Lazy Daze Owners' Group

Hello! I posted awhile back looking for some ideas on my planned solar install for my 2003 24' FL, and got a lot of useful feedback. I especially want to thank Larry Wade (whose Flickr albums are a font of useful ideas), and Andy Baird.

Anyway, I finished the install, and took step-by step photos along the way, so, I figured I'd post a nice, detailed, write-up for the benefit of anyone else thinking of doing similar, and looking for ideas.

The full install is 400w of panels (4 x 100w panels), with an MPPT controller. I also added a battery monitor, and battery cutoff switch, a new fuse panel for the high-current part of the DC electrical system, and better (thicker) battery cables.

Getting Rooftop Access:

So, to start with, my rig did not originally  have any factory-installed solar panels, as they were still only an option at that time on the 24' models, so I was starting from scratch. Also, the battery box, and all of the electrical panels are on the drivers side, whereas the fridge is on the curb side, making using the fridge vent problematic, so I needed to add a new access opening to the roof.  This was the most unnerving part for me, since one of the better bits of RV advice is "Don't put holes in the roof", however, I pretty much needed to, so I proceeded carefully. 

The access itself is a 6" x 6" weatherproof PVC junction box I got from the home center (Lowes), with an appropriately-sized hole drilled in the center of the bottom for a 2" PVC "box adapter" fitting and a 2" conduit coupling on the bottom, with the whole thing solvent-welded together with PVC cement.  (Sorry, but you are not allowed to access the gallery)
(Sorry, but you are not allowed to access the gallery)

The access was placed to open into the space above the microwave in the kitchen. I had to be careful placing the hole as there is electrical cables in the ceiling. It's hard to see in the picture below, but there is a beam in the ceiling (you can see the line of  'buttons' covering the nails holding up the ceiling panels) in the middle of the microwave opening. This beam also runs along the rear of the AC unit opening, so it is a barrier to running wires, thus I was able to place the hole 3" to the right of this beam without hitting anything. (Sorry, but you are not allowed to access the gallery)

The 2" coupling on the bottom of my access box has an outside diameter just under 2-3/4", so I used a 2-3/4" hole saw to make the opening. I let the hole saw just cut through the ceiling panel, then pulled it out, so I could push the insulation out of the way and check the opening for any wires, this way, unless I was unlucky enough to knick a wire with the pilot bit, I wouldn't cut anything important.  Once that was clear, I put the hole saw into the hole in the ceiling, and just used the pilot bit to create a neatly centered small hole through the actual roof. (Sorry, but you are not allowed to access the gallery)

This let me go on the roof and drill the rest of the hole downward. This makes a cleaner hole in the aluminum roof, since it's supported by the wood underneath while drilling. (Sorry, but you are not allowed to access the gallery)

One thing that surprised me was just how thin the roof structure actually is. Here is all three layers of the roof (I would have thought that the plywood under the aluminum sheet would be thicker): (Sorry, but you are not allowed to access the gallery)

Once the access box was test-fit, I just lightly sanded the bottom of the box and the roof surface with some fine sandpaper, and cleaned them with acetone (not alcohol, which I was about to use, until I noticed the directions on the sealant specifically recommended against that). Once that was dry, I put down a copious bed of 3M-5200 adhesive sealant. The box was  set down on this, and screwed down with some 3/4" stainless steel screws. I sealed around the edges of the box, and over the top of the screw tabs with more sealant. (Sorry, but you are not allowed to access the gallery)

By the way, I was actually able to get the 3M-5200 sealant at the local Lowes store, surprisingly enough. It was even on sale $10 for a 10oz tube, it's usually twice that. I got two tubes, since normally, once you open a tube, anything left in it will go bad in 24hrs, and I was working as time permitted on weekends.  However, I found that if you vacuum-seal a partly used tube in a FoodSaver bag, and keep it in the freezer, it will last for weeks. Thus I only needed one 10oz tube for the whole project.

