Solar panel efficency

The economics of hydro are good, if there's a suitably place to build one. Suitable means that the topography and rainfall have to be appropriate, and it's mustn't be too far from the place where the power will be used.

Sylvia.

How about Tidal Power? Looks like PG&E is interested in San Francisco bay tides.

"Exploring Tidal Power in the San Francisco Bay"

"In a 2006 study, the Electric Power Research Institute (EPRI) identified San Francisco Bay as a potential resource for electricity generation using tidal power technology. Pacific Gas and Electric Company (PG&E), the City and County of San Francisco (CCSF) and the Golden Gate Energy Company signed a statement of collaboration in June

-Bill

In addition to this, the utility companies want a full dam in the morning (and empty in the evening) to compensate for the daily load variations.

Wind power people would like to have full dam when the wind dies out and sufficient dam capacity, until the wind starts blowing again.

Overnight the power people can pump water back up into the dam for tomorrow, use up the base load from nuke stations?

Grant.

The pumping efficiency is lower than the hydroelectric production efficiency, thus the total annual energy consumption would be larger than using the water in the hydroelectric plant only once. The night energy should be really cheap for the pumping system to make sense.

Oh sure, it only makes sense when soaking up the base load, maybe these days there's less daily fluctuation because large industrial users like aluminium smelters can adjust their usage to suit the generators?

They used to sell off-peak for about a 1/3 of peak price here for overnight hot water heating. But soon we getting 'smart' metering with the day divvied up into 30 minute blocks, then they charge depending on cost -- soon sort out those high peak home users with airco and no local solar ;)

A trial solar plant started near here recently too, we got the sun, the deserts, and various ideas mooted for solar, not all are based on PV panels.

Grant.

On a sunny day (Sat, 05 Jun 2010 09:17:45 +0300) it happened Paul Keinanen wrote in :

I have just invented the oil-pressure generator. You connect it to leaking oil wells, the oil flow pressure drives a generator. ;-) No CO2

Screw the CO2. Burn the oil.

I once designed a controller for a natural-gas-powered generator that was used to charge a battery bank to run instrumentation and radio gear on oil rigs. They didn't ignite the gas... they just ran it through a sort of gear motor thing to drive the generator, then vented it.

No CO2 generated!

The mechanical engineers I was working with had convinced themselves that such a controller was impossible. All it took was a couple of comparators and a flip-flop.

John

On a sunny day (Sat, 05 Jun 2010 09:28:36 -0700) it happened John Larkin wrote in :

The 'mechanical way' sometimes involves a centrifugal thing that closes a valve. Even old Edison knew that, used to sync up his steam powered DC generators. If the flow MUST persist, then use a bypass. I dunno what is simpler, electronics or the centrifugal thing. The last is probably more reliable :-)

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The distance to usage point is no where as significant as you think. They ship hydropower electric from Washington state to LA and San Diego, over

I suspect that is true, but it may not hold for too much longer if screen or inkjet printable semiconductors become stable enough to be worth using in this application. Or some other thin film PV trick.

Again being seen to do something may get brownie points even if it isn't particularly effective. Be interesting to see the numbers.

Or you can be clever and use hydro pumped storage at two different levels to supply fast peak demand and then run it backwards at night when generation for base load is more than demand. The overall efficiency is not that great, but the very fast start capability is worthwhile for key aspects of load balancing. Dinorwig hydro in Wales is still I think the flagship for this technology in Europe.

Regards, Martin Brown

Since Nanosolar claim that they can now manufacture PV for $0.70 per peak watt, and it's currently selling at around $2, it gives an indication of the scope for prices falling when supply finally exceeds demand by a large margin. The key being economy of scale.

You must be really desperate, if you start thinking about pumping storage :-).

At low latitudes in which the annual peak load is in the summer, due to air conditioning, it is economically sensible to build solar (PV or solar thermal) plants with a total power as large as the day/night consumption difference. Building more than that will require desperate measures as pumping storage or accumulators. Check your local day/night consumption figures.

At higher latitudes (Central and Northern Europe), the peak consumption is during the winter months, with minimal solar production. During the summer months, when the solar production is high, the consumption is low (and nuclear power plants are shut down for annual maintenance during the summer) and hence the price that you can get from the solar electricity is quite low.

It is faintly useful for transient load balancing - quick to come onstream with full power and synchronisation in 12s from standby. And it is probably better to use some pumped storage than smelt a bit more iron, aluminium or make sodium and chlorine which are the ultimate load balancing energy dumps on lowest rate very interuptable tariff.

And/or put them on the roof so that some solar power goes into PV cells and the roof itself is not heated by direct sunlight.

I agree. PV is a dead loss at our latitude since it hardly generates anything at all in the dull grey winters. To my amazement though in the bleak midwinter on the few sunny days with blue skies my friends 2kW PV array generates about 800W despite the low midday solar elevation of just 26 degrees. The cold improves the overall efficiency somewhat - and conversely a hot panel derates its output with extra losses. The combined water heating and PV designs look like a smart idea if the reliability can be improved.

Regards, Martin Brown

Esp using a small PV array to pump the water round the solar heater. No sunlight, less electricity, less water pumped

Thus the zenith distance would be 64 degrees.

At Christmas, the solar declination is -23.5 degrees,

Thus, your friend must be living at 40.5 degrees latitude (Barcelona, Athens) latitude.

In Spain, there are several solar thermal electric powerplants in the few megawatt class.