What 4 bad weather days in row looks like without a generator

zoneblue
zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
We recently had four consecutive days of the wettest dullest weather in the history of our off grid install.

Having made a decision early on to avoid generators, (mostly because of radical distaste for small engine maintenance), our pv was sized to cope with pretty much the worst case scenario. Last winter went really well, nothing longer than 3 days without float. With lots of pv it only takes (in a temperate climate) a brief clearing in a run of weather to top up the bank.

Heres what this recent storm looked like, though.

Attachment not found.

By the third day i was starting to manage discretionary loads, and on the forth day actively shedding anything that wasnt absolutely necessary. Rest voltage got down around the 24.3 mark, and the minimum we saw was 23.6, both on day 4. It was the one day in 18 months when our system needed some user input.

And by the way the classic rebooted twice in those for 4 days somewhat muddling its SOC reading (the graph is the corrected values). Still a little work to do there... before anyone goes relying on SOC. Always good to watch the bank voltage.
1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar


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Comments

  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    zoneblue wrote: »
    Having made a decision early on to avoid generators, (mostly because of radical distaste for small engine maintenance), our pv was sized to cope with pretty much the worst case scenario.
    <snip>
    Rest voltage got down around the 24.3 mark, and the minimum we saw was 23.6, both on day 4.

    Impressive. It's nice to know that all of us who have been saying a generator is essential are wrong :cool:

    Don't you have any baseline loads? ... I mean, how do you measure resting voltage in an active system?

    One thing I notice (and like) is that your AGMs have less voltage sag under load than my flooded batteries. I have my LVD set to 24 volts (~50% SOC), but I cannot take the bank down to less than 60% SOC because of voltage sag under load.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: What 4 bad weather days in row looks like without a generator
    vtmaps wrote: »
    Impressive. It's nice to know that all of us who have been saying a generator is essential are wrong :cool:

    Not wrong, just live in the wrong place ;)
    Quite a few installs in Spain are generator free with oversized PV arrays. As long as you're prepared to do load shedding when the poo hits the fan it's perfectly doable. I know one guy who swears by amorphous panels as the key to getting by without a gen because of their better cloudy weather performance. His panels are the schott asi, which are double junction aSi. I went and put an extra 1.4kW of micro-amorphous sharp with similar hopes but they don't produce anything more than plain old poly in cloudy weather.

    Our biggest loads are well pump, oven, kettle, bread machine and washing machine. All of them can easily be load shifted for a few days which cuts consumption by about 50%. Last year I decided not to shift any loads and just live as if we were grid connected, and had to run the gen for a total of about 20 hours for the whole year!
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    *ahem* Been running the gen just about every day for two weeks now due to incessant rain. Even though it's a pain, it's way cheaper supplementary power than a hugely over-sized battery bank and matching gargantuan array. It's also dependable and works 24/7 regardless of weather. Sort of like a power plant on the grid.

    What the OP has actually demonstrated is that the generator is essential. His up-sizing to avoid it cost more money than needed and most of the time the capacity is not used. I would never suggest running solar on account of the problems like this. And if any of the system breaks down the gen is instant back-up power.
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Just being curious ? How do plot these graphs ? which software is used for this ?


    OP can also install a windturbine, if budget and weather permits, to supplement his Solar array.
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,730 ✭✭✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Totally agree! Have not needed one for the last 9 years of my 22 years offgrid. Neither do all the south west systems I try and design for. I immensely dislike the beast!
    stephendv wrote: »
    Not wrong, just live in the wrong place ;)
    Quite a few installs in Spain are generator free with oversized PV arrays. As long as you're prepared to do load shedding when the poo hits the fan it's perfectly doable. I know one guy who swears by amorphous panels as the key to getting by without a gen because of their better cloudy weather performance. His panels are the schott asi, which are double junction aSi. I went and put an extra 1.4kW of micro-amorphous sharp with similar hopes but they don't produce anything more than plain old poly in cloudy weather.

