Raleigh Convention Center

[Jones_]

How much of that 22 GW is consumed in residential settings? Like 20% ? These small arrays are of course more costly per watt installed....but there is no price for fuel. Bird poop is cheaper to clean than sulfur dioxide from smokestacks and lungs. The massive industrial sector could offset a good chunk of its use with large rooftop arrays or solar run fuel cells. And I think you are exaggerating...its more like 3-5 times coal or gas, and maybe double nuclear.

[orulz]

What solar really does have going for it, is that it works best when it's needed the most. Around here, peak electricity demand is in the middle of the day on the hottest, sunniest days of summer.

[ctl]

I don't think I'm exaggerating the cost because I recently looked into a reasonably sized solar energy installation. Sure, when you go from acres to square miles, the panels get cheaper -- but on the other hand, the electronics and the sheer amount of copper (in tons!) necessary to connect all those panels goes up.

I don't defend coal. I will say, however, that emissions scrubbers are mainly a capital investment not an operational expense. Scrubbing grime from solar panels is something that goes on forever, and it's proportional to how large the arrays are. By the way, arrays are quite susceptible to hail, tornado, and hurricane.

Nationwide about 35% of generated electricity is consumed in the residential setting.

Ambient temperature doesn't have anything to do with photovoltaic output, at least at temperatures that we have in North Carolina. A clear sunny cold day will have just as much solar energy as a clear sunny hot day -- more, in fact, because there is less humidity in the air and therefore more of the direct sunlight makes it to the ground. Electricity consumption here does peak on hot summer days, but those days are often partly-cloudy for us (or even downright stormy). Different story in Nevada, Arizona, etc.

[Jones_]

Peswiki has the most complete list I can find though it does not confirm that the costs noted are life cycle which is the only relevant number. Scrubbers most certainly do have significant maintenance costs involving the ash landfills and subsequent wastewater treatment, but I admit I do not know the cost per kWh of desulfurization maintenance versus wiping bird poop off a solar panel. Though a squeegee seems a lot cheaper than maintaining a 40 acre ash pond.

I am straying way off topic but couldn't help but notice that the N&O noted wind potential off the NC coast at 20GW. That is right there with the 22GW capacity that PE has right now so it certainly seems like clean renewables have the ability to almost offset fossil fuels. Something that will of course have to happen...one day...provided disease, an asteroid, super volcano or the boogey man don't thin our numbers substantially first.

[orulz]

Ambient temperature doesn't have anything to do with photovoltaic output, at least at temperatures that we have in North Carolina. A clear sunny cold day will have just as much solar energy as a clear sunny hot day -- more, in fact, because there is less humidity in the air and therefore more of the direct sunlight makes it to the ground. Electricity consumption here does peak on hot summer days, but those days are often partly-cloudy for us (or even downright stormy). Different story in Nevada, Arizona, etc.

True that temperature has little or no impact on the operation of solar panels. But, what I was referring to, is that on summer days, the sun's apex is at a higher angle in the sky and it stays at a higher angle for longer in the day, thereby making solar panels work better.

I'll allow that the days that are the hottest outside are often partly cloudy and frequently have afternoon storms. However, during the cloudiest and stormiest hours, electrical consumption is probably not at its peak. I don't have any scientific studies to prove this, but it would certainly make sense that the absolute maximum electricity usage occurs on the hottest, brightest, mostly sunny days when the sun's radiative heating has the greatest impact. Radiative heating has an outsized impact on the cooling needed inside buildings.

Ask any power company what is the most expensive power is for them to generate and they will tell you it is not the base load, usually handled by coal or nuclear power, (which, as you point out, solar is terrible for), but the peak of the peak of the peak, because they have to invest capital in a plant with enough capacity to meet the absolute peak demand, even though that plant will almost never be used at full capacity. The fact that solar cells incidentally generate the most power when it's needed the most (without any need for storage whatsoever) certainly helps to balance out the cost of solar generation somewhat. I'm not saying it's equal with other peak load plants like natural gas, but maybe with increasing costs of fossil fuels it will be closer in the future.

[ctl]

I agree that peak load is the financial problem. You'll have to invest in non-solar peak capacity (i.e., natural gas plants) anyway because you can't be certain that large-scale solar will be there when you need it. I haven't seen simulation results on the coincidence of summer demand peaks and projected large-scale PV output, but I can imagine that there will be times when the temperature on one side of Wake County is near 100 while there's a thunderstorm directly overhead the solar array on the other side of the county. Bear in mind that a utility is expected to be reliable at least 99.9% with respect to factors that are foreseeable. When a utility can't meet immediate demand, either bad things happen or the utility has to buy from the interconnect grid at high spot prices that are eventually passed down to customers.

In North Carolina (as opposed to the West), wind has similar constancy issues. Also I've got misgivings about wind turbines in a hurricane-prone Albemarle Sound.

The other way, and maybe the better way, to address the peak load financial problem is demand management, instead of the supply side. Progress Energy does this to a limited extent already. So far, however, most consumers and politicians have preferred to pay extra to avoid demand management.

[orulz]

Regarding the correlation between PV generation capacity and peak demand, a quick search on google scholar reveals that at least some research has been done on the subject and the two papers I read generally seem to support the hypothesis.

Clearly solar has to be constructed with geographic diversity in order to compensate for the differences in weather and cloud cover. Unlike in the Mojave Desert, where the sky is dependably clear all day every day, a single large array definitely wouldn't cut it from the dependability point of view in Wake County.

An ideal scenario would be in a future with the oft-hyped "smart grid" where solar panels are installed on the roofs of buildings all over the region, both residential and commercial, wherever it makes the most sense: probably locations with an unobstructed view of the southern sky. That would meet the need for geographic diversity.

Clearly, the convention center roof by itself is not geographically diverse. But imagine 10 or 100 or 10,000 similar installations all over Wake County, or all over North Carolina. This could reliably generate power exactly when it's needed the most.