Saturday, March 14, 2015

The Solar Power Hobbyist

I've recently started to dabble in 'hobbyist level' household solar power.
It's 'hobbyist' and not 'serious' primarily due to costs.
A solar system with enough capacity to power a household (on a sunny day), requires at least 3000 watts of power generation and maybe $20-30,000 in equipment.

My humble system generates a maximum of 450 watts and costs around $1000.

I recently added the 2 100 watt  panels on the left, boosting my power from 250 to 450 watts and wanted to see if I could run my computer system during the daytime and still have power to spare to save away in the storage battery for nighttime use.

I began my trial after the morning sun had reached a little over 1/2 the panel area

The panels are in the backyard, foregoing the expense and care needed to safely mount them on the roof.
At this exposure a quick look at the charge monitor shows that the battery is getting 8.6 Amps of current (the monitor is at the bottom of the photo, the battery is at the top):
This is good.  The battery that I have recommends a starting charge current of 8 Amps up to a maximum of 35 Amps.

The charge controller regulates the charging current to the battery and the power output when power is being consumed.   I will be simultaneously powering my computer system AND charging the battery with any left over electricity from the solar panels.  The charge controller will be managing the juggling of input and output power.


This the basic computer system that I want to power,  computer, some extra monitors, external speakers and internet modem:
I hook up a power inverter to the charge controller output.  The power inverter will take 12 volts DC power and turn it into 120 volts AC power that my computers 120 volt AC to 19 volt DC transformer expects to see. 
There is a lot of power waste lost in the inversion from 12 VDC to 120 VAC, it would be more efficient, just for the computer, to take the 12 VDC and transform it to 19 VDC instead of wasting the power sticking 120 VAC 'in the middle'.
Anyhow I turn on the inverter and feed to the 120 VAC to a real time power meter.  The power meter allows me to see how much 120 VAC power is being used.

I hook up my computer system and see that it is drawing about 1.52 Amps of AC current (the middle line in the read out):

It is interesting to go read the DC current output to see how much DC current is required to provide 1.52 Amps of AC current:
It is taking 9.6 Amps of DC current to get me the 1.52 Amps of AC current that my computer system needs.   A ratio of almost 10 to 1  !

Now, I'm drawing off 9.6 Amps for use but is there anything coming in from the panels that's leftover that we can save away in the battery ?

We do a quick check:

Yes, there is 10.1 Amps of DC current being fed to the battery.
So happily, I am both running my computer AND charging up the battery with juice that I can use to continue running the computer after dark.
This make a total of  9.6 Amps + 10.1 Amps  =  19.7 Amps of current coming in from the solar panels.
As the morning sun has covered more of the panel area, we went from  8.6 Amps to 19.7 Amps coming in !
Note:  the red box to the left is the 1000 Watt Power Inverter.

My daytime computer session ends and I check the AC power meter to find out how much AC energy I used today:
That's it..  260 watt hours  from the Sun to my computer with change leftover for the battery !





Sunday, June 29, 2014

Pride Day above Market Street

It's Gay Pride Sunday and I'm on BART heading for the city.

Someone has arranged 2 beautiful baskets of artificial iridescent flowers. 
(my cell phone picture doesn't do them justice !)


While sympathetic, I'm not on my way to the parade and festivities.
Instead I'm looking forward to my favorite Sunday morning activity:

Ballet class at SF DanceCenter.

The 'morning class' is a ritual that all professional Ballet dancers do daily.  I will never know the life of a professional, but once a week I can indulge in the spirit of starting the day with 'morning class' just like the pros do.
There's a live pianist to accompany the dancers, the air is still cool and fresh, it's heavenly being immersed in an atmosphere full with art and aesthetic.

Class started at 10am as scheduled.
The Pride parade started at 10:30am as scheduled.
We are 4 stories above the parade route along Market street and soon catch the full sonic fury of the parade's motorcycle contingent.
The piano is overwhelmed for a few minutes until they pass out of earshot.
Time for a quick peek or two at the spectacle below.