    Our biggest loads are well pump, oven, kettle, bread machine and washing machine. All of them can easily be load shifted for a few days which cuts consumption by about 50%. Last year I decided not to shift any loads and just live as if we were grid connected, and had to run the gen for a total of about 20 hours for the whole year!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Counting SOC requires to many variable perimeters to be much more than a guide line. It is Impressive to watch a Battery bank recover from below 50% SOC all it's capacity in one sun day though on PV. Congrats !! I have to many runs of 10-12 dark days to to get through without a fall back. One more day you'd of been out of business. It's always the roll of the dice.
  • cupcake
    cupcake Solar Expert Posts: 254 ✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    *ahem* Been running the gen just about every day for two weeks now due to incessant rain. Even though it's a pain, it's way cheaper supplementary power than a hugely over-sized battery bank and matching gargantuan array. It's also dependable and works 24/7 regardless of weather. Sort of like a power plant on the grid.

    What the OP has actually demonstrated is that the generator is essential. His up-sizing to avoid it cost more money than needed and most of the time the capacity is not used. I would never suggest running solar on account of the problems like this. And if any of the system breaks down the gen is instant back-up power.


    Checking my journal I see that the last time it has rained here was Feburary 3rd, 2014.... its now June... I almost miss rain... a bit...

    I agree with your post... extra generator is cheaper than extra [unused] panels...
    ~1.5Kw PV in parallel
    Morningstar MPPT-60 controllers (2) in parallel
    3 Trojan tr-1275's in parallel 450ah total
    Samlex 2,000 watt 12-volt inverter hardwired


  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    cupcake wrote: »
    Checking my journal I see that the last time it has rained here was Feburary 3rd, 2014.... its now June... I almost miss rain... a bit...

    I agree with your post... extra generator is cheaper than extra [unused] panels...

    The situation reverses if you have frequent bad weather; then the extra solar capacity will be used more often which makes it a sounder investment. Planning on compensating for the occasional, short-duration spell of inclemency by buying lots of solar and batteries is not sensible. Where you have good sun most of the time the back-up gen offers cheap compensation for those occasional days when you don't.

    Of course some people prefer to do things backwards just to prove they can I guess.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: What 4 bad weather days in row looks like without a generator

    "Over paneling" is actually getting pretty cheap... Around $1 per watt for panels (and close to another $1 per watt for mounting them).

    But--If you live in an area with long stretches of very gloomy weather--Your array may produce 5-10% of its typical average sunny day production... doubling the array for a 5% day--You only get a 10% day production.

    If you can shed loads during bad weather--That will be a big help.

    The real killer issue is, generally, the battery bank. Large lead acid battery banks are expensive and take a lot of solar power (and generator backup--if used) to keep them happy. Many times, a "reasonable size" bank + generator is good enough for most people (reasonable being around 2 days of backup and 50% maximum discharge).

    And, if you accidentally "murder" your battery bank, the "over-sized" battery bank can be a real killer for your savings account to replace.

    But, as I like to say, energy usage is a high personal set of choices. For those folks where generators are not wanted/practical--Then over paneling has never been cheaper (and over battery sizing has never been more expensive).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    You don't actually need a bigger battery bank just for more panels: you can use additional Watts of array to increase charging on marginal days. But it does require some charge management (such as the FNDC or multiple Classics) to prevent the array from supplying too much current when the weather is good.

    However I don't think I'll be upping my array to 3500 Watts just to see me through the rain spells. The $1200 generator and gasoline (even @ $1.42 per litre) is still cheaper and more practical than $4000+ in panels, mounts, wiring, and controllers.
  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Nice to see ive generated some discussion on the subject.

    Firstly the graphs are from blackbox, and the SOC is midnites own algorithim which is understood to be fairly basic. Temp compensated Ah counting. Even without the reset bug, id still as others have mentioned be weary of relying on it too much. Still its data roughly corelated with rest voltage. And by rest voltage here i mean with my overnite loads, which is the fridge, 3 laptops in standby, blackbox, classic, in descending order, totals about 60W. Ive calibrated my mind on rest voltage with those base loads, as there is little else you can do with AGM.

