Winter has set in... With cold temperatures and inclement weather more often than not, outdoor work on the wagon has crept to a stand-still. Even so, Siobhan and I have been busy...
We have been considering power options. Everything we have used so far in our wagon is natural--all the building materials and furnishings are of wood, brass, copper, iron, cotton, wool, and clay. Even our walls are painted with all-natural milk paint. All of the wagon's furnishings are antique--with the exception of our "antique icebox", which is really a compact refrigerator in disguise. (Sorry, but a refrigerator is one modern luxury we couldn't do without!)
Even though we now need it, it seems a shame to wire our wagon for modern electricity amidst all our lovely antiques... not to mention, the necessity of "hooking up" to an electrical source seems to tarnish the very freedom our wagon stands for. So as a compromise, we have decided to use a small portable solar system as a power source for our wagon--and while it is certainly modern, at least it is semi-mobile, self-reliant, and green! (Hmmm..."green" gypsies!)
We plan to use our solar power primarily to run the mini fridge and (6) 12volt reading lights. ( Doesn't sound like much, does it? ) Now that winter had driven us indoors, it seems like a good time to plan and buy the components for our system. With a vague idea of what we want (and no earthly idea how to build it) we begin...
Three books and much online research later, we were more confused than when we started! At least, until I came across an archived 8 page post on rv solar systems @ chromolywally.com. If you're feeling a little confused about solar power systems in general, give his article a read.
According to Wally, it's not that complicated. In a nutshell, this is what we have do:
Buy some panels, a junction box, batteries and a solar charge controller, wiring, inverter, connectors, two kill switches and some fuses. Mount the panels wherever they’re going to go. Mount the charge controller in our wagon, and put the batteries wherever they’re going. Wire batteries together. Then connect the batteries to the charge controller, with a kill switch and a fuse on the positive lead. Connect the solar panels together in a junction box with a fuse near the positive terminal of each solar panel. Wire the solar panel junction box to the charge controller, adding a kill switch on the positive lead. Sounds pretty straight-forward...
And Wally's diagram seems simple enough--right? Easy cheesy.
At this point,
I know what you're thinking--
"Those damn gypsies are going to kill themselves, and burn their wagon to the ground."
NOT!
This is just the basic plan, the mere tip of the iceberg...We have to decide how much power we need--how many solar panels, what size wire and combiner box, what size charge controller and inverter, how many and what size 12v batteries. Also, we have to buy fuses, breakers, and a system monitor. ( This is all covered in the rest of Chromolywally's series.) We are to use the following formulas to determine our power needs:
amps x volts = watts
watts divided by volts = amps
watts divided by amps = volts
amps hours to be powered each day = ah
To begin with, we need to power a mini refrigerator and (6) 12v lights. Our power usage calculations are as follows:
.
*Refrigerator-
*Reading lights, (2) for each sleeping berth-
(4) 12 volt lights, one automotive incandescent bulb ( #1383) each-
1.5 watts x 4 = 6 watts
6w / 12volts = .5 amp
.5 amps x 6 hr. = 3.0 amps = 3 ah per day
** Average daily use (?) = 6 hrs **
(4) 12 volt lights, one automotive incandescent bulb ( #1383) each-
1.5 watts x 4 = 6 watts
6w / 12volts = .5 amp
.5 amps x 6 hr. = 3.0 amps = 3 ah per day
** Average daily use (?) = 6 hrs **
*Reading lights, (2) for Siobhan's reading nook (small bench by wood stove)-
(2) 12v lights, 13w x 2 = 26w
26w / 12v = 2.16 amps
2.16amps x 1.5 hr = 3.25 ah per day
(average daily use, 1.0 hrs.)
26w x 1hr = 26w per day
***Est. total daily power needed =1152 +36 + 26 =1214 w,
9.75 ah + 3 ah + 3.25 ah = 16 ah
After comparing our power usage figures with several other bloggers, we decided to build our solar power system with the following components:
single axis solar tracker kit (expandable in case we want to add more solar panels)
(4) 100 watt solar panels, Renogy brand
60' 10 awg wire, 30' red/30' black (to go between panels and combiner box)
(4) 20 amp in-line fuses (1 per wire leading to combiner box)
(1) 4-string combiner box
50' 6 awg cable, 23' red/25' black (to go between combiner box and charge controller)
30 amp 6 awg fuse/in-line fuse
(1) 30 amp MPPT charge controller
20' 02 awg cable, 10' red/10' black (to go from charge controller to battery bank)
1000 amp 02 awg fuse/in-line fuse holder
(4) 6v 230 ah deep charge batteries for a combined voltage of 12v 460ah (enough that batteries
won't fall below 50% charged)
(1) 1500/3000 watt inverter
pk of (10) MC4 solar connectors
Four and 1/2 hours of direct sun will produce 1800w of power from four 100w panels.
( 400 x 4.5 =1800 )--so we're well under that with our estimated 1214w.
Combined amperage of solar panels = 5.62 x 4 = 22.48 amps, within the 30 amp limit of the charge controller.
Combined amperage of solar panels = 5.62 x 4 = 22.48 amps, within the 30 amp limit of the charge controller.
Batteries will store 460 ah of power. (460a x 12v = 5520 w) .
Our power requirements are: 1214w / 12v =101a (w / v = a)
Our solar tracker runs on DC from our system, using <0.5 amps with no-load current, and 3 amps with maximum load current.
90% of 1500 = 1350w continuous
90% of 3000 = 2700w surge/start-up
Fingers crossed and breath held, this should power our wagon--at least, on paper! Stay Tuned--we'll let you know once it's hooked up...
180 w / 120v = 1.5amps