Well, there was a little inverter called the Micro Sine, made by Trace. A 100w 12v or 24v input grid-synchronous inverter designed for mounting right on the frame of a solar module. It was great for “Guerrilla Solar” – back feeding power without the utility’s permission or knowledge. It was a feature in Home Power, people took photos with their little (and even pretty big) arrays wearing gorilla masks, articles were often written in a sort of tongue-and-cheek style. It was pretty neat. As time went on big arrays got cheaper, the big HV input MPPT synchronous inverters came on the market and utilities started becoming more willing to make legal protocols for grid tie systems. Trace got bought by Xantrex and the Micro Sine fell off the market. Guerilla Solar disappeared out of Home Power. Small distributed grid tie inverters have never caught on.

As with all things, however, you can count on the Chinese catch on about 10 years late and bring a facsimile of something the western market has disappeared for, but make it cheap enough to sell them anyways. So when I mentioned to my friend Micah that I had a 160w 12v PV array he mentioned that he had picked up a Chinese 12v/250w grid synchronous inverter in the style of the old Micro Sine- but he didn’t have enough solar to push it. He offered that I should try it out.

It worked fine- just as it should have. And I have to say, it was a bit of a thrill to see that 100w of rogue energy flowing back online, PG&E none the wiser.

The biggest improvement is brought by the box I built to house the batteries and system components. It lives outside the house, so I can finally get my closet back and not worry about acid spills or charging gasses.

The box is actually dual-purpose- it is designed to house the charging cord for the EV Miata so that once I park it in the driveway the charging cord will always be available.

I rewired the system (again) including a fuse and shunt for the Bogart Tri-metric meter. The charge controller and gray box are still from the very fist version of the system.

I also installed new wiring from the panels, using 8/2 tray cable. This replaces 6ga THHN in plastic conduit, which replaced exposed 8ga THHN. I added MC3 leads to the panels and soldered MC3 pigtails to the top end of the tray cable run. Either of the previous wiring solutions would probably have worked OK, but I really wanted to get rid of some of the persistent crappyness in the system. The cable is then connected to the charge controller using a SB 50 connector (and some leftover pink 6ga THHN… it’s not all gone). The 2 L 16 batteries are hooked up with a 200A class T fuse and block. 16/4 tray cable runs inside to power the Tri-metric and another run of 8/2 tray cable runs inside with a SB 50 to power loads. I made a SB-50 -> 3x powerpole pair adapter to break out the power and be able to use powerpoles for distribution.

So far I’ve just been running my computer on my old modified sine wave inverter, which makes everything buzz. I have plans for a DC-DC adapter for my laptop, as well as some direct DC hookups to other lights and things.

The Tri-metric meter is very useful for being able to tell what’s going on with the system, it’s really the confidence gained by that knowledge as well as the security of having the gassy batteries outside that makes me willing to use the system. Which I have been- in fact I’m using it right now to power my computer as I type. On a good day the panels generate far more energy than I need to run just my computer and stereo, I need to find more loads I can transfer over to the system.

It always feels good to “finish” a project (electric Miata? heh. soon, soon).

I set this system up for my Northwest roadtrip, as previously described. It worked like a charm, supplying me with laptop charge and ample stereo bass all 2300 miles of my trip. What’s this about subs and bass exactly?

One of the prime objectives of the system was to power up my subwoofer system- because what’s a roadtrip without a subwoofer? You may be thinking to yourself, WTF? So let’s get this straight. I mounted an 80watt polycrystaline PV panel to the roof of my station wagon. I ran the power to a charge controller and 90AH SLA battery pack behind the drivers seat. And with the resulting charge I ran a small inverter and a subwoofer amplifier.

'90s Japanese midsize wagons aplenty

Simple enough- and in all seriousness, it worked really well. Here’s the details:

The module is an 80 watt Photowatt module I purchased several years ago and borrowed from my roof.

It’s anchored to the Camry’s factory-installed roof rails by way of 2×2 lumber, U bolts and plastic tube

Note to self- beware that the distance between the rails on the Camry gets bigger toward the front of the car!

12GA landscape-lighting cable is run in through the rear hatch- I’ve found that landscape lighting cable is widely avaiable and not too expensive, as well as water and sunlight resistant.

The cable is run forward to the driver side rear footwell

From there, the charge controller and batteries are hooked up, as well as the loads.I used the parts I had on hand- 2x  tired old PowerSonic batteries, a BZ Products M20 charge controller. The terminals are insulated with tape, I neglected to add fuses aside from the charge controller’s internal fuses- not a good idea, but I was lucky and was spared any disasters during my trip.

A small mod-sine inverter was sufficient to charge my laptop while I was camping. I made its leads long enough to move around the front seat area.

