Jan 08 Utility Inverter
Utility ownership of the inverter Why it makes sense Jim White, P.E. Chelan County Public Utility District
Why would we want to own that? “A utility-owned inverter? Why would we want to own that? The inverter is one of the most unreliable parts of the whole system.”
PAGE 2
Why? To make solar cost effective today. 50% 45%
% Total Electricity from Solar % Impact on Electrical Rates
40% 35%
25% 20% 15% 10% 5%
Year
6
5
20 3
4
20 3
3
20 3
2
20 3
1
20 3
0
20 3
9
20 3
8
20 2
7
20 2
6
20 2
5
20 2
4
20 2
3
20 2
2
20 2
1
20 2
0
20 2
9
20 2
8
20 1
7
20 1
6
20 1
5
20 1
4
20 1
3
20 1
2
20 1
1
20 1
0
20 1
9
20 1
20 0
8
0%
20 0
% Increase
30%
PAGE 3
Solar Performance Incentives $0.60
0.2%
Performance Incentive, $ per kWh
$0.50 0.2% to 0.44% 0.44% to 1.00%
$0.40
1.0% to 1.5% 1.5% to 3.0%
$0.30
3.0% to 5.0% $0.20
5.0% to 10%
$0.10
$0.00 2008
2009
2010
2011
2012
2013
2014
2015
Year
2016
2017
2018
2019
2020
2021
2022
PAGE 4
Why would utilities want to own the inverter? • Improve solar system reliability • Simplify interconnection • Dramatically reduce upfront cost for customer • Provide full cost recovery and profit for the electric utility • Ideally suited for performance incentives instead of rebates • To have greater control over the specifications and operations of the inverter PAGE 5
Conventional PV system costs Solar Module
Solar Module Purchase Price $4.25/Watt + Mounting Rack $0.50/watt
Inverter
Inverter $1.00/Watt
Electrical & Wiring
Misc. Electrical Wiring, Conduit & Switches $0.50/Watt
Permits
Electrical Permits, Building Permits, Utility Fees $0.15/Watt
Install Labor
Solar Module Install & Electrical Contracto r $1$4/Watt
Total Cost = $7.40 to $10.40 per Watt PAGE 6
Conventional system hardware costs • • • • • • • • • •
Solar Modules Mounting System Wiring/Grounding DC Disconnect Switch DC-to-AC Inverter AC Disconnect Switch *Utility Service Disconnect Switch *Utility Meter & Base (in WA and >100 kW CA) Connection to Circuit Breaker Panel *Replace Standard Meter with Net Meter
(*Note – Many utilities may not require this item.) PAGE 7
Administrative costs of a conventional system • • • • • • •
Contractor selection or do it yourself System design Arrange financing Rebate or production incentive application Utility interconnection approval process Electrical permits & inspection Utility inspection
PAGE 8
Conventional net metered system
PAGE 9
Conventional net metered solar system
Customer Utility
PAGE 10
Conventional metered system
PAGE 11
Conventional solar system with utility production meter
Customer Utility
Utility
PAGE 12
Use inverter’s meter on customer-owned inverter
Customer Utility
METER
PAGE 13
Utility production meter inside utility-owned inverter
Customer Utility
METER
Meter Base Adapter
PAGE 14
Use two utility meters with utility-owned inverter
Customer Utility
Duplex Meter Base Adapter PAGE 15
Use two utility meters with customer-owned micro inverters
Customer Utility
Duplex Meter Base Adapter PAGE 16
Utility-owned inverter and meter inside of revenue meter
Customer
Utility
Inverter Inside of Meter
PAGE 17
utility-owned inverter inside revenue meter with built-in DC switch
Utility Customer
PAGE 18
utility-owned inverter that fits in meter base
PAGE 19
One inverter inside two utility meters
PAGE 20
Utility meter with built-in inverter, DC disconnect switch and 2 meters SOLAR METER & DISCONNECT SWITCH
PAGE 21
Solar DC plugs into meter when DC switch in OFF position
PAGE 22
Solar DC cannot be unplugged when DC switch in ON position
PAGE 23
Solar cannot be plugged in when DC switch in LOCK position
PAGE 24
Ideal installation process • Solar array installed on roof • Solar modules are plugged together • Customer contacts electric utility to request a solar meter • Utility service personnel replaces revenue meter with utility-owned inverter (UOI)
PAGE 25
Customer’s cost with utility-owned inverter • • • • • • • • • •
Solar Modules Module Mounting System DC Wiring/Grounding DC Disconnect Switch DC-to-AC Inverter AC Disconnect Switch *Utility Service Disconnect Switch *Utility Meter & Base (in WA and >100 kW CA) Connection to Circuit Breaker Panel *Replace Standard Meter with Net Meter
