Some more notes on solar electrical

A friend recently asked some advice for setting up a solar electrical system for someone's van. Here's basically what I told him, from my experience.

A solar electrical system is a misnomer. It's not really a solar electrical system. It's a BATTERY electrical system. The battery is the single most important and crucial gating factor in the system, especially if you're going to be living in it full-time. It's all about the battery. This is because sunlight is ephemeral: it's there, then it's not, and you can't really predict how much you're going to get and when. It's not like you just plug into a grid and the power is always on. So you really are running on battery most of the time. Scrimp on battery and your system is going to be a mess. Get the battery right and everything will work fine, and even will tolerate mistakes.

I recommend only the best AGM batteries. Don't bother with flooded batts or even deep-cycle marine batts. Go for the good stuff: AGM's from the top manufacturers (when I bought mine, the best was Concord Lifeline, it may still be today, I don't know).

The next thing is: actually COUNT up your load! Do it in AMP/HOURS AT 12 VOLTS. It's crucial to keep the units consistent, and to use the units your battery capacity is measured in. My friend argued with me about this, but I'm going to stick to my guns. In a purely mathematical sense, he's right: you can use any units. But psychologically, and for simplicity, and to avoid errors, use the units your battery is specc'ed out in: amp/hours @ ~12v. So convert ALL your loads to amps @ 12v, and calculate the duty cycle-- how long you're going to be running it-- and make that amp/hours. Example: I run my netbook for 12 hours a day on average, and it consumes 1Amp, so it's burning 12A/h per day. For 120v devices, convert to 12v by multiplying the amps by 10. So 5A @ 120v is 50A @ 12V. That would be... a lot! See what I'm saying about psychologically? It's a larger number at 12v. This is important for realizing how much you're really drawing out of that battery.

Actually MEASURE the loads of your devices, don't go by the garbage that's on in the manual or printed on the back of the device or on its power brick. The UL listing on electrical items is for the maximum rating OF THE WIRE, not what it actually draws. So if you see 5A @ 120V, that means the wiring won't catch fire at 5A @ 120v. It doesn't mean the thing actually draws that! It might draw a tiny fraction of that. So put an ammeter or a kill-a-watt on the things and see what they draw (and then convert that to 12v).

Avoid 110V devices as much as possible. I have ZERO 110v devices running in my van on a daily basis. Once every few months (and only in bright sunlight!), I hook up my laser printer and turn on the inverter, for a few minutes. Everything else in here is converted to run on straight 12v. I have 12v-5v DC-DC converters (often called "chargers" or "adapters") for running things like phones and tablets. My refrigerator is 12v. I have a 12vDC shaver. My computers all have DC-DC converters that go straight to 12v. Lights are all 12v (and LED to boot, which is super low current).

Another thing is: you will overdesign your system by a huge margin, because you have to. Batteries can only use 50% of their rated capacity, and ideally you don't want to go less than maybe 75% of it. So if your battery says "130 Amp/hours", that's BS. It's more like 60Amp/hours, or really 50Amp/hours if you don't want to stress your battery too much. Same with solar panels: they only give their rated capacity in perfect full sunlight at noon. Most of the time they put out a LOT less. Like Flava Flav said: "don't believe the hype". Figure on a lot less.

Use only MPPT controllers. Don't bother with PWM controllers; they are not nearly as efficient, and you'll be wasting precious sunlight (plus PWMs are noisy and they give off more heat than MPPTs). I recomend the TrakStar SunSaver MPPT controller.-- quite possibly the best thing I ever bought for my van. It was the only affordable MPPT controller on the market at the time; I think I paid $150 for it used on eBay, but most MPPT controllers cost like $600 or thousands of dollars. So that's a good deal.

Also, batteries take TIME to charge and they can only absorb a certain amount of current at a time-- another reason to overdesign your battery capacity. High quality batteries will come with a data sheet showing the actual curves and giving the formulas. You can get away without all the math, perhaps, but do consider that they take time.

