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Old 10-28-2022, 04:20 PM   #1
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Join Date: Mar 2015
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Solar System Update on Berkshire Diesel Pusher Motorhome

This report discusses the updates I made to the solar panel system of my motorhome. The solar panels are often given the name “photo-voltaic,” with the acronym PV.
An earlier 2015 description of my installation is at http://www.forestriverforums.com/for...er-105674.html and at https://www.forestriverforums.com/fo...ml#post2299957. These are of historical interest, but they are completely superseded by this report.
Many of the issues that I discuss in this report are relevant to other RV and even home installations, but some issues are specific to a Diesel Pusher Motorhome (Coach):
• The Coach has two battery systems: 2 x 12 Chassis or Starter maintenance-free sealed batteries and 4 x 6 volt House flooded deep cycle batteries.
• The Coach has 5 electrical bays, and some are not well suited to installation of components.
• A prime need is to have the system maintain battery charge while in storage, where winter temperatures can drop to -30°F, snow can cover the panels, winter days are short, and the sun is low at 51° latitude.
• A secondary desire is to maintain the residential refrigerator while in storage in temperate climates like Tucson at 32° latitude while snow-birding in winter.
• While boondocking and living off-grid might be nice, the Coach has a 5 KW diesel generator for air-conditioning, cooking and other activities, although this is subject to noise restrictions in some campsites.
I have updated an older system and now have the following components:
• 4 x 100 Watt solar panels, a mix of 2015 vintage GoSolar and 2022 vintage Renogy, all flexible panels glued to the roof.
• The panels are connected in series for a nominal voltage of approximately 80 Volts. Schottky bypass (shunt) diodes are mounted in parallel with the older panels to reduce the risk of hotspots.
• A 40 Watt Renogy Rover Maximum Power Point Tracking (MPPT) charge controller feeds power to the 4 House batteries.
• A Xantrex Digital Echo Charge bleeds some of the charge and bleeds it to the Chassis batteries, while avoiding high voltage situations that may arise from the Renogy MPPT controller.
• The panels are glued to the Coach roof with Sikaflex construction adhesive and 3M Very High Bond (VHB) double-sided tape.
• MC4 wiring carries the panel electricity down a hollow space on the rear end-cap of the Coach to the rear-most electrical bay that holds the Chassis batteries and now also contains the Renogy and Xantrex charge components.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:21 PM   #2
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Solar System Performance

It is important to understand that a 100 Watt solar panel will not produce anything near 100 Watts of power under realistic conditions. I used a calculator for my system that is provided by the US National Laboratory of Renewable Energy Laboratory (NREL) website at https://pvwatts.nrel.gov/pvwatts.php. A technical document of the NREL procedure and assumptions is at https://www.nrel.gov/docs/fy14osti/62641.pdf.
The NREL website gives hourly estimates of electrical output for a given location and date, which considers the angle of the sun throughout the day and historic weather or cloud cover. There is significant daily variation in their estimates, suggesting that they calculated the cloud cover over a very short historic time series, so you need to look at performance over several days to make realistic expectations. In terms of maintaining a battery charge during winter storage, the NREL calculator says that for mid-January in Calgary at 51° latitude, a nominal 400 Watt system would be expected to provide peak charge power to the batteries of only 70 to 90 Watts — an efficiency of only 17%-23% at mid-day. It would only produce power for 8 hours of the day, and the morning and afternoon power outputs would be much less. For six batteries, that is just a trickle (float) charge of 6-8 Amps, at best, and only for a brief period each day.
Before the updates to my system, I had my panels connected in a series-parallel arrangement whereby 2 new Renogy RSP-100DL-36 panels were connected in series, 2 old GoSolar panels were connected in series, and then the two series strings were connected in parallel through blocking diodes to a Zodore MPPT controller. I discuss blocking diodes and shunt diodes later, but they are intended to reduce power losses due to panel “hot spots”. A hot spot occurs when some cells in a solar panel are shaded, at which point they effectively become a resistor that consumes the power generated by other cells on the panel.
For mid-September in Calgary, the NREL calculations suggest that a 400 Watt system should produce 50-220 Watts at mid-day (depending on cloud cover, of course). But, on a sunny mid-September day at noon, my pre-upgrade system only generated 6.5 amps at 13 volts (84.5 Watts), which is much lower than what the NREL calculator predicts at the high end (for a sunny day).
I also conducted some experiments where I shaded parts or all of the panels. When all panels but one of the GoSolar panels was covered, the system produced no power, suggesting that either the Zodore controller was underperforming or that the shaded GoSolar panel was producing a massive hot spot that consumed all the power produced by the unshaded panel. With similar shading, a single Renogy panel would produce power, which suggests that their claim of “no hotspots” has some validity. If only a lengthwise (“vertical”) strip of a single Renogy panel was exposed to the sun, it would generate power, but if only a widthwise (“horizontal”) portion of a single Renogy panel was exposed to the sun, it could not generate power. Thus, the claim of absolutely no hotspots with a Renogy panel is not completely sustained. I discuss the details of the Renogy panel later in this report.
Thus, I had concerns that the Zodore controller wasn’t working properly and perhaps the GoSolar panels needed hotspot protection, so I upgraded the system, as I describe next.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:23 PM   #3
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Solar Panel Choice and Installation

