Re: [RE-wrenches] AC wiring loss on micro-inverters
Thanks David and Marv: I appreciate the feedback, and have considered the center tap option. However, I have prefered to either divide the arrays into lower amp circuits (10-12 modules per circuit, depending on the wattage) or to run two AC homerun cables to two half length strings (2- 7 modules strings) per and then combine them at the Soladeck/Combiner Box. Does Enphase offer the center tap cable on its price lists? Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: David Brearley david.brear...@solarprofessional.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, June 11, 2010 1:04:13 PM Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Re: [RE-wrenches] AC wiring loss on micro-inverters Maybe Marv can help out here. I’ve talked with tech support at Enphase and am under the impression that you can center tap their branch circuits to reduce voltage drop. This technique was used on a project that we profiled in SolarPro: http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1search= David Brearley, Senior Technical Editor SolarPro magazine On 6/11/10 2:50 PM, Nick Soleil nicksoleilso...@yahoo.com wrote: Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8% Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From:ma...@berkeleysolar.com ma...@berkeleysolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, June 11, 2010 7:02:00 AM Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Nick, Good to see other wrenches looking at this issue. However, remember that in the interconnect cable between the last and the second to last Enphase, the current is small. If you really want to see how the loss is adding up you need a more detailed analysis that averages the voltage drop for the entire system of interconnect cables. Mark Frye Berkeley solar Electric Systems Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htmhttp://www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.orghttp://www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org http://www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
Nick,
We do not offer a T cable, but that's a great idea. I'll shop it
around and see what comes out of it. By the way, the Soladeck seems to
be a great product. For residential rooftops it also allows you to go
directly through a roof penetration and transition to Romex
immediately. Makes a very clean installation.
See ya!
Marv
707 763-4784 x7016
Nick Soleil wrote:
Thanks
David and Marv:
I appreciate the feedback, and have considered the center tap
option. However, I have prefered to either divide the arrays into
lower amp circuits (10-12 modules per circuit, depending on the
wattage) or to run two AC homerun cables to two half length strings (2-
7 modules strings) per and then combine them at the Soladeck/Combiner
Box. Does Enphase offer the center tap cable on its price lists?
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037
From:
David Brearley david.brear...@solarprofessional.com
To: RE-wrenches
re-wrenches@lists.re-wrenches.org
Sent: Fri, June 11,
2010 1:04:13 PM
Subject: Re:
[RE-wrenches] AC wiring loss on micro-inverters
Re: [RE-wrenches] AC wiring loss on micro-inverters
Maybe Marv can help out here. Ive talked
with tech support at Enphase and am under the impression that you can
center tap their branch circuits to reduce voltage drop. This technique
was used on a project that we profiled in SolarPro:
http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1search=
David Brearley, Senior Technical Editor
SolarPro magazine
On 6/11/10 2:50 PM, "Nick Soleil" nicksoleilso...@yahoo.com wrote:
Did you
notice that in my calculation I divided the total amperage by 2 to get
the average ampacity across the string. This seems to be the best way
to deal with that. Otherwise the loss would have been over 2.8%
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037
From: "ma...@berkeleysolar.com" ma...@berkeleysolar.com
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Sent: Fri, June 11, 2010 7:02:00 AM
Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters
Nick,
Good to see other wrenches looking at this issue. However, remember
that
in the interconnect cable between the last and the second to last
Enphase,
the current is small. If you really want to see how the loss is adding
up
you need a more detailed analysis that averages the voltage drop for the
entire system of interconnect cables.
Mark Frye
Berkeley solar Electric Systems
Hello wrenches and Marv:
How many Enphase inverters do you put on a single parallel
string?
The Enphase manual allows for up to 15, but I have found that a
single
string of 15 can have very high voltage rise on the AC wiring. Up
to
1.5% loss just on the Enphase cables, and that does not take into
account resistance at the plug connectors or any home-run wiring.
15 inverters x 190 watts = 2850 watts
2850 watts / 240 Volts = 11.875 Amps (however at the beginning
of the
string it is 0 Amps)
Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps
length of contacts + internal wiring = ~6'
Total Enphase cabling length (6' x 15 inverters) = ~90'
5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss
It is pretty hard to design for 1.5% voltage drop if you have to
size for
0% loss on your wiring! I hope Enphase will increase the size of
the wire
in their cables soon. Have you experienced issues with
micro-inverters
shutting off due to high AC voltages?
