A bit of context: In Spain, one of the European countries with better sunlight for solar production, some laws were passed recently that make it basically impossible for individuals to resell excess energy to the grid, so selling/buying from the grid on demand instead of using batteries is not really an option.

That's why when we see countries like Germany (not so much sun) going strong for solar Spanish people complain and try to change a corrupt government that passes laws that strongly favors utility companies. Not to say that some of this government relatives work in these utilities.

Its incredibly satisfying going off-grid. We have an off-grid cabin and its awesome turning up and finding the batteries fully charged and ready to dispense free electricity.

During the summer, rain water, solar power, cooking over a wood fire and walking or cycling to the beach means you can actually live at entirely carbon zero. One of the kids was fascinated by the idea that his iphone had been powered up using on energy from the sun.

Kudos to OP for doing all this in a city apartment!

Nice project, but I disagree on one point:

> For lighting, it's impossible to fall back on grid power because I had to cut the power cords of all lamps to make them compatible with the 12V DC grid

Why not get a cheap-ass car battery charger? He's using lead-acid batteries anyway, and a charger for these is approx. 50 €.

Or bypass the battery entirely and use a 12V 200W power supply instead of the battery voltage (to avoid overloading your PSU with powering the equipment AND simultaneously charging the battery).

>Some important challenges remain, most notably the washing machine, the bathroom and the laser printer. The problem with washing machine and bathroom is that they're on the north side of the building, far from the solar panels. We could go to a laundromat but there are none in town. A pedal powered washing machine requires space that we don't have.

You could try washing your laundry by hand. It isn't as much work as it might seem if you have never tried it. There must be something magical in the detergent because I can get clothes cleaner than I ever had with a washer back home with little work.

For example, to wash a shirt I just put the water / detergent mix in a basin and agitate the shirt with my hands for a couple minutes. Leave the shirt in the basin for 15 minutes for the detergent to do it's work. Agitate for another few minutes and then hang. First hang in the bathroom or outside for 20 for the shirt to quit dripping and then I put in front of a fan. The shirt is dry within a couple of hours.

Pants can be a bit more work depending on the material. Denim is heavy and eats up the dirt. I do the same as with the shirt but I use a tide bar to spot soap areas which get more dirt (bottoms of the pant legs) and brush those areas.

This does take longer than using a washing machine. But the clothes last longer and get cleaner. You aren't using electricity, buying an appliance and birthing a hung of metal and plastic that you may one day have to dispose of.

One weird effect that doing laundry by hand has for me is that it sort of puts me closer to my stuff. It's too easy to get something dirty, throw it in the washer and forget about it. Hand washing makes me more aware of how what I own also owns me and the energy it takes to maintain and carry this stuff around with me.

Could people with houses use legacy PSTN wiring to distribute 12V throughout the house?

Why is it a good idea to get off the grid? Genuinely curious. I would think that a networked connection of energy input/output nodes that is globally optimized would be a good thing. Not sure why it's better for anyone to have every node (home) operate independently.

Nice, but a lot of apartment managers would freak out over those kinds of installations being visible, at least for any halfway decent apartments.

Sad that we don't have a 12V power socket standard that is better than the lighter socket.

Grid actually is good (easier to balance etc). "Utility grid" is what causes most inconveniences.

What is this, Hacker News or something? :) (Just nice to see this kind of thing on here)

It's great that the author wrote up their approach, but one thing I don't see is how this was managed with the landlord. There is some clue in that the landlord installed the solar water heater. My interest comes from my belief that my landlord (or more likely the condo association that our apartment is in) would never allow this sort of installation. Aside from "aesthetic concerns", solar panels can potentially cause insurance rates to go up (firefighters don't like to douse electricity generators with water).

I recently built a flat roof 35m2 home office/gym at the back of my garden. I'm currently using an electrical convection heater and a 9kw instant water heater for shower/basin.

What would be the most cost effective way to use solar instead for heating/shower? I was thinking about putting a 100-200 litre insulated tank either inside or outside, and heat that with solar to about 70c, to use for both heating in the winter, and showers. I don't need cooling in the summer.

Has anyone done this?

It is great to be knowledgeable about energy consumption and conservation methods and to try to spread that knowledge. Realistically however, any action is negligible unless it is done by industries that will have a huge effect on the environment (airlines, for instance).

If you want to achieve X, it is ultimately best to spend your time convincing a certain number of local businesses to do X, or petitioning governments, etc.

You might also want to check the batteries you are using for your system. Due to the nature of the small space and high use, I remember from my armature radio license exam that some batteries vent gas when under operation. If I remember correctly, one such battery is NiMH.

You should really read into your batteries and your charge controller specifications before doing anything like this.

Other than that, this looks great!

Laser printers need much power for heating. Would it be possible to switch to a ink printer? They should work fine on 10 to 20 Watts. They even have external Poweradapters like a Laptop.

It depends on the usagepattern. Not printing enough would dry up the ink. Printing to much could be to expensive or to slow.

But heating dust up with a laser to melt it down on paper seems to be very inefficient in terms of energyefficiency.

Nice use of an in house microgrid. To me the striking thing was how the LED bulbs designed to be plugged into 220VAC 'just work' when plugged into 12VDC; I know this is because of their switchmode power supplies, it's still surprising.

You could consider doing this with "19.5V" (popular with laptops), although many will work just fine from 12V, or power-over-ethernet's 48V.

Why not place two 250 watt solar panels vertically in the windows. They are big enough.

All that work to get 150Wh per day? That's what, 20 cents worth of grid electricity?

