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Having grown up in central NY state (a place with possibly marginally worse winters than Buffalo) and spending 25 yrs of my adult live in/around Buffalo, NY, I appreciate the winters here in N. San Diego county - which, BTW, and to not let you (or anyone else) either by ignorance or intent, or design or anything else infer by your desert reference, while drier and sunnier than a lot of places, is most certainly not desert, although I've lived in the desert as well.
I'm not picking on you and certainly not Bruce, but I've lived in dryer sunny, winter climates including several years in Albuquerque, besides the 20+ yrs. of what many consider the goldilocks climate in N. San Diego county and places with what many consider brutal winter climates. Can either of you say that ?
I've also designed PV and thermal systems as well as several residential housing designs and retrofits for both climate types. Can you say that ? I appreciate the design differences imposed by both climate types and other climates as well. Many of the same principles I learned and practiced while designing and stamping power and process system designs for the power, petrochemical and chemical process industries carry over to alternate energy system design, including dealing with the design requirements (and tradeoffs) imposed by environmental considerations in various climates.
So, I'll chalk up your blinding flash of the obvious statement about climate variation and its importance in PV system design to your ignorance. I forgot more about the subject than you might ever know.
To say or write to me or anyone who has the capability to design systems, or for that matter anyone who has ever lived in either type of climate you mention - including readers, members or lurkers here - that it's no surprise optimal alternate energy systems might be designed differently for different climates is not only no surprise, but a blinding flash of the obvious.
However, one thing that is common to most all PV and solar thermal systems is that for stationary, flat plate solar energy devices there is one orientation that optimizes the integrated annual POA irradiance on the device. That orientation will almost always lead to the optimal operating efficiency and greatest annual energy harvest. Other orientations will, by definition, harvest less.
1X/a while, but I'd suggest rarely, there may be practical aspects to an application where there is more than one orientation that maximizes annual POA irradiance. If they exist, I've not seen one.
However, that's not to say, and I never meant to imply (although others it seems want to infer and so ascribe it to what I've written) that other design considerations that can and probably will most likely change the system orientation from the one that gathers the most energy to one that better meets other design requirements do not need to be considered. The impact of TOU tariffs on system cost effectiveness being one such example.
After designing, running and managing engineering projects for a long time and doing so while trying to keep 10-20 balls in the air simultaneously and trying not to drop any of them - including cost/budget considerations, optimization and client perceptions as well as profit considerations my bosses may have - I think I appreciate managing priorities and design comprises more than at least some others.
Why do you seem to be implying I don't appreciate several viewpoints and opinions about a subject ? IMO, a good, that is to say sizeable part of the value of forums such as this is indeed the opportunity it affords to offer opinions.
While all opinions are to be respected, that doesn't make them equally correct or safe. Some are dangerous when expressed or acted upon. That leads to another good part of the value of these forums: To call out errors in expressed opinions that may be wrong/dangerous/just plain B.S. or lead to bad outcomes, personal injury or worse. I cite your temporary banishment some time ago as an example.
All folks are to be respected, but not all opinions are based on reality. Those opinions that are incorrect or needing clarification need to be identified and called out. Peer reviewed literature does that quite nicely for the most part. Here, IMO only, we suffer fools all too much to the detriment of the forum credibility.
Bruce's opinions are based on reality and experience, and as I've written several times, I pay a lot of attention to what he writes and feel I ignore his opinions at my peril.
However, to Bruce:
Take this FWIW, and meant respectfully but just as seriously. It looks to me that you're under some misapprehension(s) about the solar resource. One such misapprehension may be that, while environmental considerations may and probably will require orientation changes, it looks to me that you have a notion that, base on annual harvest per installed STC panel W, using several panel orientations will improve the annual harvest of your system(s), or that maybe it'll be more economical or cost effective. That may be correct, but based on what I think I might know, I doubt it. I asked for your orientations and array sizes for the purpose of doing some work w/PVWatts/SAM/my private stuff. While I note your use of multiple tilts to improve harvest and help with snow mitigation, I also note such adjustments are also possible with single orientation arrays.
