Subi & The 5

Installing Solar Panels – Alfa See Ya Motorhome

We love boondocking and/or dry camping since we both like to get away from the big RV parks and do hiking and exploring in the less crowded areas so I started thinking how we could improve the experience. We have a 40′ DP which has a 7.5 kVA diesel generator so we had lots of power but it is noisy and running it twice a day for 45 min or so was something we really wanted to avoid if possible, hence the solar.

I estimated how much energy we typically used per day and from that I did some very rough calculations and figured that somewhere between 400W and 600W worth of panels should be able to meet our requirements on a typical winter day in the south. Our biggest power consumers are the propane furnace (somewhat surprisingly the fan draws a lot of current), the satellite receiver, the TV and the sound system. The lights, water pump, charging portable equipment etc. are relatively minor draws and we don’t use the microwave on the inverter or any other heavy draw appliances when we are out in the boonies.

I decided to install 400W worth of solar initially but designed the system to be readily expandable to 600W by simply adding two more panels. I bought four 100W panels instead of fewer large ones for two reasons: 1) they are a lot easier to handle if you do the installation by yourself as I did and 2) they have much less surface area so aren’t so susceptible to damage during high winds if you tilt them up.

Those Young Guys - Alfa See Ya Motorhome - Solar Panels
Installing the panels
Those Young Guys - Alfa See Ya Motorhome - Solar Panels
Panel installation

I also did some calculations to see what the benefit of tilting them would be in southern AZ or CA during the winter months and discovered that I could gain about 50% more energy by tilting the panels at the optimum angle so I made brackets that I can tilt to about 45degrees which seems to be just about optimum in January in the south.  If you are interested here is a link to a java applet that you can use to see what effect tilting your panels will have at different locations during different times of the year.

Those Young Guys - Alfa See Ya Motorhome - Solar Panels
Mounting brackets for tilting the panels
Those Young Guys - Alfa See Ya Motorhome - Solar Panels
Panels tilted

Another consideration is what type of charge controller to buy. There are two basic types, Pulse Width Modulation (PWM) and Maximum Power Point (MPPT).

The PWM controllers are a lot cheaper and provide smart charging of your battery bank but you must wire your panels in parallel and not use the high voltage panels. Because your panels are in parallel you have relatively high current on the wires from the panel to the controller and if you don’t have sufficiently heavy wires you will suffer significant losses in this wire. Also the “12V” panels, which typically have an open circuit voltage of about 21V, will be operating well below their optimum voltage which is typically around 17- 18V. So this type of controller is less efficient and requires heavier wiring but is much cheaper.

The MPPT controllers use a DC to DC converter to step down the voltage from the panels to the optimum charging voltage for the battery bank. This gains some efficiency and allows you to wire the panels in series. By wiring the panels in series the voltage is much higher but the current carried by the wiring from the panels to the controller is correspondingly less. My coach had 8ga wire already in place but I still went with a 40A MPPT controller to get a bit more efficiency out of the panels and minimize the losses in the wire.

Edit:  There is a downside to running solar panels in series that I didn’t anticipate.  I discovered after using them for some time that if one of the panels is shaded by a tree or other object the entire string will be effectively putting out no power even if the other panel(s) are in direct sunlight.  This makes sense because the shaded panel is effectively an open circuit so even if the other panels are up to voltage, no current will flow through the shaded panel.  I think if I had it to do over I would use 24V panels wired in parallel instead of the 12V panels wired in series.

Alfa designed a battery system where two 6V batteries were wired to power
the DC systems in the coach while the remaining four 6V batteries were wired
to power the inverter thus powering the AC systems in the coach. There was
also a large relay (commonly called “bigboy”) which connected these two battery banks together based on the voltage levels of the battery banks.

While this system looks good on paper it has some shortcomings.  In particular
some of the batteries may be discharged to a lower voltage more often and the banks will
not be charged at the same time/rate meaning that some batteries may be overcharged while the others are undercharged.

Tying all six 6V batteries into a single bank ensures that the entire capacity of
the bank is available for both DC and AC (inverter) and they are all charged at
the exact same rate.

Having a single bank also makes the addition of a solar array and charge
controller much more straight forward as there is a single point of connection
required which will charge all the batteries.

Those Young Guys - Combining battery banks diagram
Combining battery banks diagram.
NOTE: The above diagram applies to Alfas where the left two batteries are wired to the House and the remainder are wired to the inverter.  This was the arrangement in my ’04 SeeYa but I have been informed that not all Alfas were configured the same way.  If you have a different arrangement you will need to modify the connector accordingly.

