Solar Panels Installation Kit

I always wanted to write down my experience with the installation of the solar panels kit mounted on Gigi and last week, after a nasty surprise, the occasion to both review the kit and showing a “new installation” did arose.

To better understand why Gigi is parked so close to the container, it is because last week, while on the roof for cleaning I manage to dislodge one of the solar panel by simply lifting it up.. 🤔 I was just shocked to see how easily the panel could be lift off the roof, and dread at thinking what it could have happened if I didn’t found out about then, just to find out while on the road next week instead…

I always pride myself of “do it properly do it once” but this time I failed. One of those times, where I didn’t follow what I normally preach. Simple as that. When I purchased the solar panel I asked the salesman what would have been the best silicone to use for gluing the panels to the roof. That was my first mistake. He was a very good salesman, but he never claimed to be a professional installer. Once at Bunning I picked up, based on a very short and quick search online, what I thought to be the best silicone for the job, the Sikaflex 11FC. Now perhaps the 11FC would, possibly could have done the job, but because of my next mistake, we’ll never know.

I had just painted the roof and I also cleaned the solar plastic mounts with methylated spirit. The next missing step, turned out to be fatal one, the one that gave me the chance to do the job all over again! It wasn’t the cleaning with methylated spirit per se that made the installation failed, bus simply the fact that most Sikaflex products do not stick to plastic properly, unless the plastic is primed with Sika 215 first!

A little unknown to me, $60 bottle of primer that ended up to cost me another $380 just to repeat the job, but this time properly. This time I called the company Sika directly and clearly explain the job I was performing. That’s when the technician told me that without Sikaflex primer 215, there was no hope for the 11FC to ever work. He also recommended using the Sikaflex 252 instead of the 11FC as it is the right tool for this job. While on the subject he also mentioned to really perform the job successfully, to also prime the roof again with Sika 206 G+P primer.

Finally, if you have watched the thousands of videos on Youtube regarding solar panel installation, you will quickly realise that just about all of them have made, like I did, one final huge mistake. For most, if not all polyurethane adhesive such as Sikaflex 252 as per product data sheet, (that I strongly recommend being read before any silicone job), you must have a bead of at least 5mm high for the product to be able to perform as intended. Most Youtube video have a bead of not more than a couple of mm. Nowhere near enough!

First picture show the lack of Sikaflex on the plastic, second picture show the advantage of using the container as a giant scaffolding. Picture with n1 does show the before and picture with n2 shows the after with the proper 5 mm bead. Just to recap, prime both surfaces to be glued together, and apply a bead of silicone of at least 5 mm thick. That’s it! Now that the proper installation has been taken care of, lets concentrate on the actual components.

Solar panels:

They come in rectangular or square shape and in at least three possible composition. My first suggestion here would be to cover the entire roof if possible with panels and for three good reasons:

• Panels do offer to the actual roof, protection from the direct heat of the sun, so covering the entire roof or as much as possible it is like free extra insulation. Considering the fact that you may have to park under the sun… 😂
• No matter what, you cannot ever have enough energy coming through your installation. Be the cloudy day, the panel at the wrong angle or simply a very hot day. It really doesn’t take much..
• Many panels, gives you the choice to install them in both serial and parallel, possibly partially eliminating the shade effect on the system and also still allow power to come through even if one panel is damaged

You must remember that, when you get energy out of the sun, everything (as usual) works against us: The temperature, the shade, the quality of the crystals, the geographical location, the length of the cables.. Anything between the sun, the panel and the controller will take precious power away from your final result!

In my case I started with 6 large panel for a combine power of around 2KW and planned to eventually fill the gaps with smaller panels. You could also go for a split system where one group of solar panel goes to one battery bank (main RV batteries), while the other group of panel goes to a second battery bank (Engine bay batteries). The different composition of the solar cell are clearly explained almost on every site that deals with solar panels and also in the book “Solar that really works” by Collyn Rivers.

After valuating all pros and cons I opted for the Sunpower Monocrystalline panels as the Poly still takes too much space for the same performance and the thin or flexible panel are just not there yet. Again, do your homework before opening your wallet..

Batteries:

The batteries are as important as the quality of the solar panel and again we have few choices available.. If money is not an issue go for Lithium-ion, otherwise the conventional Lead acid or one of the AGM variant is going to be the usual choice. As a rule of thumb, the cheaper and lighter the battery (not the Lithium obviously), the worse the quality and/or purity of the lead and number of cycles will be. Whatever your final choice may it be, just make sure you get the right amount of Ah required for your needs. You can’t ever have enough solar panel, but you can definitely have too many batteries connected to your system.

Charge Controller:

This is where, due to a large choice and options, things can get a bit complicated. As the name imply, the Charge Controller job is to keep your battery fully charge. Today, the most popular charger is the MPPT type, and they sell in Amps size, or at least that is what normally represent the number of a given model. For example a FLEXmax Outback 80 is an 80 Amps while a Victron 150/45 is a 45 Amps Controller. Bottom line is that, the choice of your battery bank (12-24-36 or 48 Volts) and size in Ah, in conjunction with your solar panels size (Amp, Voltage and Wattage), will dictate what Controller you will get.

Again the Outback 80 can handle up to 150 VDC, and the Victron 150/45, based on the first number, also does handle 150 VDC. I did purposely mention the FLEXmax and the Victron brands as I honestly believe those to be the best in quality and performances out there. So, how do we figure what we need for our system? Is not really that hard. This is what I did..

• Step 1: The Voltage. Based on the knowledge that the higher the voltage, the thinner the cable, it just seems obvious to try to go for the highest voltage you can go for. We are talking about the solar panel voltage here, not the battery’s voltage, as most MPPT can easily accommodate either 12/24/36 or 48 Volts battery’s bank. The two ways to achieve that is by connecting solar panel in series or by using large high voltage panels.
• Step 2: Roof Space or Wattage. After you have chosen a brand of solar panel the idea is to see how many panels you can fit by without loosing precious real estate. I manage to fit 6 large ones and have provision for another possible 8 smaller one. Off course, you could also find the total area available and then choose the brand of panel that best fit..
• Step 3: The maths. I then used pen and paper to calculate my power daily requirements. Here is where an “honest” and somewhat “conservative” list will go a long way to avoid future disappointments. What I mean is that if you try to run everything like at home, you are probably better off going for the usual 10000 Watt Generator that we see so often in the luxury RV in the US. Nothing wrong with that, if that the adventure you are after. But I digress now. After a couple of hours I came to the magical figure of 96 Ah
• Step 4: The Batteries. This is where the majority of people try to buy as many batteries as possible, in thinking that the more the merrier. Unfortunately they couldn’t be more far from the truth. Yes, more batteries equal more power available, but it also means more power required to fully recharge them. More weight to carry around and more money for the initial outlay and future replacements.

Truth is, the roof space available and the size of the solar panel, will dictate in a way the size and number of batteries and therefore the Ah available every day. Off course, you could also use portable panels or/and the roof of your trailer, if you have one..

With 2kw of solar power and 4 batteries that did allow me to have my 96Ah and only using 20% of the battery. This also mean that most days, my batteries are fully charged again before midday, making it easier to manage other situations, like cloudy and rainy days. Lots of people say that solar power is free, but again, that’s simply wrong. Beside the initial layout for the components, you also will have to replace the batteries every x many years (based on the quality and percentage daily discharge). For example if I get ten years out of my batteries, that means that I have paid around .43c per day. By adding another two batteries and possibly get 12 years, (from 20% down to 15% daily discharge) the daily cost would be of .54c per day. That’s why it pays to do your maths as more batteries doesn’t automatically mean cheaper electricity.