Re: [RE-wrenches] Diversion load for AC coupled system
At 18:38 -0800 29/11/11, jay peltz wrote: Hi Kent, You can't parallel them. They each must have their own load. But you can connect two Tristars to the same battery, each with its own load and this is normal recommended practice. The two controllers may not agree exactly about when to move to the float stage, but when you think it through that doesn't actually matter at all. At 18:30 -0800 29/11/11, Kent Osterberg wrote: The Tristar 60 manual says to keep diversion loads below 45 amps (or somewhere close to that). Load sizing is very confusing, but no, you can use any resistive load that will not exceed 60 amps (at EQ voltage). The 40 amps is the maximum renewables input (source current) if you are going to conform to the NEC requirement that the dump load must be sized to 150% of the maximum rated current of the solar, wind and hydro sources combined. In short you can use a 40 amps source provided that you have the capacity to dump 60 amps, and this depends on finding a suitable load. (In reality a load that dumps 60 amps at 60 volts will only dump 54 amps at 54 volts float so you are down to a 36 amp source current but this may be built into the safety margin already, who knows?.) I normally choose a big wire-wound resistor. In this case one ohm 4kW would be suitable. In reality this would be built from several 1kW or whatever I could find. For example 4 resistors at 1 ohm and 1 kW, configured in two pairs series/parallel. More about the subject here. http://scoraigwind.co.uk/?page_id=637 Best wishes, -- Hugh Piggott Scoraig http://www.scoraigwind.co.uk ___ 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-wrenches] module storage
Hi All, I've got a project coming up that might need 2 modules just to fill in some space but not be electrically used. So how best to install them VOC or ISC thanks, jay peltz power ___ 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] calculating low string voltage
Here¹s a link to an Excel version of our c-Si PV module specifications table: https://solarprofessional.com/webexclusive/ It includes coefficients for Voc, Pmp and Isc. For Vmp calculations, use the coefficient of Pmp, which is primarily voltage driven. (Temperature coefficients of current are VERY small, as seem in the Isc values.) David Brearley, Senior Technical Editor SolarPro magazine NABCEP Certified PV Installer david.brear...@solarprofessional.com Direct: 541.261.6545 On 11/30/11 12:18 AM, Ray Walters r...@solarray.com wrote: I pulled the voltage temp coefficient off of an article from Solar Pro Magazine. It is indeed listed for Voc. I have never seen a separate coefficient for Vmpp. Maybe we should use the Power mpp coefficient and then factor the slight rise in current by temp (which would make Vmpp even worse). My Solar world example shows a Pmpp coeff. of -0.47, while the current coeff. (short circuit though) is positive 0.04 so correcting just for voltage, that would be at or slightly worse than Bill's suggested -0.5 coefficient for Vmpp. Which would pull the Vmpp from 35 to 28 in my example, not 30.4 v. The degradation and mismatch Bill points out make sense, but is it really another 15% combined? Would it be fair to say different modules and manufacturers would degrade at different rates? Finally, the ambient temp I picked was the opposite of the NEC suggested ASHRAE low temp. Is that really the best number for calculating this? Or is that too extreme a temperature, that wouldn't occur most of the time? Now I have to correct that coefficient for my next class..but that's why I asked for everybody to look it over. Thanks Everyone, Ray On 11/29/2011 8:08 PM, Doug Wells wrote: Ray, I agree with what you have calculated, but the temp. coef. listed is for a Voc. For voltage sag, the temp. value would be a Vmp value and I don't know how much of a difference that makes. I have seen some manufacturers offer a temp. coefficient for Vmp as well as Voc. Not sure what the difference would be, but if it gets down to a few volts with the PE, it is would be worth checking. Doug Wells The Solar Specialists Morrisville, VT 05661 (p) 802-223-7014 (c) 802-498-5856 www.thesolarspecialists.com http://www.thesolarspecialists.com On Nov 29, 2011, at 5:55 PM, Ray Walters wrote: I'm prepping for a class on this very subject tonight, so I'll just wrap up everybody's good points: V min = Vmpp