Planning a Solar Install

So I'm planning to install a Solar Panel on my van...

I'm starting with 100w, I've gone with a flexible panel partly because I'm not 100% sure where I'm going to put it on the roof yet and partly because of the lower weight because we're always sailing close to the wind with a 3500kg MAM, every kilo counts. I have a 20A MPPT controller to allow room to add an extra 100w at a later date without replacing the controller, the controller also has a trickle charge feature for the starter battery.

Now I know most installs put the fused output from the regulator directly to the battery but I've been working through the electrics that are installed to understand what's there and how best to tie in with it. I've found the main control unit and also have an electronic copy of the manual. The control unit itself has an unused AUX input identified as being suitable to receive the input from a solar panel as well as an unused Charger input which would be connected to the DC output of an AC/DC converter, however the AC/DC converter on the van is connected directly to the battery leaving this input unused.

If I connect the output of the regulator to the AUX input, I should have the neat feature of being able to use the main control panel in the van to shut off the solar if necessary and it should also read the live current / voltage / power output of the regulator but an intermediate control unit between the Solar Regulator and the Battery may impair the Regulation function of the Solar Regulator and the Bulk / Absorb / Float / Equalization stages if the Regulator cannot correctly sense the battery voltage. It should be possible to do a bit of investigation with a multimeter to understand if this is a problem or not, that's the first job on the list.

The other potential problem is that the circuit diagram shows a 10A fuse on the AUX input, however the unused Charger input has an identical connector but shows a 30A fuse on the circuit diagram so unless the traces on the PCB look significantly smaller on the AUX circuit, it should be OK to uprate the fuse to 30A, particularly when there is no power coming into the Charger Port but probably best swap the 2 fuses to maintain a maximum 40A combined input. Worst case I could connect the solar feed to the Charger Port but lose the slick integration with the main control panel.

Connecting direct to the main control unit also allows for very slick cable routing behind a panel in the back of the wardrobe which already carries a plethora of cables, I think it will be wise to future proof the system by running 20A cables between the top side of the roof and the controller which would comfortably allow for up to 300w in parallel at a later date without drilling through the roof again. Even If I find some reason not to connect through the control unit, I think it's a good place to tie into the system, there is a direct connection to the Leisure and Starter Batteries from the Control Unit.

The goal is to have the install complete ahead of a trip to France later in the year, I'll try and document what I'm doing as I go, I must remember to take photographs. I'm open to any advice anyone has to offer or to any questions you may want to ask.

Simple is good. especially when fault finding later.

A solar panel installation thread (with pics) would be very good!

I am not able to just post the wiring diagram but if you take a look at. ( from Victron Energy )
BlueSolar-PWM-Pro-Charge-Controller and then click on Manuals, on page 2 there is a very simple wiring schematic that I fitted and it works great on my van

The Irish agent for Victron Energy is. JTM Power products. The Village Mill Enterprise Park, Co. Wicklow

I've been doing a bit of poking around, a bit of reading and a lot of thinking over the past two weeks and I've made a few decisions...

1. Water can pool on the roof of the van. I think it will be best to locate the solar panel near the front as it rolls down from the top of the domed section over the overcab bed down to the flat area. This will ensure water should never pool on the panels.

2. Although a fully watertight seal at the cable entry gland is a must, having the cable entry gland at a higher point on the roof is also probably the best course of action to minimize any problems down the line should there be any deterioration in the seal.

3. While connecting direct to the main control unit might be slick, the panel and cable entry location lend themselves to running the cables down neatly concealed in the enclosure for the fridge which is right behind the passenger seat, under which the leisure battery is located. Keeping the cable run as short as possible would dictate the controller should stay beside the battery and there's room in the enclosure under the passenger seat to fit the controller. There's already a cable running across to the starter batteries under the Driver seat so running the output for the starter battery along side this again kind of seems like the way to go. I have a power meter that can sit beside the main control panel which also has bluetooth functionality so it's not much different.

I just can't help myself however and I have ordered some block connectors to plug into the inputs on the main control unit because I'm a bit of a tinkerer and I just want to see how it works. I haven't probed the PCB yet, but visually the AUX input designed to receive a solar panel input and the charger input (the two unused cream coloured connectors at the bottom centre of the PCB as shown) share a common ground and they appear to connect to a common 12v trace via individual resettable fuses.



I've also had the panel hooked up to the controller, power meter and battery.



No power really being produced on a dull evening with the protective plastic film still on the panel but the basic setup is ready for testing in a bit more sun before moving to install in the van.

The manual says specifically that the Aux is used for a source of external energy such as the output of a solar panel regulator. The schematic shows the two connector pins as ground and +12v, an operational solar panel will be around +18 and need regulation. The board does not have regulation functionality apart from what looks like a resettable fuse which will limit current.

Visually, the circuitry from this input to the main connection to the batteries is very rudimentary but I haven't probed it to fully confirm this. My initial concern was whether any function of the board would impair the ability of the regulator to sense the battery voltage and charge in the appropriate mode.

I've moved away from the idea of directly connecting to the board but I probably will experiment a little to understand it better.

It pays to keep things and circuits simple.

The output from the solar charger/controller can go directly to the battery(s), that's the simplest and most straightforward.
The output can also be connected to the + & - from the onboard mains charger, this will mean the MH control panel and circuit board will see the input from the controller as if the charge is coming from the mains charger. That's the way I've mine wired, its a simple connection and it's problem free.
I wouldn't go messing about with more 'exotic' connections.

Water pooling on the panel shouldn't be an issue, if it's raining there will be little or no charge generated and as soon as you move the pool will slosh off, though I cant see the problem arising as panels are flat and shouldn't be saucer shaped.

I would mount the panel on a horizontal surface, not a sloped one, to maximise output for all sun elevations, if the panel is sloped it will happen that you will be parked sometimes east, west or north facing which will adversely affect the output. remember maximum output is achieved when the suns rays strike the panel at 90°

So the basic concept to route the wiring from the roof to the battery underneath the passenger seat (left hand drive for the eagle eyed among you)

There's more than enough room behind the fridge to run the some flexible conduit with easy access once the vent grilles are removed...



I'll be securing the conduit to the woodwork on the left of the cavity to keep it clear of the fridge gubbins.

The conduit came with glands, not in anyway watertight but they clamp onto the grooves on the conduit and have a little plastic nut to keep it closed. I got a few 1/2" nylon washers to fit in between to act as a little flange to squish the mastic and form a nice seal. I did a little prototyping to check the fit. On the roof, the cable entry gland will sit over the top of this conduit gland, both of which will be sealed to the roof.





The leisure battery is under the passenger seat. There is space in the enclosure for the Solar Regulator. There were also some some unused threaded inserts in the metalwork so I decided to use them to mount a board on which to mount the controller, note the little rubber grommet circled in the background, this is my cable entry point, pop this out and add a conduit gland with a nylon washer each side and I can bring the cable into the cab without drilling.



And with the Regulator mounted and the conduit gland in place but no cables yet and no sealant applied, I'll mention more about this later.



That's all the detail you're getting for this evening, the progress update is that the cables are running all the way from the roof to the cab, mc4 connectors crimped on the roof. The cables are running through the cable entry glands which will be sealed in place tomorrow over the rooftop conduit gland which is sealed to the roof on the top side and another sealed to the floor from the bottom.

Excellent post. Very informative.