Finally, I put a pair of busbars in the access box for connecting panels in parallel. I used these Blue Seas 100A Busbar. I glued them down with more sealant, mostly because I had it and didn't know if it'd keep. I also used a little sealant around the conduit coming through the ceiling inside, just for sturdiness sake. (Sorry, but you are not allowed to access the gallery)
(Sorry, but you are not allowed to access the gallery)

Mounting and Wiring The Panels:

I decided on 4 of these Grape Solar GS-Star 100 Watt solar panels. Grape Solar has a good reputation, and many of the well-known RV solar installers use their panels.  From there, given the space I had on the roof, it was either their 100W or 160W panels, and the 100W better fit into the space, and were a better price per watt. These panels are available from several sources, including Amazon, but I ordered mine from Home Depot. They had them on sale for $109 each, and I could pick them up from the local Home Depot store once they came in instead of having them shipped. That seemed like a better idea for large, fragile panels.

The panels are wired in series-parallel. That is, I have pairs of panels wired together in series, and then the pairs are connected together in parallel at the combiner box. Here is the reasoning: Connecting panels in series boosts the voltage. MPPT solar controllers need a little bit of 'overhead' voltage to work, so the panel voltage has to be a few volts above the needed battery voltage. The panels normally output around 18v, which should be plenty for 14v of battery charging, but solar panels become less effective as they get hot, loosing voltage as well as current. And given dark-colored solar panels in full sun, the panels can get quite hot. On a hot day, with bit of voltage loss from the wiring,  that 18v could drop too low for the controller to properly charge the battery. Also, the power loss in the wiring depends on the current. Sending the same power at a higher voltage means less current, and less wiring losses. (By a fair bit. The wiring loss is proportional to the square of the current.) 

Given this, it would seem to make sense to wire all the panels in series. Unfortunately, when you wire panels in series, the voltages add, but the current is equal to the current of the lowest outputting panel. If you shade a solar panel, the voltage doesn't change much, but the current drops off dramatically. This will cut the output of all the panels in series with that one. This is made worse by the fact that solar panels are made up of a bunch of small solar cells the size of  the palm of your hand, all wired in series. The same rule applies to the individual solar cells. Consequently, with a large solar panel array wired in series, you can shade an area size of your hat on one panel and loose most of the power output of the whole array.  When you wire panels together in parallel, the currents add, and the voltage is the lowest panel voltage. Since the voltage doesn't change much on a shaded panel, shading one panel doesn't affect the others.

The series-parallel wiring I used is a compromise between the two options, giving plenty of voltage overhead for the controller, while lessening possible shading issues.

I mounted 4 100W panels. If I was willing to sacrifice the TV antenna, I actually have room for 6. I don't really use the TV antenna, but I do want to use the mast to mount a WifiRanger or similar, plus, at the moment, I only have a 200AH battery bank, so the 400W of panels is more than enough. If I upgrade the battery bank, I can mount an extendable pole to the rear ladder for the wifi, and ditch the batwing to make room for 2 more panels. I've sized the wiring and solar controller to handle 6 panels in case I do that. I did have to remove the (unused) CB antenna to mount the front left-side panel, but that was easy enough. Removing a screw on the side of the antenna lets you remove the actual antenna whip, and once that's off there's another screw uncovered that you can remove to take the tilt-mount part of the base off.  (Sorry, but you are not allowed to access the gallery)

For the actual, physical mounting of the panels, I used these Tektrum Z-Brackets. They are taller than most such brackets (2 1/8"), which gives better air circulation, and keeps the panels cooler. As I mentioned before, solar panels become less efficient as they get hot. Also the bigger space makes it easier to reach under the panels to access wiring, or clean under them. The brackets are also aluminum, which, for attaching aluminum panel frames to an aluminum roof, is a good idea to prevent corrosion issues. I bolted the brackets to the panels on the ground, first, then lifted the panels onto the roof. The panels are surprisingly heavy, they weigh 20lbs each, and together with their size, this makes them very awkward to handle. It would be very useful to have another person help you get them up onto the roof. I didn't have that, so I had to hoist the panels onto the roof with a rope. Basically, I just leaned the panel against the RV with the bracket-feet outward, and the rope securely tied through the holes in the top two brackets, then stood on the roof and hoisted the panel up. Draping a tarp, or piece of carpet over the side of the roof is recommended if you do this, as the sharp corners of the panel frames can scratch up your paint.  Once the panels were on the roof, attaching them was simple. Set them in place in a good location, then lift one side of the panel, clean the roof where the feet will sit with acetone, then put down a bed of 3M-5200 sealant for each foot. Set the panel feet back down onto that, and secure to the roof with a stainless-steel screw. Then cover the foot and screw with more sealant. Repeat for the other side of the panel.  (Sorry, but you are not allowed to access the gallery)
 