The photos below show the installed panels on the roof of my motorhome, surrounding a roof-top air conditioner. The panels are connected in series to generate a no-load voltage of approximately 80 Volts. The older GoSolar panels have 24 square cells and are rated at 5.62 Amps and 17.8 Volts. The new Renogy Black Division RSP100DL-36-US panels have a dimpled surface as in the third and fourth photos (rotated 90°) and have 36 cells. They are rated at 5.2 Amps and 19.4 Volts.
The panels are connected with MC4 wiring and connectors. The second photo above shows my system of Y-branch connectors and MC4 Schottky diode packages. These diodes are readily available online, and I bought some that can carry 20 Amps and that are actually sold as blocking diodes, but I used them as bypass (shunt) diodes. I discuss the principles of how bypass and blocking diodes reduce the power loss from hotspots in a later section. When solar cells and/or panels are connected in series, it is appropriate to use bypass diodes. I assumed that the 2015-vintage GoSolar panels did not include such diodes, since they were not mentioned in any of the advertising literature. The literature for the Renogy panels advertises that they use two diodes and have no hotspots, so I assumed that they had some shunt diode protection. I discuss the Renogy panels in greater detail below.
Thus, I used one MC4 Schottky diode in parallel with each of the GoSolar panels, but no additional diodes for the Renogy panels. The package of diodes and MC4 Y-branches is shown next to one of the Go-Solar panels in the second photo above. The Y-branches come with a convenient hole for a screw to mount them to the roof.
The Schottky diodes come in a package with male and female connections on either end. The positive-negative polarities of the diodes and the package connections allow current to pass in the correct direction, but not the reverse direction, when used in either a blocking diode or bypass diode configuration. The diode wires are just crimped into the terminals of the MC4 connectors, so I soldered them in place for a more reliable connection. One connection is easy to solder and the other needs a pencil-tip soldering iron. Even then, it is hard not to touch the iron to the plastic case, but the point at which it damages the plastic does not impair the electrical or water-proof characteristics of the connector. I discuss these Schottky diode packages in greater detail below.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:23 PM   #4
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Panel Hookup: Series and Parallel

There are two issues to consider in the panel hookup:
• Series vs Parallel connection
• Using diodes to mitigate hotspots
First, let us consider the choice of series vs parallel connection. When panels are connected in series, their voltages add up but the current is limited to the smallest amperage current capacity of the panels in the string. When connected in parallel, their current capacities add up, but their voltage tends to become the lowest voltage of the panels in the array. To connect panels or panel strings in parallel, one can use pairs of MC4 Y-branch connectors, as shown below.
The GoSolar panels have 32 cells in series and the Renogy panels effectively have 36 cells in series, so the Renogy panels have a slightly higher voltage. If a group of GoSolar panels are connected in parallel with a group of Renogy (as in my original setup), there is a potential waste of power because of the voltage mismatch. On the other hand, the two panels have approximately the same 5-6 Amp current capacity, so there would be little waste by connecting them in series.
Moreover, Maximum Power Point Tracking (MPPT) solar converters work best by taking a high voltage and cutting it up with some sort of switching power supply to generate a higher current output and the lower voltage that is need by our 12 Volt batteries. MPPT refers to an algorithm of how to convert the power with high volts and low amps to power with a nominal 12 Volts and higher amps, with a minimum of wasted power in the process. They need to start with a higher voltage than the desired output in order to work — they won’t take a low voltage and deliver a high-voltage output. The conversion algorithm has to respond to bright days with high voltage and current and dark hours or blocked panels with low voltage.
Thus, it is best to have the solar panels connected in series to give more voltage for the MPPT controller to work with, in sunny as well as shaded conditions. But, there is a maximum voltage that an MPPT controller can take and my old Zodore controller couldn’t take more than 55 Volts, which is why I originally had a series-parallel connection. The new Renogy Rover MPPT controller can accept up to 100 volts, which is more than enough to handle 4 panels in series, which generate approximately 20 volts each.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:25 PM   #5
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Solar Panel Hotspots

