[Greenbuilding] PV Tracking

Fri Aug 5 02:09:43 CDT 2011

Radiation is a word that describes anything that radiates away from 
something.  Audio speakers emit radiation in the form of air pressure 
waves that our ears are able to sense.  Audio radiation is very 
different from electromagnetic radiation which in turn is very different 
from nuclear radiation.

Heat is infrared radiation/electromagnetic radiation with a frequency 
from 300 GHz to 400 THz.
Visible light is electromagnetic radiation with a frequency from 405 THz 
to 790 THz.
Both of these forms of electromagnetic radiation are produced by 
campfires, fireplaces, and light bulbs...things we are very familiar with.

Microwave ovens use electromagnetic radiation approximately centered 
around 2.4 GHz to heat objects.
Radios and TVs use electromagnetic radiation in the KHz and MHz 
frequencies to transmit their signals wirelessly.
Mobile phones use electromagnetic radiation in a range of frequencies 
under 2.4 Ghz, mostly 850-900 MHz and 1800-1900 MHz.

Wireless devices all use some portion of the electromagnetic spectrum.
Solar tie-in: In fact, one could consider solar panels (thermal AND 
electric) to be wireless devices/wireless receivers that are used to 
collect electromagnetic energy that the sun transmits to the Earth.

The intensity of wireless signals various significantly, largely 
depending on the frequencies and communication distances involved.  
Wireless smart power meters are on the lower end of range of 
intensities.  We regularly accept and use stronger transmitters in our 
lives everyday in things like cell phones an wifi devices (laptops, 
smartphones, iPads, etc.).

It is useful to keep in mind that the actual risk posed by a potential 
danger is a function of:
1.) peak dose
2.) cumulative dose for things that accumulate
3.) repair rate/damage tolerance

If a peak dose is too high, repair/control mechanisms cannot keep up 
with the damage.  It is like receiving 12" of rain in an hour vs. 1" per 
day over 12 days.  One is a flash flood disaster, the other leaves 
everything soggy.

If the cumulative dose is too high, trouble can also ensue.  This is 
like receiving 1" of rain everyday, day-in-and-day-out.  If you live in 
a closed basin with no drainage, the water levels will first saturate 
the soil and then start to rise and flood you as it accumulates.  If 
there is drainage, you now live in a rain forest.

Repair rates might be thought of the sandbags around homes and sump 
pumps placed in basements to keep the basements and homes from 
flooding.  If a sudden sustained peak water ingress rate or median water 
ingress rate (determined by soil permeability and sandbag wall 
effectiveness) exceeds the pumping capacity, then damage will occur.  In 
workstation/server class computers and on CDs/DVDs, error correcting 
codes (ECC) provide the repair and data integrity mechanisms to protect 
against random data corruption (single bit flips, media scratches, 
etc.).  In humans there are DNA repair mechanisms that attempt to 
correct damage to our DNA strands.  As long as the repair mechanism is 
stronger than the damage dose, no permanent harm is done.

Finally, it is useful to keep risks in perspective.  As a society we 
have spent billions to prevent some low probability events while 
ignoring the opportunity costs of not preventing other higher 
probability events.  An example...we have decent estimates for the 
numbers of preventable medical errors and related deaths that occur each 
year, yet that's not given nearly as much attention as it would likely 
otherwise have if those were related to air travel or foreign boogymen.

