PG&E continues to demonstrate their leadership in greenwashing. Of course there is a mandate in California so the cost are passed on to the rate payers.

Then there is this, “Both projects are contingent upon the extension of the federal investment tax credit for renewable energy and processes to expedite transmission needs.”

While I am in favor of the PTC because reducing the demand for natural gas benefits all US taxpayers indirectly. I thought one of the claimed benefits of solar was that new transmission lines would not be needed.

Then there is this, “ .... which convert sunlight directly into electricity and produce the greatest amounts of power during the afternoons, when electricity demand is high.”

Not exactly, solar PV produces the most electricity in the late morning and early afternoon. On the California ISO electricity demand is high in the late afternoon.

I'd like to know what the acre/MW ratio is - how many acres of PV panels per MW electricity. What's more efficient - PV or mirrors?

Not exactly, solar PV produces the most electricity in the late morning and early afternoon. On the California ISO electricity demand is high in the late afternoon.

That depends on how they are mounted. Direct them towards south west and end up with more electricity in the late afternoon.

I'd like to know what the acre/MW ratio is - how many acres of PV panels per MW electricity. What's more efficient - PV or mirrors?

Solar thermal cannot be placed on existing roofs, thus PV generally produces more MW per acre. The roof area of a one family house is more than sufficient to power the entire house with PV alone.

Also, concentrated PV (PV with mirrors) is slightly more efficient than solar thermal but also more expensive.

This will help provide power to the people in central CA, but PG& E also needs to build this technology closer to the larger population areas in the north and south.

"..patented SunPower Tracker solar tracking systems at the site,"

Tracking can really help in the late afternoons. SunPower has 20% efficient panels and tracking extends the number of hours per year that they get good output.

Kit does make a point about new power lines. Any technology that winds up delivering energy via old-style high voltage power lines loses its luster due to line losses. While it is admirable to see PG&E struggling to enter the 21st century - they may have elected to do too little, too late.

For these big solar farms to compete with low cost residential power units they will need to lay HVDC underground cable - which of course is another major capital cost.

It would be interesting to see how transmission line losses compared to large scale, transportable ESS in terms of MW deliverd to end users.

California geography creates many micro-climates. I'd say the best potential for solar power is east of the coastal ranges where the marine influence (summer fog) is much less--hence California Valley location in SLO County.

The biggest population centers are south (SD to LA) and north/central (SFO Bay Area, but there are plenty of customers for this amount of power in central CA.

CA is rich in solar potential. Solar hot water is a no-brainer and should be required for all new construction, IMHO.

Line Losses are ~5-10% across thousands of KM. Therefore not an issue.

Residential solar is about 2x more expensive than solar farms. Economy of scale.

http://www.solarbuzz.com/index.asp

http://en.wikipedia.org/wiki/Electric_power_transmission

Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998. [3]

Afternoons may have some reserve / storage built up from daytime surplus.
Underground dc high voltage lines may not be cost prohibitive.

"I'd like to know what the acre/MW ratio is - how many acres of PV panels per MW electricity. What's more efficient - PV or mirrors?"

Concentrating solar is about 40% efficent, while PV is far less, especially thin film (something like 10% efficency).

typo error correction.
to - may be cost prohibitive.
but lets say say "Would be"

Massive production of solar electricity will require concentrated either PV (using multi-junction cells) or steam or stirling engine place in very sunny area like Mojave desert, added tracking and more efficient conversion of these 3 technologies compared to even the best silicon technology from SunPower will result in 3 times more electricty per unit of surface not mentionning the possibility of storing heat for night production. Solar panel on the roof of individual home will be an interesting contribution but only be a minor one.

For now, solar electricity can be used to supplement fossil-fueled power plants. When fossil fuel will be scarce and hence more expensive, more solar collectors will be erected to turn surplus solar electricity into H2 for electrical generation later in the evening or in the winter, or for transportation use.

Solar panel on the roof of individual home will be an interesting contribution but only be a minor one.

120000 km2 of the US is built. If only 10% of that area has roof area, that's 12000 km2.
With a PV efficiency of 10%, that's a maximum power of 1200 GW.

Once thinfilm PV below $2 per Watt will be available, the kWh costs less than 7 cents with 1500 sun hours and 20 years of lifetime.

Oerlikon claims $0.7 per Watt is possible by 2010:
http://guntherportfolio.blogspot.com/2007/09/oerlikon-solar-almost-at-work-ersol.html

Btw, China has already 84 GW of solar hot water capacity installed. Although this is not PV, it is definitely not minor.

These actions are highly dependent unfortuneately on the continuation of the federal renewable tax credit. A continual break along partisen lines which could derail around 19 billion dollars of investment in alternative energy just this year alone. Thank you short sighted politicians.

http://ap.google.com/article/ALeqM5icrolgbXr0mlnZQmLr-1svIyNDpwD9289B8O0