On the sunny side of the street

So I've been fantasising about the irony of running an off-grid city apartment on solar panels.  And then it comes crashing down to earth when I realise that, in our situation, it's likely impossible and pointless anyway.  Solar panels will be expensive, we'll need too many of them, they probably don't capture much energy... that was the impression I had always got about solar power over the decades.

But costs must surely be coming down, and panel efficiency up (and thus fewer panels needed), right?  That's what happens with computers, does it happen with other technology too?  And in fact computers, fridges, washing machines etc. all now come emblazoned with low power ratings and power-saving "eco" modes.

And the installation cost could be regarded as an investment in the future of humanity (if burning a little less fossil fuel helps) or at least in the future of our household (if the Trumpocalypse reaches this far South).

Would it be possible to run an urban apartment on solar power?

Well, I've been reading Solar Electricity Handbook by Michael Boxwell. It has everything I needed to get some understanding of the options and complexities and challenges.

At the outset, it's clear that a big part of running a house on solar electricity is in fact just reducing the amount of electricity you use.  Which we could just do anyway, right?  So how much do we use?

I went around all the things we plug into the wall and read their power adapters etc. to find out their wattages.  For those that don't have Watts explicitly written, I know the voltage is 220V here, so I need to multiply that by Amps to get Watts.  Yay for maths!  Except some things (most importantly our fridge!) don't have Watts or Amps, and it turns out to be difficult to find out as I don't have the manual any more and the only one I could fine online didn't say.  So it's a bit tricky.

But I did discover that (according to the adapter at least) my desktop computer is surprisingly ridiculously power hungry, at 2 Amps. 2A×220V = 440W!  That's, like, almost half a fan heater, isn't it?!  My laptop is half that, and it's a faster computer!

Really, it would be better if I could measure their real consumption, so I can know if my PC uses a wopping 440W all the time (even when idly doing nothing all night) or whether it's just when actually doing some work.  The answer could make a big difference to whether I start religiously turning off my computer at night or not.

Fortunately, you can measure to consumption of appliances with a watt meter - a meter with a wall socket in the front and a plug in the back, that you plug in between the appliance and the wall.

Watt Meter

Unfortunately wattmeters don't appear to exist in this country.  They're available in Brazil, Chile, and Uruguay, but not Argentina. At all the hardware and electricity-stuff shops where I ask, they give me the "are you an alien" look, and tell me they've never heard of such a thing, and do I mean an electrical timer, or that they saw one once, at some faraway shop, where it turns out they give me the "alien" again look and tell me they've never heard of such a thing.

Not Meter

So I guess I have to trust the adapters and manuals...

If I'm aiming at just the water pump and the fridge (i.e. emergency power-cut supply), then it turns out we'd need to generate 2.4kWh per day.  If we wanted to cover everything we use electricity for, in the way we currently use it, including air conditioning and heating, we'd need a maximum of about 30kWh, and if we cut temperature control out of that equation, use laptops off their batteries that we charge as required, etc., then it would be 10kWh per day.

Unless we tried to go for the 30kWh, we'd still be probably consuming grid-supplied power, so it would be reducing rather than eliminating evil fossil fuel use (and with it the power bill).  I assume we simply don't have the roof space to generate 30kWh from the sun all year round, but that brings me to the next question...

How much can we do with the space we have, what would we actually need to install, and how much would it cost?

I have to get further through the book to find out...