The panels were mounted with the cable connections on the back towards each other (the electrical "box" on the backs of the front panels is on the rearward edge, and the box on the rear panels is on the frontward edge) to make it easy to wire the panels together (the cables on the panels are not exceptionally long). Connecting the panels in series is simple, just plug the negative (-) MC4 connector of one panel into the positive (+) of the second, then run the (+) of the first panel and the (-) of the second to the combiner box. I used these 10AWG MC4 Solar Panel extension cables, they are nice in that they are color-coded, with good connectors, and 15ft was plenty long. These particular cables are rather stiff, however. The cables were zip-tied in place to the mounting legs of the solar panels.  It's not shown in the photos, but I did use a blob of sealant in the middle of the longer runs of cable to  help pin them to the roof. Don't use 3M-5200 for this, it's a little too permanent. I used a less tenacious polyurethane roofing sealant for that.
(Sorry, but you are not allowed to access the gallery)
(Sorry, but you are not allowed to access the gallery)

Finally, the extension cables were run to my access/combiner box. I drilled holes in the sides of the box, and used waterproof cable glands to run the cables through. The connections are on the sides, not the front of the box, to make it less likely for water to be driven through the joint when driving in the rain.  The cables are all connected using the busbars I mounted in the box earlier.  The connection from the rooftop access box to the solar controller was done with some 4AWG Ancor Marine-grade tinned battery cable. I wanted the thicker wire to keep the voltage loss down. I did goof slightly in this, as the 4awg wire was slightly too thick for the terminals on my solar controller, and required some creative cable-trimming to fit. If I had used 6awg, that wouldn't have been a problem. 
(Sorry, but you are not allowed to access the gallery)

Controller and Battery-Monitor install, and Battery re-cabling:

Besides installing the solar controller itself, I had a few other changes I wanted to make to the electrical system. Namely:

• Install a battery monitor: This acts as a power-meter for your battery, and keeps track of all power going in and out. This is important for keeping track of the actual state-of-charge of your batteries, and prolonging the life of your battery bank by not over-discharging it.
• Install a battery cutoff switch: I like being able to easily, completely, disconnect the electrical power if I need to. This is handy if I need to do electrical work, or am storing the RV somewhere where I can't rely on the solar panels to keep the battery charged.
• Replace the existing DC circuit breakers: High-current DC circuit breakers are just not the most reliable of things. My rig (and most Lazy Daze) has two of them, a 100amp breaker located in the battery box on the connection between the battery and the chassis electrical system, and a 50amp breaker located inline between the battery box and the main converter/fusebox panel. (mine is in the wiring channel along the wall behind the rearward barrel chair). I had already started having mysterious electrical issues (house power cutting off for a minute or so at random) that I traced to that 50amp breaker, which was uncomfortably warm to the touch. Fuses are just a better idea for this, so I wanted to replace the breakers with high current fuses.
  
• Better battery cables: the cables going to the batteries are thin (6awg and 2awg), and I wanted the system ready if I ever install a high-current device like an inverter, so that called for thicker battery cables

Hello! I posted awhile back looking for some ideas on my planned solar install for my 2003 24' FL, and got a lot of useful feedback. I especially want to thank Larry Wade (whose Flickr albums are a font of useful ideas), and Andy Baird.

Anyway, I finished the install, and took step-by step photos along the way, so, I figured I'd post a nice, detailed, write-up for the benefit of anyone else thinking of doing similar, and looking for ideas.

The full install is 400w of panels (4 x 100w panels), with an MPPT controller. I also added a battery monitor, and battery cutoff switch, a new fuse panel for the high-current part of the DC electrical system, and better (thicker) battery cables.

Getting Rooftop Access:

So, to start with, my rig did not originally  have any factory-installed solar panels, as they were still only an option at that time on the 24' models, so I was starting from scratch. Also, the battery box, and all of the electrical panels are on the drivers side, whereas the fridge is on the curb side, making using the fridge vent problematic, so I needed to add a new access opening to the roof.  This was the most unnerving part for me, since one of the better bits of RV advice is "Don't put holes in the roof", however, I pretty much needed to, so I proceeded carefully. 

