Solar Energy: Large Scale Production
Large Scale Solar Energy Production
The key is to connect facilities to the power grid and sell
power to the consumer at a competitive rate:
De-Centralized vs. Centralized Mythology
- Current costs are about 25-50 cents per KWH for Solar
- Average price for the country from coal, hydro, nuclear, etc.,
is about 13 cents per KWH
Because transmission losses are low (approximately 1% per 60 - 100
km) a solar PV facility that is within a few 100 km of the community
is a more cost-effective investment than the decentralized model.
- Decentralized idea --> individual rooftops of homeowners
and businesses decouple the community from the power grid
- Centralized --> large facility in sunny climate is connected
to the community via transmission lines (e.g. Eastern Oregon sends
power to the Willamette Valley)
How Can Solar Large Scale Production Then Occur?
- Subsidize the industry so that the government absorbs most
of the costs
- Wait for technological breakthrough --> amorphous silicates;
2 and 3 band systems
- Make the consumer pay the real costs of energy generated by
- TAX fossil fuel consumption!
What Large Scale Facilities Are There?
California has 90% of the current world's solar electricity production!
How much is 370 Megawatts?
- Solar Thermal dominates over Solar PV production but that
- Capacity is currently 371 Megawatts
- A new coal fired plant has a capacity of 1000 Megawatts
- Total capacity requirements of US are about 100,000 Megawatts
- Current solar production is thus 0.4% of total
- 300,000 KWH over an 8 hour period
- Typical home would use about 10 KWH in this period
- So 30,000 homes could be supplied with power
What about PV production facilities?
Conclusion: PV technology is likely to offer improved efficiency and
lower manufacturing costs over time. If subsidies can be used to offset
initial capital costs, then the price to the consumer becomes competitive.
- Capital costs are huge
- Operating costs are trivial
- Therefore it's difficult to meter the product - electricity
- PV power is not subject to price fluctuation like fuel-based
- Reliability is high; annual variation in insulation is about 1%
and failure rate of PV's is known so can be compensated for
- In many respects a large scale PV facility is like a hydroelectric
dam high capital costs, low operating costs, river flow subject
to fluctuation due to precipitation
but Hydro is 15 times more
efficient than PV panels (so KWH costs are 15 times less!)
- PV facility is ideal for supplementing the power grid
- PV is a cost-decreasing technology as the price drops by
about 30% when manufacturing output doubles --> suggests that one
should invest in this technology now
- Polluting technologies have enormous hidden costs which
PV's don't have
- PV plants do fit in the corporate hierarchy!
Read More about PVs
Currently there is a big Marketing Problem with Electric
Vehicles. Consumers simply won't buy them. Here are
some attempted marketing strategies:
- Reduced range of electric cars is irrelevant since most people
drive less than 40 miles per day. This is true and electric cars
are certainly practical for "getting around town".
- Fossil fuel use in internal combustion engines is the single
largest environmental problem on the planet. This is debatable but
certainly there are direct health hazards as well as global warming
- Conversion of gas powered cars to electric cars is a good form of
consumer recycling true but we don't have noble consumers and
conversions cost at least $9,000
- Electric cars are more efficient per dollar and yield better
air quality this is mostly true; decreased fuel costs for EVs
make them more cost-effective in the long run
- An electric car bought today, will only get better over time. Within the next 3 years, batteries will be available
which will double and triple your per-charge-range.
one can hope this is the case!
Array of solar collectors on the car's surface delivers
electricity to batteries which then power the car and can
- Tradeoff between Range and Power
- Battery storage technology is the key
A practical motor vehicle needs about 30 KWH of deliverable energy
for a range of 100 miles.
For reasonable performance about 20 hp must be delivered to
the drive train.
Efficiency of energy delivery from batteries to drive train is
- Delivered energy = 40% of stored energy
- So you need 30 KWH/0.4 = 75 KWH of stored energy
- Energy storage density of lead-acid batteries is .04 KWH
- So you need 75/.04 = 1875 = 4125 pounds of lead-acid batteries
- Power: 20 hp/0.4 = 37.3 KW
- Power density of lead-acid batteris is .07 W/kg
- So you need 37.3/.07 = 533 = 1172 pounds
So the range requirements are more severe than the power
Improvements in battery technology are definitely required.
Other types of batteries:
|| Energy Density (W-hrs/kg)
|| Power Density (W/kg)
| Lead Acid
|| Long Cycle Life
| Nickel Iron
|| Very Long Cycle Life
| Sodium Sulfur
|| 300-350 C operating temp
| Lithium-Iron sulfide
|| > 100
|| 400-450 C
|| low cycle life
Driving Habits and Requirements
It is very unlikely that electric cars will ever have prodution
line performance that satisfies the Interstate requirement.
- Long distances - Interstate --> 75 mph and 400 mile range
- Daily Commute --> 55 mph and 35 mile range
- Puttering around town --> 35 mph and 20 mile range
Most practical application is for in town commuting/shopping
and this would then eliminate a major source of air pollution
your questions or comments about this particular lecture