- This topic has 4 replies, 4 voices, and was last updated 3 years, 3 months ago by Anonymous.
- June 12, 2019 at 05:26 #32551JoelParticipant
I thought I would do a write-up on my solar install. My system design is the result of considerable research on RV solar installations that began long before I bought my truck camper in December of 2017. At this point, I have to give credit to Handy Bob and his informative, though rant filled, RV solar power blog. It is perhaps the most comprehensive, one stop resource to learn about RV solar power. In addition, Bob and his wife lived full time on solar power with no generator so he is absolutely walking the walk. The install was completed in January this year, and has worked great during about 10 weekend trips since. In the winter with temperatures around freezing and running the furnace overnight, we saw no lower than 88% charge overnight. If there was sun, we could recover that 12 percent during the day even with the low winter sun angle. Of course with the high summer sun and longer days, we are fully charged by noon on a sunny day. I just installed the compressor fridge, so that will probably increase the discharge somewhat. I’m anxious to learn how many cloudy days we can live through.
Photos of system are at: https://www.smugmug.com/gallery/n-9xfpPC/
My system includes 2, 100 watt solar panels, a battery monitor, a charge controller and two, 6 volt, 235 Amp-Hour golf cart batteries. My loads are: compressor fridge, furnace, water pump, led lighting, and a 300 watt, sine wave inverter that powers a tv, phone, laptop charger, and my Milwaukee M12 battery charger. I hope someday to replace the water heater and furnace with the Truma Combi system, but so far it is not offered for sale in the US (only to camper manufacturers, which sucks).
Solar Panels: I chose two 100 watt Vikram polycrystalline solar panels. Mine are from Backwoods Solar and cost $160 each including shipping. After I bought my panels, I saw that big orange has Grape 100 watt panels for about $110 each shipped. Shop around, as availability is improving and price is decreasing. To mount the panels, I fabricated custom brackets from readily available aluminum angle. I designed in a tilt capability, though I haven’t yet tried tilting my panels. I spent considerable time fabricating these mounts, so in hindsight, I would probably just purchase commercially available mounts. This is especially true if you don’t care about tilting the panels because you could use simple “Z” brackets.
Combiner box: Being a cheap ass, I didn’t want to spend $70 for a combiner box. It’s just a plastic box with 2 bus bars after all. After months of looking at what parts would work, a configuration finally came together. It consists of a PVC electrical box and two bus bars that are cut down to fit snugly on each side of the box. I got the box and the bus bars at Lowes.
Charge Controller and Battery Monitor: I chose the Bogart SC2030 coupled with the Bogart TM-2030-RV. With this pair you can enter the parameters for your particular battery setup, thus ensuring optimal charging of the batteries. The display toggles between battery voltage, net current into or out of the batteries and percent charge. I also got these from Backwoods Solar. They and Bogart both have excellent customer service.
Fused Disconnect: This was another place where I was able to cheap out (thanks Bob). I used an air conditioner disconnect that uses two cartridge fuses. I use one leg for the combiner box to charge controller IN and one leg for charge controller out to Battery +.
Mounting panel: I chose to mount the charge controller in a narrow spot opposite the freshwater tank. Given the tight clearance I decided to mount the Charge Controller and the Fused Disconnect to a piece of plexiglass, do the wiring I could on the work bench, then slide the whole assembly into place and secure it with screws. This was still tricky to install since I still had to install the wire from the combiner box after it was in place, but it was easier than doing it all in that tight space.
Wire: The wire from the panels to the combiner box is UV resistant 10 AWG stranded wire. The wire from the combiner box (through the disconnect) to the charge controller is 6 AWG stranded. This run is not exposed to the sun, so it doesn’t need to be UV resistant. I used #4 from the charge controller to the batteries.
Batteries: Two Crown CR-235 6 volt golf cart batteries wired in series to provide 235 Amp-hours at 12 Volts. I was able to get them locally for about $135 each.
My camper came with a single Marine Starting “Deep Cycle” battery. Of course Marine Starting batteries are not true deep cycle. “Deep-er” cycle than a car battery, but not true deep cycle. True deep cycle batteries come in three basic flavors, flooded wet cell, Absorbed Glass Mat (AGM), and Lithium. Given the cost of Lithium, I never really considered them. I’ve seen claims that they are the best value for the money, but I just don’t see it. I looked hard at AGMs, but ultimately chose flooded golf cart batteries. In addition to being the cheapest deep cycle option, I like that I can directly check their state of charge with a hydrometer. Plus they have been around forever, and I feel like manufacturers have better perfected how to charge and maintain them. The downside is that they have to be vented, which makes installing them inside the living space more difficult. This was my situation and I searched long and hard to find a battery box that would fit in the same location where my single battery box had been. I got lucky and found one where I bought my batteries. To make it fit, I had to move the water pump and re-route some pex water lines. I also modified the top of the battery box to provide ventilation to the outside.
Inverter: Morningstar Suresine 300 watt pure sign wave, also purchased from Backwoods (current price $266). This was wired right from the battery through a dedicated fuse.
Well that’s the system. Check out the photo link for more details on the install. I’m happy to answer any questions.
- June 12, 2019 at 17:08 #32557ardvarkParticipant
You did a nice job not only with your install, but also your diligence in researching rather than just “throwing parts” at things, as well as your pictures. I used to tell people on anything other than a simple install, I often spent more time planning than I did installing. You likely did the same!
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SC
- June 13, 2019 at 02:51 #32584Mello MikeKeymaster
Looks good, Joel. One question: why didn’t you flush mount your charge controller?
- June 13, 2019 at 04:35 #32591JoelParticipant
Thanks Mike! Do you mean the charge controller or the battery monitor? For the battery monitor, I used the plastic mounting box that came with the RV version of the Trimetric. I could have discarded that and screwed the unit directly to the wood panel, but I wanted the protection and the strain relief that the box provided. I may eventually add some spacers to get it deeper in the hole and closer to flush. As for the charge controller itself, it wanted to be as close to the batteries as possible and that space opposite the fresh tank is where I landed. Installing the charge controller and making room for the 2 batteries were the most challenging part of the installation. – Joel
- June 14, 2019 at 13:56 #32649AnonymousInactive
Very Nice job Joel, and I especially like the way you did your panel mounts!
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