The access itself is a 6" x 6" weatherproof PVC junction box I got from the home center (Lowes), with an appropriately-sized hole drilled in the center of the bottom for a 2" PVC "box adapter" fitting and a 2" conduit coupling on the bottom, with the whole thing solvent-welded together with PVC cement.  (Sorry, but you are not allowed to access the gallery)
(Sorry, but you are not allowed to access the gallery)

The access was placed to open into the space above the microwave in the kitchen. I had to be careful placing the hole as there is electrical cables in the ceiling. It's hard to see in the picture below, but there is a beam in the ceiling (you can see the line of  'buttons' covering the nails holding up the ceiling panels) in the middle of the microwave opening. This beam also runs along the rear of the AC unit opening, so it is a barrier to running wires, thus I was able to place the hole 3" to the right of this beam without hitting anything. (Sorry, but you are not allowed to access the gallery)

The 2" coupling on the bottom of my access box has an outside diameter just under 2-3/4", so I used a 2-3/4" hole saw to make the opening. I let the hole saw just cut through the ceiling panel, then pulled it out, so I could push the insulation out of the way and check the opening for any wires, this way, unless I was unlucky enough to knick a wire with the pilot bit, I wouldn't cut anything important.  Once that was clear, I put the hole saw into the hole in the ceiling, and just used the pilot bit to create a neatly centered small hole through the actual roof. (Sorry, but you are not allowed to access the gallery)

This let me go on the roof and drill the rest of the hole downward. This makes a cleaner hole in the aluminum roof, since it's supported by the wood underneath while drilling. (Sorry, but you are not allowed to access the gallery)

One thing that surprised me was just how thin the roof structure actually is. Here is all three layers of the roof (I would have thought that the plywood under the aluminum sheet would be thicker): (Sorry, but you are not allowed to access the gallery)

Once the access box was test-fit, I just lightly sanded the bottom of the box and the roof surface with some fine sandpaper, and cleaned them with acetone (not alcohol, which I was about to use, until I noticed the directions on the sealant specifically recommended against that). Once that was dry, I put down a copious bed of 3M-5200 adhesive sealant. The box was  set down on this, and screwed down with some 3/4" stainless steel screws. I sealed around the edges of the box, and over the top of the screw tabs with more sealant. (Sorry, but you are not allowed to access the gallery)

By the way, I was actually able to get the 3M-5200 sealant at the local Lowes store, surprisingly enough. It was even on sale $10 for a 10oz tube, it's usually twice that. I got two tubes, since normally, once you open a tube, anything left in it will go bad in 24hrs, and I was working as time permitted on weekends.  However, I found that if you vacuum-seal a partly used tube in a FoodSaver bag, and keep it in the freezer, it will last for weeks. Thus I only needed one 10oz tube for the whole project.

Finally, I put a pair of busbars in the access box for connecting panels in parallel. I used these Blue Seas 100A Busbar. I glued them down with more sealant, mostly because I had it and didn't know if it'd keep. I also used a little sealant around the conduit coming through the ceiling inside, just for sturdiness sake. (Sorry, but you are not allowed to access the gallery)
(Sorry, but you are not allowed to access the gallery)

Mounting and Wiring The Panels:

I decided on 4 of these Grape Solar GS-Star 100 Watt solar panels. Grape Solar has a good reputation, and many of the well-known RV solar installers use their panels.  From there, given the space I had on the roof, it was either their 100W or 160W panels, and the 100W better fit into the space, and were a better price per watt. These panels are available from several sources, including Amazon, but I ordered mine from Home Depot. They had them on sale for $109 each, and I could pick them up from the local Home Depot store once they came in instead of having them shipped. That seemed like a better idea for large, fragile panels.

The panels are wired in series-parallel. That is, I have pairs of panels wired together in series, and then the pairs are connected together in parallel at the combiner box. Here is the reasoning: Connecting panels in series boosts the voltage. MPPT solar controllers need a little bit of 'overhead' voltage to work, so the panel voltage has to be a few volts above the needed battery voltage. The panels normally output around 18v, which should be plenty for 14v of battery charging, but solar panels become less effective as they get hot, loosing voltage as well as current. And given dark-colored solar panels in full sun, the panels can get quite hot. On a hot day, with bit of voltage loss from the wiring,  that 18v could drop too low for the controller to properly charge the battery. Also, the power loss in the wiring depends on the current. Sending the same power at a higher voltage means less current, and less wiring losses. (By a fair bit. The wiring loss is proportional to the square of the current.) 