Not that it matters much, but if/when I design an array for a ground mount application where there's usually a fair degree of orientation flexibility, I start with a duty (load) and find the optimum orientation based on the solar resource availability. I then base the first design iteration on that orientation and modify the design as site conditions/constraints and project goals dictate with the goal of meeting all or as many of the design goals and constraints as possible while keeping as close to the max. output orientation as possible. Roof applications devolve to a rating type design based on picking the best, that is, most productive orientation among the available but probably more limited orientation choices. In such cases, multiple orientations are sometimes necessary to meet a duty, but, like life, they're not perfect, just the best available for that application and seldom optimal. Another of many reasons why ground mounts are usually better if given the choice.
Even with few environmental constraints - no snow, sunnier climates, different temps., it looks to me that you are of the opinion that using orientations based on the idea that making a flatter output curve for sunnier days over a year will be better both for system efficiency and cost effectiveness. It also seems to me that you've come to that conclusion, or at least landed upon the notion that using the ratio of your annual harvest to your installed inverter capacity is a useful figure of merit. I am of the opinion that's not a good or maybe even valid criteria for measuring either system collection efficiency or for economic optimization.
Annual harvest per installed STC (panel) W is a better metric, both for system efficiency (annual utilization) in terms of kWh/yr. harvested per installed STC panel W, or (and with a slightly different azimuth but similar tilt for TOU systems) average annual bill reduction per installed STC W.
If one design goal is broadly defined as most bang for the buck, size the array STC wattage to the duty that gives the lowest LCOE mix of PV and POCO power and size the inverter with an eye to the max. panel array power output. Sometimes the inverter size limits can control a design for such things as off grid applications or for battery charging rate considerations or POCO demand rates if applicable and maybe some other conditions, but not usually or most often for common residential grid tie applications.
I don't think I've read where you've written you have such imposed limitations (If I'm wrong or missed something on that, I apologize).
Other environmental site conditions, limitations or application mandates or goals may require more than one orientation. But to be clear, while those other conditions may very well mandate off optimal orientations, and maybe even - although unlikely from my experience - splitting orientations, for most applications, I can't see a way that spreading out (lengthening) average daily average harvest times can, in and of itself, create a high(er) probability of improving system efficiency or cost effectiveness for most any residential grid tie application, pretty much regardless of climate.
To restate, the one thing I've found to be most common to all active solar energy systems, PV or thermal - that there is almost always one orientation for PV panels or thermal collectors, active or passive, that optimizes yearly integrated POA irradiance on a flat plate solar device. And, maximizing annual POA irradiance is the surest and easiest way to get a leg up on system optimization.
Parenthetically, and a bit off topic, for the PV/TOU rate considerations, there is also and usually a single (and probably different) orientation that optimizes the system cost effectiveness with respect to the system's ability to offset part or all of a residential electric bill that's different from the orientation that maximizes annual system output per STC W.
Bottom line on all this: What happens with multiple orientations done for the purpose of spreading out the harvest so that inverter sizes might be reduced is that while inverter sizes may be reduced, the required array sizes in terms of total panel STC wattage will increase. That is, the average annual output per STC panel W (or m^2 of panel) will decrease, requiring corresponding increases in array costs due to increased array sizes required to meet the same duty including costs for panels and B.O.S material costs and any non DIY labor costs as expressed per installed STC W. At least to my experience those panel and B.O.S incremental are usually greater per STC W than the incremental material acquisition cost increases of inverters as expressed per nominal W increase in inverter capacity.
I'm not picking on you and certainly not Bruce, but I've lived in dryer sunny, winter climates including several years in Albuquerque, besides the 20+ yrs. of what many consider the goldilocks climate in N. San Diego county and places with what many consider brutal winter climates. Can either of you say that ?