When a solar cell is shaded, it stops producing electricity and, even worse, it effectively becomes a resistor that drains power from any cells that are generating electricity. These are called “hotspots”. This hotspot effect can be prevented by using diodes to prevent any reverse current from flowing through the “resistor” of a shaded cell. The best diodes for this are Schottky diodes, and they are included in some solar panels and solar chargers to avoid some hotspot problems. I used some Schottky diodes that came in an MC4 package, as shown below. The package has the wires crimped, so I soldered them for a better connection. Pay attention to what parts of the plastic are safely sealed inside the large red O-ring, so you only damage water-sealed plastic with the soldering pencil. When assembled, the package is compatible with the positive-negative polarity of wiring from solar panels, so it allows current to leave the panel, but not reverse back into it. (Below, I discuss the possibility that the MC4 diode package was assembled improperly and the diode inserted backwards.)

When panels are connected in parallel with MC4 branch connectors, the output or input to the branch connector for each parallel element should go through one of these MC4 Schottky diodes, and this is called a “blocking diode”. This will prevent any shaded panel or group of panels from getting reverse current from other elements of the parallel system and becoming a hotspot. It doesn’t matter whether the diode is on the positive or negative end of the wiring — only one is needed to block the flow. If an MC4 diode package is built improperly with the diode in reverse, using it as a blocking diode will not damage the panels, but could burn out the diode — in either case, no electricity would be produced.

When panels are connected in series, a shaded panel can drain electrical power from the panels in the string before or after it by becoming a hotspot. The solution to this is to use a Schottky diode in parallel with each panel, to allow current to bypass the panel if it becomes a resistor. The Schottky diode presents very little resistance in the forward direction. Used in this manner, it is called a “shunt” or “bypass” diode. We can use the same MC4 diodes by installing them in a branch of a pair of MC4 Y-branch connectors, with the panel using the other branch. These branches are defined by the tips of the Y, and the bases of the Y connectors are open to provide solar output power to the charger.

Keep a very clear head when you wire up a MC4 shunt diode with a pair of Y-branch connectors, since you have a loop of wiring from the solar panel output to its input. Make sure that the other side of the loop has a diode in it to prevent the panel from shorting itself out. Of course, there is a small risk that the diode was improperly installed in its MC4 package so that it does not block the short-circuit flow. You can check the logic of everything with a multi-meter. Another simple approach would be to cover the panel before assembling the loop and then gradually opening it to the sun. If you are getting voltage across the bases of the Y-connectors that are not part of the loop, and the MC4 diode package is not heating up, then things are working properly. If you can buy the MC4 diode package from a well-known reputable supplier, you should be OK, but the big-name suppliers like Renogy don’t seem to be providing these diode packages.
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2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:29 PM   #6
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MPPT Charger Choice and Installation

I bought a Renogy Rover LI40A MPPT Solar Charge Controller, model RNG-CTRL-RVR40. It has a maximum charging current of 40 Amps and charges 12V or 24V systems of Flooded, Gel, Sealed or Lithium Ion LFP batteries. Fortunately, the price seemed to dip when I bought it — prices change with the C$.
The Rover came with a sensor for battery temperature, which I attached to the lift lug on one of the house batteries with a cable tie. I bought a Renogy BT-1 Bluetooth module that plugs into the RS232 port, so that I can use the Renogy Bluetooth apps to monitor the charger performance and history, and to adjust the charger from my phone.