Given this, it would seem to make sense to wire all the panels in series. Unfortunately, when you wire panels in series, the voltages add, but the current is equal to the current of the lowest outputting panel. If you shade a solar panel, the voltage doesn't change much, but the current drops off dramatically. This will cut the output of all the panels in series with that one. This is made worse by the fact that solar panels are made up of a bunch of small solar cells the size of  the palm of your hand, all wired in series. The same rule applies to the individual solar cells. Consequently, with a large solar panel array wired in series, you can shade an area size of your hat on one panel and loose most of the power output of the whole array.  When you wire panels together in parallel, the currents add, and the voltage is the lowest panel voltage. Since the voltage doesn't change much on a shaded panel, shading one panel doesn't affect the others.

The series-parallel wiring I used is a compromise between the two options, giving plenty of voltage overhead for the controller, while lessening possible shading issues.

I mounted 4 100W panels. If I was willing to sacrifice the TV antenna, I actually have room for 6. I don't really use the TV antenna, but I do want to use the mast to mount a WifiRanger or similar, plus, at the moment, I only have a 200AH battery bank, so the 400W of panels is more than enough. If I upgrade the battery bank, I can mount an extendable pole to the rear ladder for the wifi, and ditch the batwing to make room for 2 more panels. I've sized the wiring and solar controller to handle 6 panels in case I do that. I did have to remove the (unused) CB antenna to mount the front left-side panel, but that was easy enough. Removing a screw on the side of the antenna lets you remove the actual antenna whip, and once that's off there's another screw uncovered that you can remove to take the tilt-mount part of the base off.  (Sorry, but you are not allowed to access the gallery)

For the actual, physical mounting of the panels, I used these Tektrum Z-Brackets. They are taller than most such brackets (2 1/8"), which gives better air circulation, and keeps the panels cooler. As I mentioned before, solar panels become less efficient as they get hot. Also the bigger space makes it easier to reach under the panels to access wiring, or clean under them. The brackets are also aluminum, which, for attaching aluminum panel frames to an aluminum roof, is a good idea to prevent corrosion issues. I bolted the brackets to the panels on the ground, first, then lifted the panels onto the roof. The panels are surprisingly heavy, they weigh 20lbs each, and together with their size, this makes them very awkward to handle. It would be very useful to have another person help you get them up onto the roof. I didn't have that, so I had to hoist the panels onto the roof with a rope. Basically, I just leaned the panel against the RV with the bracket-feet outward, and the rope securely tied through the holes in the top two brackets, then stood on the roof and hoisted the panel up. Draping a tarp, or piece of carpet over the side of the roof is recommended if you do this, as the sharp corners of the panel frames can scratch up your paint.  Once the panels were on the roof, attaching them was simple. Set them in place in a good location, then lift one side of the panel, clean the roof where the feet will sit with acetone, then put down a bed of 3M-5200 sealant for each foot. Set the panel feet back down onto that, and secure to the roof with a stainless-steel screw. Then cover the foot and screw with more sealant. Repeat for the other side of the panel.  (Sorry, but you are not allowed to access the gallery)
 
The panels were mounted with the cable connections on the back towards each other (the electrical "box" on the backs of the front panels is on the rearward edge, and the box on the rear panels is on the frontward edge) to make it easy to wire the panels together (the cables on the panels are not exceptionally long). Connecting the panels in series is simple, just plug the negative (-) MC4 connector of one panel into the positive (+) of the second, then run the (+) of the first panel and the (-) of the second to the combiner box. I used these 10AWG MC4 Solar Panel extension cables, they are nice in that they are color-coded, with good connectors, and 15ft was plenty long. These particular cables are rather stiff, however. The cables were zip-tied in place to the mounting legs of the solar panels.  It's not shown in the photos, but I did use a blob of sealant in the middle of the longer runs of cable to  help pin them to the roof. Don't use 3M-5200 for this, it's a little too permanent. I used a less tenacious polyurethane roofing sealant for that.
(Sorry, but you are not allowed to access the gallery)
(Sorry, but you are not allowed to access the gallery)

Finally, the extension cables were run to my access/combiner box. I drilled holes in the sides of the box, and used waterproof cable glands to run the cables through. The connections are on the sides, not the front of the box, to make it less likely for water to be driven through the joint when driving in the rain.  The cables are all connected using the busbars I mounted in the box earlier.  The connection from the rooftop access box to the solar controller was done with some 4AWG Ancor Marine-grade tinned battery cable. I wanted the thicker wire to keep the voltage loss down. I did goof slightly in this, as the 4awg wire was slightly too thick for the terminals on my solar controller, and required some creative cable-trimming to fit. If I had used 6awg, that wouldn't have been a problem. 
(Sorry, but you are not allowed to access the gallery)