    The AGMs have a published internal resistance of 1.5m ohm per 2v cell. The 400Ah rating is at C10, so C20 should be up into the 520 ballpark. Based on those figures id say it was a little under 50%.

    Now as to the view that a genset is required, if you live in the arctic north, then fine, i agree. But at 39 latitude, I think i have shown that a generater is not needed, surviving as we did a 1 in 5 year weather event. Indeed about 100K homes lost grid power during that storm. At least load shedding is optional, you have a choice.

    The extra PV was considerably cheaper than the honda you guys recomend which will set you back an eye watering $2K+ here in NZ. A 2K investment that gets once per 18 months, doesnt sound like a very good return to me. Not to mention having to mange fuel storage and rotation over such long intervals. 2K is a fair bit of PV these days.

    I realise that double not very much is still not very much, but my experince over the last 18 months has very much been than it is very very rare that there isnt a brief lightening during bad weather, and its these brighter periods that do the job. I can show you dozens of bad weather events with this pattern. Of course weather is extremely localised so you have to do your own analysis. In most countrys, you can download daily even hourly insolation data over a 10 year period and simple net daily analysis shows you what you have to work with. It just maths. See my original spreadsheet on my install page.

    Attachment not found.

    The remaining factor is quantifying how hard on the battery the routine shallow cycles are. Without any hard data on the matter, we are no further off. Ill let you know at the 8 year mark.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    I'm glad to see 'Coot at least sees the light on over paneling, I'll likely be able to generate over 20% of my battery capacity, when I finish my system (on those rare perfect days), I don't want or feel I need a generator, but the worst spell I can recall is 8 days of poor weather, though I think there was a half day of pretty good charging, This happens in the winter when my system is much larger than my needs and I haven't had issues, we've had a little heat with overcast days this spring, but I checked and was reaching float on most of those cloudy days, but only running the A/C in the evening, and it does still cool off, so 2-3 hours.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator

    With 2K NZD in Pakistan you can buy a 2.4KW array but you will need additional batteries to store that extra energy.

    Best solution for bad weather is load shedding.
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    drraptor wrote: »
    With 2K NZD in Pakistan you can buy a 2.4KW array but you will need additional batteries to store that extra energy.
    NO, you don't have to store the energy, you just don't use it, you limit the storage with your charge controllers, with the additional array you can charge the batteries even on cloudy days, at least enough to keep from drawing them down too much. I'm perfectly willing to reduce my loads, but with a minimal investment, I don't need to worry about having a generator.

    A generator is yet another electric and mechanical system and it requires care and upkeep. I don't have to maintain fuel, change oil, be sure things are working, but I also haven't had to endure 2 weeks of little or no charging, I do understand what 'Coot is facing.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator
    Photowhit wrote: »
    NO, you don't have to store the energy, you just don't use it, you limit the storage with your charge controllers, with the additional array you can charge the batteries even on cloudy days, at least enough to keep from drawing them down too much. I'm perfectly willing to reduce my loads, but with a minimal investment, I don't need to worry about having a generator.

    In that case, you can have 2 sets of Array with 2 CC, one for regular use labelled X and second one for cloudy days labelled Y . You can switch off the array Y one very sunny days.


    A generator is yet another electric and mechanical system and it requires care and upkeep. I don't have to maintain fuel, change oil, be sure things are working, but I also haven't had to endure 2 weeks of little or no charging, I do understand what 'Coot is facing.
    I personally hate generator, because of the noise generated and fuel they consume . With Petrol already over Rs 100/liter and unreliable supply of Natural Gas (sometimes there is not enough for cooking) I can't rely on a generator.

    Two of my relatives installed Gensets a few years back. My advise was to use a either a UPS system or UPS system backed up with Solar Panels, but they went with Generator on natural gas, now both houses don't have enough Natural gas to turn on their respective generators. :cool:

    They were of the opinion that a generator can run all their loads including the Iron (can't ironing wait for 1-2 hours of blackouts/load shedding :grr) and the Fridge( Nothing is going to get rotted with 1-2 hours of blackouts/load shedding;) )
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    drraptor wrote: »
    In that case, you can have 2 sets of Array with 2 CC, one for regular use labelled X and second one for cloudy days labelled Y . You can switch off the array Y one very sunny days.

