Solar Thermal and PV in AK: Predictions Performance … of Solar PV and...•Alternatives to solar: energy efficiency, conservation, heat recovery, diesel genset upgrades, maintenance

Solar Thermal and PV in AK: Predictions Performance Potential Brian Hirsch, Senior Pro ject Leader, Nat ’ l Renewable Energy Laboratory David Lockard, Solar Energy Program Manager, Alaska Energy Author i ty David Pelunis-Messier, Energy Outreach Coordinator, Tanana Chiefs Conference

Denali Park Solar Thermal Water Heating

Golden Valley Electric Assoc. owns and operates this system

Provides hot water to Denali National Park facilities

36 Heliodyne flat panel solar thermal panels

50’x30’ array with 3,000 gallon heat/storage tank

Serves laundry, 13 guest cabins, Riverside Complex, and Sheldon Visitors Center

2,000’ insulated pipe system

System came on-line in August 2009

Commissioning continued through 2012

Operates only from late May to mid-September

Saved $8,000 in propane and electricity in 2012

Estimated capital cost $180,000

Solar PV Challenges in Alaska: •Minimal Sun, particularly in winter months when loads typically peak

•Shading

•Snow (Eagle AK has snow on the ground 7 months of the year. 13” average depth in April.)

•Siting and Site Control

•Diesel gensets are often oversized and manufacturers’ recommend 30% minimum loading

•Peak solar output (mid-day, April-July) is sometimes coincident with minimum electric loads

•Economics

•Alternatives to solar: energy efficiency, conservation, heat recovery, diesel genset upgrades, maintenance improvements, distribution system upgrades, etc.

•Cost of maintenance and repair can quickly wipe out savings at remote sites (Lime Village)

Solar PV O&M Model Description Annual Frequency

panel cleaning 2

Snow removal 20

Retro-commissioning 1

SCADA sensor upkeep 1

Inverter service, BOS inspection 1

unscheduled repair/travel 1

Inverter replacement reserve 1

insurance 1

(from a Cummins Diesel Genset applications manual) A.2.2 Minimum Genset Load/Capacity

Running a generator set under light load can lead to engine damage and reduced generator set reliability. Cummins Power Generation does not recommend running generator sets at less than 30 percent of rated load -- this is the default setting in GenSize. Load banks should be used to supplement the regular loads when loading falls below the recommended value. A generator set should not run at less than 10 percent of rated load for any extended period.

Part load operation also allows unburned fuel to gather in the engine exhaust and lube systems. This type of operation can result in unsightly leakage from the exhaust system, as well as increased maintenance costs. An oversized engine will more likely have these problems. A generator set operates best from 50% to 90% of full rated load. Long term operation at less than 30% of full rated load is not recommended.

John Deere Engine Recommendations

Lime Village Solar PV

1997- 4kW solar PV w/ battery storage installed. No data.

2003- upgraded to 12kW solar PV. Solar ran for one month.

2011- Two new 12kW gensets installed (10kW/gal peak eff.)

Two sets of batteries have failed

Brush and fence shading on lower array

Has not functioned effectively in diesels-off mode

No solar PV operation reported since 2003

FY12 PCE residential rate was $1.71/kWh before PCE

AVEC Solar Initiative in NW Arctic RE Fund Round 1 Grant to study and design solar PV in Ambler, Shungnak, or Noatak.

With AEA approval, converted to solar siting and feasibility studies in all three villages

Total of 11 sites investigated

50kW solar PV output possible during mid-day in mid-summer in Ambler, coincident with minimum loads of 60-70kW and smallest genset operation (360kW C-9 Caterpillar). (Current smallest genset is 350kW Cummins?).

Issues: Permafrost Lack of local gravel Risk of wet-stacking genset during periods of high solar/low load Solar PV simple payback estimated at 24-59 years for these sites

Grant termination requested in 2010

AVEC Kaltag Solar PV System 10 kW solar PV array

Owned and operated by Alaska Village Electric Cooperative

2011 Grant for $90,000

AVEC match: $10,000

Estimated savings: 8,191 kWh annually (equals 600 gallons of diesel)

Project not expected to be economic (B/C ratio of 0.6)

2012 solar kWh output:

September (partial month) 120 kWh

October 186 kWh

November 60 kWh

December 8 kWh

2013 January 3 kWh

Issues:

Inverter fan needs to be replaced

Possible shading from trees to the south

Alaskan Solar PV Lessons Learned

Cost savings are not equal to the residential cost per kWh of electricity

Snow on the panels does affect solar PV output

Solar output during the heating season may decrease the benefits of a heat recovery system

You cannot properly design a medium penetration, grid-connected, rural Alaska solar PV system without analyzing and understanding the diesel powerhouse and electric distribution grid. Unless those systems have been upgraded recently, they may need to be upgraded before integrating a solar PV system.

You should work with the electric utility before putting a solar PV system on a rural Alaskan electric grid

Not all rural electric utilities are required to allow solar PV systems on their grids.