Controller and Battery-Monitor install, and Battery re-cabling:

Besides installing the solar controller itself, I had a few other changes I wanted to make to the electrical system. Namely:

• Install a battery monitor: This acts as a power-meter for your battery, and keeps track of all power going in and out. This is important for keeping track of the actual state-of-charge of your batteries, and prolonging the life of your battery bank by not over-discharging it.
• Install a battery cutoff switch: I like being able to easily, completely, disconnect the electrical power if I need to. This is handy if I need to do electrical work, or am storing the RV somewhere where I can't rely on the solar panels to keep the battery charged.
• Replace the existing DC circuit breakers: High-current DC circuit breakers are just not the most reliable of things. My rig (and most Lazy Daze) has two of them, a 100amp breaker located in the battery box on the connection between the battery and the chassis electrical system, and a 50amp breaker located inline between the battery box and the main converter/fusebox panel. (mine is in the wiring channel along the wall behind the rearward barrel chair). I had already started having mysterious electrical issues (house power cutting off for a minute or so at random) that I traced to that 50amp breaker, which was uncomfortably warm to the touch. Fuses are just a better idea for this, so I wanted to replace the breakers with high current fuses.
  
• Better battery cables: the cables going to the batteries are thin (6awg and 2awg), and I wanted the system ready if I ever install a high-current device like an inverter, so that called for thicker battery cables

First off, I had to find a location to install the solar controller (unlike many, it has a remote control head, there's no buttons/display on the controller itself), plus the sensor for the battery monitor, battery cutoff switch, etc. Fortunately, thanks to Larry Wade's excellent Flickr album, I realized that the pedestal table that conceals the battery box has a large unused space in the top, which is perfect for a small electrical bay. All I had to do was use a piece of 2x4 and a hammer to push in the wood on the front, and break the glue seam, then score the thin luan plywood with a sharp utility knife. That let me snap off the top part of that panel, and expose the space (I saved the piece of the panel I removed for later):
(Sorry, but you are not allowed to access the gallery)

The space above the battery box is 11" high by 11" deep, and 17 1/2" wide at the front (closer to 20" at the back), plenty of space for my electrical gear. (The battery box itself is the black 'floor' you see in the photo) 

As it came from the factory, there is 5 separate wires connecting to the battery. There is 2 wires on the negative side, a 2-awg wire connecting to the chassis frame ground, and a 6 awg wire to the negative side of the main DC fusebox above the converter. There is also 3 wires on the positive side. One 2 awg wire connecting to the starter on the generator, one 6 awg wire to the diode isolator in the engine compartment (this is what lets the alternator charge your house batteries while the engine is running, without letting either the house or chassis electrical systems drain the other one if you leave something on.), and one 6 awg wire to the positive connection on the main DC fusebox. Besides upgrading the size of the wires, this all needs to be re-wired for two reasons: One, the battery monitor. The battery monitor measures power going in and out of the battery with a sensor called a "shunt" which connects to the negative side of the battery. In order for it to work correctly, all the power going in or out needs to go through that shunt, there cannot be anything else connected between the battery and the shunt. Second, the cutoff switch. In order for me to really turn everything off with the switch, all of the positive connections need to go through that switch.  So I need to have just one positive and one negative coming from the battery bank.

Here is the wiring on the batteries themselves, before re-wiring:
(Sorry, but you are not allowed to access the gallery)

And with the batteries removed (you can see the 100amp circuit breaker for the isolator connection to the alternator in the back of the battery box):
(Sorry, but you are not allowed to access the gallery)

Now, here is the batteries after re-wiring (Pretty much the hardest part of this rewiring was chopping out the incredibly tenacious sealant the old cables were embedded in where they went through the holes in the top of the battery box):
(Sorry, but you are not allowed to access the gallery)