Also, your SunSaver MPPT will only put out 15A maximum in full sunlight no matter how many solar panels you've got. So that will limit how many solar panels you can practially actually use, and that in turn will also limit what you can draw at night.

And, if you have lots of battery capacity, and you make the mistake of deep discharging them (I did this, and found out the hard way), you'll never get them charged back up with just solar: you'll need a converter and you'll have to find some 110V place to plug in and charge back up in those situations. From there, the solar will keep the batteries topped up. So it's very good to have a 110V converter/charger around for those situations. And if you're going to be boondocking, and can fit one, a gasoline genset is a good backup to have.

Now, put all this together, and you realize: I really don't have a lot of power here to work with. It's true. Which brings us to the last thing:

WORK THE DEMAND SIDE! Try to limit how much load you have. Sell your MacBookPro and get a netbook: instead of drawing 4Amps you're drawing only 1Amp. Run your refrigerator on propane or get a super efficient Danforth-based 12v refrigerator. Use only LED lights. Don't run your fan if you don't have to.

The general process I recommend is an iterative one:
1) calculate your load 
2) calculate how much battery you'll need to run that load through a day or two without sun
3) decide how much solar you'll need to charge up the battery from that level of discharge
4) repeat and find ways to reduce your load (when you realize you'd need acres of solar panels and a thousand pounds of batteries to live as if you were in a stick house).


Thinking in terms of conserving electricity takes some getting used to. This is why I recommend calculating in terms of amp/hours instead of watts. TIME is an important factor! You only have so many hours of sunlight. You only have so many hours of battery. Amps-per-hour is the correct measure to use, not so much because it's any more mathematically correct than, say, watt/hours, but because it is psychologically good to get into thinking differently about electricity and how you use it.

The biodiesel preparation project finally done!!

Last week, I finally reattached the fuel bowl drain hose. And, at last, after nearly 5 years of running biodiesel, I'm finally completely prepared to run biodiesel. 

It turns out I had to remove the alternator/pulley bracket, and remove the clamp holding the drain line on, then I could kind of wiggle the drain line enough to slip the hose onto it.

Drained the fuel bowl: no runs, no drips, no errors! Life is good. Also noticed a great deal of increased power, and no more clouds of unburnt fuel at startup. That means my "water in fuel" sender is probably disconnected or faulty, and I've had water in the thing all along.  Not good. I'm going to get into the habit of draining the thing on a regular basis now, maybe once a month since it's always cold, wet, and foggy here.

I realized I have to paint my rear roll-up door again. Only 2 years and the old paint is gone. Thinking of just using regular exterior house paint this time, not spraypaint, and see if that weathers the winter better.

Battery replacement

My 7.3L diesel requires two starter batteries: one under the frame rail and one under the hood.

When I bought this van a little over 4 years ago, it had terrible no-start and hard-start problems. The battery under the frame rail was fried, so I immediately replaced it with a new one. It was a Group 65 so that's what I replaced it with. The battery under the hood was dated from 2005, and it was a smaller 58R battery. That one tested out as still good, so I didn't replace it. I assumed it was the correct type, and perhaps there was just less room under the hood, but I should have smelled something wrong. The battery was held in with zip ties.

Well I eventually removed the zip ties and bought a proper correct bracket for the under-hood battery, but, since the battery was still good, I left it in place.

In the meantime, strange things happened. I fried several glow plug relays. Not sure why they fried. I have always had hard starting, even after fixing lots of stuff like the glow plugs and relays and filters and hoses and buying better fuel, but I attributed that to just something unavoidable when running biodiesel. Other than that, everything was fine.

Last year, I noticed that the resting voltage of the batteries was a bit lower than I remembered it being. Still, I didn't have good baseline data, and I got lazy, and didn't take the batteries out to check.

Last month, after parking from a long drive, I smelled smoke and ozone. Smelled to me like an electrical fire. I frantically looked around the interior of the van, and checked my solar house wiring and house batteries carefully, but the smell appeared to come from outside the van. So I figured maybe it was something not related to me.