x (1- temp diff x Temp coefficient) So first, I'd take your ambient temp from ASHRAE Extreme Annual Mean Maximum, then add Scott's adder (ie roof mount off 6 = +30C) so let's say the ASHRAE # is 35C, then you have 30 + 35 = 65C cell temp then, 65C - 25C(STC) = a differential of 40 deg C from standard test conditions The Aug/ Sept 2010 edition of Solar Pro shows the coefficients for numerous modules, Solar world for example is -0.33 %/degC With a 40 degC differential then, the voltage would change by 40 x .33, or 13.2% So just assuming Vmpp = 35v, the adjustment would be 35v x (100%-13.2%), or 86.8% of 35v, which gives a Volt min of 30.4 v Somebody please correct my math if I got that wrong. Also probably more interesting is the actual Power coefficient, which shows the total power losses from higher temperatures, not just voltage. The calculation would be similar. Ray On 11/29/2011 2:07 PM, Darryl Thayer wrote: I am on road so I have no texts with me, but the same formula applies about 0.4% per degree (less voltage) or use the module label voltage coefficent. However you must use the MPPT voltage and the temperature = (temperature ambient (2% high) plus roof temperature warming) The roof temperature is hard to find good values because it depends upon spacing between roof and module. I add 15 deg C for most situations. Best I can do from memory. DT From: Kirk Herander k...@vtsolar.com mailto:k...@vtsolar.com To: RE-wrenches re-wrenches@lists.re-wrenches.org mailto:re-wrenches@lists.re-wrenches.org Sent: Tuesday, November 29, 2011 1:48 PM Subject: [RE-wrenches] calculating low string voltage I am in debate with a PE over calculation of low voltage of a series string on a hot day. He insists that an arbitrary high cell temp is factored in, not just ambient temperature. Could someone please give an accepted formula for this calculation? Thanks. I cannot find a clear reference to low voltage calculation on a hot day (but every reference material is clear on how to calculate high voltage on a cold day). Kirk Herander VT Solar, LLC dba Vermont Solar Engineering NABCEPTM Certified installer Charter Member NYSERDA-eligible Installer VT RE Incentive Program Partner
Re: [RE-wrenches] calculating low string voltage
Thanks for all the good response. Speaking of monkey wrenches, these are Sanyo HIT Double panels, mounted on a rack which is 5 ½ feet above the roof surface. They will absorb reflected light on the backside, so I assume the cells will operate at a higher temp. But they are elevated enough to simulate a pole-mount, thus lowering operating cell temp. So what operating temp to use? If I use 25 C as the operating temp, the low voltage calc comes out to 301 vdc (inverter min is 300 using SMA US8000). If I use 15 C the calc is 308 vdc. This is for a 6 panel string. Unfortunately I really dont want to use 7 panel strings due to the layout. If I used a US7000 it would work since min vdc in is 250. However the inverters are part of a SunnyTower and I cant swap a 7000 for an 8000 without voiding the Tower UL listing. Kirk Herander VT Solar, LLC dba Vermont Solar Engineering NABCEPTM Certified installer Charter Member NYSERDA-eligible Installer VT RE Incentive Program Partner From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of b...@midnitesolar.com Sent: Wednesday, November 30, 2011 1:03 AM To: RE-wrenches Subject: Re: [RE-wrenches] calculating low string voltage If you really want to throw a monkey wrench into the mix, bring up partial shading... Or, maybe that's just not allowed in that debate ??Just a thought. boB On 11/29/2011 8:39 PM, Kent Osterberg wrote: Kirk, You've got some good feedback on this from Ray and Bill. I'll try to add a little more. Most module datasheets show a normal operating cell temperature, NOCT, value that's typically 47.5°C. That's 20°C ambient temperature, 800 W/sq m, and calm wind and nothing blocking the airflow on the back of the module. That 27.5°C temperature rise should be pretty close to the temperature rise that occurs for a pole-top mount. It's common to see people use 25°C for modules on a pole and 30°C or 35°C on a roof and there are data that support these typical values. With 1000 W/sq irradiance, the temperature rise can obviously be more too. Between the intensity of the sun, the direction of the sun, the color of the roof, the spacing off the roof, and the wind speed there is a lot that is