I've also designed PV and thermal systems as well as several residential housing designs and retrofits for both climate types. Can you say that ? I appreciate the design differences imposed by both climate types and other climates as well. Many of the same principles I learned and practiced while designing and stamping power and process system designs for the power, petrochemical and chemical process industries carry over to alternate energy system design, including dealing with the design requirements (and tradeoffs) imposed by environmental considerations in various climates.
So, I'll chalk up your blinding flash of the obvious statement about climate variation and its importance in PV system design to your ignorance. I forgot more about the subject than you might ever know.
To say or write to me or anyone who has the capability to design systems, or for that matter anyone who has ever lived in either type of climate you mention - including readers, members or lurkers here - that it's no surprise optimal alternate energy systems might be designed differently for different climates is not only no surprise, but a blinding flash of the obvious.
However, one thing that is common to most all PV and solar thermal systems is that for stationary, flat plate solar energy devices there is one orientation that optimizes the integrated annual POA irradiance on the device. That orientation will almost always lead to the optimal operating efficiency and greatest annual energy harvest. Other orientations will, by definition, harvest less.
1X/a while, but I'd suggest rarely, there may be practical aspects to an application where there is more than one orientation that maximizes annual POA irradiance. If they exist, I've not seen one.
However, that's not to say, and I never meant to imply (although others it seems want to infer and so ascribe it to what I've written) that other design considerations that can and probably will most likely change the system orientation from the one that gathers the most energy to one that better meets other design requirements do not need to be considered. The impact of TOU tariffs on system cost effectiveness being one such example.
After designing, running and managing engineering projects for a long time and doing so while trying to keep 10-20 balls in the air simultaneously and trying not to drop any of them - including cost/budget considerations, optimization and client perceptions as well as profit considerations my bosses may have - I think I appreciate managing priorities and design comprises more than at least some others.
Why do you seem to be implying I don't appreciate several viewpoints and opinions about a subject ? IMO, a good, that is to say sizeable part of the value of forums such as this is indeed the opportunity it affords to offer opinions.
While all opinions are to be respected, that doesn't make them equally correct or safe. Some are dangerous when expressed or acted upon. That leads to another good part of the value of these forums: To call out errors in expressed opinions that may be wrong/dangerous/just plain B.S. or lead to bad outcomes, personal injury or worse. I cite your temporary banishment some time ago as an example.
All folks are to be respected, but not all opinions are based on reality. Those opinions that are incorrect or needing clarification need to be identified and called out. Peer reviewed literature does that quite nicely for the most part. Here, IMO only, we suffer fools all too much to the detriment of the forum credibility.
Bruce's opinions are based on reality and experience, and as I've written several times, I pay a lot of attention to what he writes and feel I ignore his opinions at my peril.
However, to Bruce:
Take this FWIW, and meant respectfully but just as seriously. It looks to me that you're under some misapprehension(s) about the solar resource. One such misapprehension may be that, while environmental considerations may and probably will require orientation changes, it looks to me that you have a notion that, base on annual harvest per installed STC panel W, using several panel orientations will improve the annual harvest of your system(s), or that maybe it'll be more economical or cost effective. That may be correct, but based on what I think I might know, I doubt it. I asked for your orientations and array sizes for the purpose of doing some work w/PVWatts/SAM/my private stuff. While I note your use of multiple tilts to improve harvest and help with snow mitigation, I also note such adjustments are also possible with single orientation arrays.
Not that it matters much, but if/when I design an array for a ground mount application where there's usually a fair degree of orientation flexibility, I start with a duty (load) and find the optimum orientation based on the solar resource availability. I then base the first design iteration on that orientation and modify the design as site conditions/constraints and project goals dictate with the goal of meeting all or as many of the design goals and constraints as possible while keeping as close to the max. output orientation as possible. Roof applications devolve to a rating type design based on picking the best, that is, most productive orientation among the available but probably more limited orientation choices. In such cases, multiple orientations are sometimes necessary to meet a duty, but, like life, they're not perfect, just the best available for that application and seldom optimal. Another of many reasons why ground mounts are usually better if given the choice.
