Doing the math - solar potential and solar panel wattage

[ManitobaMark]

So, I'm having a house built in southern Manitoba, Canada. I thought, hey why not add some solar panels during construction?
I did some research on the potential energy if I put solar panels on my garage roof. It comes out like this:

--------------------------------------------------
Garage Roof Size (feet): 25ft x 10ft (metres) 7.62m x 3.05m = 23.25m2

Daily Insolation (South facing, angle at latitude): 4.9kwh per m2 (daily, annual average)
Daily Insolation for garage roof size: 23.25 * 4.9 = 113.9kwh daily

Current Energy price: 6.94c / kwh
Annual Energy Generation: $0.0694 * 113.9 * 365 = $2885
--------------------------------------------------

Great! Nearly $3000 in free energy per year. But then I look at panels and see 125w, 250w, etc - and I have no idea how to plug panel wattage into my calculations.
Am I right to assume that the total solar power is a theoretical maximum, and that the higher the panel wattage the more I can capture of it?

If so, can anyone help me figure out how much of the potential I could capture? Like I said, I'm just not sure how to plug 250w panels (for example) into my kwh potential.

And, yes, if these questions make no sense, it's because I'm a complete newbie and in no way an electrician or physicist!

Ref: http://pv.nrcan.gc.ca/index.php?n=360&m=u&lang=e

[russ]

Comments in bold - part to be corrected in italics

Garage Roof Size (feet): 25ft x 10ft (metres) 7.62m x 3.05m = 23.25m2

Daily Insolation (South facing, angle at latitude): 4.9kwh per m2 (daily, annual average)
Daily Insolation for garage roof size: 23.25 * 4.9 = 113.9kwh daily

Current Energy price: 6.94c / kwh
Annual Energy Generation: $0.0694 * 113.9 * 365 = $2885
Daily Insolation for garage roof size: 23.25 * 4.9 = 113.9kwh daily * panel efficiency which for grid tie is in the 15% to 20% range or maybe (at 17.5%) 19,93 kWh/day
19,93*,0694 = 1,38$ per day

--------------------------------------------------

And, yes, if these questions make no sense, it's because I'm a complete newbie and in no way an electrician or physicist!

Ref: http://pv.nrcan.gc.ca/index.php?n=360&m=u&lang=e

[rick1]

Comments in bold - part to be corrected in italics

With you producing $1.38 worth of electricity per day. If you have all 100% sunny days you will make $1.38 x 365 days = $503.70 each year. Your electricity is so cheap you cannot make solar PV pay without a good FIT or a lot of rebates or tax credits. I pay .943 per KWH.

[bonaire]

Your electric price is quite low and your estimate on power possible from a system are very high.

If your bill truly is < .07/kWh after you sum up your daily power bill and divide by your kWh after removing the fixed costs then I wouldn't do solar. Under .07 is fantastic as a fixed price electric rate. I'd be buying a 2nd Volt if I lived there.

Our rate in PA (SE Pennsylvania, USA) is 16.7c per kWh and that means monthly power bills of upwards of $200 for me. So, I've looked into Solar as a "help" but even here, conservation still wins over Solar PV for saving money. It is a cool thing to do to self-fuel an EV or power your own house. But it's expensive to do for what you get out of it.

Over in Ontario, they had an outrageous FIT (feed in tariff) which made doing solar a "no branier" but that was because they were paying system owners way too much per kWh. Far beyond what it would take to really induce people to do systems.

[Sunking]

At $0.07?Kwh it would be foolish to go solar.

[000111]

the numbers are looking good this week!

http://www.securingthefuture.co.uk/energy/13639-solar-panels-do-what-they-say-on-the-tin

[Naptown]

At $0.07?Kwh it would be foolish to go solar.

I have many people tell me that they are paying 8 or 9 cents a kwh here. what they are looking at is the cost to compare number which is the cost of the electricity without transmission, distribution, taxes etc etc. When those are added in the true cost is more like 12-14 cents a kwh.
I suspect the OP has done the same thing.
to get a true cost per KWH delivered you need to add all the things that you are charged by the KWH for or simply take a bill and subtract the fixed items like subscriber charge and divide by how many KWH you used.

[russ]

The UK site is quite cute really - everyone types in their number and hits send. 99% of the respondents will lie rather than admit they are not doing perfect.

[toddbailey]

Near Seattle Wa I'm paying .10 per kwa. In less than 10 years the rate has doubled, I'm sure it will double in the next 10 years.
I chose Solar as a means to make the house more affordable during upcoming retirement. My winter power use is fairly low but in the summer months, using a/c, fans and a hot tub add to the bill.
The four months the sun is at it's highest is also when my usage is up. Solar here makes sence to help level off the spikes in the bills.
Plus covering 80 % of the roof with panels will aid in keeping the house cooler. Another win. During the roof repair and prep work, I replaced the plywood decking giving exposure to the attic space,
I took the opty to install many layers of insulation, instead of maybe R19, It's now between R30 to R80 depending how much space I had to work with.
Another win.

Solar by itself is good, as is conservation and bldg inprovements. When joined together even better