The unit comes with 4 push buttons: Up-Down and Left-Right. Although not labelled as such, the Right button is also the Enter button, which is crucial.
Press the Up-Down buttons to move through various information displays for the LCD Display screen. The screens appear in the sequence below when you press the Up button and the reverse sequence when you press the Down button.

The hard copy and online manuals for the unit provide a lot of details about the performance of the unit, but unfortunately are rather opaque in the discussion of how to adjust the charge parameters in the LI and USER modes. One version of the manual simply says “Battery charging parameters in LI mode and USER Mode can be programmed using the Solar Monitoring Software or Renogy BT App.” Another version of the manual is more helpful and says “The charging parameter setting (Equalizing voltage, Boost voltage, Floating charging voltage, over-discharge return voltage, Over-discharge voltage) are only available under the battery “USER” mode. Press and hold the right arrow to enter the programming settings and continue pressing the right arrow button until you see the desired voltage screen.”
After some searching on the Internet, I saw a helpful YouTube video. I went to the screen for “Programming Battery Type” by following their instruction “To enter the battery programming settings hover over the Battery Voltage screen and press [hold] down the Enter button. When the Battery Type starts to flash press the Select [Up/Down] button[s] to cycle through the battery types and press Enter to finalize selection.” This gives a choice of GEL, LI, SLD, FLD and USE. You might need a magnifying glass or the magnifying feature of your smartphone camera to read these choices. To adjust the charge parameters, select USE, which is the USER mode. When the Battery type screen shows USE, press the right Enter button to scroll through the programmable parameters in the photo below.

The user can adjust the parameter with the Up/Down buttons. The charger is designed to enter an equalization mode once per month for 2 hours. This is an over-voltage situation that can boil the flooded house batteries dry, so I prefer manual control of this. Thus, I reduced the Equalizing voltage to the 13.8 Volts, which is the default Float voltage. The Boost voltage is the point at with the charger will switch from Bulk Charging to Constant (often called “Absorb”) Charging. In the Constant charging mode, the charger maintains the Boost voltage for an unspecified period of time, after which it switches to the Float Voltage state. The Rover Default Boost Voltage is 14.6 Volts. The Magnum ME-RC controller for Shore Power charging that came with our motorhome has defaults that are slightly lower: Boost/Absorb transition of 14.4 Volts and a Float Voltage of 13.2 Volts. I’ll have to watch the performance of the solar system in storage: I’ll lower the voltages if the batteries are boiling dry too quickly or leave them at the Renogy defaults of 14.6 Volts and 13.8 Volts if I am having trouble keeping the batteries charged while in storage.
After the desired parameters have been set, one must hold the Enter button down to leave the Charger in User mode with these settings.

Renogy has two mobile apps (DC Home and Renogy BT) that can be used to connect to the BT-1 module and see the current and historic performance of a Renogy MPPT controller. One of them, Renogy BT, is supposed to be able to set the voltage parameters as an alternative to using the Renogy unit itself. I didn’t know the password for the app, and so I wasn’t able to test this. I subsequently found the documentation for the app and the password at https://www.renogy.com/content/files...BT-1%20APP.pdf. Note that your smartphone can only connect with one of these apps at a time. It seems that the Renogy BT app will do everything that DC Home will do, plus change the charger parameters. This extra feature can be useful, if used properly, and dangerous if accidentally used to create a bad configuration.

I discuss my location choice and wiring layout below, but a few details of the Rover installation are noteworthy.

The Rover has 4 keyhole slots in the back flange, which are hidden by the front of the unit. It would have made more sense to make that flange wider, so that the mounting screws could be easily accessed from the front. The Rover did come with 4 standoffs that can be bolted to the back flange and then provide screw access from the front. This is ungainly and setting the panel away from the wall breaks the venturi tunnel that Renogy built into the back flange for improved ventilation. It is just an odd design.
The Rover only has labels for the electrical connections that are viewable from the bottom of the unit, so I wrote the same information on some white tape and put it on the front of the unit. (During the installation, I covered all the holes with tape, so that they wouldn’t collect debris.)

