4 Comments

1. 
   user-984364 | May 13, 2013 05:59pm | #1

   0.1% (and growing)
   EIA says MA had 31 thousand MWh of solar generation in 2012, up from only 5 in 2011. That's out of 35,397 thousand MWh of total generation, or about 0.1%. Still, that's gaining some serious ground in a single year.

   Here in MN we seem poised to pass a solar mandate somewhere between 1% and 4% by 2025. I have to think that once we reach 1%, the visibility and "neighbor effect" might just accelerate things well beyond the mandate. At least I hope so.

2. Expert Member
   Dana Dorsett | May 14, 2013 03:19pm | #2

   There's reason to hope
   As the "rest of system" costs of grid-tied PV begin to fall for residential sized system there's no reason why the system cost wouldn't fall below $2/watt-peak, at which point the lifecycle cost of PV becomes EXTREMELY competitive, even without subsidy. Under the Solarize Mass program (where much of the permitting red tape gets streamlined) it's already hitting near and sometimes under $4/watt for residential sized systems, and pushing under $3/watt for some larger systems. The PV module costs are currently less than half the hardware costs (and falling), but there's room for lower cost inverters, racking, and more efficient installation.

   The net metering/other compensation methods for compensating PV still need to get ironed out. A Net Zero Electricity house still represents some stranded cost to the utility for maintaining the local grid and back up capacity, but the value of the PV output is higher than the grid-average per kwh cost, since there's good overlap with summertime peak demand hours. It's not simple math, but screwing it up can make it uneconomic for small operators in a hurry.

   The volatility of PV from the very-local grid perspective can be difficult to control too. A cloud moving over a small region can turn the local grid from significant net-power source to significant net load in short minutes once PV becomes a large fraction of the power source for that grid segment. There are some grid-smarts and power regulation hardware to be developed there too. All soluble, but not free.

3. 
   user-984364 | May 14, 2013 09:09pm | #3

   Red tape & white clouds
   I wish the MN legislation moving through had addressed some of the red tape, as far as I can tell, it did not - it just mandates a % of total generation w/o seeming to address any of the barriers. Hmm now that it's about done, I wish I'd tried to bend somebody's ear about that.

   Interesting that you talk about variability, we just had a highly variable solar day, and I collected 5 minute data from about 30 public Enphase systems in the Twin Cities area to see how much it smoothed things out. Since we don't have a huge number of systems, I cheated a little and normalized every system to % of its output capacity (so that the couple of very large systems wouldn't swamp the little ones; with more systems it would be a more evendistribution), then took the average of those. It did a pretty good job of smoothing things out, graph is attached. But that is over the cities, not over little sub-grids.

   
4. Expert Member
   Dana Dorsett | May 15, 2013 11:24am | #4

   The bigger the fraction, the bigger the volatity issue
   In some parts of AZ and Germany with massive PV infrastracture already installed the output volatility issue has already been pushed onto the grid operator's plate (not as the main course, but a significant side dish), as outlined in this recent bit o' bloggery a couple of months back:

   http://www.greentechmedia.com/articles/read/Solving-the-Next-Grid-Challenge-Volatility

   At some point the responsibilities for stablizing output will become defined, but at the moment it's unregulated in most US markets, and falling into the grid operator's lap, (which may not be the lowest-cost method of getting there.)

   Germany's very low installed cost of ~$2-2.50/peak-watt for rooftop solar is in no small part due to the streamlining of the red tape. Qualified installers take the call, install the goods, and mail in the documentation to the permitting & regulating authorities AFTER they throw the switch, no prior permission required. But there the basic deal is nation wide for both utilities and PV owners, with little ability of local authorities to jam up the process. In the US you have 50 different state regulators, tens of thousands of historical commissions, municipal zoning official, etc, and the utilities range from privately held, municipal, investor owned, publicly owned etc. it's a zoo with many stakeholders. The Solarize Massachusetts program is an attempt to streamline it on a town by town, city by city basis, and it HAS brought the average price down, but it's still nearly 2x the cost of what Germans pay. But only part of it is the red tape- the labor content of a MA installation is still more than 2x that of Germany, for reasons that aren't entirely clear. It's a productivity issue unrelated to hourly costs- there are simply more labor hours per installed watt going into it here than in Germany.