Discussion on:

Big-box stores lead the pack in solar power use

I keep hearing about how all the big box stores were evil...

They are stealing all that light and not paying for it. (some day, the government might come up with a tax based on one's annual solar energy received, whether it's put to use or not.)

OK well, such businesses are not really evil. There's greed, but any business wants to make money and successful businesses are 'cheap' in what they want to expense, so that the business retains more funds at the end of the day. Solar energy is an advantage, why not?

On a truly bright day, the panels covering a 1000 sq ft house can generate 10-13KW. That is twice what the central a/c unit uses. so cut it in half due to inefficiencies, and put in place a means to store one's power for night use, and there is a bargain (based on an 18 sq. ft panel making 250 watts).

How big is that Ikea store in the picture? If the panels supply even half of the store's lighing and air conditioning costs during the day, that is a huge reduction in energy use and lessinging the strain on the grid in summer.

Having worked in industrial facilities where the roofs are always changing, as a vocal proponent of renewable solar energy, I'd been asked many times if it would be valuable to put solar panels on the roof of the factories I worked at. I kind-of laughed.

Industrial electric demands can be extremely high, running and cooling powerful machines inside. Industrial roof-lines are always changing to install new equipment like scrubbers, VOC systems, reoriented chilled & heating water systems, air handlers and condensing units to fit the needs of what is going on inside the building.

But on a relatively static roof as in big-box stores, malls, homes, and other commercial buildings, solar installations make complete sense.

The only question I ask - because the highest cost is the new infrastructure including the conduit, roof supports, and the high voltage DC to lower voltage AC inverter - "Is the installation designed to be retrofit with much higher efficiency panels in the near future?"

Most solar panels sold today are about 14% efficient (140 Watts per meter). Some thin film products reach as high as 24% efficient in the lab. But likely very soon, lead-selenium quantum nano dot technology will reach the market with projected efficiencies of 40 to 50% and better yet, the nano antennae technology may extend efficiency to 80% or higher.

So for a big box store with 1,000 square meters of solar panels installed at 14% efficiency, they might produce about 140,000 Watts of power today, but might be able to hit 800,000 Watts of power not too long in the future (say 10 years from now.) If cleaned regularly, those 14% efficient panels can produce electricity for 25 to 100 years. At the potentially high output from upgrading to the latest high efficiency panels some time down the road, it may be very valuable to install everything to upgrade up-front. The the old panels will likely be valuable for resale to other uses, other installations, paying part of the upgrade costs.

Something that has always irritated me was that solar panel manufactures are not required by law to rate their panels on a "Watts per square meter" basis as "full assemblies with a 1,000 Watt per square meter source". (The "average" sunlight intensity across the US is often cited as 1,000 Watts per square meter, though it is higher in many locations at noon on a cloudless summer day.) Such ratings would offer consumers a better feel for how much energy they can produce and how much roof they need.

The largest building/complex with mostly one story I ever worked on was OP-1 & OP-2 in Pittsfield Mass at about 2M square feet, or about 93,000 square meters, about 5,100 panels, about 1,300 kW using your 250 W per 18 sqft panel.

The next largest building I worked on was the 7 story + basement Kaiser Sunset building at about 1M square feet - but with a roof about the size of a medium sized big-box store.

So I roughly guess a big box store could produce about 100kW at high noon with the sun directly overhead if my calcs are right. Almost 500kW if the drop-dead best solar technology was available on the market today.

Taking that into consideration, it is a shame we can't push the envelope on deploying the technology from the lab to the street (or roof) with push-me-pull-you incentives and corporate competitions and the like. Of course there'd be folks who wouldn't like that, but they better start moving out of the way or get ready to get hit by the bus coming down the street.

If the US could make ourselves the leanest meanest, most efficient, most renewable/sustainable economy on earth, we'd only be less exposed to the price shocks certain to come as the global economy heats-up out of this recession.