Sun and Cloud

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Subject Author Date Sun and Cloud bealiba 06-07-2008  Re: Sun and Cloud Eric Sears 06-07-2008  Re: Sun and Cloud bealiba 06-07-2008  Re: Sun and Cloud wmbjkREMOVE 06-09-2008  Re: Sun and Cloud bealiba 06-09-2008  Re: Sun and Cloud Solar Flare 06-10-2008
Posted by on June 7, 2008, 12:18 am Please log in for more thread options Well now. We all know that wayne has this theory on solar power design. It is one of his biggest soap box rants. Lets have a look at this theory. It goes like this; Small battery bank and large array of PV panels. The idea is that you use the energy produced while the sun is out to run as much as you can. On the face of it it can be made to look like a sound basis for a solar power system design. Of course there might be a few thousand square miles of land around the world where the sun shines consistently enough for this to work. So what does it mean if you live where cloud is a common occurrence. Ok, You want to run your washing machine (waynes favourite pastime) straight off the panels, well, via the inverter at any rate. Alright, the sun is out and you fill the washing machine and turn it on, the sun disappears behind a cloud, the washing machine draws it energy from the batteries, the sun appears again, the washing machine draws its energy from the panels, mind you this same energy should be going back into the batteries, a bit more cloud, a bit more drain on the batteries. It doesn=92t take much of this sort of thing to create a net loss in your batteries. Of course you can stand there and turn the washing machine on and off as the clouds scud past. After all you have nothing better to do with your time, have you. wayne gets away with this type of system, not because it is a good design, but simply because of where he lives. Move waynes system a hundred miles in any direction and it will be a failure. Move it to NY state and you will live in the dark most of the time, same for 95% of North America, hell 95% of the worlds surface. After a day and a half wayne is on the generator full time, or, he just suspends his normal life style so he will have enough energy to watch Green Acres again. That day and a half is the total sum of his useful battery storage. Today, its been about half and half sun and cloud. As it was yesterday and the day before. Tomorrow it=92s supposed to rain till around Monday. The laundry was done on the generator on Thursday, just as it always is, rain, hail or shine. And tonight I will be working until one or two in the morning as usual. You too can have a system just like wayne=92s. But unless you live next door to wayne your system will just be so much scrap. And who would want to live next door to wayne. Design for your needs and location. Posted by Eric Sears on June 7, 2008, 4:32 am Please log in for more thread options On Fri, 6 Jun 2008 21:18:43 -0700 (PDT), bealiba@gmail.com wrote: >Small battery bank and large array of PV panels. The idea is that you >use the energy produced while the sun is out to run as much as you >can. > >On the face of it it can be made to look like a sound basis for a >solar power system design. > >Of course there might be a few thousand square miles of land around >the world where the sun shines consistently enough for this to work. > >So what does it mean if you live where cloud is a common occurrence. I probably serves me right for even making a comment on this one - flames seem to be a fact of life. However here goes! Of course, if you want best performance, you must size all of your system's components correctly - so in general I agree with the writer's assertions. However, whether the "large solar array" (compared with battery size) will work, depends on what you use the excess power for. Clearly if it is an "essential" use, then you will run your battery down. ("essential?" - YMMV) But suppose (as in my case), I feed the excess power to a hot water cylinder - which has other means of heating if required (eg wood). This reduces the amount of wood needed. If its cloudy for a few days, I just "light the fire" if I need. But the advantage of the large array is that even on cloudy days, or in winter when the output is reduced, the output from the array, which is oversized, will probably supply what I need for other appliances. Of course, it will also depend on what other sources of energy you have available (in my case, grid power!). Just a comment. Each system will actually depend on its particular circumstances. Cheers Eric Sears Posted by on June 7, 2008, 9:03 am Please log in for more thread options On Jun 7, 6:32 pm, phon...@025379386.for.email.address (Eric Sears) wrote: > On Fri, 6 Jun 2008 21:18:43 -0700 (PDT), beal...@gmail.com wrote: > >Small battery bank and large array of PV panels. The idea is that you > >use the energy produced while the sun is out to run as much as you > >can. > > >On the face of it it can be made to look like a sound basis for a > >solar power system design. > > >Of course there might be a few thousand square miles of land around > >the world where the sun shines consistently enough for this to work. > > >So what does it mean if you live where cloud is a common occurrence. > > I probably serves me right for even making a comment on this one - > flames seem to be a fact of life. However here goes! Ah well, Aside from raising waynes blood pressure the questions of excess energy and its possible use is a valid question. > > Of course, if you want best performance, you must size all of your > system's components correctly - so in general I agree with the > writer's assertions. > However, whether the "large solar array" (compared with battery size) > will work, depends on what you use the excess power for. > Clearly if it is an "essential" use, then you will run your battery > down. ("essential?" - YMMV) > My point exactly. If the need is to run an essential load, the control must be able to sense battery voltage so as not to mindlessly run down your power supply. Living where the system is likely to be affected by cloud cover, either intermittently during a day or for days at a time, could lead to your essential load does not run. I hope it is not too essential. > But suppose (as in my case), I feed the excess power to a hot water > cylinder - which has other means of heating