioners can be observed in the Desert SW as well as auto tracking arrays.  There are some serious solar installs out West.

The majority of the time we park with the door side to the south.  I had to take this into consideration when placing the panels so as to minimize shading the panels.  Normally I would not place any part of my panels along the side of an air conditioner.  Sometimes roof real estate helps dictate placement.  In the photo below the satellite dish played a roll in locating the door side string of panels.
  

Roof Panels

                                                                       

My panels are connected using #10 tray cable and are wired series and in pairs, known as a string.  I have three strings consisting of two panels each.  The panels are wired positive to negative for each two panels in the string.  This leaves a positive and a negative left for each string.  These leads go to a combiner box on the roof.  The #10 tray cable from the strings of panels to the combiner box are wired parallel, positive to positive and negative to negative at the combiner box.  My panels have a J box or makeup box on the underside of each panel.  These J boxes have lugs to connect the #10 tray cable for each panel.  Panels that have MC4 leads would use a similar method when wiring just as I am doing.   The leftover positive and negative connections from each string use #10 tray cable.

Not everyone would be comfortable with doing their own install like my install.  It will be necessary for attachment lag bolts and a 1" hole to be drilled in the roof and a method to route cables to where they need to go.

Drilling a small hole  and installing lag screws is not as doomsday as you might imagine.  These holes and screws do need to be sealed with Dicor rubber roof sealant.  Others with more  complex installs than my install, have also experienced no leak results.  In fact I have not read of anyone having a roof leak when they installed their own system .  I suppose it could happen, just like any sealed roof penetration such as  skylights, vents, and satellite dishes that could develop leaks.

This is the 1" hole in the roof for the #4 welding cable drop to the front bay for the Big Baby Box and the solar charge controller.  The hole is located under the combiner box and sealed with Dicor.  It will not leak when sealed properly.  The cables are dropped behind the main panel in a void to the basement.

It is possible to use the vent cap drop method at this point   when routing the cable to the roof.   You do not need to place the combiner box or a vent cap under a panel.  The combiner box or roof entry plate allows you to place the cable drop in a convenient location and save on cable runs.  It also eliminates the need to drill or create a cable exit from the plumbing vent in the basement. 

Combiner Box on Roof

The combiner box is sealed with Dicor under the box at the edges and around the outside.  A liberal amount of Dicor is applied to the oblong hole with riser curbs for the cable entry inside the box.  The Dicor fills the drill hole void.  Inside screws are also sealed.

                                                                   

Two Sets of Panel Mounting Brackets

                               

I am using tilt mounts to mount my panels to the roof.  Starlight Solar in Yuma, AZ  carries a good selection of panel mounts.  It is not all that difficult to make panel mounts and tilt arms from store bought materials.  Four sets of my mounts and tilt bars are leftover.  Tilt mounts make it fairly simple to raise the panels for cleaning the roof under the panels and to make possible any  panel servicing needed.  I have never serviced a panel, an example of servicing would be to replace a diode or to rewire the Jbox.  Diode replacement is probably very remote.  I might want to change the wiring for some other reason and tilting the panel would assist with this.  Tilting the panels would also help increase solar gain during the winter when the sun is at the low point.  I really don't plan on climbing on the roof and tilting the panels.  I have not had to do much of that in the past. I am using lag screws and a blob of Dicor sealant to attach the panel mounting brackets to the roof.  This is normally more than adequate to keep the panels on the roof.   Each lag also has a blob of Dicor on top of it.

                                                                 

Combiner B0x Wired

When mounting the panels it was handy to decide where to locate the combiner box.  My combiner box is a leftover AM Solar combiner box from my previous rig.  Starlight Solar in Yuma, AZ also carries this type combiner box.   In this combiner box I am using a stereo distribution hub for the panel cable connections and the #4 welding cable leading to the solar charge controller in the front bay.  Discount Solar in Quartzsite, AZ carries this type stereo distribution hub for $18.

I like to place the combiner box under a panel if possible and over a closet if possible.  A combiner box can also be made from those weatherproof plastic boxes and buss bars found at the local hardware supply outlet.  These boxes are too tall to fit under most panels.  They can be cut down to accommodate mounting under a panel.  The combiner box I am using is designed to be able to be placed under panels if needed.