I mounted the controller as close to the battery bank as feasible and used 4ga wire on that short run. I also installed a remote monitor on the dash so I can see what the battery charge state is and how much the panels are putting out.

I bought the panels from Renogy which seemed to have reasonable prices and were very efficient and good to deal with. The installation was pretty straight forward although I should say I am a retired electrical engineer so I am very comfortable working with most things electrical.

Last winter we boondocked and dry camped in various locations so it was a pretty good test for the system. I discovered that during sunny conditions (which was most of the time) the battery bank would be fully charged well before noon. With high overcast it took a couple of hours longer and even with fairly heavy overcast we would be charged before the sun went down. I should mention that I have 6x6V batteries for the house. I never had to start the generator during the entire time boon-docking.

Those Young Guys - Alfa See Ya Motorhome - Solar Panels
Testing the panels at Joshua Tree on short days in the winter – December 21
Those Young Guys - Alfa See Ya Motorhome - Solar Panels
Testing the panels at Joshua Tree on short days in the winter – December 21

I decided that, given our lifestyle, 400W is sufficient to keep our batteries charged so I don’t plan to add the extra two panels.

I should also mention that in preparation for going solar I swapped out some of the most power hungry incandescent light bulbs in the coach. I just went around and felt the bulbs we use most and any that were too hot to touch got swapped out for LEDs. I also modified a couple of the fluorescent fixtures in the kitchen replacing the tubes and ballast with LED strip lighting. This last mod only saved about 1A per fixture so maybe not worth the effort,
those fluorescent are already pretty efficient.

I summary we are very pleased with the installation. It meets our power requirements very well and is much less obtrusive than that diesel generator.

Those Young Guys - Alfa See Ya Motorhome - Solar Panels
Solar Panels up and running in Borrego Springs – yay



  1. Great article. I have a 04 See Ya. 40 ft. I have installed solar 300w with mppt 45A controller. I’m adding 150 watt panel and switching the panels to 48 volt.Where is the best place to connect to batteries and did you connect the inverter and house batteries together. I have mine connected to the inverter batteries but not sure if the big boy relays will work properly and switch power to the different battery banks. Maybe with the extra panel they will. I would appreciate your comments.

    1. Hi Roger. Thanks for the comment. We are just packing up the motorhome this morning and moving to a new location. We will get back to you later today.

    2. Hi Roger,

      I hard wired the House and Inverter batteries into a single bank and completely bypassed the big boy. I highly recommend combining them so that all the batteries are drained and charged exactly the same. The single bank of batteries is now connected directly onto the terminals of the Xantrex converter and I connected the output of the solar charge controller directly (through inline 40A fuse) onto the same terminals.

      I left the big boy relay between the house/inverter bank and the chassis batteries so I hear it engaging then dropping back out a few times as the solar brings the batteries up past the 13.4V threshold for the big boy.

      Good Luck with the installation,

      1. Norm I’m hoping you can help me with a few things I’m wanting to tie all the batteries together as you talked about with a long battery cable tieing all 6 together . As for isolating the the big boy switches can you help me with a diagram of what I need to do there ? I’m capable but those big boy switches look a little overwhelming to me

        Thanks robert

        1. Robert, I just left them in place, see my comment below for a bit more explanation.

          Good luck with the solar mods, I am still very pleased with the functioning of our system.

  2. Hi Norm and Lisa! This is a great update. I own an ’04 SeeYa and am planning on adding solar for boondocking. I may get ahold of you when that project begis later this spring. Thanks for posting! :thumbsup:

  3. Hi Norm and Lisa. I have an 03 SeeYa 40 pusher and have been seriously considering addition of solar. I saw a fellow from TX in Quartzite this past weekend with an Alfa solar system and he told me there were already wires in one of the toilet vents running up to the inverter compartment area. I understand about half of the process to install solar but the details of hook up to batteries and inverter area leave me scratching my head. WHERE can we get detailed instructions for an install?
    George in Mesa

    1. Hi George,

      I have never actually seen a complete step-by-step set of instructions so I can’t help you there but I can offer to walk you through what I did since we are currently camped at Usery Mt Regional Park in Mesa. If you are able to drop by either Thursday or Friday I can show you what my istallation looks like and answer any questions you have. Let me know if you are interested and we can co-ord the time/place.


