Roof needs solar panels

[msimerson]

reasons to do soon

1. WA state sustainable production incentives expire in 2020
2. 30% federal tax credit starts shrinking in 2019
3. WA state sales tax exemption

todo

• get quotes from installers
  • Sunergy: 9.90 kW for $30,424
  • NW Wind & Solar: 9.86 kW for $33,341
  • Puget Sound Solar: 8.1 kW for $32,762
• choose installer
  • schedule installation
• panel installation
  • permitting, ~7 days
  • Fill out SCL interconnection agreement
  • interconnection approval, ~7 days
  • install panels on roof (starting May 19th).
  • electrical inspection (May 24)
  • install new production and digital net meters, ~7-10 days (expected May 31, actual June 8)
    • get "made in WA" confirmation, 30 days (June 6)
• receive 30% Federal tax credit (Federal Tax Incentives #70)

options

• put panels on East/West facing garage roof
  • roof is nearly new
• put panels on South facing house roof
  • depends on two South roofs are aged #18 (replace roofing)

See also

• Roofing
• building code requirements at mybuildingpermit.com
• related to electrical system upgrades & capacity planning #15 (electrical system)

[msimerson]

Annual Solar Production for 98155 (modeled with PVWatts)

Azimuth	Tilt	Annual kWh
180	20	10675
180	35	10917
180	40	10875
270	5	9536
270	10	9539
270	20	9433
270	30	9199

[msimerson]

Payback Tracking

Year	Expenses	Rebates	Incentive(1)	Net Metering	Net Cost
2016	$33,341	$10,002	(#69) $688	$664	$21,888
2017			$3,633	$1,088	$17,004
2018			$3,778	$1,360	$11,661
2019			$3,815	$1,439	$6,192
2020			$3,500	$1,517	$948
2021				$1,517	$-859
2022				$1,621	-$2,736
.....				.......	..........
2030	$1,500			$2,066	-$14,187
.....				.......	..........
2046				$3,869	-$68,104
Totals	$34,841		$15,414	$67,416

1. The 2030 expense is an expected inverter replacement.
2. WA state renewable energy production incentive.
3. WSU Renewable Energy System Incentive Program
4. Senate Bill 5939

Notes

• Estimated annual electric rate increases are conservatively estimated at 4%. The 2017 and 2018 increases are 5.6%
• the production incentive is expected to diminish over time, ending in 2020.
• the net metering value increases in value as retail electric rates increase.
• future $ amounts should be inflation adjusted but are not. Yet.

[msimerson]

View from the South:

[msimerson]

install completed

[msimerson]

energy meter

The green line is solar production, the green area is solar delivered to the grid. The huge red spikes in the evening is the Nissan Leaf arriving home and getting plugged in.

The graph is showing three typical grey May days. Soon, the grey will clear and the production line will rise to the systems peak capacity. Then our production will greatly exceed our consumption for at least the rest of the summer.

[msimerson]

cloudy -vs- sunny

Enquiring minds keep asking, "Solar in Seattle?" In this image are 5 cloudy (ranging from mostly-to-entirely) May days followed by one day of full sun and a mostly sunny day with late afternoon haze.

The takeaway is that on cloudy days, a 10kW system can can produce more electricity than our house and car uses. On a sunny day, it produces considerably more.

[msimerson]

solar panels

• iTek IT 290 HE
• 12 panels facing East, 22 facing West
• cells: 60
• efficiency: 17.3%
• Type: Mono PERC
• Size: 65.9" x 35.4"
• Vmp: 32.6V, Voc: 39.5V

Itek was acquired by Silfab Solar in 2019.

inverter

• Solectria PVI 7600TL
  • grid tied
  • type: single phase, transformer less
  • array: grounded

[msimerson]

Mid-2017 Update.

With a full year of electric production and consumption measured, and rate updates for 2017 and 2018 known, I have updated my estimates. The Net Metering benefit has substantially increased due to:

1. Seattle City Light electric rates are higher in Shoreline than Seattle.
2. The 2017 and 2018 rate increases are 5.6% (estimated at 4%)
3. An added RSA surcharge of 1.5% on electric bills
4. The coldest winter in 32 years
5. More electricity use than I predicted.
   • I was still adding insulation to the house deep into the heating season.
   • I guesstimated the kWh it would require to heat a 1955 house with heat pumps.
   • I installed a fast (level 2) charger for our Leaf. We were able to use it more, offsetting gasoline with electricity.
6. The increased usage is all at the higher 0.14¢ price tier.

Reasons 1-4 weren't known during my initial estimates. Reasons 5 and 6 were planned but their scale was unknown. I knew I'd be removing all natural gas appliances (furnace, water heater, fireplace) but I hadn't yet decided whether to install tankless electric or a heat pump water heater. I hadn't chosen the heat pumps for house heat yet so I didn't know their HSPF. I also didn't know how much more we'd be able to use the Leaf.

The net result is that I now estimate a 100% return on the solar array in the 6th year instead of the 8th year. Instead of a lifetime gain of ~$40,000 I now expect a profit in excess of $50,000.

Notes

• I did not include the cost of the heat pumps or the heat pump water heater. Those were efficiency upgrades that I'd have done anyway. If I were keeping natural gas, I'd have replaced the old 80% furnace with a 97% modulating furnace and the "well past it's expected lifespan" gas water heater with a gas tankless. In both cases the costs are comparable and just like replacing the fridge, the efficiency increases have their own ROI schedule.

[msimerson]

2018-01-01 Update: Net Zero Mission Accomplished

[msimerson]

I just received my 2018 production incentive payment notice. When the check arrives (before Dec. 15th), we'll have recovered 2/3 of the cost of the array before the end of the 3rd calendar year. I now project recouping 100% of the array cost at the end of the 5th year.

[msimerson]

Updated SCL rate increases. The projected increases for future years is 4% per year. The actual increases as approved by the City Council are:

2019	2020	2021	2022	2023	2024	Average
5.8%	5.4%	3.6%	3.9%	4.0%	4.2%	4.5%

With future rate increases averaging more than 4% per year, the payback period will be sooner, sometime in the 5th year.

[msimerson]

My inverter died on Aug 5th. On Aug 14th I noticed. The breaker had tripped and when I flipped it back on, the inverter would arc and pop and trip it again. I called Northwest Wind & Solar and the next day they came and swapped it out.

[msimerson]

• 2020-07-27: inverter throwing errors
• 2020-07-28: Inverter offline again
• 2020-07-29: Inverter offline again
• 2021-04-13: Errors 402, 442, 433, 471
• 2021-04-17 - one brief fault
• 2021-04-18 - Offline 90% of the day
• 2021-04-19 - Offline 20% of the day
• 2021-04-20 - offline 2/3 of the day
• 2021-05-11 - still waiting for inverter replacement
• 2021-05-27 - 2nd visit from NW W&S (Hector)
• 2021-06-03 - installed my own inverter
• 2021-?? - 2nd replacement inverter from NW W&S
• 2022: arc fault in disconnect box
• 2023: 2nd inverter failed, replaced with mine.
• 2024-07: moved solar panels to enphase microinverters on SW roof
• 2024-10: moved solar panels back to North roof