PAGE 26
Customer’s PV system cost with utility-owned inverter Solar Module
Inverter
Solar Module Purchase Price $4.25/Watt + Mounting Rack $0.50/Watt
Inverter $1.00/Watt
Electrical & Wiring
Misc. Electrical Wiring, Conduit & Switches $0.50/Watt
Permits
Electrical Permits, Building Permits, Utility Fees $0.15/Watt
Total Cost = $5.75 per Watt
Install Labor
Solar Module Install & Electrical Contracto r $2$5/Watt $1.00/Watt
PAGE 27
Customer’s administrative costs with utility-owned inverter • Check utility rate schedule for performance incentive amounts • Obtain financing for solar modules & installation • Utility interconnection issues greatly simplified • Electrical Permitting – Simplified, eventually eliminated • Utility Inspection – Done once when UOI is installed by utility service personnel
PAGE 28
Who gets the PV power? Two options – • Utility – 100% of PV output and renewable energy credit goes to utility, but customer receives premium $ for 100% of solar generated kWh’s. • Customer - Net metered PV output is credited against customer’s consumption and customer keeps the renewable energy credit.
PAGE 29
utility-owned inverter costs and revenue • •
• • • •
Cost of inverter/meter based on lowest life cycle cost, not lowest first cost. Monthly fee charged to customer recovers cost to purchase, install, and maintain the inverter, as well as read the meter. No retail revenue lost from net-metering. Investor owned utilities entitled to rate of return on capital investments. Public utilities could use 0% CREB to purchase the inverters. Renewable credit could belong to utility. PAGE 30
Other benefits to the utility • Easier to change inverter characteristics: – Add ability to ride through momentary outages – Remove 5 minute delay – Add automatic meter reading capabilities – Provide utility control of the inverter output and power quality
PAGE 31
Questions? Contact: Dr. Jim White, P.E. Senior Energy Services Engineer Chelan County Public Utility District 327 N. Wenatchee Ave. Wenatchee, Washington 98801 Phone 509-661-4829 email: [email protected]
PAGE 32
Why would we want to own that? “A utility-owned inverter? Why would we want to own that? The inverter is one of the most unreliable parts of the whole system.”
PAGE 2
Why? To make solar cost effective today. 50% 45%
% Total Electricity from Solar % Impact on Electrical Rates
40% 35%
25% 20% 15% 10% 5%
Year
6
5
20 3
4
20 3
3
20 3
2
20 3
1
20 3
0
20 3
9
20 3
8
20 2
7
20 2
6
20 2
5
20 2
4
20 2
3
20 2
2
20 2
1
20 2
0
20 2
9
20 2
8
20 1
7
20 1
6
20 1
5
20 1
4
20 1
3
20 1
2
20 1
1
20 1
0
20 1
9
20 1
20 0
8
0%
20 0
% Increase
30%
PAGE 3
Solar Performance Incentives $0.60
0.2%
Performance Incentive, $ per kWh
$0.50 0.2% to 0.44% 0.44% to 1.00%
$0.40
1.0% to 1.5% 1.5% to 3.0%
$0.30
3.0% to 5.0% $0.20
5.0% to 10%
$0.10
$0.00 2008
2009
2010
2011
2012
2013
2014
2015
Year
2016
2017
2018
2019
2020
2021
2022
PAGE 4
Why would utilities want to own the inverter? • Improve solar system reliability • Simplify interconnection • Dramatically reduce upfront cost for customer • Provide full cost recovery and profit for the electric utility • Ideally suited for performance incentives instead of rebates • To have greater control over the specifications and operations of the inverter PAGE 5
Conventional PV system costs Solar Module
Solar Module Purchase Price $4.25/Watt + Mounting Rack $0.50/watt
Inverter
Inverter $1.00/Watt
Electrical & Wiring
Misc. Electrical Wiring, Conduit & Switches $0.50/Watt
Permits
Electrical Permits, Building Permits, Utility Fees $0.15/Watt
Install Labor
Solar Module Install & Electrical Contracto r $1$4/Watt
Total Cost = $7.40 to $10.40 per Watt PAGE 6
Conventional system hardware costs • • • • • • • • • •
Solar Modules Mounting System Wiring/Grounding DC Disconnect Switch DC-to-AC Inverter AC Disconnect Switch *Utility Service Disconnect Switch *Utility Meter & Base (in WA and >100 kW CA) Connection to Circuit Breaker Panel *Replace Standard Meter with Net Meter
(*Note – Many utilities may not require this item.) PAGE 7
Administrative costs of a conventional system • • • • • • •