different from one system to the next or even one day to the next. Most PV module spec sheets don't give you a temperature coefficient for Vmp. I've seen people use the the Voc coefficient, usually expressed as a percentage, for both Voc and Vmp. Big mistake. Data from NREL indicates as Bill said, the temperature coefficient for Vmp is higher than that the temperature coefficient for Voc. That's particularly true when the coefficient is expressed as a percentage per °C. Since there are very few manufacturer's that give both temperature coefficients, I'll use a value from an old Evergreen module for an example. The Evergreen ES-195 datasheet shows Voc = 30.5 volts with a coefficient of -0.34%/°C and Vmp = 27.1 volts with a coefficient of -0.47%/°C. Since one shouldn't add volts and percents, I'll put the temperature coefficients in volts/°C: Voc = 30.5 V - 0.10 V/°C and Vmp = 27.1 V - 0.13V/°C. So Vmp is moving faster than Voc, but not a lot faster. That's generically true for c-Si or poly-Si. Kent Osterberg Blue Mountain Solar, Inc. www.bluemountainsolar.com t: 541-568-4882 On 11/29/2011 11:48 AM, Kirk Herander wrote: I am in debate with a PE over calculation of low voltage of a series string on a hot day. He insists that an arbitrary high cell temp is factored in, not just ambient temperature. Could someone please give an accepted formula for this calculation? Thanks. I cannot find a clear reference to low voltage calculation on a hot day (but every reference material is clear on how to calculate high voltage on a cold day). Kirk Herander VT Solar, LLC dba Vermont Solar Engineering NABCEPTM Certified installer Charter Member NYSERDA-eligible Installer VT RE Incentive Program Partner ___ 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] Diversion load for AC coupled system
Thanks Kent, Kirpal, Jay, Hugh, Et al, At 3.8kW, each TS-60 will divert up to 34 amps @ 56 volts, well under 75%. I will have isolated loads for each controller. Kent, what am I overestimating? One concern about two controllers is that if one has a lower turn on voltage than the other, the total load might be applied to it until voltage rise causes the second controller to to divert power. Without a way to limit controller current, I think this could be a problem. Over-current failure of one controller would cascade to the second then cause battery over-voltage until the Magnum shifted frequency to stop the grid inverter. Has anyone done diversion with two controllers? Another thought I had is to use a single controller for relay control of a 120 or 240 volt load. I'm thinking this will be easier but I'd sure like some input if you have done this. Thank you, Larry Crutcher Starlight Solar Power Systems On Nov 29, 2011, at 7:30 PM, Kent Osterberg wrote: Larry, I think Magnum's recommendation is more about proper battery charging than safety. I'll second Kirpal's and Jeremy's recommendations for loads. The Tristar is probably the best choice for this job, but you are overestimating what you can do with it and paralleling two may have some coordination issues. The Tristar 60 manual says to keep diversion loads below 45 amps (or somewhere close to that). I think its a reliability issue so with a secondary shut down method, you might be okay pushing it a bit. I'm not sure how you get two of them to work together. Kent Osterberg Blue Mountain Solar, Inc. www.bluemountainsolar.com t: 541-568-4882 On 11/29/2011 5:35 PM, Larry Crutcher, Starlight Solar Power Systems wrote: Hello Wrenches, I would like some advice on diversion load control of 3800 watts of PV solar. The battery bank is 48 volts and the battery inverter is the MS4448PAE. This will AC couple with a grid tied inverter during an outage. Magnum Energy recommends the addition of a dump load for safe battery voltage control. The customer may leave the home unattended for weeks so I am looking for reliability here. Quality, as well. A pair of Tristar 60's should be suitable for the 3.8kW output but I haven't been able to find a load that is sized for this job. I welcome any advice on this subject. Thanks in advance. Larry Crutcher Starlight Solar Power Systems ___ 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] Diversion load for AC coupled system