      1. Hi guys. I ordered my charge controller and Amazon they say it is on the way with a March arrival. I am exploring the option of using four Unisolar “stick down” panels in lieu of the 100W panels you used if I can work out the real estate issue they present (EvPL 136 or 144s). If not, I will use Renogy panels due to good price but will try to add a linear actuator so I dont need to crawl on the roof all the time. I’m still not clear on wiring the two battery bank together but plan to do this when I buy new batteries in a week or so. A wiring diagram similar to the one in our Owner’s Manual would be helpful. Hope you enjoyed Cottonwood. Check in next time you are in town and thanks for the time you spent with me.

        1. Hi George,

          It sounds like you are well on your way to going solar. Those flexible panels sound interesting and I believe they are getting more efficient as well as robust. Put enough panel up there and you will only have to get up on the roof once in a while to clean the dirt off of them, or wait for a good rain.

          I have added a diagram above showing how I have the batteries wired in a single bank. Hope this helps.

          Look forward to seeing your installation, and all the other cool mods you’ve made, next time we are in the area.

          1. Norm, hope you guys are doing well. The addition of that diagram helped a lot! I installed the controller and monitor yesterday. Alfa had tied one of the roof cables off and it was easily identifiable in the inverter compartment but they had terminated the other wire into the ground/common block making it difficult to locate. (We used a tone to find the 2nd wire). 3 Panels should arrive Wed for a total of 408 watts. I will take the Pos/Neg out of the controller into the inverter connections as you did. Looks straightforward. Just where did you use the 4 guage wire you mentioned above though? I could only find 10 guage in the auto store and plan to use that from the controller to the inverter terminals (with a 30A fuse inline on the positive connector.) I decided to buy new batteries before hooking everything up. Thanks for the clarification. I’m into the project to the tune of $679 so far with controller, monitor and panels. Just need the connectors and cables and misc stuff to complete so it looks like I will be well under $1000 when done. Well, out to scrub the roof now. Stay safe!

  4. One other thing and not sure just how to ask but….we were wondering how to “manage” the final configuration given the options of running the genset, plugging into park/home AC while solar is installed?. Shouldn’t there be a disconnect or “off” switch somewhere to avoid damage with the generator or 30/50amp AC service in operation? Or, are these systems able to co-exist? I know there is an off switch for the inverter but is there a chance of damage as solar is produced when plugged in to household or park current or with the generator running? Seems like I read not to use the genset when plugged in. But, that solar power will be continuously coming down from the roof.

    1. As you say the DC sources can and do co-exist. The engine alternator, the Xantrex converter and the solar charge controller all will charge the batteries as and when required. There will be no dammage to the controllers with two or even all three systems active at once. The one that has the highest output voltage will be doing most of the charging while the rest of the systems will do little or nothing. The output of each system is protected by a diode so there is no way for power from one to be fed to another. I often see the solar panels “helping” with charging the batteries while driving down the road, the alternator just doesn’t have to work as hard.

      Of course the ideal situation is where just one system is providing the DC charging current so that it can follow its proper 4-stage charging profile. If two or more systems are working at the same time there is no guarantee that they will be on the same stage at the same time, i.e. the Xantrex might ‘think’ the batteries should be on Float while the Solar controller ‘thinks’ they should be charging at the Bulk stage.


      1. It is true that if one were attempting to combine multiple AC sources they would need to be synchronized in phase, but that doesn’t have anything to do with Georges question which was about combining multiple sources of DC.

  5. Hey Norm. Not sure if my last comment got to you as I do not see it posted on your blog so would like to be certain before I attempt final wiring changes. Your diagram (thanks by the way) indicates a pos line with a 200A fuse to the battery charge controller (BCC) AND another pos line with a 300A fuse going to the “inverter.” Were these lines already in place including the fuses or did you add them?

    Then you show a neg line to the inverter and you mentioned a 4AWG short run to the inverter? I thought the inverter connections were simply made via connecting cables OUT of the BCC to the 3/8 pos/neg inverter terminals so I’m a little confused about where one pos line with the 200A fuse goes into the BCC and why you show the 300A fuse circuit also going to the “inverter?” I was under the impression solar goes into the 2 BCC positions as indicated on the BCC and the BATTERY connections went FROM the BCC battery output to the inverter pos and neg respectively. What am I missing here? The other question I had was related to “managing” the final configuration given the options of using, solar, generator or house/park power. I was wondering if there had to be a switch somewhere to disable solar so as not to conflict with other options as I recall reading somewhere not to run the genset when connected to commercial power, etc.

    1. Re: Fuses. Both fuses are installed by Alfa. The 200A fuse was for the House batteries and the 300A for the Inverter batteries.