On 8/4/2011 10:11 PM, natural building wrote:
> It's fascinating and frustrating to read about the Ontario MicroFIT PV 
> program while here in BC we are having so-called wireless 'Smart 
> Meters' forced upon us without consultation or choice.
>
> The World Health organization very recently listed EMF radiation as a 
> class 2b carcinogen - alongside DDT, Lead and gasoline exhaust, to 
> name a few - and yet the BC government in its wisdom thinks it's safe 
> and prudent to authorize the installation of new wireless meters on 
> every house in the province without the owners consent at a cost of 
> almost $1 billion and the loss of at least 400 meter-reader jobs.
>
> What they really should be doing is investing that money and effort in 
> renewable, like Ontario...
>
> Steve Satow
>
> www.naturalbuildingsite.net <http://www.naturalbuildingsite.net>
> naturalbuilding at shaw.ca <mailto:naturalbuilding at shaw.ca>
>
> On 2011-08-04, at 7:21 PM, Frank Tettemer wrote:
>
>> Hi All, Here's some more fun data to add to the mix!
>>
>> I mentioned our non-tracker/over-loaded-panels before, briefly.  I'll 
>> describe it again.
>> We've mounted 13,000 watts DC panels, in agreement with the Ontario 
>> Power Authority to sell, at max., 10 Kw per hour.
>> Our thinking is to be able to produce (and sell) 10 Kw per hour from 
>> 9AM to 4 PM,
>> with variously smaller hourly productions before and after those 
>> times of day.
>>
>> These sunny summer days, we vary from 75 to 92 Kw per day sold to the 
>> power authority.  We, of course produce more than that, from 9 until 
>> 4, but the inverters cut off the over-production, sending only the 
>> allowed 10Kw per hour to the grid.
>>
>> This corresponds to the tracker claims, mentioned by others on the 
>> list.  And as expected, the trackers generate their 35% more, on 
>> these summer sunny days.  However, for over half the year, our 
>> seasonally adjusted array produces only 15% less than other local 
>> trackers. And in Winter, our array produces almost the same amount as 
>> other local trackers with 11,000 watts DC on them.
>>
>> We change the angle to 45 degrees around Late August/Early September.
>> We change again to about 65-70 degrees to horizontal in October/Early 
>> November.
>> We change again, back to 45 degrees, in Late February/Early March.
>> And we change to Summer Mode, at 25 degrees, in Late April/Early May.
>>
>> Please Note that we definitely Do Not change angles on the Solstice 
>> nor the Equinox.
>> That timing would be exactly the Wrong Time to change angles!!!
>>
>> Some background to the Ontario microFIT program:
>> They pay 81 cents per Kw produced, up to a maximum of 10 Kw per hour, 
>> for ground mounted arrays, for the early adapters of last years 
>> applications..
>> A common installation has about 11,000 watts DC of panels.  We have 
>> added about $6,000.00 more in panels, or 2,000 more watts DC.
>>
>> This means we produce more full 10Kw each hour than the standard 
>> 11,000 watts arrays, because we have invested more in panels but not 
>> in tracking devices.
>> A common fixed, seasonally adjustable array with 11,000 of PV's is 
>> averaging a little over $10,000 income from production in this area.
>> And like John Staube has mentioned about his area of Southern 
>> Ontario, there are over 100 microFIT installations now in production 
>> in our local County of Renfrew, all within a 45 minute drive of us, 
>> any direction,
>>
>> and 95% of these people are small family farms.
>>
>> So if an installation varies from $65,000 in cost to $95,000 in cost, 
>> or with trackers, $120,000 in cost, you can see how an annual gross 
>> income of about $10,000 would take close to half of the 20 year 
>> contract to pay off the investment.
>>
>> Our over-paneled-array will hopefully average us over $13,000 per 
>> year. As we did our own design, purchasing and installation, with 
>> about $3,000 paid input from a local electrician, our initial 
>> investment of time and cash will pay off in a bit under six years.
>> We won't get rich, after that, but we won't be concerned about 
>> tracker maintenance, either.
>>
>> Frank Tettemer
>> Living Sol ~ Building and Design
>> www.livingsol.com <http://www.livingsol.com>
>> 613 756 3884
>>
>>
>>
>> ================= More Forwarded material ==================
>>
>> WatJohn and I have a mutual friend (Don Fugler) here in Ottawa , now 
>> retired, who used to pedal to and from work every day, year round.
>>
>> In winter, those bike trips both ways would be in the dark ... the 
>> sun not yet having risen in the mornings (7-ish) and already long 
>> gone in the evenings (4:30-ish).
>>
>> OTOH in summer the northeastern sky will often be a spectacular 
>> blazing red in the hour before 6 am and I remember many June nights 
>> working outside until almost 10 pm without having to use artificial 