David, Ah..I think I see what you are saying. But, don't you mean .2 volts lower than the diversion load? That way there will only be limited current left for the diversion controller to handle. If it is the other way, what stops full current from flowing through the diversion controller if the .2 volts is not reached? Or is .2 volts two close to worry about that? Larry Crutcher Starlight Solar Power Systems On Nov 29, 2011, at 8:51 PM, David Katz wrote: Larry, If you need a bigger diversion than a Tristar can handle, you can use a relay controlled by the auxiliary output of a charge control or inverter and have the relay close when the voltage is 0.2 volts higher than the diversion voltage. You can switch on a load that is 50 to 75 % of the diversion load and let the diversion controller do the fine tuning. Let me know if that does not make sense. David Katz - Original Message - From: Larry Crutcher, Starlight Solar Power Systems [mailto:la...@starlightsolar.com] Sent: Tuesday, November 29, 2011 05:35 PM To: RE-wrenches re-wrenches@lists.re-wrenches.org Subject: [RE-wrenches] Diversion load for AC coupled system Hello Wrenches, I would like some advice on diversion load control of 3800 watts of PV solar. The battery bank is 48 volts and the battery inverter is the MS4448PAE. This will AC couple with a grid tied inverter during an outage. Magnum Energy recommends the addition of a dump load for safe battery voltage control. The customer may leave the home unattended for weeks so I am looking for reliability here. Quality, as well. A pair of Tristar 60's should be suitable for the 3.8kW output but I haven't been able to find a load that is sized for this job. I welcome any advice on this subject. Thanks in advance. Larry Crutcher Starlight Solar Power Systems ___ 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] module storage
Open circuit. If something comes apart internally at short circuit you have a possible arc. Bill. -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of jay peltz Sent: Wednesday, November 30, 2011 7:07 AM To: RE-wrenches Subject: [RE-wrenches] module storage Hi All, I've got a project coming up that might need 2 modules just to fill in some space but not be electrically used. So how best to install them VOC or ISC thanks, jay peltz power ___ 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] Diversion load for AC coupled system
Larry, I think you want the PWM controller to start first so the turn on will be smooth. If the current capacity of the diversion controller is exceeded then you want the relay to switch in the big load. At that point the diversion controller will back off and pickup the difference. That is why I suggested the the relay controlled load be 50 to 75% of the pwm diversion load, so that whenever it turns on the pwm controller will be working, too. David David Katz CTO Founder AEE Solar Inc P: 707 825-1200 F: 707 825-1202 dk...@aeesolar.com www.aeesolar.com From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Larry Crutcher, Starlight Solar Power Systems Sent: Wednesday, November 30, 2011 8:49 AM To: RE-wrenches Subject: Re: [RE-wrenches] Diversion load for AC coupled system David, Ah..I think I see what you are saying. But, don't you mean .2 volts lower than the diversion load? That way there will only be limited current left for the diversion controller to handle. If it is the other way, what stops full current from flowing through the diversion controller if the .2 volts is not reached? Or is .2 volts two close to worry about that? Larry Crutcher Starlight Solar Power Systems ___ 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] Recycling failed modules
Take them to Quartzsite, AZ in January. You'll sell them in a day. Recycle that junk into cash! Seriously, we often get calls from desert rats (picture some occupy wall street types with wiry hair and leathery, dust covered skin from dwelling in the desert too long) looking for used or busted modules. Larry Crutcher Starlight Solar Power Systems On Nov 30, 2011, at 10:17 AM, Allan Sindelar wrote: Wrenches, Over the years we have gathered a collection of failed and shattered modules of various brands. It's a collection because we haven't wanted them to go into our landfill. It's time to get them out of here as our space needs increase. What's the sustainable and responsible way to deal with them? I'd be willing to remove the aluminum frames where possible and ship the rest to a center that would be equipped to responsibly recycle the materials, but I don't know where to begin. I suspect we're not the only ones facing this, and solutions are out there. All suggestions appreciated, thank you. Allan -- Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com ___ 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] Recycling failed modules