      Re: 4AWG cables: Sorry for the confusion. The cable I was referring to runs from the Solar Controller directly to the Inverter terminals. Since this run could be carrying up to 40A, in my installation, I used the heavier cable to make sure there would be little or no voltage drop on that cable. It is probably overkill but I didn’t want to waste any of that precious solar energy due to cable losses.

      Hope that helps..

  6. Thanks Norm. Installation is complete! Only problem I have now is the 3 136 watt panels are actually putting out more voltage than the charge controller allows (it’s limited to 100VDC and I have seen more than 137v coming down from those 3 panels! When this happens, I get the “P” red light and no charging).

    So, thanks to you, I successfully (?) installed the panels and controller and added the additional 9′ cable to tie the battery banks together. I also changed out all of my batteries that were in pretty bad shape to begin with. It took longer to change batteries than it did for installation of the solar system. I’m considering moving up to the Tracer 4215BN 150V Solar Charge Controller to get the extra voltage since my current Tracer “P”s out for most of the day here in sunny AZ and there is no green charging light on during that condition. Or, I could disconnect one 136w panel to see how two work and keep one in reserve. Or, I guess I could move to a parallel array condition if I don’t move up to the 150v controller. Decide on all that later.

    I’m still trying to figure out the MeTer directions for the day/night settings and settings for AH with 6 new 215AH batteries (which I have set to 700 on the MeTer now).

    I’m anxious to see how this new system impacts my dry camping/generator use. Happy trails!

    ( project is adding central vac to the Alfa. Should be far less confusing!)

    1. Congrats on the successful completion of your project!

      Re the over voltage from the panels: both your solutions sound good although paralleling the panels would certainly be cheaper. Also a consideration is that the voltage output of the panels is inversely proportional to a solar cell’s temperature (typically -0.45%) so if you are getting 137V now (presumably on a warm sunny Mesa afternoon) you could get quite a bit more on a really cold, sunny morning – just something to consider if looking at a 150V controller.

      For example; assume the panels put out 140V open circuit at 45degC cell temperature. These same panels would then put out about 165V open circuit at 5degC which would exceed the maximum input voltage of the 150V controller. It may not cause a problem if the controller is well self-protected but I would be cautious about long-term use in this configuration.

      Best of luck with your solar and your next “straight forward” project.

  7. Good morning, Norm!

    I know this thread is getting a little old but I am hoping you still monitor it. We also have an Alfa See Ya 40FD and are trying to install a Trimetric battery monitor. We are curious how & where others have installed their monitor. How did you get the wires from the monitor to the batteries? We tried fishing through the existing conduit above the entry door down but hit a roadblock somewhere behind the dash & above the battery/generator bay. Where, in the dash, did you mount the monitor and how did you run the wires through to the battery compartment?

    1. Hi Beverly,

      I mounted the charge controller monitor in the plastic compartment at the top center of the dash console. The monitor was a fairly nice fit in the compartment and it is visible from well back in the lounge area.

      I drilled a small hole in the top-front of the compartment where the Xantrex and my controller are mounted. From there I ran the cable up the front of the firewall then drilled a small hole in the wooden shelf at the top of the firewall (under the dash) and finally a hole through the back of the plastic compartment where the monitor is mounted. Of course I sealed all the holes once the cable was in place and left enough slack under the dash so that there is no interference when lifting the dash. Nothing is visible and it was a quite short run of Cat-5 cable from the controller to the monitor. Running from your batteries to the dash would be even shorter if you choose the same route.

      Hope this helps and good luck.

      1. That is what we suspected since the monitor fits almost perfectly in that cubby and has easy access by lifting up the dashboard. Unfortunately, my husband uses that cubby for his cell phone & wallet while we travel which it is also the perfect size & location for. I will look for options to stick over on the drivers side for his wallet & cell phone. Command strips/hooks to the rescue again!

  8. Is there a diagram you can provide to disconnect the big boy switches when I connect my 6 batteries together and tie in the solar? I did my last motorhome with a very small simple system and this is a little more complex but I’m excited to go solar

    1. Hi Robert,
      I didn’t physically remove either of the big boy relays. The one between the two original house/inverter battery banks no longer has any function. I decided to just leave it in place as it causes no issues other than used space.

      The big boy that connects the new combined house battery bank with the chassis batteries is still in place and still performs the intended function of connecting those two battery banks when the sensed voltage of the house bank is above about 13.4V. It disconnects them when it drops below about 13V. This ensures that the chassis batteries will be charged during each solar cycle and they can also add to the overall energy available to the inverter when they are charged and you draw a heavy load.

