Thursday, May 19, 2011

Photovoltaic Panels Almost Cost Effective

I have mentioned in the past that I would dearly love to go photovoltaic--it just is not cost effective here until the purchase price gets down to $2 per watt.  I see Wholesale Solar offering Trina 225 watt panels at a price that comes to $2.00 per watt.

A few gotchas:

1. The 225 watt rating is an optimal output.  They admit elsewhere on their website that a more realistic output is 200 watts.  (What a gratifying concept: honesty from alternative energy vendors.)

2. That of course is the price of the panels alone.  You still need inverters and a grid-tie, or a battery backup system.

Still, this is beginning to get attractive--and the tax credits make it more attractive.  There is still a big chunk of capital involved here.  As an example, our last electric bill was for 677 kWh, at about 6.5 cents per kWh.  A pallet quantity of the Trina 225 watt panels would produce about 4 kW, and cost $9000.  I expect that a fixed panel array (not the rotating scheme that I was experimenting with before I found out that there is no real interest in alternative energy systems) would give me at least 32 kWh per day (or 960 kWh per month) for most of the summer, and maybe 12 kWh per day (or about 360 kWh per month) on average in the depths of winter.  That means that for most of spring and fall, we would produce enough power to be self-sufficient, and in summer, we would run the meter backward net--and actually quite impressively backward.  In winter, we would still be consuming power from the grid--and often for many days on end, we would be producing no electricity at all.  I am quite sure that a grid-tie system of this size would probably mean no net electricity bill each year.  Since we spend about $700-$800 a year on electricity, even $12,000 invested in panels, inverters, and grid-tie, would be equivalent to about a 6% return on investment.  (Of course, 30 years from now, those panels are likely to be producing quite a bit less power than they do when new.)

A battery system would be attractive from the standpoint of self-sufficiency--although battery systems are expensive and require frequent maintenance.  If you are expecting the end of civilization (I mean, other than the one scheduled for May 21st that I keep seeing on billboards), this would be worth it.  It would take a lot of batteries, however, to carry over the summer or even fall surplus into winter.

Wholesale Solar does offer a "starter kit" using one Trina panel and an inverter for $729, which they advertise as $556 after rebates and federal tax credit.  This is cheap enough that it might be tempting to give it a try to see how effective it was.  At a minimum, 200 watts continuous at the height of summer would go a long ways towards covering the demands of air conditioning, which is mostly needed, shockingly enough, when solar power is at a maximum.

3 comments:

Allen Cogbill said...

Clayton,

A couple of years ago an engineer from Placitas, NM, published the following in the Albuquerque Journal. FYI.


http://www.abqjournal.com/opinion/guest_columns/15920553228opinionguestcolumns01-15-09.htm
Thursday, January 15, 2009
Free Solar Power Is Hoax

By James P. O'Loughlin
Placitas Engineer

The article N.M. Solar Energy Plan Expanded, about the state Public Regulation Commission's promotion of grid-tied photovoltaic (PV) power generation states that homes and commercial establishments that invest in PV installations will have “free” electricity.

I evaluated such an installation for our house using Public Service Company of New Mexico PV information on its Web site. I checked the results against more sophisticated resources and found the PNM results to be in good agreement.

For my house, the required system has a DC rating of 4 kw to accommodate a match to our average energy consumption of 475 kw-h per month. The PNM Web site states that a PV system's cost is about $10,000 per kw, or for our case about $40,000.

This is consistent with the numerous PV system components and integrated packages available, plus the installation, fees, periodic inspections, maintenance, taxes, insurance and other incidentals. Based on a 20-year life and 6 percent cost of money, this comes to a monthly cost of $286.57. The monthly cost for the same amount of energy from PNM service is $42.75 — where is the “free” electricity?

There is an insurmountable fact of nature that forces photovoltaic to be several times more expensive than conventional power generation: The sun doesn't shine for 24 hours a day. This requires that a PV generation installation must have a power rating that is about six times higher than a continuously running convention installation for the same energy output.

At this time, PV panels account for around 50 percent of a system's cost, or $5,000 per kilowatt. The other part of the PV system is based on mature technology, the cost of which cannot be reduced. The only way to reduce the PV power generation cost is to reduce the cost of the panels. Even if we take the most extreme, totally unrealistic case of reducing the PV panel cost to zero, the immutable factor of six in power rating still dominates and results in a cost of $143.29 for $42.75 worth of electricity.

The cliché about investing in research and development to decrease the cost of panels and make PV power generation competitive is an unachievable myth that is fanatically pursued by the government and other groups having various and peculiar reasons.

When reality is not acceptable, the government can fix it with political alchemy. Through the influence of pressure groups and lobbyists, state and federal governments decree that photovoltaic power generation must be implemented. To fix the inherently expensive PV power generation problem, governments provide tax credits, incentives and other forms of subsidy to cover up the excessive cost.

This does not reduce the actual cost; it just transfers it to the general taxpayer or ratepayer.

There are both state and federal incentives. PNM has a PRC approved plan that pays 13 cents a kilowatt-hour for grid tied PV power. Actually PNM doesn't pay it. It is charged to rates paid by their regular customers to help subsidize PV power. Even with this money shuffling, those who buy into PV power installations still pay considerably more for electricity and will never recoup their investment cost. The rest of us get stuck for the subsidized difference.

rghahin said...

Wow, my high rate here in commie berkeley is 29 cents per kWh been running a KillaWatt device to check $$ for items like my molding machine and compressor. I would love 6.5 cents...

Kelsey O'Flaherty said...

I see that this was posted quite some time ago. For those of you coming across this article 2 years later as I am, you may want to know that solar panels have become much more affordable. You can buy a pallet of Perlight solar panels from Edison Solar that produces 5,290W of power for $3,938.

They also have solar kits for sale. They are made up of Sharp solar panels and Enphase micro inverters, which appear to be some of the more expensive components out there, but a 5.5kW solar kit is listed there for $7085.30 after the rebate. That's $1.29/Watt.

I'm sure that if you were to use the inverters with the Perlight panels instead you could make your own kit for pretty cheap.