if required (eg wood). > This reduces the amount of wood needed. > If its cloudy for a few days, I just "light the fire" if I need. Fine. But the thought does occur, will your system light the fire for you when you are not there and clouds prevent the use of excess energy to heat the water? I mean you do need hot water every day. > But the advantage of the large array is that even on cloudy days, or > in winter when the output is reduced, the output from the array, which > is oversized, will probably supply what I need for other appliances. Yeah, Except that a correctly sized system will do that for the designed days of autonomy with out being oversized. > > Of course, it will also depend on what other sources of energy you > have available (in my case, grid power!). Ah, in that case the excess from your system is fed back into the grid. Right. > > Just a comment. > Each system will actually depend on its particular circumstances. Just a reply. Posted by on June 9, 2008, 10:29 am Please log in for more thread options On Fri, 6 Jun 2008 21:18:43 -0700 (PDT), bealiba@gmail.com wrote: >Small battery bank and large array of PV panels. The idea is that you >use the energy produced while the sun is out to run as much as you >can. No, the idea is to maximize investment benefit by not buying any more battery than necessary and not wasting expensive PV energy. For example, my float time (in minutes) for the last 7 days has been 196, 175, 107, 118, 249, 90, 125. That's nearly 16 hours when the solar and wind controllers were throttling and/or dumping excess, and >10kWh lost. Not a huge amount, but well worth harvesting if one can use it, which is why better inverter and charge control models include such functionality. Read the manuals for Xantrex SWs or the Outback MX for examples. >On the face of it it can be made to look like a sound basis for a >solar power system design. > >Of course there might be a few thousand square miles of land around >the world where the sun shines consistently enough for this to work. Or it might be that there are 114 thousand square miles in Arizona alone http://www.netstate.com/states/geography/az_geography.htmmany, and it might be that you gave as little thought to your estimate as you did to your overall premise. >Alright, the sun is out and you fill the washing machine and turn it >on, the sun disappears behind a cloud, the washing machine draws it >energy from the batteries, the sun appears again, the washing machine >draws its energy from the panels ... which is different than any other load, exactly how? >mind you this same energy should be >going back into the batteries No, the energy "should" go where one can make the most efficient use of it. What's important is the net result of charging and consumption, the resultant wear on the batteries, and the backup fuel required. >, a bit more cloud, a bit more drain on >the batteries. Gosh, it sounds like a death spiral! Yet most of us have survived by using common sense. >It doesn’t take much of this sort of thing to create a net loss in >your batteries. LOL >Of course you can stand there and turn the washing machine on and off >as the clouds scud past. After all you have nothing better to do with >your time, have you. You might try thinking a bit. If one has excess power, that doesn't mean that it must be used exactly when it's produced. For example, let's say it's cloudy today, and you have a load of laundry to wash. You know it will be sunny tomorrow, and that your charge controller will be throttling early. It's most efficient to wait until the next day, but if that's inconvenient for whatever reason then you run the load beforehand and suffer a larger dose of inefficiency due to the energy having to make a trip through the batteries. Either way, the strategy is to harvest the energy that otherwise would have been wasted. If you want to get down to the short strokes, then you should consider that in case of an inverter running at low power, adding extra loads can often increase efficiency. You seem to be having extreme difficulty grasping these concepts. Why not learn by asking those with more experience to explain things to you, rather than denying the undeniable? >wayne gets away with this type of system, not because it is a good >design, but simply because of where he lives. > >Move waynes system a hundred miles in any direction and it will be a >failure. That type of quack proclamation might be useful to folks with solar power setups mounted on trailers, or those who are at risk of having their setups teleported to distant locations. Regardless, you should have paid closer attention to what I've written about our site. It's shaded by mountains morning and evening. Our nearest neighbor 3 miles SW receives a good hour of extra sun each day. And the entire area (NW AZ, below the Grand Canyon) receives less sun than most locations farther south. >Today, its been about half and half sun and cloud. As it was yesterday >and the day before. Tomorrow it’s supposed to rain till around Monday. You seem to be implying that your place is chronically sunless. Yet previously you've written that you have an average surplus of 400Wh per day. Instead of all the contradictory spinning, why not simply use your own numbers, which state a surplus of 2.8kWh per week. Isn't that enough for the loads you're running off the generator? If you're short in winter, then the average summer excess is even higher. Why would anyone choose to burn fuel even part of the time instead of utilizing excess energy? >The laundry was done on the generator on Thursday, just as it always >is, rain, hail or shine. You waste hundreds of hours per year in these newsgroups painfully and self-destructively attempting to convince readers that you're a *solar* "power consultant", and yet here you are bragging that you use a generator for a routine load. Since you seem so reluctant to shift loads from the generator to solar, let's consider some numbers. If one hour per week of 6kW generator time is good, and the solar portion is 7.7kWh, then why wouldn't eliminating the solar in favor of 2 hours total of generator time be even better? > And tonight I will be working until one or >two in the morning as usual. Considering that the total daily load is 1.1kWh, we might estimate that this "work" <snorf> is powered by substantially less than 1kWh of storage, which is less than half the capacity of 2 golf cart batteries. Is that capability supposed to impress anyone? >Design for your needs and location. ... and to use as little fuel as possible. Wayne Posted by on June 9, 2008, 8:14 pm Please log in for more thread options On Jun 10, 12:29 am, wmbjkREM...