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037
From: i2p i...@aol.com
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Sent: Thu, June 10, 2010 4:50:47 PM
Subject: Re: [RE-wrenches] Real world PV production
On Jun 10, 2010, at 7:57:53 AM, "Kelly Keilwitz, Whidbey Sun
Wind"
ke...@whidbeysunwind.com
wrote:
PV Watts VASTLY underestimate PV production
in our area.
PV Watts underestimates in Central Ca too.
Don
___
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules etiquette:
www.re-wrenches.org/etiquette.htm
http://www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
http://www.members.re-wrenches.org
___
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenc
Re: [RE-wrenches] AC wiring loss on micro-inverters
Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
Nick, Good to see other wrenches looking at this issue. However, remember that in the interconnect cable between the last and the second to last Enphase, the current is small. If you really want to see how the loss is adding up you need a more detailed analysis that averages the voltage drop for the entire system of interconnect cables. Mark Frye Berkeley solar Electric Systems Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
Hi Nick, You bring up a good point that Enphase should address more clearly. However, I think the math should be done section by section to accurately account for the wire loss and not the total combined amps for the entire length. If the loss's are too high then reducing the number in each string to an acceptable wire loss would be my recommendation. On Jun 11, 2010, at 12:14 AM, Nick Soleil wrote: Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax: 707-769-9037 From: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8% Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: ma...@berkeleysolar.com ma...@berkeleysolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, June 11, 2010 7:02:00 AM Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Nick, Good to see other wrenches looking at this issue. However, remember that in the interconnect cable between the last and the second to last Enphase, the current is small. If you really want to see how the loss is adding up you need a more detailed analysis that averages the voltage drop for the entire system of interconnect cables. Mark Frye Berkeley solar Electric Systems Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
Maybe Marv can help out here. I¹ve talked with tech support at Enphase and am under the impression that you can center tap their branch circuits to reduce voltage drop. This technique was used on a project that we profiled in SolarPro: http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1search= David Brearley, Senior Technical Editor SolarPro magazine On 6/11/10 2:50 PM, Nick Soleil nicksoleilso...@yahoo.com wrote: Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8% Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: ma...@berkeleysolar.com ma...@berkeleysolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Fri, June 11, 2010 7:02:00 AM Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Nick, Good to see other wrenches looking at this issue. However, remember that in the interconnect cable between the last and the second to last Enphase, the current is small. If you really want to see how the loss is adding up you need a more detailed analysis that averages the voltage drop for the entire system of interconnect cables. Mark Frye Berkeley solar Electric Systems Hello wrenches and Marv: How many Enphase inverters do you put on a single parallel string? The Enphase manual allows for up to 15, but I have found that a single string of 15 can have very high voltage rise on the AC wiring. Up to 1.5% loss just on the Enphase cables, and that does not take into account resistance at the plug connectors or any home-run wiring. 15 inverters x 190 watts = 2850 watts 2850 watts / 240 Volts = 11.875 Amps (however at the beginning of the string it is 0 Amps) Average Amps on the Enphase cables is 11.875 / 2 = 5.9375 Amps length of contacts + internal wiring = ~6' Total Enphase cabling length (6' x 15 inverters) = ~90' 5.9375 Amps @ 240 V running 90' on #14 AWG CU = 1.4% loss It is pretty hard to design for 1.5% voltage drop if you have to size for 0% loss on your wiring! I hope Enphase will increase the size of the wire in their cables soon. Have you experienced issues with micro-inverters shutting off due to high AC voltages? Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 From: i2p i...@aol.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Thu, June 10, 2010 4:50:47 PM Subject: Re: [RE-wrenches] Real world PV production On Jun 10, 2010, at 7:57:53 AM, Kelly Keilwitz, Whidbey Sun Wind ke...@whidbeysunwind.com wrote: PV Watts VASTLY underestimate PV production in our area. PV Watts underestimates in Central Ca too. Don ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm http://www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org http://www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org http://www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
