Climate Policy

[kandrathe]

Next, to compare prices, you use $2/W as a basis and add about 50% for other provisions. Let's make it $3/W, then. Since you already have corrected for 80% inefficiency in the previous part of the calculation, that $3 would be for each netto Watt. So, 28 m2 would cost 3*30*28 = $2520. Now, is that per day? No, that's for the lifespan of the installation. At 20 years, that would be $10.50 per month. That seems a lot lower as $270 per month to me.

Nope. I think the 150W/m2 is the results of measuring the suns angle and the number of cloudy days. If is as you say, average out for an entire year, then it is useless for calculations, since you really need to plan for peak need.

For watts, you need to look at how many watts you would use for the entire 24 hours period, and then assume you will capture and store that during the sunny part of the day (hoping there is one). I started by looking up the average usage here in Minnesota, and that being 600 KWh /month divided by 30 is 20,000 watts hours per day. A day has only so much time for which you can generate the load, so I figured 8 in the winter,and more like 16 in the summer. So, there is where you get 20000 watt hours / 8 hours = 2500 watts for winter and 1250 watts for summer. Then, you need to go back to insolation calculations to figure out how much power you get per square meter to calculate the total area required. 150 W / square meter looks about right for what we get in Minnesota, compared with the amount of the 1000 W per square meter at sea level on the equator with a cloudless sky. Now you can factor in the 20% efficiency if you like here, so in terms of capture you would get 30W / square meter. So, if we look at 2500 / 30 we get 83.34 square meters again (I used 160 instead of 150).

Something is wrong with your calculations. Do you use 2520 / $3 = 840 watts in a day? That would be equal to four 50 watt light bulbs left on for a little over 4 hours. Look up the price of solar panels. Here is an description of one persons journey with installing solar power. His bids ranged from $38K to $60K after rebate(s).