Reviewers on Amazon complained that their screwdrivers kept slipping off the screws used for the electrical connection. These reviewers probably used Phillips screwdrivers, which are designed to “cam-out” or slip under high torque. But, the cross-head screws are actually Posidriv screws (marked with diagonal stampings between the crosses in the head), and they will not cam-out if you use a Posidriv screwdriver. A Phillips screwdriver had tapered flutes, but a Posidriv screwdriver has flutes with parallel faces. Some Phillips screwdrivers have a pointed tip that prevents the driver from bottoming in the screw head, and such heads can be ground down to reduce the cam-out problem. The best solution is to buy a Posidriv 2 screwdriver bit from Internet vendors or some hardware stores.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:32 PM   #7
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Panel Mounting, Wire Routing and Choice of Electrical Bays

In my original 2015 installation, I was advised by GoSolar that a good installation procedure for the panels was to use 3M Very High Bond (VHB) double-sided tape and Sikaflex construction adhesive, which is specifically designed for outdoor use and exposure to sun, rain and freezing temperatures. They said that either alone was sufficient, but I used both, not bothering to use the supplied screw holes. I have found this to work well for 7 years. I continue to use the Sikaflex adhesive to seal holes and mount other items on my roof. The Sikaflex provides a flexible bond and water seal, and does not crack in sunlight or at extremely low temperatures. It does not allow the growth of mold. It is reasonably priced and readily available in home supply centers, usually near their construction adhesives (like Lepages PL series), rather than near the caulking compounds (like silicone sealants). There is some Dicor in the original construction of my coach, and it doesn’t perform any better than the Sikaflex but is more expensive and harder to find, which is an issue if you don’t use it for a year and need to buy a new tube every year. Note that my roof is not rubber, but fibreglass bonded to a thin plywood sheet. I’m not sure how well Sikaflex would work on rubber.

My motorhome has 4 electrical bays on the driver-side plus a sliding drawer at the front for the generator, which has no room for additional components. The front side bay is small and provides no room for a solar installation. There are 3 side bays behind the rear wheels: a bay containing 4 flooded house batteries, a bay containing a Magnum inverter/charger system (and shore power components), and a bay containing two sealed maintenance-free chassis batteries for starting the engine, running headlights and so forth.

In 2015, I installed my solar charger in the middle rear electrical bay, because I was concerned about the effect of corrosive battery vapour on the solar charger components. Unfortunately, that middle bay has very little space for the solar components and 7 years of experience with the coach showed that the rear bay with the sealed chassis batteries was safe for solar components, with no corrosion evident (as distinct from the corrosion and salts filling the flooded house battery bay). Moreover, that bay had extra space for solar components, so I installed the Renogy charger in that bay and moved the Xantrex Digital Echo Charger (for the chassis batteries) to this location. This is shown in the earlier photo of the Renogy Rover charger.

At the top of that photo, you can see a light blue flexible Carlon conduit that brings the wiring in from the solar panels. It enters from a hole provided by the coach builder to the hollow space covered by the fibreglass end-cap of the coach. In my pictures of the roof installation of the solar panels, you can see a grey electrical box mounted at the top of the dark end-cap. The Carlon conduit is connected below it. This follows on from my 2015 installation, and I have always wondered why people would go to great lengths to run the solar wires inside the coach, rather than using this direct and easy route through the end cap.

Note the liberal use of in-line fuses in my installation. This provides protection from short circuits and also allows the installation of electrical components and wiring with the fuses removed so that they aren’t live while making connections.

My system has all 4 solar panels in series, with MC4 shunts alongside each of the 2 older GoSolar panels. I haven’t (yet) installed shunts alongside the newer Renogy panels, even though I am unsure of how they use diodes in their design.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:34 PM   #8
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The Renogy RSP-100DL-36 Black Division Flexible Solar Panels

I am generally pleased with these Renogy panels, which appear to be their latest design, introduced to Amazon in October 2021. The older model is called the 100 Watt 12 Volt Flexible (RNG-100DB-H), and Amazon says they started selling it in April 2018. The older panels have a slightly higher price.
I have trouble reconciling what I see on my panels with the advertised specs of these panels. I suspect that they have two shunt diodes, between the pairs of physically adjacent 12-cell blocks. This would mean that a totally shaded Renogy panel could have a current path that only has shunts for 2/3 of its route, while 1/3 of the panel would be a hotspot.
I made the following post on the Renogy DC Home website, hoping for more information about my RSP-100DL-36 panels, but have not seen any replies, yet. https://pc.renogy-dchome.com/#/detail/11439. I make slight changes, below, to that post for greater clarity, as noted in square braces.
The Specifications Datasheet at https://images.thdstatic.com/catalog...1752b8436d.pdf says that it has 36 (12 x 3) cells and 2 Diodes. When I look at my panel [as shown above], I see 3 lengthwise columns of 12 blocks. There are busbars at either end that put the 12 blocks in series, to give 36 blocks in series. Each block has 9 columns of wire-like traces (parallel to the long axis of the panel). At the ends of each trace in a block is a three-pronged "trident" that points to the next block (before and after, so both ends of the trace have a block).

