The RETROvan will be powered by a combination of solar energy, 120V shore power and a 12V deep-cycling battery bank. Note that this “house” system is completely separate from the system that starts the engine and runs the original cockpit equipment, although it’s possible to combine them in the future.
InputsLet’s start with the most interesting input. Four of these flexible WindyNation panels will be affixed to the roof with Gorilla Tape, just behind the forward vent. Each 12V panel generates up to 100W for a combined output of 400W when wired in parallel. The panels are very durable and flexible enough to hug any curves. In fact, they’re so tough you can walk on them. These should provide ample power, but here in Portland we’re above the 45th parallel and have gray skies for several months of the year. So we’ll see how it goes.They’ll be connected via a variety of standard MC4 adapters using 8 AWG cable, and then a single pair of cables will drop into a waterproof gland mounted through the roof.This is a component I initially thought I could do without, but now I know it’s vital. It’s a 40-Amp MPPT Charge Controller made by Renogy. It maxes out at 400W (they say, conservatively), so it’s a good match for my four PV (photovoltaic) panels. Each panels can generate up to 6 Amps for a total of 24 Amps, well within the controller’s limits.
The controller monitors the batteries and regulates the flow of current from the solar panels, optimizing how the batteries get charged. It also prevents the current from discharging from the batteries back into the panels, which could fry them.
This is similar to what the inverter/charger does, but the controller uses DC while the inverter uses AC. In other words, the solar panels charge the batteries from the sun via DC. The inverter charges them from AC shore power. So, the big question is, what switches safely between them when AC is available? Will I need some big master switch or knob?
Here’s the Marinco stainless steel shore power port I mounted through the side of the hull next to the entry door.With this cool little adapter, I can connect any ordinary 15 or 20-amp household extension cord. How convenient is that?
AC/DC — For Those About to Rock!
Here’s the helm console, the RETROvan’s nerve center. Scotty would be proud. It’s made for pontoon boats. It’s hollow, and just happens to be the perfect size and shape for the power it will pack.
Two 6V AGM deep cycle batteries will sit end-to-end inside the helm console, wired in series to form a single 12V battery. They’ll deliver up to 200 amp-hours of off-griddy goodness, and are much more performant than one or two 12V batteries. Not only are they a perfect fit, but at 60 pounds each they’ll hold the helm console down on the floor (with the help of some bolts, of course). A solid base is important because the helm will also act as a bulkhead for the passenger seat.Here’s the power plant, and by far the most expensive component so far. It’s a ProMariner pure sine wave inverter, charger and transfer switch — all rolled into one. AC connects to one end and DC to the other.
Here’s the basic wiring schematic for the ProMariner. But, it doesn’t describe how to connect solar panels. Hmmm…
This system can supply up to 2000W of AC power from the batteries, which is enough to run most of my 120V appliances at the same time. But for ovens and coffee makers (basically anything that generates heat), you must be careful about how much power you draw. A coffee maker, for example, can gobble up 1000W or more for a short period of time. And off-gridding a 15,000 BTU RV air conditioning unit on battery power is out of the question. It can only be run continuously while on 120V shore power. So, circuit panels and gauges are as important as being energy-conscious:
This the AC panel, mounted on the right side of the helm. Its backlit labels will read something like:
- WARP DRIVE
- IMPULSE POWER
- PHOTON TORPEDOS
This is the DC panel, mounted on the left side. Its backlit labels will read something like:
- CABIN OUTLETS
The AC galley outlets will simply terminate in a Belkin surge suppressor.
12V lights, fans, TVs and other accessories can plug into these matching sockets.
And there’s even one for USB. These are all made by Blue Sea Systems in Bellingham, Washington where my kids go to college.
I still have to figure out all the right cable sizes, lengths, lugs, fuses and so on, and that’ll take some time to research. When connecting the main power and the batteries, for example, one wrong choice can spell disaster.
You may have noticed the helm console is sort of designed around a steering wheel. So in the case of the RETROvan, we’ll just mount an iPad instead. I did it by modifying a unique iPad stand made by AboveTEK. The result looks like something right out of Star Wars.
You may also have noticed a theme so far in my design and purchasing decisions. Virtually all of these components are black, white or gray in keeping with my branding theme. So that means if, say, a company’s product is some ghastly color combination like yellow or green, it doesn’t make the cut as long as I have other choices.