There is a German turkey farm with long sheds with the roof-line running north to south where they have put panels on the east and west facing roofs as this gives the smoothest match to actual demand, avoids a wasted peak at midday and in the summer months when the sun moves through 270 degrees, they generate solar electricity for up to 17 hours of daylight. The overall loss in generation is about 10%, but far less than 10% is wasted and either dumped or exported to the grid at a very low price. This method also reduces the cost of the hook-up to the grid because the midday peak output is considerably less.
Home Brewed Electricity: It’s interesting to calculate Dr Bard’s cost of his home brewed electricity. After his tax refund, the 10kW system cost him $25,200. In the UK or Germany, a 10kW system would have cost less than $15,000 if installed today.
I have seen solar PV panels in the UK that are over 30 years old and generating 90% of the electricity generated in their first year. Dr Bard is generating slightly over 16,000 kWh per year. Over 30 years he should generate about 480,000 kWh. Assuming that inverters have to be replaced during the 30 years costing, say, $6,800, the lifetime cost of the system is $25,200 + $6,800 = $32,000.
The cost of each home brewed kWh is therefore $32,000 divided by 480,000 = 6.7 cents/kWh. According to Wiki, the retail cost of US electricity is 8 to 17 cents. Taking a middle price of 12.7cents, over 30 years, Dr Bard will save $28,800.
However, he would have paid for grid electricity out of taxed income. Assuming a marginal income tax rate of 25%, the real benefit when grossed up is $28,800 divided by 0.75 = $38,400 at today’s prices. His Year 1 benefit is (16,000 x 0.06) divided by 0.75 = $1,280.
Assuming inflation runs at 2.5% per year, over 30 years, the total gain is £56,195 and the $32,000 investment is paid back after 11 years or in 9 years’ time when Dr Bard will be 78, I would hope well within his lifetime!
He might also look into using any surplus solar electricity for pumping water from his two wells to an elevated storage tank and then running it back down to the wells to generate hydro-electricity when farm electricity demand exceeds supply (at night-time etc). Electric pumps these days can be reversible and have efficiencies in excess of 80%. In my view, water pumped storage is the simplest of available batteries and is much neglected. Most farms could become electricity self-sufficient by using wind, solar and pumped-storage. Chemical batteries are all expensive and have limited lives.
Why make storage so complex? The easiest form of storage is to use surplus solar or wind generated electricity to pump water from a lower reservoir/storage tank/stream to a higher storage tank (preferabley one that is also spring fed. When demand exceeds the renewable electricity supply, the water is run back down hill to the lower tank through a reversed turbine to generate hydro-electricity. We appear to be in the thrall of the battery and inverter industry. Most electrical appliances nowadays prefer to run on DC (LED lighting etc). Keep it simple....
Best means of electricity storage for a farm in hilly country is to pump water between a lower tank to a higher tank and then reverse the pump to generate hydro-electricity when you need the electricity. In the UK we receive feed-in-tariffs for pumping the water uphill using either wind or solar PV and then further FITs when we generate the hydro-electricity. The Grand Old Duke of York would have been delighted. If scaled properly, there should be no need to draw on the grid and this would just be used 'in extremis' when there has been a prolonged windless and cloudy period. This would save on the exorbitant hook-up charges levied by the local grid operator as the farmer would no longer have surplus renewable electricity to export to the grid. Farms have a wide range of relatively cheap slurry tanks that can be used for pumped storage. If the upper storage tank can be sited below a spring, there would be natural filling of the tank to supplement the pumped storage. This is little different from the Victorians who stored spring water in reservoirs for use when milling. Not everything needs a technical solution!
Gage Williams, Cornwall, UK
As the article portrays, time is running out with the threat of brown or black outs by the winter of 2015. However, one major advantage of switching to renewables is the speed with which they can be installed. The UK's largest solar PV array, 34MW comprising 130,000 solar PV panels at Wymeswold Airfield, was installed in under eight weeks during January and February 2013, a period of dreadful weather. The earliest that the next planned gas fired power station will come on line is 2016; Hinkley C by 2022 if all goes well.
I would be interested to know whether the study has included income and sales tax when assessing the 'point of sale' costs. Home brewed electricty is tax free; the electricity bought from PG&E that it replaces would have had to have been paid from taxed income. While I do not know Californian income tax + sales tax, in the UK the basic rate of tax is 20% plus a sales tax of 5%. In which case, to pay for a kWh of PG&E electricity costing 31 to 35 cents, the consumer would have to have earned a grossed up 41.3 to 46.6 cents. At the projected 54 cents in the article, this would rise to a grossed up cost of 72 cents/kWh. No wonder the utility companies are so fearful of 'home brewed' electricity - 'socket parity' was achieved long ago.