Even with few environmental constraints - no snow, sunnier climates, different temps., it looks to me that you are of the opinion that using orientations based on the idea that making a flatter output curve for sunnier days over a year will be better both for system efficiency and cost effectiveness. It also seems to me that you've come to that conclusion, or at least landed upon the notion that using the ratio of your annual harvest to your installed inverter capacity is a useful figure of merit. I am of the opinion that's not a good or maybe even valid criteria for measuring either system collection efficiency or for economic optimization.
Annual harvest per installed STC (panel) W is a better metric, both for system efficiency (annual utilization) in terms of kWh/yr. harvested per installed STC panel W, or (and with a slightly different azimuth but similar tilt for TOU systems) average annual bill reduction per installed STC W.
If one design goal is broadly defined as most bang for the buck, size the array STC wattage to the duty that gives the lowest LCOE mix of PV and POCO power and size the inverter with an eye to the max. panel array power output. Sometimes the inverter size limits can control a design for such things as off grid applications or for battery charging rate considerations or POCO demand rates if applicable and maybe some other conditions, but not usually or most often for common residential grid tie applications.
I don't think I've read where you've written you have such imposed limitations (If I'm wrong or missed something on that, I apologize).
Other environmental site conditions, limitations or application mandates or goals may require more than one orientation. But to be clear, while those other conditions may very well mandate off optimal orientations, and maybe even - although unlikely from my experience - splitting orientations, for most applications, I can't see a way that spreading out (lengthening) average daily average harvest times can, in and of itself, create a high(er) probability of improving system efficiency or cost effectiveness for most any residential grid tie application, pretty much regardless of climate.
To restate, the one thing I've found to be most common to all active solar energy systems, PV or thermal - that there is almost always one orientation for PV panels or thermal collectors, active or passive, that optimizes yearly integrated POA irradiance on a flat plate solar device. And, maximizing annual POA irradiance is the surest and easiest way to get a leg up on system optimization.
Parenthetically, and a bit off topic, for the PV/TOU rate considerations, there is also and usually a single (and probably different) orientation that optimizes the system cost effectiveness with respect to the system's ability to offset part or all of a residential electric bill that's different from the orientation that maximizes annual system output per STC W.
Bottom line on all this: What happens with multiple orientations done for the purpose of spreading out the harvest so that inverter sizes might be reduced is that while inverter sizes may be reduced, the required array sizes in terms of total panel STC wattage will increase. That is, the average annual output per STC panel W (or m^2 of panel) will decrease, requiring corresponding increases in array costs due to increased array sizes required to meet the same duty including costs for panels and B.O.S material costs and any non DIY labor costs as expressed per installed STC W. At least to my experience those panel and B.O.S incremental are usually greater per STC W than the incremental material acquisition cost increases of inverters as expressed per nominal W increase in inverter capacity.
Including the fees I think my retail rate with JCP&L is about 14.5 cents per kWh last bill I checked.
Contacted once again and insisted on a written acknowledgment and looked like the agent typed up a PDF in a hurry (typo and grammar) to shut me up lol. I will see real soon if how far off the numbers are this month. According to my consumption meter, as of right now I've banked 500KWh for March. Every month since start of winter, my billed kWh from JCP&L has been at least 300kWh more than what my consumption meter says. Last month I expected to be billed 160kWh but was billed 480. It was an actual reading. I took a couple of readings on a fully sunny day this week. This past Friday by 6PM, per the consumption meter I generated 60kWh in surplus, and the 40 reading on the JCP&L meter had gone up by exactly 60, so I have no doubt as to the accuracy of the consumption meter.
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