[Note that the picture I took of my panels is slightly different from the pictures and illustrations on the Datasheet.]

When I shaded the long sides of the panel (left or right) from the sun, I was able to generate solar output, but when I shaded the short sides of the panel (top or bottom), I got no output. This suggests that there are shunt diodes between adjacent pairs of the three columns, to prevent a whole column from becoming a hotspot. Is this why there are only two diodes in the spec sheet — i.e. are they bypass shunt diodes between adjacent columns?

Questions:
1. Does this mean that the only diodes in the panel are two bypass shunt diodes? That seems to be inconsistent with the DataSheet that the panels have “No hotspots guaranteed”.
2. Is there a shunt diode parallel to the whole panel, to prevent it from it becoming a hotspot when connected in a series string of panels?
3. Are there any blocking diodes to prevent a whole panel from becoming a hotspot when connected in a parallel array of panels?
4. How are the 9 columns of traces connected? Are they connected in parallel within each block, or in series to the next trace and then gathered up by the bus[es] at the end of the panel?
5. Are the 3-pronged trident ends of the traces in each block some sort of solid state device such as a blocking diode? This would seem to be consistent with the claim of no hotspots anywhere on the panels.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 10-28-2022, 04:35 PM   #9
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Concluding Thoughts

Overall, I am happy with my system, despite my inability to understand the diode properties of my GoSolar and Renogy panels, and my difficulties in configuring the Renogy Rover charger.

I haven’t had a chance to test my system fully. I am posting these interim results because this might be of great interest to other users.

I installed the system under the cover of some trees in my alley, so the panels never got full sunlight. However, I was please to see them charging my batteries. I then put my coach in storage and it immediately became covered by 8” of snow. It produced no power in this situation, but when I swept the snow off of just one Renogy panel, the system started to charge. That means that I had an effective combination of diodes built into the panels, plus my two shunt diodes on the older GoSolar panels.

–Gordon
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2015 Berkshire 34QS
The Manual I wrote for our 34QS:
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Old 05-04-2023, 01:37 PM   #10
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Update: the system won't keep my fridge running

In April 2023, I tried running my refrigerator for several days with full sun at 51° Latitude in the Spring with 15 hours of daylight. The solar panels could run the refrigerator during the day, but didn’t charge the batteries enough to make it through the night, so my Magnum inverter generated a fault when the battery voltage fell to 12.1V, and stopped inverting to produce AC power. The fault clears when the battery voltage rises to 12.5 V. Looking at the history of the Renogy converter over this period, it seems that the voltage would fall at night, and then the batteries would charge enough during the day to allow the inverter to clear the fault and start. This cycle would repeat daily whenever there was enough sunlight to clear the fault.

However, if I can charge the house batteries first, the solar system should be able to keep the refrigerator running during daylight hours after that.
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 11-13-2023, 04:01 PM   #11
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Posts: 17
Thumbs up Keeping the fridge running