In the UK and Germany, we have nearly reached the goal of $1.50/Wp and passed the $2.00/Wp target about six months ago. My 4kWp ground-mounted array in March 2012 in the UK cost $9,300. It will generate 4,000 kWh per year for 30 years = 120,000 kWh. Adding two new inverters during those 30 years brings the capex up to $12,000 giving a cost in cloudy southern UK of 10 cents/kWh. California has better insolation than Cornwall (we have about 1,000 kWh/kWp/yr) and it should be possible to drive the tax free 'home brew' cost below 7 cents/kWh.
UK Solar PV in 140 words (£:$1.55):
A typical house installs 4kW of solar PV (20 panels) costing £5,000. Over 30 years this generates 120,000 kWh and requires one replacement inverter costing £1,000. The cost of electricity generated is therefore £6,000 ÷ 120,000 = £0.05/kWh. If half of the electricity is used to replace daytime electricity with a tariff of £0.16/kW, £0.11/kWh is saved and the other half is exported at £0.05/kWh revenues of (60,000 x £0.11) + (60,000 x £0.05) = £9,600 will be generated over the life of the solar PV. However, the export revenues are income tax free and the electricity saved would have been taxed at 20%. So the real benefit is £9,600 ÷ 0.8 = £12,000. To this should be added the 25 year £0.1544 Feed-in-Tariff adding a tax free £15,440 (£19,300 grossed up).
It would work if people keep it simple, perhaps using micro-finance. A single 250W solar panel with a DC output in most of Africa can generate about 500 kWh/yr. The output can be used for recharging 12V and/or 24V batteries for use at night-time. LED lighting prefers to run on DC rather than AC. An 80W equivalent LED light bulb uses 8W. If used for about 6 hours per night, this would use 17.5 kWh per year. In other words, a single solar PV panel costing about $300 will provide sufficient light for 28 LED light bulbs. Obviously, the electricty could be used for a small fridge, some limited cooking etc if less lighting is required.
With care, the system should last 30 years (I have seen solar PV panels in the UK that are 32 years old and still generating 90% of their original output). During that time, the solar panel will have generated 15,000 kWh. Divide this into the original $300 cost gives a simplistic lifetime cost of generation of $0.02/kWh. In much of Africa, electricity costs $0.30/kWh. Therein lies the market with plenty of margin to repay the $300 dollar micro-finance loan. Let's suppose that the interest rate is 20% as suggested by the article and that the entrepreneur buying the solar PV system wishes to make an additional 20%. On this basis, the 500 kWh will need to generate revenue of 40% x $300 = $120. The electricity would need to be sold at $0.24/kWh which is considerably less than the grid rate, if the village is connected, and about 25% of the cost of diesel generated electricity. The $300 loan would be repaid in 5 years.
The above is reverting to the original solar PV pioneers who used solar PV for their log cabins in the Rockies to charge lead acid batteries to provide 12V lighting at night-time.
Great article. The cost of solar is falling and will soon have a global rice as solar PV becomes commoditised (like flat screen TVs, laptops etc). In the UK our prices are now comparable to German prices. The cost of a 5kW system in the UK today is about $10,000, well below the $15,000 that you would currently pay in California. The only problem that you have in the USA is the 100% import tariff you have slapped on solar PV modules which will do two things: protect inefficient US made solar PV equipment which will no longer have to compete; and keep prices high for American consumers. Adam Smith would be appalled.
The Orkneys have many lakes at different elevations and about 1.3m of rain per year. Pumped storage between lakes (lochs) at different elevations would be a far cheaper and more cost effective option than what must be an extremely costly lithum battery based system. The hydro-turbines could be reversed when there is surplus electricity being generated to pump water from a lower to a higher loch. When the grid falters or there is demand greater than what is being generated by the wind-turbines, the water hydro-electic turbines can be reversed to generate hydro-electricity, the only instantaneous and most responsive form of electricity generation enabling premium spot tariffs to be earned.
As a Brit, we applaud the USA's decision to impose a tariff on Chinese imports of solar PV to the USA as it will cause yet a further drop in the price that Europeans have to pay for their solar PV installations. The only losers will be Amricans who will continue to pay about twice what we pay for domestic solar PV installations. In the UK, a roof-mounted solar PV system no longer has to go the local council for planning permission and can be installed in a matter of days. A 4kWp system now costs as little as $8,000. As there are virtually no running costs and the system should generate 120,000 kWh over its 30 year life, the householder can enjoy paying less than $0.07/kWh compared to the current UK daytime retail price of electricity that he would paid one of our six monopolistic electricty supply companies of $0.23/kWh. Without subsidy, this is a saving from taxed income of $0.16/kWh. A standard rate taxpayer pays 20% tax, so grossed up this saving is $0.20/kWh.
18 months ago, the same 4kWp solar PV system would have cost $21,000. There is a parallel when IBM recognised that PCs & laptops were becoming commodities with a global price that it could no longer compete with which is why it sold its PCs to Lenovo. Lenovo has since then ensured that the price of laptops has continued to fall as predicted by Mr Moore. We once had a King called Canute who thought that he was more powerful than a global tide. We also had Adam Smith who realised that the only losers in a trade war were the participants themselves.