[Greenbuilding] Energy and Power...

[RT]

On Sat, 06 Aug 2011 16:25:28 -0400, Gordon Howell -- Howell Mayhew  
Engineering <ghowell at hme.ca> wrote:

> people who "apparently" understand how to
> "figure it out" then making huge calculating errors when the look at
> solar PV economics or sizing (as I've seen many times) because they
> don't fundamentally know the difference between energy and power.
>
> I would suggest that it is extremely important to not mix up these units.

I can understand how an electrical engineer or a TA marking papers might  
get upset when people get their units mixed up but I would venture that  
it's' pretty low on the priority lists of most people.

I think that everyone knows and can recognise the difference between a 5  
watt bulb  and a 25 watt bulb and I also think that people understand the  
ramifications of the "kiloWatt-hours" number on their electricity bill and  
have an inkling of the difference in meaning between the two units.

The rest, as they say, is just semantics IMO.

In Nick Pine's case, the problem was not a miscommunication of units but  
rather, a complete failure to  understand the reality of real world  
application of what are to him, merely numerical concepts to be plugged  
into a BASIC routine. ie a 10 kW array x 10 hrs should generate 100 kWh of  
electricity. Right ? So what's this nonsense from some "nitwit" about  
buying enough panels for a 13 kW array to make a 10 kW-capacity plant ?

OTOH, if we were to have a discussion about the merits of panels using a  
cell type costing $8 per watt (as is the case for my LlamaRancher  
neighbour's/nearby Enphase arrays, (mono or polycrystalline?) and panels  
of a cell type costing $3 per watt (as mentioned in Frank's recent message  
(amorphous thin-film ?), and the cells costing $1 per watt that have  
popped up in articles here and there, I think that more than a few ears  
and eyeballs would perk up.

In the case of these MicroFIT installations (10 kW) in Ontario, we're  
talking about ~$80,000 as compared to ~$30,000 for similar-sized arrays. A  
difference in  cost of $50,000 is, I think, pretty significant to most  
people whereas the difference between kiloWatts and kiloWatt-hours, not so  
much.

[And no, I do not think that Frank is anything remotely resembling a  
"nitwit". Far from it. ]
-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at  Y a h o o  dot  C A >
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