I prefer the combiner box over using a vent drop for several reasons.  Among those reasons the vent does not have to be altered on top of the roof and does not have to be drilled or cut and tampered with in the basement.   It is much easier to locate a combiner box or roof plate to cover the small hole required to route the drop cables, and can be placed where you need to place the cable drop without running excess cable to a vent stack.  It can become a matter of preference for which method you use. 

Combiner Box Closed

By locating the combiner box over a closet there is a way of routing the #4 welding cable to the floor level on its way to the front bay.  My main panel is located at floor level at the entry.  Above the panel there is a void space at the end of the pantry all the way up to the roof which is a natural place to drop a wire run and to help route cable to the main bay and on to the forward compartment with the solar charge controller.

It is important to do a voltage drop calculation to make sure the wire from the combiner box to the solar charge controller is of the correct size to keep a 2% or less voltage drop.  I shoot for 1% or less.  5% drop is a stated acceptable standard.  In most cases #4 welding cable is adequate and has room for expansion of the system.  The solar panel wiring and the MPPT charge controller can also help with a different wiring arrangement in this area of the install.  Calculator

                                                                 

Midnightsolar Big Baby Box

                                            

The Midnightsolar Big Baby Box is a way of disconnecting the solar panels from the system.  It serves as a safety breaker box and as a way to service the system beyond that point.  The Big Baby Box can also be replaced using manual reset breaker devices.  There are many choices out there.  The breaker box contains a 6o amp and a 40 amp Midnightsolar MNEPV breaker.  MNEPV breakers are special DC breakers, they have a wire coming in and a wire going out.  They mount on a rail in the Baby Box.  From the distribution hub in the combiner box on the roof, the #4 positive welding cable is routed to the input at the bottom of the 40 amp breaker and then out to the solar charge controller.  From the charge controller #4 positive cable travels back to the bottom input of the 6o amp breaker, then out of the 60 amp breaker onto the positive power hub for the DC side of the system.   I have used an air conditioner fused disconnect in place of the Baby Box previously. It  worked very well for the purpose. 

Charge Controller

                  

                                                                                
        


Midnightsolar Classic 150 
       Charge Controller 
                       In Operation                                      

The Midnightsolar Classic 150 is my choice for a MPPT Solar Charge Controller.  It was important to choose a charge controller for the system and while spending the money, buy a big one.  My previous charge controller was a Tristar 45 amp PWM controller.  I had very good service from that charge controller.  It was simply not capable of handling my new demands.  The new Classic 150 controller is fully programmable with push buttons and LED display on the front panel and it can handle the wattage of the new system.  Several other options for programing are included using a laptop and a wireless connection.  I chose the Classic 150 over the Tristar MPPT 60 because the Classic 150 will allow for most any system expansion I may want to do in the future and it comes with an LED display.  With the Tristar MPPT 60 I would have had to purchase an add on LED Display and it has less system options.  Cost for either one is about the same.  

Midnightsolar Status Panel

 

Cradlepoint Router

More on monitoring the charge controller. The Midnightsolar charge controller can be monitored from your kitchen table if connected via a network.  The status panel above  displays this option on my laptop.  The Cradlepoint wireless router is an old router I had in the closet from when I used it for internet with Millenicom back in the day.  There are several options for networking the charge controller.

                                                

                                                                     

Batteries

                                                                    

First off, my Bighorn battery compartment is inadequate to support 6 AGM batteries or flooded cell batteries.  Four batteries could be marginal along with the 50Lb inverter.  The choice is to relocate those batteries to the main bay or beef up the battery compartment.  Since the AGMs are sealed they can be located in the compartment with the charge controller and the inverter. It is not so with flooded cell batteries.  To be safe the flooded cell batteries need to be separated  from the charge controller and the inverter and be vented to the outside.  This is to prevent a possible explosion from the gasses given off from flooded cell batteries.  AGMs do not need to be vented to the outside.

It is an acceptable practice by many to place flooded cell batteries in the same front bay as the inverter and charge controller. When this is the choice they are contained in a sealed battery box vented to the outside and better if they are raised slightly off the bottom of the box and have a bottom draw from the outside.  Holes in the side of the box at the bottom is acceptable also.  The key is sealed battery box.  When you get into more than 2 batteries, the battery boxes on the market for the most part are not totally sealed.  The multiple cable holes and the lid that just sits on top does not seal well.  They need to be taped and holes sealed.  Now when you get into more than 4 batteries, boxes are more scarce and difficult to find and costly if you find one.  When tape is used to seal the box top it becomes more difficult to check the water level  and do a specific gravity test.  Battery height also becomes an issue if you stray away from standard golf cart batteries, it becomes harder to find boxes tall enough.  This is where AGMs fit into an install and simplifies battery placement.    