Soon, happily, all's back to normal...   and we return to our labor of love...



What a great day !




Saturday, June 28, 2014

The Quiet Circle and the TimeBomb and the Generational Divide

Recently I took a trip to Coos Bay, Oregon.   I was last there in the '70s when it was a busy logging town.   While the logging industry is still in operation, it has declined and is nowhere near as large in scale as it had been in the past.

Predictably, and sadly, there are consequences for the vitality of the rest of the Coos Bay.

A visit to a nearly deserted downtown showed well kept streets, but no amount of cleanliness could brush away an overwhelming sense of decline and doom that comes with empty store fronts and a few businesses that you just *know* cannot compete with Amazon or eBay in the long run.

There was one spot of brightness in the midst of this, however, a shining champion of a spirit determined to go forward and 'make it happen' with a freshness and flavor uniquely its own.

Welcome to 'TimeBomb' !

A clothing, sports gear and specialty skate 'exchange'.    I gather that declaring the business as an 'exchange' is in line with the contemporary notion of a 'sharing economy', except that instead of individuals 'sharing' their clothing or sports gear, the store acts as the intermediary to 'share' the items amongst community of sharers.

Pretty cool.

Here's shot of the brightly colored store and uh, the company car.



Inside the store hanging on the walls are various t-shirts adorned with the names and logos of vintage bands from the punk, new wave and metal eras.  Sets the tone, nice flavor.    I think I got a little 'look' when I mentioned that I still had some 'Buzzcocks' and 'Circle Jerks' at home in the originally issued vinyl  :-)

I bought a tank top that has their mission printed on it:

'Get it, Rock it, Swap it'

Like it ?   Then get it and have fun with it.   When that's over swap it and let someone else rock it for a while.    The store has 'funky community' written all over it.   It's a place where one 'wants' to go visit even if there might not happen be anything to buy, err...  swap.




It just so happens that only 1 block away from the 'TimeBomb' is it's antithesis:
the 'Quiet Circle'.
The Quiet Circle is your classic 'Thrift Store'.
The kind of place that Cher once sang about:

'I never had no money, I bought at the second hand store.   The way this old town laughs at me, I just can't take it no more'.

There's no Rocking or Swapping here, it's all 'second hand stuff' and nothing to sing about (ha ha).



Is there any more poignant scenario that shows the contrast between the old and the new as these 2 'used article' stores, one block apart from each other, one of them being the  'Quiet' place and the other the 'Bomb' ?

Sunday, June 23, 2013

The Combat Ballerina !

I rented "Assassin's Run" from my local video store and brought home what I thought would be your typical action B-movie.

Well, it was your garden variety B-movie but with an unexpected twist.  No, it wasn't about some paramilitary assassins as depicted on the DVD cover art, instead it was about an avenging Russian Ballerina out to get her husband's killers (of the Russian mafia: St Petersburg

division), rescue her daughter and recover a half billion dollars or so of missing loot.

Suspend all belief those who enter here !

Facing near defeat in a prison yard fight with a Mafiosa, she defeats her shocked opponent with a flurry of pirouettes with hooking elbow blows.   Of course, it's a minor technical detail that the ground is dirt and not a smooth dance floor (did I mention the need to suspend all belief ?).

A burly enforcer is warned:  'watch out, she can kick behind her head !'   *thud*  oops, he didn't listen !

The heroine *does* defeat all opponents, rescues her daughter and recover the loot, all in requisite B-movie tradition.

I can only imagine the shock of anyone that rented this DVD expecting to see Christian Slater suited up to do the action, but getting his Ballerina widow delivering the goods instead !

Thursday, October 11, 2012

A Better Breed of Faux Brick

Hot on the heels of the recent post about the cost of aesthetic in which the unattractiveness of a slab of concrete that was surfaced in an attempt to make it resemble the brickwork around it, and in which it was said that maybe painting the concrete to look like brick might have been a better choice.....