This weekend, I wanted to get out of civilization so I went to a beach in a fairly distant area. I spent the day there. At nightfall, I tried to start the van. No dice. The battery meter level quickly identified the problem: dead battery or dead batteries. I checked with a meter: the under-hood battery seemed fine. I pulled off the case for the under-rail battery-- the one I'd bought in 2008--, and saw, the + terminal caked in corrosion and the whole top of the battery filthy with what appeared to be soot. And, a really bad smoky smell like an ashtray inside the battery box. The rail battery was showing low on the multimeter too.

I managed to get a jumpstart and cut my vacation short; heading back into civilization so as to buy a new battery the next morning. And I did just that-- after first cleaning off the corrosion (baking soda, warm water, toothbrush, worked great). And then... no start, still had low battery. Huh? Checked with multimeter, and the under-hood battery was showing 11.48v. Um, OK, that one is toast too, so off I go back to the parts store.

But the guy behind the counter said, you know, that van takes TWO group 65 batteries. This 58R is not the correct battery. It did seem like the battery shelf might be able to hold a bigger battery, so I took his word for it, and bought an additional group 65. It fit perfectly. The service manual doesn't really say what battery size to use, only that it must be 78 amp/hours or greater. But it does seem like the group 65 is correct in both locations.

So that'd explain a few things. First of all, why I kept frying glow plug relay contacts-- over current due to lower voltages from not having the correct battery. Also, that nasty burning smell I'd discovered a month ago was my under-rail battery dying. As was the low voltage I thought I'd seen a year ago. And the hard starting may have had to do with never really having the correct battery.

So now, several years later and several hundred dollars lighter, I have the correct batteries for this vehicle. It does seem to start faster, but I'll have to wait for more cold and/or wet weather to find out for sure.

Floor insulation complete

I did it; I put in isocyanaurate under my floor. The "joists" or crossmembers holding up the floor are 3" tall, so there's a 3" gap between the bottom of the floor and the frame rails. I inserted the insulation in those gaps, just like you'd do in a house, except I didn't use the pink stuff, I used these 2" sheets of insulation. The floor itself is 1.75" thick wood, so I used 3" wood bullets with a 1.75" fender washer to screw the insulation into the floor above.

Above the floor is a sheet of polyethelene, a sheet of some kind of sound-dampening insulation, then a sheet of spongey stuff to make the floor give, then finally my fake-hardwood pergo.

I've noticed already that the floor stays warmer, especially after driving (the air whizzing across the underside of the truck cooled the floor down a lot). This is good. We'll see what happens after a night of cold air. Temperature here lately has been very warm during the day, like 65 degrees, then down to a cold 45 degrees at night. It's an unusually dry winter so we're getting desert-like temperature fluctuations. The wind is from the east so we're not getting ocean humidity.

I notice it's also a bit quieter in here now too! That's a big win.

The whole project cost me like $80. It took me from 9am to 6pm. I was exhausted afterwards-- I am not used to working like this. But it felt good to use my body for a change, instead of spending 14 hours a day in front of a computer.

I hope this insulation will help in the summer too. I noticed that the van would get intolerably hot on some afternoons after the sun went low enough to heat up the ground underneath the van. I noticed that the floor would be warm. I think the insulation will help prevent that heat from radiating inside. If this summer will be like this winter, I'll have plenty of opportunity to find out.

Happy summer in California

This is pretty amazing, it's like 65 degrees, it's New Year's Day, January 1st.

I've been spending lots of time on the beach. I love it. It's warm and sunny.

On the days we've actually had winter weather, I have found ways to use passive solar heating too: I just open up the door to my box, park facing south, and make the huge 3-sided solar collector known as "The Cab" do its work to heat the place up.

