9/04/2015

Going Solar


Some people insist that solar PV has achieved "grid parity" but to claim this they obviously have to consider grid connected PV.

The real cost of solar PV is masked when grid connected. In order to better understand the real cost of solar PV, let's make a simplified exercise here.

What would be needed to go off grid? The following:

  • Obviously, the solar PV panels.
  • Storage batteries
  • A gasoline electric generator (unless you plan to store heroic amounts of electricity, you would need the backup generator).
We'll consider the following parameters in our installation (feel free to substitute your own numbers):

  • Annual solar capacity factor: 18%.
  • Cost of the PV installation (including inverters, installation, etc.): $3 per Watt.
  • We'll use Tesla storage batteries (the 7kW version) at a cost of $6,000 including installation.
  • Solar panel useful life: 20 years.
  • Batteries useful life: 10 years.
  • Annual electricity usage: 8,400 kWh.
So, this house would consume the following electrical energy in 20 years: 20 x 8,400 = 168,000 kWh.

The average electricity consumption is: 8,400 kWh / 354 / 24 = 959 W.

To supply (on average) that amount of power we need the following PV capacity: 0,959 kW / 0.18 C.F. = 5.3 kW of solar panels. Let's round this off to 6 kW to be on the safe side. 

To minimize cost, we'll consider storing only 3 days of electricity, That would be: 8,400 kWh / 365 x 3 = 69 kW. Let's round this off to 70 kW.

We would then need ten 7 kW Tesla batteries at a cost of $6,000 each: 10 x 6,000 = $60,000.

Finally, we'll need a gasoline backup generator at a cost of $1,000.

If we use it 10% of the time, we should be consuming ~$300 of gasoline per year.

So, the total cost to produce 168,000 kWh (in 20 years) would be:
Solar Panels: $18,000
Tesla batteries: $60,000 x 2 = $120,000 (considering the batteries last 10 years).
Backup generator: $1,000
Gasoline: $300 x 20 = $6,000

Total: $145,000

If we divide the above by the total kWh generated in 20 years, we get the cost per kWh:
$145,000 / 168,000 kWh = $0.86 / kWh.

Currently, the average cost of the residential kWh in the US is $0.13, thus the solar kWh as calculated here is 6.6 times more expensive.

Sure, the assumptions above can be modified and the costs will vary, still, once the total costs of solar PV are included it is very doubtful that this technology has reached "grid parity" or that it will achieve it any time soon. 

Feel free to double check the numbers above. Thank you.

References:

Average cost of residential kWh in the US:
http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_5_6_a

Cost of Tesla battery:
http://www.cnbc.com/2015/05/07/teslas-new-bet-a-home-battery-to-slash-energy-costs.html






9/03/2015

It Doesn't Work That Way

Note: this article is a team effort between Susan Chapelle and myself.
I am sometimes too harsh, Susan is more diplomatic. We hope our collaboration will continue in the future and be fruitful.
Thank you, Susan!




There is a misconception that in order to solve a problem, the most important step is "finding a quick solution." In our current political climate, this seems most evident with global climate change.

For example, in this subject people may present any or several of the following "solutions:"

  • Implement heavy carbon taxes.
  • Subsidize renewables.
  • Ban Arctic drilling.
  • Aggressively ramp up nuclear power plant construction.
  • Offer generous tax incentives in the purchase of EVs.
  • Divest from fossil fuels

At times, these approaches do not work as intended, and may even be counterproductive. 

Why?

The world is infinitely more complex than a bunch of bureaucrats working on spreadsheets in a government office, and the climate is infinitely more complex than can be resolved by a single financial institution. 

Historically, when a problem is declared unsolvable, often there comes an entrepreneur and proves them wrong.  





Yes, Henry Ford saved the cities from being drowned in manure.
Fracking is helping the USA reduce its reliance on coal.

Who will "fix" Global Climate?

The answer might lie in a variety of not yet available solutions, but in the end it may be a bunch of entrepreneurs that find innovative ways to resolve an extremely complex issue.

The "manure" conferences achieved nothing aside from producing even more manure.

We wonder, is is time to discontinue climate conferences for good?

Is there a better way to examine global energy use?

Feel free to add to the conversation on Twitter.