                                                              

Battery Compartment Reinforcement

                            

I chose to beef up the battery compartment with steel fence posts.  These fence posts were on hand and came from Home Depot.  They make great stiffeners with 3/4" plywood on top as support for the batteries.  They span from the inside lip of each outside main frame rail.  They are then screwed to the bay floor at each end to keep them in place.

                                                                      

Completed Battery Compartment

                                     
The 3/4" plywood is attached to the metal fence posts with a few screws to hold the plywood in place.  About 10" needs to be cut off one end of the plywood to be able to get it through the front bay door.  The inverter will sit on that end with the cut.

My previous rig had a sealed separate generator prep bay where I placed the inverter and the charge controller.  In the other front bay with the batteries some very minor corrosion happened on fittings from gasses given off from the batteries.   The batteries were housed in a sealed four battery box and vented to the outside.
I have AGM batteries for this install.  AGMs cost twice as much as flooded cell batteries.  They are known to take a charge quicker and can hold a charge longer and can sit for long periods without depleting to the level that flooded cell batteries do.  They can be placed with the charge controller and the inverter in the same compartment and do not have to be vented.
I had my flooded cell Interstate U2200 batteries for 5 years and they were still going strong.  They were always kept watered and charged at 14.8 volts.    My AGMs came from Discount Solar in Quartzsite.  Best prices I found and they also gave me another discount on the spot.  Good people to work with for pricing.

My batteries are wired in series positive to negative then paralleled to produce 12 volts at output.   Each battery is rated 224 amps.  The amps become 224 amps for 2 batteries and 672 amps of total storage  for the 6 batteries.     When connected in series with a second 6 volt battery amps stay the same for two batteries and the voltage accumulates to 12 volts. 

                                                                 

Battery Wiring Drawing

                                                      

                                                                   

Xantrex Freedom SW 2000 Inverter/Charger

                    

Inverter DC Connection Lugs

                                                         

 My Xantrex Inverter is 5 years old and is still going strong.  It is a 30 amp inverter/100 amp charger.  I use a sub panel for the circuits I want to power in the coach.  The charger is an option I have used only once in the past 5 years.  This was to see if it worked.  The solar charge was always enough to handle my demands.  My demands were to use the microwave, coffee maker, big TV, computers, lights, toaster, and oh yes, my wife's 1800 watt hair dryer.  We will limit our microwave use and not use the convection option on the new rig.  I also had the Norcold frig on a circuit and powered it part time.  The frig was a power hog.   I  always had to keep an eye on the battery draw down to  never deplete the batteries to less than 50%.  

The power from the main panel passes through the inverter to the sub panel to the circuits I want to power when plugged into shore power.  The inverter is actually smarter than it looks.  If I were to buy a new inverter, I would buy the latest 50 amp Magnum inverter.  It would probably be about 2800 watts.

The inverter manual will recommend DC cable size for inverter and battery interconnecting cables for the load.  

I have a residential frig and the Bighorn came with a 1000 watt Xantrex  inverter to power the frig.  I am wiring this 1000 watt inverter along with the 2000 watt Xantrex inverter.  Doing this I am not changing any wiring in the existing system except where the 1000 watt Xantrex inverter connects to the batteries.  It is connected to the AGM batteries just as it was connected to the batteries from the factory.   Essentially it just hooks to a different battery source.  It is important to keep the inverter close as possible to the battery bank.  

Inverter In Front Bay

                                                                

DC Power Hubs

                                                                   

Power Hubs are a good way to connect all those huge stud ring connectors for the DC power.  The layout of the components is very important to conserve cable runs and power hubs assist with this.  I use #2/00 for some runs and #4/0000 for other runs.  All of the cables are welding cable.  Welding cable is flexible and in most solar expert circles considered best for this application.   2/00 is about $6 per foot and 4/0000 is about $8 per foot.

                                                               

Tools needed to make up cables

Crimper, 2"Chisel, Rubber Mallet, Antioxidant, Heat Gun, Shrink Tubing.