The batteries (and wiring to the high-current fuses in the electrical bay) were all wired with 2/0 Gauge battery/welding cable (that's "2-Aught" or 00 gauge cable. 3 sizes larger than 2-awg). This thick battery/welding cable uses a large number of thin strands of wire, making it more flexible than regular cable of that size. The connectors on the cables are solid copper lugs. I didn't have a cable crimper big enough to handle cable this large, and the normal bolt-cutter-style ones are very expensive, so I got this little hammer crimper, which worked quite well. Just place the crimper on a solid surface, and give it 2-3 solid whacks with a 3lb hammer, and it makes a nice crimp. The only downside was that the hammer-crimper needs to be placed agains a solid surface to work, making crimping connections inside the RV somewhat difficult. My solution was to use a large landscape brick as a portable "anvil". It worked, although I did need to make some of the cables in the electrical bay a bit longer than I wanted, so I could pull them out far enough to reach a place I could use the crimper.  Once the lugs were crimped on the cables the connection was covered with some adhesive heat-shrink tubing, which seals the connection and keeps moisture out.

In the photo above, you might notice an 'L'-shaped bracket and small white cube just below the positive connection. That cube is actually a 250amp Marine Rated Battery Fuse, which is the master fuse for the whole system (the bracket is the fuse holder). In general, putting in a master fuse like this is highly recommended, even a fairly small battery bank can output an astonishing amount of current, at least for a little while, and having such a fuse can save you from an electrical fire if you have a short somewhere. Such fuses should be as close to the battery bank as possible. MRBF's are designed to mount directly to the battery terminals, you don't get any closer. (Remember that fuses are there to protect your wiring. Thus you want little to no wire between the power source (battery) and the fuse, to lessen the amount of unprotected wire.)

Finally, there is what looks like a thin wire connected directly to the positive battery terminal, before the MRBF fuse-holder. That is actually the temperature sensor for the battery monitor. Temperature affects battery performance, so the battery monitor keeps track of that as well. (The sensor is an optional add-on to the monitor. )

With the re-wiring of the battery bank completed, the next order of business was mounting the cutoff switch, battery-monitor shunt, and new fuses in the new electrical bay. For the high-current fuses, I wanted one 50amp (to replace the failing circuit breaker on the connection to the existing fusebox), one 100amp (to replace the circuit breaker on the connection to the isolator/chassis alternator), another 100amp for the connection to the solar controller, and a 200amp fuse for the generator starter circuit (Which had no fuse before. While the starter does draw a huge surge of power while starting the generator, fuses take both amperage and time to blow, and the starter runs for only a few seconds at a time. I've used the generator many times since installing this, and that 200amp fuse has held up fine. And I no longer have an unfused circuit exposed on the underside of the rig.).  Normally, high-current dc fuses (and their fuse-holders) take up a fair bit of space, but, fortunately, Blue Sea Systems makes a very nice high current DC fusebox. This has slots for 4 "min-ANL" aka "AMI" fuses. Despite being smaller, these fuses have ratings up to 200amps, and are perfect for what I need. This fusebox also has slots for 6 standard blade-type fuses, so if I want to add some more circuits (and I do, for cellular amplifiers, wifi gear, etc), I can do that easily.  To make it easier to install the cutoff switch, fusebox, shunt, etc, I decided to build everything out on a little electrical panel, so I can just mount the whole thing all at once:
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The panel is just a piece of painted plywood. I also put in two 250amp terminal blocks, one positive (on the left side, with the red cover over it), one negative (on the right). This will make future installs of things like inverters easier. You will note that for the connection to the cutoff switch (one of these Marinco switches), I used a piece of copper bussbar to connect it to the positive terminal block. If I had had more bussbar, I would have used that for all the connections on this panel, as working with those short stubs of 2/0 cable was annoying. Alas, I didn't have more bussbar.  :P
On the bottom right side of the panel you will see a black block with two big brass bolts. That is the shunt for the battery monitor. The monitor is a Victron BMV-702, with the optional temperature sensor. The temperature sensor plugs into the shunt, then the display (which I mounted on the back of the kitchen cabinets) connects to a circuit board on the side of the shunt with a length of telephone cable.

Once the panel was built out, installing it was simple, just screw down the four screws I had already put in place on the panel, and attach the wires. The battery cables were routed through new holes I drilled in the battery box, a bit closer to the middle of the box. These, and the old holes, were later sealed up with some black polyurethane sealant.
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With everything connected, I could then test that everything worked once more, check all the DC circuits, start the generator for a bit, etc. Since everything did work (It's nice when that happens right off the bat) it was time to install the solar controller.