>means you can actually live at entirely carbon zero

That's not enough. You need to also do something to offset the carbon dioxide that went into manufacturing everything and the transportation for it. Make sure you plant a few hundred trees if you want to be at carbon zero. You also need to plant trees to replace the wood you burn. And you need to offset the CO2 from process of making any food you bring in as well. Otherwise it's an unjustified feel-good exercise to claim you are living at carbon zero.

>> at entirely carbon zero.

Not even close. You're still eating something. Unless that came from a magic farm, fuel was used to generate/transport that food. And to complete the picture, you still have all the external resources provided by a very carbon-hungry society. That includes everything from health and education to military infrastructures ... all of which burn carbon in epic amounts. Carbon zero is an idea, not something that any one person can every accomplish.

Electricity derived from solar panels and stored in batteries is neither free from cost nor free from carbon emissions. The monetary cost and emission of carbon coincides with the manufacture of the solar panels and batteries rather than the generation and storage of the energy unlike many other technologies.

The costs and emissions of solar-derived electricity may be lower than alternatives but they are most certainly not free.

Is burning wood carbon zero? My in-law/relatives in Alaska say it can pollute quite a bit. Though I don't know how that relates to any carbon zero metric.

Up in the Yukon and Alaska plenty of people live in off-grid houses/cabins year round. It's amazing to never get a bill for your house - no water, no electricity, no garbage collections, etc. etc.

Friends have a 10kW system which in summer provides plenty of power for a sump pump for water, a big TV, espresso machine, etc. etc. In the winter they have to watch what they use, and they usually run the generator for a couple of hours a week to keep the batteries at a healthy level.

upvoted but also agree with others pointing out that you're far from being 'carbon zero', not that there's anything wrong with it :)

Sadly, giving up on the washing machine is giving up one on of the great labour saving inventions, and going back towards the time when washing took at least one woman-day per week.

http://johnquiggin.com/2012/05/03/housework-in-utopia/

http://www.ted.com/talks/hans_rosling_and_the_magic_washing_...

Don't you rinse your clothes before wearing them? Detergents can do nasty things to your skin.

Yep, and washing clothes by hand is oddly therapeutic as well. You end up looking for other items to wash, like bedsheets and towels and what not.

But it does do a number on your hands.

For me personally it's more about the dryer. I live in a cold/damp climate where it takes forever to line dry except for like 2-3 sunny/warm weeks in the summer.

POTS wires are 24 gauge [0] which can handle 3.5 amps [1] so you'd be able to transmit 12V * 3.5A = 42 Watts.

POTS often had 36V on it to power the ringer on phones so you could potentially up the power transmission by running your system at 14V. Some devices which consume a fixed amount of power would use less current, other devices would just use more power at higher voltage.

[0] https://en.wikipedia.org/wiki/Plain_old_telephone_service [1] http://www.powerstream.com/Wire_Size.htm

Yes, but you'd be better off using a higher voltage and switching DC-DC converters at the end.

The POTS lines would have ~50V on them in normal operation so they'd be insulated for 48V. However, V=I/R, and the lines have a constant resistance so if you can raise V and lower I you can get the same total wattage for a lower line loss. This is also why distribution networks are at 11kV and up.

Modern switching converters are pretty efficient, and you can also tailor them for the device so you don't have to double convert.

Yes, but only for very small amounts of power, as others have pointed out. A better idea would be to run DC on a select few runs of the existing 14-gauge romex from your breaker box to the rooms they serve. You'd be taking those 110v lines out of service and using them exclusively for DC, but you could pump a lot more power across them than you could across telephone wire. (You still wouldn't be able to run electric heating appliances or big motors or incandescent lights, but pretty much everything else in a modern house would work, modulo the need for switched DC-DC voltage converters.)

incredibly inefficiently, and only for loads of 5-10W max... phone wiring is not thick enough in gauge and 12V has very high voltage drop over distance for any appreciable amperage.

there is a good reason why we use 110-240VAC to distribute power in houses.

No. In fact most newer solar installations are using microinverters to convert to AC at the source. 20-30amps of DC requires quite a bit of copper to go even a few meters.

1 reason is you don't have to deal with the red tape of the ILEC. I've read a few stories of people installing solar onto their house. Then, when it's time to tie into the grid the electric company won't certify the install or drags their feet for months.

Even if you do get it tied in any new changes require recertification. I can understand the position of the ILEC. The homeowner just wants to get up and running quickly. The electric company wants to ensure the stability of the grid.

The article says 2/3 of the power bill was network connection cost.

>Why is it a good idea to get off the grid?

It's not necessarily. If you use solar cells in your home, CO2 emission is something like 180g per kWh. In that case you'd be better of getting you power from the grid, if you can buy power from wind farms or nuclear power plant. It's better than coal, but only marginally better than natural gas.

If you happen to live in a country where you'll need heating for large parts of the year, it also pretty hard to beat the efficiency of a large district heating plant.

It always struck me more as an engineer rig problem to solve. Sure there's an environmental aspect about divesting from fossil fuels, but the real appeal always struck me as engaging in the romanticism of being off on your own in the middle of nowhere and independent.

Sure making your apartment energy independent doesn't have to the romanticism, but it still has the engineering problem.

That's an interesting question and something I hadn't thought about. I think the biggest motivation for going off-grid is the relatively cleaner outcome. I.e. the control over the source/production (e.g. solar vs coal). So overall my guess is that the intent isn't to operate independent nodes but moreover to have control over the way the electricity is produced.

Transporting power isn't cheap. If you can generate the power where you need it, then you eliminate the need to transport it.