Thanks for posting your solar install experiences Gordon. We have a 2019 34QS and the lead acid batteries were nearing end of life, so I decided to approach the battery storage side of things before solar. I do have a 100 watt portable solar panel that I use to keep the chassis battery tendered while in storage. Keeping the residential fridge running was a priority for us in parks and Harvest host locations that do not have hookups and have limited or no generator runtime hours. We wanted to be able to overnight without shore power and still make coffee and use the furnace in the morning without running the generator. I just completed the install of 4 x 100 Amp Hour BB GC2H Lithium batteries. Once fully charged, as a test I ran the fridge for 18 hours and was still able boil water in the electric kettle and start the generator with ease. I suspect I could have ran the fridge another 18 without starting the generator. It’s a bit of an expense to upgrade, but with a background in electronics I was able to spec and install the system myself, otherwise the labour costs may have stood in the way. Fortunately, the 2019 Berkshire has a Magnum MS2012 inverter and a controller able to control/charge the lithium batteries. I had to switch out the 225 BIM with an Li-BIM to reduce the alternator charge cycles and I also added the Victron BMV-712 shunt for monitoring. I’m pretty happy with how the install turned out, I was able to pack 4 of the BB GC2 type heated batteries into the existing battery box. Next summers project may be to add some solar charging to reduce generator run time, however we’ll need to experience just how often we need to run the generator to determine the actual requirement for solar. I think the solar will only make sense if we plan to stay off grid for more than a couple of days.
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Old 11-15-2023, 05:22 PM   #12
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Join Date: Mar 2015
Location: Calgary
Posts: 994
Fix for lower half of the Renogy Rover Screen going blank

My Renogy Rover charge controller display acted up and the display only showed the top half of the characters, so that they couldn't be read accurately. The Bluetooth module still worked on my phone, fortunately.

I contacted Renogy and they recommended disconnecting all the inputs and outputs to the charge controller. And then re-connecting according to their standard instructions: connect the battery first and then the solar panels.

I did this by removing and then reinstalling the fuses (positive side only), and I'm pleased to say that the Renogy display works correctly now. I'm surprised that this fix does not appear on their website in an FAQ or troubleshooting page.

–Gordon
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 11-15-2023, 05:23 PM   #13
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Location: Calgary
Posts: 994
Update to my post of October 28, 2022

I haven’t been able to fully test my installation because a connection to the battery failed and I’ve been parked in the shade or travelling since then.

The connection failure was in the fuse link that I installed between the Renogy output post and the House Batteries. I had attempted to install connectors into that blade fuse link so that I could put an ammeter into the output line, thereby checking Renogy’s measurements. But that effort opened up the coiled springs in the blade holder and the fuse didn’t have a good connection when I reinstalled it. The fuse connector melted and failed when I got the system into good sunlight, so the panel was not working properly after that. I’ve since replaced the fuse link.

I am still concerned about the ability of the system to maintain a trickle (or tender) charge in the Calgary winter. Right now, I have the coach waiting in a service shop to get a new turbocharger, so I haven’t completely configured the battery system for the winter. It is not keeping the house batteries charged. Specifically, I have turned off the “salesman switch” at the front and turned off the Magnum inverter. But, I have not turned off the big switches at the House and Chassis Batteries, because I want the service people to be able to run the coach. Right now, the coach is parked in a position where the rear rooftop air conditioner will block 2 out of 4 solar panels as the sun moves across the sky. At 51° north and 8 hours of daylight, I’m not getting enough power to keep the batteries charged in this configuration. When I go to full storage, the coach will be parked in a position where the AC doesn’t block the panels, and I’ll have the battery switches turned off.

When I checked my system on a sunny day at 11 am on November 13, I was getting about 40 watts of output from my 4-panel 400 Watt array. The PVWatts online calculator that I cite in my report says that I should be getting 15 to 110 watts of output, using historical data for that time and date. The data variations are for historic cloud cover, so the appropriate benchmark should be 110 watts, and I was not getting that. But, this could be just due to the blockage of the panels by the AC unit.

I’ll report more next season when I get the coach up and running.

–Gordon
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Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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Old 11-16-2023, 03:35 PM   #14
2023 Allegro Bus 45OPP
 
Join Date: Feb 2020
Posts: 210
Not to high jack the thread

Quote:
Originally Posted by gordonsick View Post
Right now, I have the coach waiting in a service shop to get a new turbocharger,
Dang, sorry to hear this. What happened?
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Old 11-16-2023, 06:09 PM   #15
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Join Date: Mar 2015
Location: Calgary
Posts: 994
Adding Lithium Batteries to a Solar Installation, was: Keeping the fridge running

Wayne G makes an interesting post in this thread about installing Lithium batteries before updating to a large solar system. I notice from his Profile that he is from High River, Alberta, which is a 1 hour drive south of my home, so he is experiencing the same high latitude (50°) and cold winters (hitting -20° for lengthy times – that’s °C or °F) that I experience. That’s important for solar issues.