I put the sub amp under the passenger seat

And used this sweet pushbutton I scavenged from an old junked BMW to activate the amp

There you have it- for two weeks this system kept me supplied with charging power and sweet tunes. It was a no-brainer project for me since I already had all the equipment, but I could see something like this being very worthwile for the avid car-camper. It’s like how many RV people put up solar panels- why should they have all the fun?

If you’re interested in putting something like this together, there are a million different ways you could go about it- roof racks, solar panels, charge controllers, batteries- but here are some ideas of where to start.

PV Panels:

• Something like these is likely one of the easiest options- I have on occasion seen other panels of this sort for sale, all in one chargers with built in charge control. Not the most cost effective though.
• Traditional-style PV panels can be purchased from many dealers- this is one of my favorites. Chose a panel for output and dimensions.
• For permanent installation, particularly on lower-roofline vehicles like my Wagon (as opposed to a van) a glass-less panel may be a good investment to avoid the worry of vandalism or accidental breakage. Unfortunately the best choice, larger Uni-Solar modules appear to have been discontinued and are very hard to find.

Charge Controller

• If you found a panel with integrated charge control, you’re good to go. Similarly, if you’re using a tiny <10watt panel you are also OK- otherwise you’ll need a charge controller to keep your battery pack from getting roasted.
• A controller like this one will be suitable for panels up to around 80 watts. It also includes an LVD output that you can use to power small loads while protecting the battery from being entirely drained.
• This one can make for a very tidy installation as it mounts directly on the panel’s junction box- just beware that some small panels don’t use J-boxes.
• There are many other options. These cited in particular are just my recommendations.

Battery pack

• In order to use a battery in your car you really must use a sealed lead battery as opposed to a flooded one typically available at autopart and warehouse stores. Unfortunately these are much more expensive and pickier, but you don’t want to risk the explosive fumes collecting in your closed car that result from charging a flooded battery, as well as the danger of liquid sulfuric acid.
• You can check out Northern Arizona Wind and Sun’s selection here, or shop around. It can be worthwile to shop locally as battery shipping is often expensive due to their weight. 60+ Amp Hours will give you the best flexibility.
• Something like this is a nice option but quite expensive.

Make sure all your wires are appropriately sized (12GA min, 10 or 8GA OK) and that you use ample fusing. For systems this small an inline ATC fuseholder is generally sufficient. “Car Stereo” style fuseholders are also a good option, also easy to find locally and with higher current capacity. There is some benefit to using a fuse block, but this is one of the areas where it is easy to quickly stray from the KISS (keep it simple stupid) ideal of the project.

If you crimp terminals crimp them tight- you should be able to break the wire before it comes out of the crimp. Landscape lighting wire and ATC fuseholders/fuses can be found at your local hardware store. It’s no problem to attach an inverter to the system, or a cigarette lighter receptacle (auto parts store) for other types of chargers. A 30 amp system fuse will support a 350 watt load.

Hope you find this interesting or inspiring. I sure appreciated my purely solar powered sub tones all the way up and down the West Coast.

I realize it’s just a bit over-wired, 2/0 for a 300 watt inverter is truly ridicculous- but it’s not hurting anything and the value of just being able to hook parts up without redoing a million different things is truly wonderful every (infrequent) time it works out that way.

I ran my macbook charger on the inverter all afternoon, works great! I’m going to let the solar float charge the batteries again tomorrow and then I will be set to hook up the PFC charger to tune its voltage cutoff, now that I have a good way to pull power out of the batteries. (this is all part of the plan to characterize the behavior of the PFC’s regbus, as described previously) I still plan on hacking up a 12v laptop charger and installing some 12v lights but that can wait, it sure is cool to be able to use the solar power I haven’t been taking advantage over the last several years.

First, I picked up a pair of L16s to wire into the little photovoltaic system I set up years ago- and never bought proper batteries for. I had an inverter on the system (prosine 1000), but it seems to have broken at some point- I don’t know when or how, and I was informed that the prosine inverters are non-repairable. The charging circuit and charge controller are working just fine- the batteries are sitting there float charging. Unfortunately I have no way to use that power at the moment, I need to get some 12v CFLs and hack up a 12v powered MacBook charger, and maybe pick up a new inverter.

Second, and also purchased through Jim Ramos at American Battery in Hayward, 12 brand new, matched Optima Yellow Tops (D34) for the car! Wow, that’s a bunch of batteries! Things are looking good, so far they fit just fine in all my racks and boxes! I figure I should be able to test drive the car within a few good days of work- tieing up all the loose ends with the charging system and various plexiglass sheilds I plan to install over things will take a bit longer.