First, I needed some way to neatly run the wiring, the 4awg wires coming down from the combiner box on the roof, and the control cables going up for the displays for the battery monitor and solar controller, which are mounted on the back of the kitchen cabinets. While I could have gotten wire channel from the hardware store, I didn't think what they had would be large enough, so I picked up some 1-1/2" wire channel from a local electronics/computer networking distributor. This was a large as I could fit in the space next to the window valance:

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I cut a notch into the angled, carpeted panel that covers the wiring going from the lower kitchen cabinet where the fusebox is, to the battery box. (I cut a strip of the carpet loose first, and folded it back, before using circular saw to cut a notch into the plywood panel, that way I could fold the carpet back over to make it look neat). Once that was in place, I temporarily removed the window valence, and used a 2" hole saw to cut a hole into the bottom of the overhead cabinet, then another hole inside the overhead cabinet into the area behind the microwave where the access to the roof box is:

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Here you can see I have the display for the battery monitor mounted, as well. That just needed a 2-1/8" hole saw (although it was a tight fit, perhaps 2-1/4" would have been better?). I also mounted the display/control for the solar controller as well, although I don't have a photo from doing that.

Once the that was in place, I could run the cables for the solar panels and displays through the holes,  down the wire channel, and over up into the electrical bay inside the table.

The solar controller itself is a Victron 100/50 MPPT Solar charge controller. The Victron controllers are nice, reliable units, and if I ever upgrade my battery bank to Lithium batteries, they will support that. The 100/50 controller is large enough that not only will it support my current array, if I ever add 2 more panels for 600w, it can support that as well.

Once the wiring was in place, mounting the solar controller was simple. I did mount it on another plywood panel, but that was much simpler, since the only things on it were the controller, and the cutoff-switch for the solar array (another Marinco switch).
The panel was mounted on the side of the electrical  bay with some metal plates to attach it to the frame of the table (since the sidewalls of the table are too thin to drive screws into without them going through). I did have one complication, due to a goof-up of my own. When I ordered the solar controller, and the wire to run to the combiner box, I mistakenly thought that the terminal block on the controller would accept up to 2awg wire. It turns out that the 100/50 only accepts up to 6awg wire. (I had confused the specs with another, larger, model of Victron controller.) So, I had to trim some of the strands on the end of the 4awg wire with nail clippers to make the cable thin enough to fit the terminals on the controller. This worked, and I put some of the heatshrink tubing over the area where I trimmed to make sure a stray strand doesn't cause a short. If I had known, I probably would have run 6awg wire instead. Live and learn.

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You will also notice in this photo that I added one other, minor feature. I stuck a small, battery-powered LED light on the ceiling of the electrical bay. This is always a nice thing to have near a fusebox.

With the solar controller in place and wired up, I could turn the switch for the array on, and ta-da! Solar power. 
There was one more cosmetic thing to do.  I screwed a pair of 1x2's to the top and bottom of the opening of the electrical bay, and added some strips of velcro:

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And then took that piece of luan paneling that I removed when I opened up that area up, trimmed down the sides (to remove the overlapping area with the glue), added a grab hole near the top with a hole-saw, and some velcro on the back:

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The result, a nice neat door for the electrical bay:

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(Well, I also had to re-install the flip-up table, as well)

Ultimately here is the end result:
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In the above photo, the battery bank is charged, and the solar array is only providing "float" power to run the fan and lights I had on at the time.  When I first turned the solar array on, my battery bank was only 50% charged! I got busy installing the door to the electrical bay, and cleaning up the mess, and putting away tools, etc. before I took that photo. In a single sunny afternoon, the panels charged my battery bank (200AH) from 50% to 100% When I first turned it on, the array was putting out 330W! Not bad for flat-mounted panels.

In Conclusion:

I hope this write-up helps anyone thinking about a similar project. I've tried to link to the locations online where I got the parts I needed, and explain my choices.  For me, it's been almost two months since I finished this install, and everything has worked wonderfully. Even last weekend, when I was boondocking in a location with afternoon shade, and running the furnace at night, my batteries have always been fully charged by the end of the day.  I still have a few things I'd like to do, such as upgrade that chassis ground connection to 2/0 gauge cable to match the battery cables. Eventually, I'd like to upgrade my battery bank, and perhaps add an inverter, or inverter/charger, but RV's are projects that are never quite done, so those will be for another day.