Contractor selection or do it yourself System design Arrange financing Rebate or production incentive application Utility interconnection approval process Electrical permits & inspection Utility inspection
PAGE 8
Conventional net metered system
PAGE 9
Conventional net metered solar system
Customer Utility
PAGE 10
Conventional metered system
PAGE 11
Conventional solar system with utility production meter
Customer Utility
Utility
PAGE 12
Use inverter’s meter on customer-owned inverter
Customer Utility
METER
PAGE 13
Utility production meter inside utility-owned inverter
Customer Utility
METER
Meter Base Adapter
PAGE 14
Use two utility meters with utility-owned inverter
Customer Utility
Duplex Meter Base Adapter PAGE 15
Use two utility meters with customer-owned micro inverters
Customer Utility
Duplex Meter Base Adapter PAGE 16
Utility-owned inverter and meter inside of revenue meter
Customer
Utility
Inverter Inside of Meter
PAGE 17
utility-owned inverter inside revenue meter with built-in DC switch
Utility Customer
PAGE 18
utility-owned inverter that fits in meter base
PAGE 19
One inverter inside two utility meters
PAGE 20
Utility meter with built-in inverter, DC disconnect switch and 2 meters SOLAR METER & DISCONNECT SWITCH
PAGE 21
Solar DC plugs into meter when DC switch in OFF position
PAGE 22
Solar DC cannot be unplugged when DC switch in ON position
PAGE 23
Solar cannot be plugged in when DC switch in LOCK position
PAGE 24
Ideal installation process • Solar array installed on roof • Solar modules are plugged together • Customer contacts electric utility to request a solar meter • Utility service personnel replaces revenue meter with utility-owned inverter (UOI)
PAGE 25
Customer’s cost with utility-owned inverter • • • • • • • • • •
Solar Modules Module Mounting System DC Wiring/Grounding DC Disconnect Switch DC-to-AC Inverter AC Disconnect Switch *Utility Service Disconnect Switch *Utility Meter & Base (in WA and >100 kW CA) Connection to Circuit Breaker Panel *Replace Standard Meter with Net Meter
PAGE 26
Customer’s PV system cost with utility-owned inverter Solar Module
Inverter
Solar Module Purchase Price $4.25/Watt + Mounting Rack $0.50/Watt
Inverter $1.00/Watt
Electrical & Wiring
Misc. Electrical Wiring, Conduit & Switches $0.50/Watt
Permits
Electrical Permits, Building Permits, Utility Fees $0.15/Watt
Total Cost = $5.75 per Watt
Install Labor
Solar Module Install & Electrical Contracto r $2$5/Watt $1.00/Watt
PAGE 27
Customer’s administrative costs with utility-owned inverter • Check utility rate schedule for performance incentive amounts • Obtain financing for solar modules & installation • Utility interconnection issues greatly simplified • Electrical Permitting – Simplified, eventually eliminated • Utility Inspection – Done once when UOI is installed by utility service personnel
PAGE 28
Who gets the PV power? Two options – • Utility – 100% of PV output and renewable energy credit goes to utility, but customer receives premium $ for 100% of solar generated kWh’s. • Customer - Net metered PV output is credited against customer’s consumption and customer keeps the renewable energy credit.
PAGE 29
utility-owned inverter costs and revenue • •
• • • •
Cost of inverter/meter based on lowest life cycle cost, not lowest first cost. Monthly fee charged to customer recovers cost to purchase, install, and maintain the inverter, as well as read the meter. No retail revenue lost from net-metering. Investor owned utilities entitled to rate of return on capital investments. Public utilities could use 0% CREB to purchase the inverters. Renewable credit could belong to utility. PAGE 30
Other benefits to the utility • Easier to change inverter characteristics: – Add ability to ride through momentary outages – Remove 5 minute delay – Add automatic meter reading capabilities – Provide utility control of the inverter output and power quality
PAGE 31
Questions? Contact: Dr. Jim White, P.E. Senior Energy Services Engineer Chelan County Public Utility District 327 N. Wenatchee Ave. Wenatchee, Washington 98801 Phone 509-661-4829 email: [email protected]
PAGE 32