>> light.
>>
>> The Unbelieving Heathens on this List were having trouble swallowing 
>> the production figures for my neighbour's 10 KW single-axis tracking 
>> array. Well, those UHs are probably going to gag on the following 
>> which came from a person whose company has just brought their 
>> dual-axis tracking system out of R&D and put it on-line.
>> (I don't know him personally (but I did meet his partner when he was 
>> out pitching their single-axis system and my SlipperySalesDevil 
>> hackles were activated) so I can't vouch for the veracity of his 
>> claims as I would for those of my llama-rancher neighbour.
>>
>> ================= Forwarded material ==================
>>
>> Sent: Wednesday, June 22, 2011 7:10 PM
>> Subject: Weekly update...
>>
>> This is an excellent day for [partner] and me because our first 
>> dual-axis has been tracking perfectly for 1 week
>> <snip>
>> As my wife transcribed for me last week, we have no idea how 
>> effective our system is going to be, but for an astonishing figure, 
>> our first dual-axis has produced an average of 134 Kw per day over 
>> the last 3 days and even 38 Kw today as of 4pm in all this cloud 
>> cover and rain. These are amazing figures that NO COMPETITOR can touch.
>> <snip>
>>
>> =============== End of forwarded material ===============
>> (Presumably those are "kWh" not "kW" and yes, I too am having a bit 
>> of trouble swallowing some of the above ...the bit about the 
>> competition, in particular)
>>
>> On those June days, my llamaRancher neighbour's single-axis array was 
>> producing in the neighbourhood of 100 kWh per day, roughly 40% better 
>> the the nearby Enphase fixed array.
>>
>>
>> On Thu, 04 Aug 2011 08:09:25 -0400, jfstraube <jfstraube at gmail.com> 
>> wrote:
>>
>>> PVwatts.org is a wonderful website calculator for PV output that I 
>>> use all the time.
>> <snip>
>>> In Ottawa, it predicts a full 2-axis tracker will produce 36% more 
>>> electricity than ideally sloped fixed system. I beleive it.
>>>
>>> On 2011-08-04, at 7:05 AM, Haudy Kazemi wrote:
>>>
>>>> When most people use the power output calculators/estimators,
>>>> they look at the annual production figures not the daily figures.
>>
>>>> A tracker in a high latitude may make larger differencein the 
>>>> summer than in the winter because the arc of the sun is longer,
>>
>>>> A fixed array in those conditions will self-shade in the early and 
>>>> late parts of the day.  This may the root of the daily difference 
>>>> between the reported performance difference between the tracked and 
>>>> non-tracked array.
>>
>>>> During summer, tracked array may outproduce the non-tracked array 
>>>> by the ~40% reported in this discussion thread.
>>>> During spring/fall, tracked array may outproduce non-tracked array 
>>>> by 20%.
>>>> During winter, with a short arc, tracked array may outproduce 
>>>> non-tracked array by 5%.
>>>> On an annual basis the tracked array may only exceed the 
>>>> non-tracked array by ~20%, even it does better than that in the summer.
>>>>
>>>> Perhaps someone can check this in a calculator?
>>>
>>>> On 8/3/2011 8:00 PM, Nick Pyner wrote:
>>>>>
>>>>> I just think nobody is taking the geography in to account.
>>>>>
>>>>> There are plenty of PV installations around here , but I have 
>>>>> never seen or heard of a tracking one. This is probably because 
>>>>> there is no point in them. The situation could  be quite different 
>>>>> in the more frigid parts of the world for two reasons.
>>>>>
>>>>> 1. Even in what is laughably called the banana belt of Canada, the 
>>>>> insolation is not that great, and the skies are not so clear, so 
>>>>> you would need to chase every watt you can find.
>>>>>
>>>>> 2. In the summer, the days are longer. Hence the practical window 
>>>>> of opportunity may be as much as an hour wider, but the hourly 
>>>>> march of the sun is the same.
>>>>>
>>>>> A tracking system helps in both cases, and this heathen would 
>>>>> imagine the more polar you get the more sense a tracker will make.
>>>>>
>>>>> Nick Pyner
>>>>>
>>>>> Dee Why   NSW (Australia)
>>>>>
>>>>> -----Original Message-----
>>>>> From: greenbuilding-bounces at lists.bioenergylists.org 
>>>>> [mailto:greenbuilding-bounces at lists.bioenergylists.org]On Behalf Of RT
>>>>> Sent: Wednesday, 3 August 2011 2:59 PM
>>>>>
>>>>> I told him that I had been telling people (this List) that his 
>>>>> single-axis tracking array had produced 40 and sometimes 44% more 
>>>>> than the Enphase fixed array and that you (the Listmembers) were 
>>>>> telling me that I was full of $#!+.
>>>>>
>>>>> We both just shrugged our shoulders (as if to say "Nyeh! What can 
>>>>> you do about  unbelieving heathens ?")
>>
>>
>> -- 
>> === * ===
>> Rob Tom
>>
>> -- 
>>
>>
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