I pulled the Al off, and recycled the framing with our cans ( Al scrap is over 50 cents/lb). The glass/ silicon I took to a computer/ electronics recycling drop off. Did I do the right thing? Never know, but shipping them seems more environmentally damaging than the land fill. Many places recycle electronics, I saw a drop off at Best Buy the other day. Ray On 11/30/2011 11:32 AM, Larry Crutcher, Starlight Solar Power Systems wrote: Take them to Quartzsite, AZ in January. You'll sell them in a day. Recycle that junk into cash! Seriously, we often get calls from desert rats (picture some occupy wall street types with wiry hair and leathery, dust covered skin from dwelling in the desert too long) looking for used or busted modules. Larry Crutcher Starlight Solar Power Systems On Nov 30, 2011, at 10:17 AM, Allan Sindelar wrote: Wrenches, Over the years we have gathered a collection of failed and shattered modules of various brands. It's a collection because we haven't wanted them to go into our landfill. It's time to get them out of here as our space needs increase. What's the sustainable and responsible way to deal with them? I'd be willing to remove the aluminum frames where possible and ship the rest to a center that would be equipped to responsibly recycle the materials, but I don't know where to begin. I suspect we're not the only ones facing this, and solutions are out there. All suggestions appreciated, thank you. Allan -- *Allan Sindelar* _Allan@positiveenergysolar.com_ mailto:al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician *Positive Energy, Inc.* 3201 Calle Marie Santa Fe, New Mexico 87507 *505 424-1112* _www.positiveenergysolar.com http://www.positiveenergysolar.com/_ ___ 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] Diversion load for AC coupled system
If the current capacity of the diversion controller is exceeded then you want the relay to switch in the big load. A few questions. How do I turn on the big load based on current? The controller does not have a current detector, only voltage. Controller on first could still allow over-current if the voltage does not rise another .2 volts. Correct? Here's a scenario: Sun is up and voltage rises slowly to the diversion controller set point. PWM starts and maintains the voltage. Current continues to increase but the load is keeping the voltage constant until the controller is overloaded. It looks like the big load comes on only if power is high enough to overcome the response time of the PWM circuit in the diversion controller thus allowing the voltage pass the .2 volt offset. Also, my thoughts are the hysteresis in the SS relay needs to be broad enough to keep the big load on so it drops out last. Sorry that I'm not seeing your whole picture yet, David. The operation must be bullet proof. Can you elaborate more? Larry On Nov 30, 2011, at 11:05 AM, David Katz wrote: Larry, I think you want the PWM controller to start first so the turn on will be smooth. If the current capacity of the diversion controller is exceeded then you want the relay to switch in the big load. At that point the diversion controller will back off and pickup the difference. That is why I suggested the the relay controlled load be 50 to 75% of the pwm diversion load, so that whenever it turns on the pwm controller will be working, too. David David Katz CTO Founder AEE Solar Inc P: 707 825-1200 F: 707 825-1202 dk...@aeesolar.com www.aeesolar.com From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Larry Crutcher, Starlight Solar Power Systems Sent: Wednesday, November 30, 2011 8:49 AM To: RE-wrenches Subject: Re: [RE-wrenches] Diversion load for AC coupled system David, Ah..I think I see what you are saying. But, don't you mean .2 volts lower than the diversion load? That way there will only be limited current left for the diversion controller to handle. If it is the other way, what stops full current from flowing through the diversion controller if the .2 volts is not reached? Or is .2 volts two close to worry about that? Larry Crutcher Starlight Solar Power Systems ___ 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