@citlink.net wrote: > On Fri, 6 Jun 2008 21:18:43 -0700 (PDT), beal...@gmail.com wrote: > >Small battery bank and large array of PV panels. The idea is that you > >use the energy produced while the sun is out to run as much as you > >can. > > No, the idea is to maximize investment benefit by not buying any more > battery than necessary and not wasting expensive PV energy. For > example, my float time (in minutes) for the last 7 days has been 196, > 175, 107, 118, 249, 90, 125. That's nearly 16 hours when the solar and > wind controllers were throttling and/or dumping excess, and >10kWh > lost. Not a huge amount, but well worth harvesting if one can use it, > which is why better inverter and charge control models include such > functionality. Read the manuals for Xantrex SWs or the Outback MX for > examples. > > >On the face of it it can be made to look like a sound basis for a > >solar power system design. > > >Of course there might be a few thousand square miles of land around > >the world where the sun shines consistently enough for this to work. > > Or it might be that there are 114 thousand square miles in Arizona > alonehttp://www.netstate.com/states/geography/az_geography.htmmany, > and it might be that you gave as little thought to your estimate as > you did to your overall premise. > > >Alright, the sun is out and you fill the washing machine and turn it > >on, the sun disappears behind a cloud, the washing machine draws it > >energy from the batteries, the sun appears again, the washing machine > >draws its energy from the panels > > ... which is different than any other load, exactly how? > > >mind you this same energy should be > >going back into the batteries > > No, the energy "should" go where one can make the most efficient use > of it. What's important is the net result of charging and consumption, > the resultant wear on the batteries, and the backup fuel required. > > >, a bit more cloud, a bit more drain on > >the batteries. > > Gosh, it sounds like a death spiral! Yet most of us have survived by > using common sense. > > >It doesn=92t take much of this sort of thing to create a net loss in > >your batteries. > > LOL > > >Of course you can stand there and turn the washing machine on and off > >as the clouds scud past. After all you have nothing better to do with > >your time, have you. > > You might try thinking a bit. If one has excess power, that doesn't > mean that it must be used exactly when it's produced. For example, > let's say it's cloudy today, and you have a load of laundry to wash. > You know it will be sunny tomorrow, and that your charge controller > will be throttling early. It's most efficient to wait until the next > day, but if that's inconvenient for whatever reason then you run the > load beforehand and suffer a larger dose of inefficiency due to the > energy having to make a trip through the batteries. Either way, the > strategy is to harvest the energy that otherwise would have been > wasted. If you want to get down to the short strokes, then you should > consider that in case of an inverter running at low power, adding > extra loads can often increase efficiency. You seem to be having > extreme difficulty grasping these concepts. Why not learn by asking > those with more experience to explain things to you, rather than > denying the undeniable? > > >wayne gets away with this type of system, not because it is a good > >design, but simply because of where he lives. > > >Move waynes system a hundred miles in any direction and it will be a > >failure. > > That type of quack proclamation might be useful to folks with solar > power setups mounted on trailers, or those who are at risk of having > their setups teleported to distant locations. > > Regardless, you should have paid closer attention to what I've written > about our site. It's shaded by mountains morning and evening. Our > nearest neighbor 3 miles SW receives a good hour of extra sun each > day. And the entire area (NW AZ, below the Grand Canyon) receives less > sun than most locations farther south. > > >Today, its been about half and half sun and cloud. As it was yesterday > >and the day before. Tomorrow it=92s supposed to rain till around Monday. > > You seem to be implying that your place is chronically sunless. Yet > previously you've written that you have an average surplus of 400Wh > per day. Instead of all the contradictory spinning, why not simply use > your own numbers, which state a surplus of 2.8kWh per week. Isn't that > enough for the loads you're running off the generator? If you're short > in winter, then the average summer excess is even higher. Why would > anyone choose to burn fuel even part of the time instead of utilizing > excess energy? > > >The laundry was done on the generator on Thursday, just as it always > >is, rain, hail or shine. > > You waste hundreds of hours per year in these newsgroups painfully and > self-destructively attempting to convince readers that you're a > *solar* "power consultant", and yet here you are bragging that you use > a generator for a routine load. Since you seem so reluctant to shift > loads from the generator to solar, let's consider some numbers. If one > hour per week of 6kW generator time is good, and the solar portion is > 7.7kWh, then why wouldn't eliminating the solar in favor of 2 hours > total of generator time be even better? > > > And tonight I will be working until one or > >two in the morning as usual. > > Considering that the total daily load is 1.1kWh, we might estimate > that this "work" <snorf> is powered by substantially less than 1kWh of > storage, which is less than half the capacity of 2 golf cart > batteries. Is that capability supposed to impress anyone? > > >Design for your needs and location. > > ... and to use as little fuel as possible. > > Wayne The numbers wayne, each item you run, what it draws, how long it runs for. You love to talk the talk. Now show us the walk. The smart money says you can't. 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