Roof Top Tent…Solar System

Recently I replaced my “Soft” Roof Top Tent (RTT) with a smaller, “Hard” RTT. The soft tent was an “Overlander” from Smittybilt.

The replacement is from Roofnest and I went with the lowest profile RTT on the market, the Falcon.

There were two reasons for the move….One was the Overlander was a bear to fold up when near 8′ high on the trucks cap. Actually, folding it up wasn’t too bad….But putting the cover on was horrible, especially in the rain! The second reason was I wanted a hard roof to mount a solar panel to so my auxiliary battery would charge while driving. The Falcon gave me easy of opening and closing and a hard top for solar.

So lets talk about the solar system…..

I started with a single HQST brand, 100 watt panel that I sourced from Amazon for $89 (All prices listed in this article are from AMAZON in 2022). Price was the buying decision. As you can read in other articles on this web site, I’ve done a number of solar projects. Currently most, if not all, solar panels are very similar. You can spend lots more for a 100w panel but I’m not sure you are getting any more for your dollars.

Folks are asking how I mounted the panels to the thin aluminum top of the Falcon. I used #M 5200 adhesive, pop rivets and Eternabond tape to attach “L” brackets to the top and the panels are pop rivited to the L-Brackets. If you have never used #M 5200, be sure whatever you glue down is where you want it. You are never going to remove it once the 5200 cures. Same goes for Eternabond tape. Near impossible to remove once it is down.

You can see two mounts completed with the addition of Eternabond over the bracket’s foot. Above is a bracket awaiting Eternabond.

From the solar panel you need a charge controller. I chose a Renogy Wanderer Li 30amp. This is a very inexpensive PWM (not MPPT) controller that cost $29 (2022). MPPT controllers are far superior in lartger systems. In a single panel system like this, it is not needed. PWM will be fine as we will see later.

From the solar controller you need to store all this FREE electricity. That requires a battery. I suggest you want at least 100aH (Amp Hours). You could go inexpensive with a good AGM (Absorb Glass Mat) type battery for around $200 for a quality Group 31 size. But the price of MUCH better Lithium batteries has really come down. I went with a LISUATELI 12v 100Ah LifePo4 Lithium battery that has a BMS (Battery Management System) with all the bells and whistles to protect the battery from discharge and charge errors. $339 (2022)

Add some quality wire of the appropriate gauge, and you have a solar system. The Renogy Wanderer solar controller has USB jacks on the bottom for charging your phone and other devices. Anything else could be attached to the battery with alligator jacks.

But I’m not like that…..I went a few steps further…

First I added a Blue Tooth “dongle” so I could monitor on my phone what the solar system was doing. This is the Renogy BT-1. $37 (2022)

But the BT-1 only tells you what is going INTO the battery. It doesn’t tell you how much electricity you are taking out of your battery or your % of usable battery life left. For that I added a “Shunt” type battery monitor from Aili. Voltage Current Meter Voltmeter Ammeter 100V 350A… $44 (2022)

I also added the Renogy optional temperature sensor that keeps track of the batteries temperature and adjusts the input current as needed. $10 (2022)

I put the battery in a plastic battery box and mounted it in the bed of the pickup truck. $13 (2022)

On my battery box, I duplicated the AILI battery monitor, USB jacks and cigarette lighter socket. This is so I can remove the battery from the truck and use it on my boat or remote tent camping. Another nice thing about lithium is it only weighs about 25 pounds where AGM is around 80 pounds! Very portable…

Next, I wanted a way to be charging the battery when there was zero sun and I was traveling. This requires a device called a “DC to DC Charger”. It takes power from your vehicles alternator and sends it to the battery while the engine is running. Back in the day you could just use a simple toggle switch and flip it on when the engine was running. But Lithium is more particular of the charging profile and most modern vehicles now now have “smart” alternators that will self destruct if you simply hooked them up to another battery. I went with the Renogy 40A DC-DC Charger. $160 (2022)

I also added an inverter that takes 12VDC and gives you 120V AC. This allows me to run certain power tools, lights, coffee p[ot and other devices that need 120V household electricity. I went with the GoWISE Power 1000W Pure Sine Wave Inverter . $160 (2022)

Interesting is that one of the biggest expenses was wire. You need very large, expensive wire to go from the vehicles battery all the way to the DC to DC charger. And you need good quality wire to interconnect everything else. You will also need fuses, circuit breakers, fuse holders, wire lugs, etc. There are great youtube videos that cover all of these aspects. Plan on around $100-$150 for all of this.

I built a control panel in one of the side tool boxes of my truck cap. I added cigarette lighter sockets, ANDERSON connectors for high current devices and USB jacks. Everything nice and neat and easily accessible.

So, how does it work? I recently returned from a week long trip. Running an ICECO portable refrigerator, charging camera batteries, IPADS, laptop and phones. Running lights at night a fan in the RTT. Two HotSpot cellular devices were connected and on 24/7……I never saw the battery below 94%……But the best part of Lithium is by 11am, the battery was back at 100% ! Even on total overcast days, the speed at which the battery is back at 100% is amazing compared to previous AGM batteries.

I’m beyond pleased with how this system is performing……Hope this article might help other thinking of adding solar to their RTT.

Be sure to visit other articles on Solar, Camping, RVs and other entertainment…..

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