Making The Crimp

My decision was to make a few new battery interconnecting cables. I like to custom make all my cables.  This can be less expensive than buying made up cables and allows for custom placing of components.  It also allows for proper lengths and orientating of the stud ring connectors to allow for easy connection to the stud.  Not to mention the convenience of having the necessary cables available as needed.   Keeping wire lengths to the actual length needed helps in the overall performance of the system.   The stud ring connectors come in various sizes for cable and stud sizes.  I have found over the years of making cables one of the cleanest and easiest ways to cut 2/00 and 4/0000 cable is to use a new or sharp $12 two inch wood chisel from Home Depot and a block of wood.  I have used large long handle pruning shears with good results.  The shears did a decent job, the chisel method does a better job for me.   Another option is to buy an $80 cable cutter.  I have found the small $25 cable cutters labeled up to 4/0 found at Home Depot and Lowe's are too small to handle the job easily.  A simple lug crimper does an excellent job for crimping the stud ring connectors.  Shrink tubing comes in different sizes for these larger cables and ring connectors.  The better shrink tubing comes in colors and glue on the inside of the tubing.  This glue makes for a good seal over the stud ring connector and the cable.  I like to also use an antioxidant on the cable ends to help prevent corrosion.

500 Amp Shunt and Midnight Solar Whizbang Jr. Sensor

                                                                

The 500 amp shunt is used on the negative side of the battery.  Meters connect to the shunt.

The add on Whizbang Jr. is a highly accurate current sensing module provided with the Classic 150 Charge Controller.  The Whizbang Jr. was offered for free with the Midnight Solar Charge Controller.  It displays several accurate readings on the charge controller display.  The TriMetric display is used inside the coach independent of the Whizbang Jr.   

                                                                       

300 Amp Class T Fuse and Battery Disconnect

The Class T Fuse is inserted into the Positive cable from the battery to protect the system.  This fuse size is determined by the manufacturer of the inverter and may vary by inverter brand and size.

The Disconnect Switch is placed in line on the positive cable to isolate the batteries when needed.

                

                                                              

TriMetric Meter

Cut Outs

 

Amps In

The Tri-Metric is a meter that tells me what is going on with the batteries.  It is like a fuel gauge for the system.  It will tell me voltage and the amp information.  The Tri-Metric is a complete meter for volts and amps used for the day or between complete charges.  I mounted the Tri-Metric and the on-off switch for the inverter in the cabinet above the control panel which is a convenient location for me to access the on off switch for the inverter and the TriMetric if the slides are in.  Any hole cut in the wall paneling for these displays can be covered with a simple blank wall plate of the size and color needed if display is removed.  An X-Acto saw blade is perfect for cutting the paneling without damaging it.  Care needs to be taken when drilling or cutting any holes to not cut or damage hidden wires and other things.  Go forth boldly but with care.

 

Main Panel before moving circuits

Behind Control Panel

             

Sub Panel Wired

                                                                                                        

Six Circuit Sub Panel

                                                                                    

My sub panel is located in the pantry and is back to back with main panel with a space between them.  Circuits are removed and routed to the sub panel directly from the main panel and AC power supplied to sub panel from the inverter either by pass through power or 12 volt inverted power. Usually the circuits that run to the sub panel do not need constant on off attention.  The circuits in my sub panel are the ceiling fan, slide out plugs, GFCI circuit, microwave, and bedroom plugs.  I chose to run my residential frig on the main panel circuit for now.  In the case my 1000 Watt Xantrex inverter for the residential  goes out I could move that circuit to the sub panels empty slot and keep the residential frig going.  If a gas/electric RV frig is used, it could be run to the sub panel for powering the frig.  The RV frig is a power hog though.  Care needs to be taken when the RV frig is on the inverter for power as to not deplete the batteries to a low state of charge.  I have found in the past with an RV frig I could run an RV frig on the inverter for long periods but with consumption observation.   

                                                                   

Converter In Front Bay

                                                     

I moved my converter from it's hidden spot behind the main bay wall to the front bay wall.

My converter is unplugged from the provided power outlet.  It must be plugged into an external power supply independent of the coach system and the converter output cables are connected to the power posts.  If it were connected to the coach power supply, it would cause a conflict while solar charging or inverter/charger charging which is not a good thing.  If needed due to solar system failure I could plug the converter into an external power source independent of the coach power supply.  This would also come in handy if I have several days of rain and clouds.  I could use my Honda 2000i to charge the batteries for a couple of hours and still use the inverter for AC power for the coach.   I may use this method if needed in the future.   