      Hope this helps.

  9. Hello Norm,

    Thanks so much for your excellent article. We have been traveling the southwest in our Airstream trailer for a number of years. We also do a lot of boondocking so solar has been a very important piece of equipment for us. We are miserly with our energy needs such that just two 80watt panels and two group 27 batteries allow us to operate without use of the generator.

    However, we have grown tired of hauling the Airstream from back and forth between the southwest and our home in Massachusetts. Therefore, we just purchased a 2003 Alfa See 36FD that we will keep here for our winter wandering. Unfortunately, it doesn’t have solar yet. Thanks to you, though, I feel confident adding it myself. I have been a ham radio operator most of my life and understand all the principals. Your article gives me the details I need.

    We pick up the Alfa See on Tuesday and will take her on a shakedown trip from Tucson to Organ Pipe Cactus this coming week.

    Thanks again


    1. Hi Wayne,

      Thanks for your kind words AND a big congratulations on getting an Alfa! I am sure you will love it and I am sure you will do great with installing the solar panels. Stay in touch and let me know how it goes and we hope to see you on the road some day!


  10. Bought a 2005 40′ See Ya in October new batteries Nov 2017 had odd smell by return air grill next to the refrigerator generator is not making ac power now Wiring looks funky next to house batteries
    I ordered a new ATS WFCO T-57 50 amp . Hopefully that will help me with the ac on the coach. I would like to know how mount solar panels on the roof. Without leaking through the roof material. Will be installing the new part when it comes. Will be poking around to see where I can power down . I have a small solar panel on roof just behind the driver’s seat. How do you check out put no light on controller for the panel? Thanks Kevin

    1. Hi Kevin,
      Congrats on buying the Alfa we find it very comfortable for “half-timing”.

      As for mounting the panels, I used short lag bolts through the roof. I drilled
      pilot holes then laid down a bead of non-self-leveling sealant around the hole. When the bracket was bolted down to the roof I covered the bracket (including the lag bolt) with more self-leveling sealant. It winds up looking like the way the TV antenna and other accessories are mounted. I used Dicor sealants and find them to be excellent.

      The pre-installed wires on the roof should be inside the vent stack from the black tank. They show up at the front of the inverter compartment.

      I’m not quite sure what you are asking in the last sentence.


  11. Hi Norman & Lisa,

    We are just completing our two week shakedown ‘cruise’. Getting familiar with all the systems on the coach. Nearly everything is in perfect working order.

    I am now getting my list of materials and tools I will need to add the solar charging system as you did. I have re-read your article and the posted comments. But, I have a couple questions. I found a single wire coming into the inverter bay at the front of the coach where you indicated it should be. But, it is just a single #8 (black) wire. On that same wall through which the wire comes is a grounding block but no wire seems to come through the same opening to that block. It doesn’t seem that they would use the chasis as the ground for the solar? Also, there are two vent stacks through the roof. I presume the one on the driver side is the black water since it is over the toilet. However, it is a singe piece of PVC that is sealed to the roof membrane. Is this where I should find the wires for the roof solar panels? I am hesitant to mess with the vent without being sure that the effort will be rewarded.


    1. Hi Wayne,

      Glad to hear your first trip is going well.

      Concerning the solar pre-wire they are indeed in the vent stack for the black tank on the roof just above the toilet area. You do have to remove the cap which is held in place by white sealant. Once you remove the sealant and the cap you will see the wires stuffed down the pipe with quite a bit of spare wire to get you well out on the roof where you can connect them to the M4 solar connectors. There should be both a black and white 8-ga wire in there just below the roof line.

      Both wires should also appear at the front of the converter compartment. I had to dig around a bit to find them but they should both be there. You are right that Alfa did not rely on chassis ground.

      Good luck with the project, it is well worth it.