I’ve been considering going to Lithium Batteries (Lithium Iron Phosphate or LFP) in my coach, but I’ve got some concerns that I would love to see being discussed by knowledgable people. These issues could be relevant to Wayne G’s decisions about solar and battery capacity.

Here are the issues:

Keeping the fridge running while boondocking
Wayne discusses this issue, which is a big issue for me, as well. But, I’ll keep this post to the other part of his post, which is about Lithium batteries.

The need to protect Lead Acid Batteries from freezing in winter storage
My main concern is to keep my House and Chassis batteries from freezing in winter. I can run the generator every 3 or 4 weeks to keep them safe, but I don’t like to start the generator in really cold weather, despite the fact that I run synthetic 5W40 oil in it.

So, this pushes me consider solar charging in winter, with some periodic snow clearing.

The performance of Lithium batteries in freezing temperatures
I believe that lithium (LFP in particular) batteries are not damaged in the same way as lead acid by freezing temperatures, so it might be safe to store LFP batteries over a Calgary winter. I would love to see some authoritative information on that issue.

The other issue is that normal LFP batteries can’t be charged safely in freezing temperatures (I’m talking 32°F or 0°C, and the much colder temperatures we have in a Calgary winter). The work-around is to get a heating jacket around the battery so that it can be charged. Some LFP batteries come with an integrated self-heating jacket and a charge controller that requires them to warm up before charging. This leads to a concern about how much drain this imposes on the charger: how much current is warming the battery and is enough left over for charging the battery?

Mixing a Lithium LFP House battery with a Lead Acid Chassis battery
Our coaches have Lead Acid Chassis batteries to start the engine. The alternators on the engine are configured to charge a lead acid battery, rather than an LFP battery, so switching the Chassis batteries to LFP is not a simple matter. The simplest solution for our Berkshire coaches is to replace the Precision Circuits Battery Isolation Module (BIM) with their updated Lithium Battery Isolation Manager (LI-BIM 225). It retains the Emergency Start feature on the Dashboard and charges the Chassis Battery when the Solar, Generator or Shore Power charges the House Battery and it charges the House Battery when driving when the Alternator charges the Chassis Battery.

It manages the differences between the LFP and Lead-acid charge voltages and strategies, which is good.

But, there is a problem when charging the LFP batteries in freezing temperatures. The LFP batteries have BIM circuits in them that stop charging in freezing weather. And, when I checked with a Precision Circuits technician, he insists that if the LFP House Batteries aren’t charging, then the LI-BIM will not charge the Chassis Batteries. When I suggested that the LFP batteries would be seeing a charge voltage, which should be enough to cause the LI-BIM to charge the Chassis Batteries, he insisted that I was wrong. That is, I thought that voltage, not current was the threshold condition.

So, if I take his word as being correct, it seems that neither the LFP nor the Lead Acid batteries will be charge in freezing weather (using solar, generator or shore power). That is a serious problem for the Lead Acid batteries, but not too dangerous for the LFP batteries. It seems to me that there are 3 approaches to solving this very serious problem:

1. Assume the Precision Circuits technician is wrong and that in freezing weather, the solar panels will charge the Lead Acid Chassis batteries even if the LFP batteries aren’t charging. You could try this strategy, and just watch the voltage on the Chassis Batteries to see if they are OK.

2. Pay extra money to get self-heating LFP batteries. When the solar panel puts out a charge current, these batteries steal the current to heat the battery until it reaches a proper temperature and then switches to charging the LFP batteries. This should make the Precision Circuits do its job to charge the Chassis batteries.

3. Rely on the Xantrex Digital Echo-charge unit that I installed to bleed charging current headed for the Chassis Battery to charge the Chassis Battery. (I installed this before I understood that the Precision Circuits BIM might be doing the same job._ The instruction manual (http://www.xantrex.com/documents/Acc...0204-01-01.pdf) says that it works on voltage, rather than current and that it keeps the Chassis battery charge voltage safe, independent of higher voltages on the other side for the LFP batteries.
__________________
Gordon Sick, Calgary (51° North)
2015 Berkshire 34QS
The Manual I wrote for our 34QS:
https://www.forestriverforums.com/fo...ml#post2579202
Toad: 2019 Ford Ranger XLT 4x4; Formerly: 2005 Acura EL (aka Honda Civic)
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