It was cold enough a few weeks ago that I realized there's a huge oversight in my insulation: the floor! The floor is not insulated at all. And it was getting freezing cold in here, due to the floor. So I have to go buy some isocyanaurate sheets, cut them up to fit in between the beams of my box, and insulate the floor. Then it'll stay toasty in the winter, and, I think, stay cooler in the summer too!

I noticed last summer that the van stayed so wonderfully cool in the mornings on hot days, but as soon as the afternoon came it got way too hot. And I couldn't figure out where the heat was coming from. I think heat was rising up off of the road in the afternoons and heating the van up. So maybe insulating the floor will help me this summer, which, if this is any indication, is going to be an exceptionally hot one.

It's now an RV

After the disaster of the $250 parking ticket, I decided to re-register my vehicle as a California Housecar (RV).

I went down to the DMV, filled out the paperwork, and went through a brief inspection. Got a new set of plates, and paid my new registration-- now $90/year instead of the $350/yr I had been paying. Great, that'll make me back the cost of that ticket, not only this year but for every year in the future.

Next: I have to get some work and start making some more money!

$250 parking ticket?

I just got a $250 parking ticket, for parking a commercial vehicle in a residential area.

Really? $250? For parking? One night?

That's almost as much as my registration. And my 6-month insurance payment. Both of which are due this month. It's also more than I paid in a whole YEAR of parking tickets back before I figured out where to park without getting ticketed. Or so I thought. It's certainly more than I spent on fuel to drive to LA and back last month. One ticket.

This is a deeply troubling development.

The ticket was stamped early in the morning, before sunrise, before most people are awake, so I don't think it was a neighbor complaint.

It might have been a particularly unpleasant and sadistic cop, with either nothing better to do, in a bad mood, but that wouldn't explain the outrageous fine for something so simple; cops don't set the amount of the fines.

So it was a city government either deeply corrupt and shaking down everyone they can for money, or on some kind of weird war march against... something, I'm not sure exactly what.

This is really bad. I'm in kind of a financial hole right now, and I'm not sure how to get out of it. I spent much more than I made last month, including on that trip, and I didn't work at all because of the trip.

The registration bill is $350, and the insurance is $350 too. This is ugly. What I really should do is try to get the vehicle re-registered as an RV, then the registration will be $80 or so, and insurance will probably be less too. I have the paperwork; I just need to make the appointment to go in and get it done.

So now here I sit. My source of random programming gigs has seemed to dry up. I have one project I can and probably should complete for money, even though it probably won't amount to that much, but I can't get motivated to do it, even though I don't want to disappoint the customer who's waiting for it.

Like the ticket, this situation is really my own fault, due to fatalism and weariness really. I was really tired last night, and I just wanted to sleep, wanted to be left alone. I picked a spot that I'd parked in many times before, even though it didn't really feel right, because I hadn't been back there in a year or so. The last time I was in that neighborhood, I got a ticket for not turning my wheel properly against the curb on a hill. Still, that was only $35. And I stayed away for a while. I really should have continued to stay away. I certainly will now. Whatever is going on there regarding cops and parking, I don't want any part of it, thank you very much. $250 for parking!

My work fatalism is similar. I'm tired. Even after fixing my glasses situation, I can't really focus my brain on programming. It's torture, it's not fun, and the only reason I do it is because people will pay me to do it. Reading code and documentation makes my eyes, head, and neck ache. Doing mechanical-related stuff doesn't wear on me as much, because I don't have to use my eyes and brain so much, I can use my body, hands, etc, and that's less strain. But all my van-related projects are mostly done, and I don't see any reason in making work (or spending money) on stuff that isn't really necessary. I just want to be left alone, to maybe read non-software-related stuff, and think about more human things.

I've felt this before: like I keep getting hit, and I want to crouch down in a fetal ball and wait for the beatings to stop. I felt it a lot when I first started vandwelling. But, what I've learned over the last few years is that there is that the beatings do not stop on their own, that they just get worse. I'll have to battle back on my own in order to obtain any real relief. And I'm so tired, so much just wanting to rest, to sleep, to grow old quietly and safely. That is all I want.