  12. Hello my name is Scott Ulrey and im from Vegas. I just bought a 05 Alfa See Ya 40′ and love it and your post on solar and plan on also going solar but I have another issue i’m hoping you can shed some light on. So like a dumbbell i bought this unit that only has 50K in miles on it beleiving the owner that the only reason I don’t have 12v to coach is a bad Bi- Directional box, so ordered one from Alfa installed it and nothing. I went throught all fuses and all test good so I ordered from Alfa the both panels above the entry door one is a single momentary switch for the living room slide out the other is a double one chassis one coach. The chassis works fine red indicator light above switch is on but still nothing on the coach side. This is preventing me from going anywhere and even wont let me start the generator from inside or manually on the gen set???? any ideas? any help would be great, if I can’t figure it out soon I guess its off to Alfa service in Fontana. Thank in advance, Scott

  13. Hi Scott,

    Sounds like your problem could be related to the Battery Control Center (BCC). The battery disconnect switches above the door are connected to the BCC which controls the relays that provide 12V DC to the rest of the coach. Since you have confirmed that all the fuses in the BCC are good, I would suspect a problem with the BCC itself or perhaps the BCC is not being fed 12V from the battery banks.

    There should be three binding posts on the BCC where 12V is connected to the Chassis batteries, the House/Chassis big-boy relay and the generator. I would check to see if you have 12V on the input from the House/Chassis big-boy relay (center post). You should also try closing the knife switches associated with both of the big-boy relays to make sure the problem is not with a big-boy relay itself. Closing the knife switches bypasses the relays and should provide 12V directly to the center post of the BCC.

    I need to make clear however, that I am not an expert on the BCC and I can’t offer too much more advice here but there are Alfa owners who are experts so if you are unable to track down the problem I would suggest that you also ask for help on the Yahoo Alfa News Group or on the Alfa Facebook page. One of the guys who frequents the Yahoo group (Vonis Spencer) is especially knowledgeable on pretty much every aspect of the electrical systems on the Alfa and could quite probably offer some advice.

    Good luck and congrats on your Alfa purchase,

  14. Thank you for publishing your configuration and experiences connecting a solar system to your Alfa. Some feedback: The batteries in our 05 See Ya Gold are arranged differently. The two house batteries, for example, are on the driver’s side of the vehicle, and three of the four inverter batteries are on the passenger side.

    From an electrical perspective, I believe your diagram is correct.

    However, if a reader with little electrical experience with house and inverter batteries arranged differently from yours follows your diagram literally, they will almost certainly be surprised by the results.

    Perhaps it would be a good idea to update your posting with a disclaimer suggesting the batteries in readers’ coaches may be arranged differently from what you found in your Alfa, and when in doubt about adding or changing the electrical systems in a coach readers should consult with an electrician or electrical engineer.

    Again, thank you for sharing your experiences.

    1. Thanks for making that valid point Mark.

      I fully agree that anyone not comfortable following wires, reading an electrical schematic or using a volt meter should probably not attempt a solar panel DIY install!


    2. new to my Alfa. but have access to 8- 720w panels , and i believe i have 6 new bat-trees installed at purchase, plus the 2 engine bat-trees. the very heavy inverter was used to supply power to my house in 1999.

  15. Hi Norm. Great article. Thanks so much for posting such an informative and helpful site.

    My wife and I just purchased our first Alfa – a ’05 SeeYa 40’er with only 27,000 miles on her. Our first trip was interrupted due to a generator not putting out proper AC voltages and a black tank valve that wouldn’t close. We had to head home to Arizona to have these matters corrected.

    I took almost all of the solar system off of our 5th Wheel trailer and am getting ready now to put up the panels. I have two large 24 volt panels which give us 675 watts. We found that these panels provided ample power in the 5th wheel and I only see a little more need for power in the coach.

    My question would be the placement of the panels on the roof. I have been thinking of putting them across the roof surface rather than perpendicular as you did. The main reason is that I can aim the coach such that it is facing north/south and can then raise the panels to face south. Did you decide to put them where you did so you could face east/west on purpose or just for another reason. Both options are open to me and I don’t wish to have to ever move these beasts of panels.

    Thanks so much.


    1. Greetings David and hopefully your Alfa serves you as well as ours has.

      As for the placement of the panels, yes I like to think there was some method to my madness.

      Over the years we have come to prefer to park our coach facing West when we are boondocking. This provides us shade from the sun on the passenger side which is usually nice to have during most of the day.

      Our second preference would be to park facing North which would give us morning sun on our sitting area and shade in the afternoon as you are suggesting.

      Two big panels spaced sufficiently far apart so they don’t shade each other should work well although it could make it a bit harder to walk up and down on the roof should the need arise.

      Good luck with the installation.

      1. Thanks for your quick response, Norm. Excellent points! I was also concerned about the sun hitting one end or the other of the coach. Even during winter camping, that can either heat up the living area or the bedroom. While camped at Quartszite this year I found the “patio” area to be too cold in the morning and too warm in the afternoon. Perhaps a more easterly position would put the sun on the patio side most of the day so the awning could keep the coach cooler.

