Diary of a Mad Scientist

the ‘take my bedroom off the grid’ photovoltaics project at my house is shaping up a bit. I went over to my ex-house in San Rafael to retrieve my PV panels, and ended up borrowing Jeff’s large panel and a cheapo inverter since he can’t install them there. So I have something like this :

two Uni-Solar amorphous panels I don’t know the wattage of yet- something like 35 watts each I’m guessing

Jeff’s 120 watt full-size PV panel

Trace C-40 charge controller

Jeff’s cheapo WalMart 700 Watt portable inverter (I’ll probably buy a 2000 watt portable instead)

For the ‘full-size’ system I’ve got some Xantrex 5548’s and a 2512 (the 12Volt will probably go to Tom for the portable ‘hot tub on a trailer’ project we’re working on). My roommate has another C-40 and we’ve got our eyes on various battery banks available to us. I ended up with various interesting odds-and-ends from buying the ‘pile of inverters’ - like a DC disconnect and various cables and breakers.

We’re not planning a grid-tied system for either of these house systems.

here’s my short-term to-do list for the ‘take your bedroom off the grid’ system:

a. borrow Kill-a-Watt or Watts-up meter from Tom’s job and do a complete survey of my bedroom electrical usage. I print the Biodiesel Homebrew Guide with a bank of laser printers and have NO IDEA how much power that consumes. one advantage of printing the book myself is that I get to use recycled paper, etc, and the idea of using green energy to do it also is an appealing selling point!

b. figure out needs to meet some of this usage. I"ll probably buy a few more PVs and go with cheapo golf cart batteries for the battery bank. Right now I have no idea what my usage actually is and what my sizing for this will be.

c. figure out where the battery box is going- my bedroom is PACKED but the downstairs currently has exposed ceiling joists due to renovation. Theres actually a tiny PV/battery/inverter system down there already in Dan’s shop, and I’ll probably site my battery bank there. I"m assuming that ‘bedroom off the grid’ is going to take 2 or 4 RV batteries or 4 golf cart ones. I’ve seen some nice systems that people have built for portability, and will probably try and make a battery box on wheels with some of the other components mounted on it. In the future the idea is to take the power system on the road for powering biodiesel demonstrations (or even RV camping…)

d. I’ve already started on the power reduction. Right now all my phantom loads are on power strips mounted within easy reach so I can turn them off, but that makes a spiderweb of cords all around my room. Few of the appliances/electronics are ‘on’ at the same time, but I like to leave them plugged in as long as I can turn the power-sucking transformers off with a power strip. I just picked up a couple of other power strips and plan on mounting one or some sort of master switch near the bedroom door so I can turn ‘all’ phantom loads off when I"m gone, and figure out how to group the rest of them by similarity onto their own power strips. This means the laptop chargers and the printers are on one strip since they’re used simultaneously, and the stereo and cell phone charger (used in the evening) are on another strip of their own. I"m actually unsure if printers are a phantom load or not- doestn’ seem like anything gets hot when they’re not in use, but if there’s a transformer it might be buried deep in the guts of the system.

Our house was on the Oakland solar home tour last weekend. I realized that one feature of my room is what’s ‘not’ in there:

I had to get a new computer recently but didn’t even consider a cheap desktop machine because of the power consumption issues. I"m doing everything with two laptops even though a desktop machine would’ve been an easier choice. I’m about to put in a second wireless access point (because the home’s wireless doesn’t reach to my room very well) and I’m really hoping that I can unplug it when I"m not using it.
My printers are energy-star rated. I unplug the stereo and dont’ run one with a digital clock. My alarm clock isnt’ a plug-in AC model, it’s a battery- powered (rechargable of course) gizmo. I’ve got an alkaline battery charge as well as the fancier NiMH one, and any ‘regular’ disposable alkaline batteries that come my way get reused at least twice. The lights are compact fluorescents. I use an electric toothbrush but it’s not left on it’s charger all the time as seems customary. Any other chargers are unplugged except when in use.

e. heat: I’ve got great afternoon light in my slightly southwest windows. I plan on sewing up window quilts for keeping the warmth in at night. UNfortunately this fall I"m in school till 9 pm, so I"m not there to run them when they need to be shut. I’m hoping that if I eventually build a big enough power system, that it’d would be energy-efficient to run a small motor on a timer or on a light-sensor each evening to close the window quilt after the warming sun passes. This is just a theory, I assume that it would save energy over my just waiting to close the window quilt when I get home and turning on a heater, but dont’ know. DOn’t have a good idea how much power the quilt operator motor would take, versus how many BTU’s I’m actually retaining from afternoon sunlight. At the moment it gets quite warm in there if I have the curtains open at the right time of day, but of course it’s really warm right now in the Bay Area.

f. lights- does it make sense to do 12V lighting? If I set up a 12V circuit in the system there could be a few places where it could be more efficient. Tom wants to do some creative LED lighting in his van for RV camping, and I’m hoping to hitch onto that project to build some custom low-volt lighting for my room. I’ve had ‘electronics projects’ on my ‘fun things to do with the boyfriend’ list for a while, and been waiting for something fun to come up that would be a good excuse to learn more about basic electronics. The window quilt operator and lighting is going to be one start to that project. Yes, I am a nerd- that IS my idea of a good time and luckily I can sometimes turn that into a social occasion.

g. circuits: because we’ve got a renovation going on downstairs and the joists are going to be exposed for a while, I’ve got plenty of time to run custom wiring in my room. I think I"ll be installing a series of switched outlets with the switches by the door, so that phantom loads are easier to remove.

h. I hope to do the bigger house system after learning a few lessons from the smaller one.

i. we’ve got various solar hot water projects on the back burner here as well, and that’s somethign I"ve got a lot more of a grasp on that PV/electrical energy control, but that’s a different to-do list.

Mark