                                                                                                                                                             

Component Wiring

                                                                         

 

Front Bay

The four battery box I have will not accommodate my new AGM batteries.  The AGM batteries are taller and will not fit in the standard battery box.  I am placing the AGMs on the battery compartment   plywood floor and contained by stop blocks.  Since they are AGMs they do not necessarily need to be in a battery box. 

My plan is to enclose the batteries on the front and sides with 3/4" plywood.  This would create a shelf over the batteries and the inverter for storage. 

                                                               

Drawing of My System

 

Craftsman AC/DC Clamp Meter

 

This Craftsman AC/DC Clamp Meter Model #82369 is a handy tool to keep around when working on the Bighorn and for solar measurements.  It will measure Voltage AC and DC as well as Amps AC and DC and other measurements.

J Box 1  On Back Of Panel

J Box 2  On Back Of Panel

Let's take a look at how I wired the panels.  There are six Kyocera panels.  Panel wiring is somewhat like battery wiring when you think about it.  All six of my panels have the same VPM (Voltage to Load Rating) of 17.7 volts.  Four panels have an IPM (Current at Load Rating) of 7.63 amps.  Two panels have an IPM of 7.91 amps.  All panels are series connected with matching IPM rated panels together.  

Okay, there are 6 panels, 3 strings of two panels each.  Each string is series connected and paralleled at the combiner box.

This gives me 35.4 volts going from the combiner box to the charge controller and 23.17 amps.  The MPPT charge controller will operate most efficiently at 35 to 40 volts input.  Voltage drop calculations tell me I will have a .68% voltage drop.  I was shooting for 1% or less.

If I connected the same panels parallel my voltage drop would be 2.74%.  My goal is to have 1% or less voltage drop.  How did I get these voltages and amps?

VPM  2@17.7 volts  *2=35.4 volts   

IPM   Each string of 2 panels is 7.63 amps (2 panels connected in series)

When paralleled with the other 2 strings that are 7.63 amps each we get 23.17 amps.

35.4 volts and 23.17 amps to the charge controller.

 Different wiring techniques produce different voltages and amps.  The most efficient voltage and amps for the MPPT charge controller was my goal to achieve by using this method of wiring.  

Handy Formulas:   Watts = Amps x Volts

                                Volts = Watts/Amps

                                Amps = Watts/Volts

                                                          

Cable Run

The wire and cable is enclosed in NMUA flexible conduit a grey vinyl covered conduit for the AC runs and flexible polyethylene wire loom for the DC runs.  I have found this is one of the easiest ways to channel the wires to the front bay.

The factory wire and water supply lines channel in the photo below might also serve for this purpose.  I could have run all the wires and cable in that channel if I had not used it to run other things to the front of the rig.  I did use this channel to route the TriMetric meter and inverter remote cables.

Factory Channel under cover.

                                          
  

Front Bay Layout

                                                         

Roof Panels

My solar system is what I designed for our Bighorn 3570RS and my use requirements.  Armed with previous installation experience I took into consideration the addition of the residential frig.  I probably used no more than 156Ah max in a day at any one time in the past.  This is where the Trimetric meter is helpful determining this usage.  If I add another 100 to 110 Ahs per day for the residential frig, this would require about 266Ahs of use which is about 40% of the total storage.  This would be well under the recommended max 50% draw down on the batteries.  Most of the time the demand is much less.  Also draw down depends on the time of the year and weather conditions.  In the summer, the sun is much higher for more charging time during the day and less consumption is used depleting the storage. There are all kinds of little factors to consider about a solar system.

I always try to keep in mind I may want to change this system and make a larger system.

As a final note, if you are considering installing solar in your rig and you are unable to do the install or do not feel comfortable installing your own system,  that is okay.  There are reputable installers out there.  You do need to know good installation methods and good wiring practices.  This knowledge will help you with getting a properly working solar system that meets your needs.  The more you study the information out there on the web the more informed you will be.

I would recommend reading Jack Mayer's site.    Jack's site is the most complete informational  site I have found.  Also study other sites for methods used and sites with photos that can be most helpful.  I always ask of those who inquire of me about a solar system, how are you going to use your system?  This is a very important question. It determines the size of the system as well as equipment needed.  The answer to this question can save a lot of money to the person wanting the solar system.  Some RVers do not need an elaborate system for their use. 

Northern Arizona Wind and Sun has an excellent site to explore all the components, parts, and pieces needed for an install.  They also have informational sites.  Wind and Sun  

Happy Travels,    Brazos