I guess all this does is effectively reduce the number of inverters in each string, and create two strings from one (but without additional homerun string wiring). So you need two factory pigtails instead of one for each original string for the center tap j-box, but a small price to pay for increased system efficiency. Good idea. Kirk Herander Vermont Solar Engineering 802.863.1202 NABCEP(tm) Certified Solar Installer NYSERDA-eligible Installer VT Solar Incentive Program Partner _ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of David Brearley Sent: Friday, June 11, 2010 4:04 PM To: RE-wrenches Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters Maybe Marv can help out here. I've talked with tech support at Enphase and am under the impression that you can center tap their branch circuits to reduce voltage drop. This technique was used on a project that we profiled in SolarPro: http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1 http://solarprofessional.com/article/?file=SP3_2_pg92_Projects_1search= search= David Brearley, Senior Technical Editor SolarPro magazine On 6/11/10 2:50 PM, Nick Soleil nicksoleilso...@yahoo.com wrote: Did you notice that in my calculation I divided the total amperage by 2 to get the average ampacity across the string. This seems to be the best way to deal with that. Otherwise the loss would have been over 2.8% Nick Soleil Project Manager Advanced Alternative Energy Solutions, LLC PO Box 657 Petaluma, CA 94953 Cell: 707-321-2937 Office: 707-789-9537 Fax:707-769-9037 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
I just attended a training class in Philly last week by Enphase technical staff and my notes say they suggest up to 15 micro-inverters @ 190 watts each per string with no problem. They also are now shipping their dual module micro-inverter which should help with this wire issue since this model #D380 has two #M190 units built into the same box which is only slightly larger thana single micro-inverter. Since this new dual micro-inverter does NOT have the AC pass-through wire built-in, you are no longer limited to the wire size that comes in and out for the 240 VAC connections. HOWEVER, they require you to purchase this awful looking multi-tap pigtail cable for the AC connections which has a pre-wired connector spaced the expected distance apart the micro-inverters would be installed, and this is a $950 item for every six dual micro-inverters. When I saw this thing I thought is was a python that had swalled six pepsi cans! Not sure what this will look like on a roof or how well it can be hidden behind the array, but it uses a larger wire size so perhaps the wire loss issue has been resolved. Jeff Yago DTI SolarNetscape. Just the Net You Need. ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] AC wiring loss on micro-inverters
Hi fellow wrenches forgive me if this has been said. The AC is a special problem on MIcro inverters because the long runs modules to service are now in the AC section of the system. The DC connections are very short. The utility has a +- 5% normal tolerance, which leaves us with only 5% to count on. If the grid is high any voltage rise would put us very close to high voltage shut down. The manufacture is trying to help us prevent nuisance shut downs, and is looking for 1% voltage rise. Voltage rise or drop is easily calculated in English units by Vr=2KIL/CM where K is the coefficient of resistance for copper (12.9) I is the current in amps, (0.82x#of M190 inverters) L is the one way length of the wire run. or equally straight forward is Vr= 2LIR/1000 where the L is the one way length, I is the current as above, R is the resistance per 1000 feet of wire. The CM and R values are from Chapter 9 Table 8 of the NEC Darryl --- On Fri, 6/11/10, Jeff Yago jry...@netscape.com wrote: From: Jeff Yago jry...@netscape.com Subject: Re: [RE-wrenches] AC wiring loss on micro-inverters To: k...@vtsolar.com, RE-wrenches re-wrenches@lists.re-wrenches.org Date: Friday, June 11, 2010, 5:42 PM I just attended a training class in Philly last week by Enphase technical staff and my notes say they suggest up to 15 micro-inverters @ 190 watts each per string with no problem. They also are now shipping their dual module micro-inverter which should help with this wire issue since this model #D380 has two #M190 units built into the same box which is only slightly larger than a single micro-inverter. Since this new dual micro-inverter does NOT have the AC pass-through wire built-in, you are no longer limited to the wire size that comes in and out for the 240 VAC connections. HOWEVER, they require you to purchase this awful looking multi-tap pigtail cable for the AC connections which has a pre-wired connector spaced the expected distance apart the micro-inverters would be installed, and this is a $950 item for every six dual micro-inverters. When I saw this thing I thought is was a python that had swalled six pepsi cans! Not sure what this will look like on a roof or how well it can be hidden behind the array, but it uses a larger wire size so perhaps the wire loss issue has been resolved. Jeff Yago DTI Solar Netscape. Just the Net You Need. -Inline Attachment Follows- ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
