The original solar install was done in April 2015 about the install done on Phoenix, the bay window bus. Recently, we added a second solar panel and have gotten a lot of questions and interest regarding our setup so this post is meant to explain my research and walkthrough.
This will be a post that gets updated/fixed/ect. I am not an electrician nor do I suggest you do what I am doing, please consult an electrician prior to setting up electricity in your car/bus/wherever; IT CAN KILL.
- 2 x 100w solar panels
- solar charge controller
- deep cell battery
- blue sea fuse box [awesome little system]
- cables, fuses, clips, and other electrical supplies
- fire extinguisher
- usb charge port
Phoenix has 2X 100w Monocrystaline [this is an important distinction] panels. What does that mean?
Monocrystaline is [generally] more energy efficient per sq. ft than its cousin the polycrystalline, I’ve heard everything from mono at 20% vs poly at 12% to both at about 12%. You’ll have to do some leg work here yourself to find size to price to efficiency that is in your interests.
In the automotive world we work with DC power sources rather than the typical home with an AC [direct current vs alternating current] if you are interested in what the differences are here is a pretty decent walkthrough. I’ll get more into this later however.
So if you can remember back in school all that math you learned and most of you never used, ever, again. Well it is back to haunt me. Amps [amperage] are a measure of current, Volts [voltage/v] are a measure of “pressure” or strength of the current. Amps X Volts = Watts [wattage/w]. So I know 2 things already I have 2x 100w panels, so lets just make it easy mentally and say I have a 200w panel. My DC electrical system runs in a 12v system [the common car battery is the same voltage] so using that equation earlier using algebra I know 200w/12v= 16.6 amps. This could only occur in a perfect lab conditions, I don’t expect this high of a number in the least.
So lets round down to 16 amps potential from my shiny two panels! Hurray! Realistically I am seeing closer to 4 amps per solar panel, due to so many variables I’ll only list a couple here shortly: Cable electro resistance, solar panels heating up, charge controller creating additional resistance, Kevin installed shit wrong, being so far north, panels dirty, ect,ect ect.
Cool so we are making electricity!
What happens if you overfill a battery with electricity? The answer is: if you are lucky it kills the battery, if you are unlucky, it catches fire, or if you are as unlucky as I am normally you get a kaboom.
Remember earlier how I said this stuff can kill you? I was serious.
So, a charge controller helps that to not happen. Our charge controller is pretty smart and also turns off everything pulling from the battery if the battery hits 50% [batteries start to have long term damage and function deficit if you deplete below half, or at least the batteries we use]. Another cool function is it can auto shutoff things after X hours of no solar charge.
So we currently have a 125 amp/hour AGM [absorbent Glass Mat] Deep-cell Battery, so lets breakdown that mouthful.
125 amp/hour: I can run 1 thing @ 125 amps for one hour [for example a 120 amp welder], or waaaay more likely, our 4 amp fridge for ~31 hours.
x amps*y hours<125 amp/hours
BUT WAIT KEVIN! YOU SAID EARLIER THAT YOU CAN ONLY USE HALF A BATTERY SAFELY.
Correct, so lets halve those numbers earlier: fridge for ~ 15 hours. Or more specifically: (x amps)*(y hours)<(60 amp/hours)
AGM: So this type of battery doesn’t kill you! yay! So when batteries are getting charged they release hydrogen, thats normally in the air right so no harm right? Wrong! An enclosed area plus hydrogen production creates a scenario similar to the Hindenburg. We don’t like that, so AGM minimizes this to levels where it is safe to use.
Deepcell: contrary to a normal car battery, deep cell batteries are designed for endurance. Normal car batteries more than anything need that sharp powerful kick [to start the car] referred to cranking amps. Those batteries are sprinters, I need marathoners, in this world referred to as deep cell batteries.
But what do you use the power for?
We use this system to keep Phoenix’s [starter/driving] battery from not functioning after a nice long camping experience. By running everything through an auxiliary battery/solar system we keep that starter battery safe from all our electronics.
As of now we have a few things running on this system:
The fridge: runs at about 3 amps/hour and has a duty cycle at around 50% [half the time it is on, the other half it is off]
LED lights: runs about 0.1-2.1 amps/hour depending on color and brightness, we generally use it in the .8 amp range
Fan: ~1.1 amp [haven’t had enough testing time on this yet to know exact numbers]
USB Charge port: depends whats plugged into it. ~1amp for the average iPhone.
To figure out your needs for electricity use these graphs for your consumption range, and these to see what you need in solar panels to stay above that 50% battery range.
Connecting it all:
So this is where this goes from being understandable to downright annoying to have to deal with it.
Every time you connect objects together, you lose electricity, and it sucks. Honestly you don’t lose much, but when you don’t have much it adds up. Small cables can literally ruin your solar panels [and make them catch fire, seriously, This. Can. Kill. You]
I can’t explain this better than where I read it from originally, but the SUPER simple thing is this. The more cable you use, the more “resistance” and therefore less energy you capture. If your panels produce more than can be sent across the cables you get problems. Like the fire kind.
just read through this info here, because I can’t even hope to explain it better than them [and they made an awesome cheat sheet graph!]
There is also a fuse block to stop possible surges from destroying all my electronics. Cable routing is important [photo below is suboptimal cable routing] for a few reasons but, I can touch more on this another night.
Mounting the panels:
First, I grabbed some weights and laid them on top of the bus to test the pop-top spring’s ability to hold the additional weight from the solar panel [and it did thank god!]. Once the parts arrived, I mock set it up and started the planning aspect of mounting and cable routing.
The next step was modifying the garage door, removing the handle and adjusting the max height of the door gave me the last inch of clearance needed.
Attaching the panels to your car is very specific to the vehicle you are mounting it to. For Phoenix, since it has a fiberglass pop-top I have to create many mount points to limit cracking/breaking potential. Some people use VHB [very high bond] tape to mount their panels, I haven’t seen enough evidence [not paid for by 3M] to satisfy my concerns. Cars travel up to 80mph if gusts hit 20mph thats 100mph of wind pulling at the panel, not to mention you can see far higher numbers on the road… Just doesn’t feel safe to me.
There are simple brackets that I use on the solar panels to lift the panel slightly off the roof [keeping the panel cooler helps it work better]. Each panel has a 10 degree or so pitch to the right/left side of the vehicle, to help catch the early or late last rays of sunlight. I use rubber washers to help mitigate possible leaks; so far over a year of having a panel on the bus with no leaks.
No power inverter?
So far I haven’t found a good enough reason to setup a pure sine power inverter [unit changes a DC power source, to AC with a traditional house plug]. Everything we have needed has a DC variant. Running these inverters lose electricity in the form of heat, I don’t want to lose any more electricity than I have to personally.
This isn’t to say I will never get one. Currently we do without and we don’t feel any huge negatives from that decision.
There is so much more; but this is all I can do tonight.
Goodnight and good luck,
info sources: [some info is outdated just a heads up]
(pictures were taken when Phoenix only had 1 panel).