        I will have to make a decision soon. My roof box and MC-4 to bare wire connectors just showed up. I’m getting closer to being able to finalize my install.

        Best wishes to you and your wife.


  16. Hi again. I forgot to mention in my last message that there is a forum for Alfa owners who need to ask questions of some very knowledgeable owners. The address is This site has been very helpful to us so far. The entire site can be searched for past questions and answers.


  17. Norm,
    I have a 2003 Alfa See ya 40′. I spoke to the head mechanic at leisure coachworks (formerly alfateers) in so cal earlier this year regarding my house batteries giving me some issues.

    The mechanic informed me that closing that scissor switch would combine the 4 inverter batteries and 2 house batteries into one big 6 bank house battery system. Have you heard this before?

    I want to change my system to match your diagram, and I am planning a solar install this spring. I am wondering how you have those scissor switches set after tying all batteries together? Also, just to confirm, you did not run your wiring from the solar controller to the batteries, but instead ran it to where the batteries tie into the inverter/converter?

    Thank you for continuing to reply to this thread, not a lot of Alfa info out there!


    1. Hi Rob,

      The LC mechanic is certainly correct in that closing the knife switch between the House and Inverter banks effectively combines the 6 batteries in a single bank. The only difference is that there are still two separate fuses in the cables from each bank and you would therefore not be able to detect if one of the fuses blew other than to have less capacity. You also have to keep the knife switch closed. These are not big issues but I just wanted a cleaner solution which eliminates the knife switch, the Big-Boy relay and the BIRD out of the equation. I see no situation when I would ever want to separate the House and Inverter battery banks.

      I keep the knife switch for the Chassis batteries open and allow the BIRD to control the Big-Boy relay so that the Chassis batteries get charged when the Combined bank gets up to 13.3V It also allows the Chassis batteries to provide extra power when you use a power hungry appliance on the inverter but ensures that the chassis batteries cannot be discharged below a safe level by the inverter.

      I did connect the output of the solar controller directly (fused) to the inverter terminal. Is a very convenient place to make the connection and makes for a very short cable run with minimal losses.

      Hope that helps,

  18. Norm, thank you for the help and for this posting. I installed our solar this week on our 2003 Alfa See Ya 40. I also combined the battery banks (can’t believe I didn’t do this 3 years ago when we bought it!).

    My set up is as follows:

    2x 300 watt panels
    Renogy 40amp MPPT controller
    2 40a bussman breakers ( before controller and after)

    I ended up drilling a small hole in the top of the fiberglass above drivers seat area to run my wiring (8 gauge). The wiring runs through a small waterproof solar junction box and it dropped into the small cabinet above drivers head. I was able to fish it down the frame rail and into the front battery compartment.

    I drilled two small holes in the inverter converter compartment and ran my wiring into the MPPT controller (which I mohbted inside the inverter converter compartment as well). From the controller I ran the wiring directly onto the inverter terminals.

    The Renogy controller has a bluetooth feature which allows you to monitor solar production and battery status on your smartphone.

    We boondock in the desert here in Southern California, and the batteries have always given us problems in our Alfa. I feel a lot of relief and satisfaction knowing we’ll be able to enjoy our Alfa with no worries of running out of “juice.”

    Thank you again sir!

  19. We have a 2003 Alf’s See Ya 40’. We are currently having a problem with the chassis batteries being drained very very quickly. They are both brand new, so that is not the issue.

    We have solar installed, 2-300 watt panels, and a 40a mppt controller. We have done the upgrade of connecting the inverter and house batteries into one big 6 battery bank. The solar has done a great job of keeping the house batteries charged and provides plenty of power.

    After our last trip, we noticed the solar was only keeping the house batteries at 30-40 percent charged. While trouble shooting, we found one of the big boy relays was getting very very hot. This big boy was replaced as a precaution.

    Eventually whatever the drain on my batteries was, was so great the house batteries and chassis batteries were being completely drained to empty.

    During some trouble shooting, I pulled the Bi directional relay fuse under the dash, and it immediately caused the house batteries and rc7 controller to come back on.

    Now, the house batteries are beings charged by the solar and staying charged. So, I believe there must be a short on the chassis battery side of things which was pulling pretty substantial power from my house batteries. Causing the system to try and keep the chassis batteries charged?

    Where I am at, is I am nervous a rat may have chewed a chassis power cable somewhere and it’s shorting to ground somewhere causing this massive power draw.