I've come across a rather attractive painting of faux brick on asphalt.

Not a bad effect, yes ?






Yes, that is plain asphalt that has had a brick pattern painted on it.
I'll be keeping an eye on how well it weathers over time but for now at least it's a nice looking job.




Sunday, September 23, 2012

How long will a Snickers bar power a Cuckoo Clock

I had decided that my life would not be complete without a hand carved German Cuckoo Clock so here we are.   The basic design of the Cuckoo Clock stretches back to before 1800.  The count of the weights hanging from the clock indicate the number of features that a clock has:  2 weights one to drive the clock and the other to drive the cuckoo.  3 weights add a music box to the mix.
The fact that the clock is entirely weight driven makes it rather easy to figure out how much energy is used up driving the clock.   This posed a question that I wanted an answer to:

For how long would a standard Snickers bar power the 2 weight Cuckoo Clock that I have ?

Let's get a rough answer !

From measurement the clock weights move about  19 inches over 2 days.
This means that over two days gravity is 'calling back' the work that was done to lift the weights 19 inches.
The 'standard' value for gravity at the surface of the earth at 45 degrees latitude is 9.80665 meters/second-squared.
Because the earth is spinning the effect of gravity is less at the equator than it is at the poles because of the centrifugal effect wanting to 'throw' the object off the surface thus it matters greatly where on earth the measurement is taken.   45 degrees latitude is close enough so we'll use that.

The weight (mass) of the 2 weights totals 3 kilograms

So the amount of energy in Newton-Meters that it takes to run the clock for a day is:

Force * distance   =  m * g * d

(3 kilograms) * (9.80775 meters/ second-squared) * (19 inches/ 2 days) * (0.0254 meters / inch) = 7.099 Newton-Meters/day


From the information on the wrapper,  a 2 oz Snickers bar contains  273 nutrition calories  (a nutrition calorie is about 1000 energy calories)

Of course the human body cannot turn all of the candy bars energy into muscle power, but estimates put the conversion efficiency at between 20-25%.   We'll take the low end and assume that 20% of the Snickers bar gets turned into the muscle power used to lift the clocks driving weights.

So the energy required per day in nutrition-calories is:

7.099 Newton-Meters/day  *  ( 1 calorie /  4186.8 Newton-Meters) = 0.001696 calories/day

at 20% efficiency the required ingestion is:

0.001696 calories/day  /  0.20   =  0.00848 calories/day

The Snickers bar  contains    273  calories

So this yields

273 calories  /  (0.00848 calories/day)  =  32193 days  =  88 years

So there we have it.

One Snickers bar is enough to run my clock, bird call and all, for about 88 years.









Wednesday, September 19, 2012

Aesthetics are for those that can afford it

I went to a Post Office to buy some stamps the other day and was soundly disappointed with what came out of the machine





This has got to be the *worst* looking USPS issued stamp that I've ever seen.  Despite it's message, there is nothing worth celebrating here, not for an instant and *certainly* not FOREVER !

Contrast the workmanship and care that used to go into US Postal Service stamps printed from engraved plates:





Look up close and marvel at the beautiful detail:







I for one certainly can't fault the new stamp for being cost efficient:  stamps printed on location on demand.   With all of the financial trouble that the USPS is in it would be irresponsible now to spend what it takes to produce stamps the old fashioned way.

Near the Post Office where the stamps came from, at Market and Powell is a sidewalk repair eyesore.   Where there used to be a hand laid brick sidewalk, the repair job consisted of concrete surfaced to resemble brick.  








This eyesore might have been palatable if the concrete could have at least been painted to resemble masonry.

With tight budgets the organizations producing these visual disappointments really have no choice but to do a functional job for the lowest price possible.   I think Ronald Reagan referred to this as 'getting the government off our backs'.

Such as it is, aesthetic costs money and right now we can't afford it.