    Has anyone ever had a problem like this? Or have any ideas where to begin troubleshooting where my problem may be?

    Thank you and sorry for this Lonnng post, just want to be as detailed as possible.

    Rob Springer

    1. Hi Rob,

      Luckily I have never encountered an issue like yours but one thing you could do to confirm that the drain is from a load on the chassis side is to use an ammeter either clamp-on or in-line on the cable at the chassis batteries. As you say, it could be a partial short somewhere in the wiring harness or in the Big Boy relay itself?

      Best of luck with the trouble shooting.

  20. Great post!

    Is their a way to charge the 2 chassis batteries as well as the 6 up front (house/inverter)?

    1. Hi Jocob,

      The “Big Boy” relays actually do just that. In the original configuration
      the inverter batteries are charged first, and when the voltage reaches a
      preset level the Big Boy relay joins the house & inverter batteries which
      are charged together until they reach a certain voltage (going from memory
      it is about 13.4V) the relay that connects the house/inverter with the
      chassis batteries closes and all six of the house/inverter batteries and
      the chassis batteries are connected and charged together.

      Of course if you have wired the house/inverter batteries into a single
      bank like I did, then you only have one Big Boy relay which connects
      the combined bank to the chassis batteries when the voltage is reached.

      That Big Boy relay stays closed until the voltage drops below a threshold
      when it opens disconnecting the chassis from the house/inverter bank so
      you can’t drain the chassis batteries if you happen to drain the house

      Hope that is a bit clearer than mud!

      1. Thanks Norm. Almost done with my installation! One more question for you. Where exactly did to connect the negative cable coming from your charge controller? I want to ensure it is in the correct position for the best results.

        1. I attached it directly to the negative post on the inverter which also terminates the negative cable from the combined house/inverter battery bank. I mounted the solar controller on the front wall of the compartment so it was a very short run to the inverter and I used heavy (probably overkill) cables.

          Hope that helps.

  21. Hey Norm, what did you guys use to Secure your solar panels to the roof? I have a 2005 Alfa see ya founder 36’ and am getting ready to install solar on it. Thank you in advance for any help!

    1. Hi John,

      I built my own brackets out of aluminum angle stock because I wanted to be able to elevate the panels to maximize the solar output during the low-angle sun in the winter and I didn’t like the cost of commercially avaliable tilt-up brackets. I bolted my brackets to the roof using lag bolts. I put Dicor sealant in the pilot holes that I drilled in the plywood roof and then a applied a liberal application of Dicor over the lag bolts.

      I had no leaks and the panels stayed put during transit and high winds when the panels were elevated so overall I was satisfied with the result.

      Hope that helps.

      1. Thank you for getting back to me so promptly and yes that was very helpful! When you positioned the brackets did you try to get them to hit the aluminum crossmembers in the roof or just arranged them to optimize the open areas of the roof? Do you happen to have any close up photos of your install you could share?

        Thanks again for all the help it’s greatly appreciated!

        1. I didn’t try to hit any cross members and I’m not too sure how one would go about finding them? I just laid out the panels for what I thought was the best arrangement to avoid shading and wanting to have the coach pointing West in the winter (i.e. patio in the shade). I also wanted to save sufficient room for two more panels in case the 4x100W weren’t sufficient. Sorry, I don’t have any close up photos of the brackets and the Alfa is long gone…

  22. Hi you all, in 1999 we built a shelter, we had installed 8- 720 watt panels, for the shelter, the inverter was about 1.5 ft long , 10″ tall and deep. my brother still has the equipment and is willing to sell it to me not sure of the brand, all i remember was the inverter was green and white with a digital screen telling all the functions, i believe the inverter alone was $3000, dont remember a controller maybe it was built into the inverter.
    i would really like to install this system in my 2004 Alfa See Ya. any thoughts if its possible.

    Thank You in advance

    1. Just a few thoughts:
      1. That inverter would probably fit into the place taken up by the existing inverter. It would give you more capacity and is probably a Pure Sine Wave which would work better than the existing Modified Sine Wave inverter supplied by Alfa.
      2. You will also need a Solar Charge Controller. I installed a 40A controller on the forward wall of the electrical bay but if you intend to install several 720W panels you will need a much larger charge controller.
      3. I doubt you will find room on the roof for all 8 panels but you will need to handle way more than 40A. You will probably need a pair of 40A or 60A controllers in parallel. I would also wire the panels for 24 or 48V so you could use the existing wires from the roof to the electrical compartment.

      Good Luck with the install!

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