    I think you miss the point, it doesn't hurt anything to leave them hooked up and have your charge controller only allow the correct charging parameters(allow for correct voltage and current), That is why I have charge controllers, I don't want to do the charge controllers job. It does not hurt solar panels to not produce electricity. why would I want to turn any of them off?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Adding a Y watts array to controller which only support X watts, can cause damage to the CC especially on Sunny days. e.g using MorningStar MPPT 60A and 255Watt panels I can't add 4000Watts of panels in any combination, http://www.morningstarcorp.com/string-calculator/#manufacturer=89&module=7514&product=23&vmin=23&vmax=31&tmin=0&tmax=36&tminunits=c&tmaxunits=c

    Yes you can overpanel to a certain extent but not like 10Y.

    So the question arise what is the maximum limit to which you can overpanel a CC ? e.g Midnite Classic 150
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: What 4 bad weather days in row looks like without a generator
    drraptor wrote: »
    Adding a Y watts array to controller which only support X watts, can cause damage to the CC especially on Sunny days. e.g using MorningStar MPPT 60A and 255Watt panels I can't add 4000Watts of panels in any combination, http://www.morningstarcorp.com/string-calculator/#manufacturer=89&module=7514&product=23&vmin=23&vmax=31&tmin=0&tmax=36&tminunits=c&tmaxunits=c

    Yes you can overpanel to a certain extent but not like 10Y.

    Co-incidentally received a tech notes from Morningstar the other day on exactly this subject: http://www.morningstarcorp.com/wp-content/uploads/2014/02/MPPT-Technology-Primer.pdf

    "Morningstar’s MPPT controllers can operate with an oversized array that is several times larger than the
    maximum Nominal Solar PV ratings, while still limiting the maximum battery current to the controller’s
    maximum current rating. M
    "
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator
    stephendv wrote: »
    Co-incidentally received a tech notes from Morningstar the other day on exactly this subject: http://www.morningstarcorp.com/wp-content/uploads/2014/02/MPPT-Technology-Primer.pdf

    "Morningstar’s MPPT controllers can operate with an oversized array that is several times larger than the
    maximum Nominal Solar PV ratings, while still limiting the maximum battery current to the controller’s
    maximum current rating. M
    "


    Yeah, I also received the same mail, but it is little bit vague, what they mean by this
    is several times larger than the
    maximum Nominal Solar PV ratings,

    I mean is it 2Y, 6Y or 10Y ? there should be a number for this otherwise you might overheat the CC.

    This guy reached that limit https://www.youtube.com/watch?v=l1D6y0Nz1kw
  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    Re: What 4 bad weather days in row looks like without a generator

    In practice I can't think of it ever making economic sense to have 2x the limit installed. If the aim is to over-panel for bad weather days, as zoneblue mentioned above you get a lot charging done from the brief sunny spells between clouds. If you can't take advantage of that to charge the battery because the controller is the limiting the output then it's not money well spent. It would be better to use a cheap PWM controller for the extra PV panels to take full advantage of the solar output rather than building a twice as big solar array.
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    stephendv wrote: »
    In practice I can't think of it ever making economic sense to have 2x the limit installed. If the aim is to over-panel for bad weather days, as zoneblue mentioned above you get a lot charging done from the brief sunny spells between clouds.
    But only to the limit that the battery bank can handle, 13-15% perhaps more in some AGM batteries.
    stephendv wrote: »
    If you can't take advantage of that to charge the battery because the controller is the limiting the output then it's not money well spent. It would be better to use a cheap PWM controller for the extra PV panels to take full advantage of the solar output rather than building a twice as big solar array.
    Since you can't use the extra energy, it's better/cheaper to use the single charge controller.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Not quite as cut-and-dry as that.

    Multiple controllers (good ones) can be programmed to limit their output so that the combined total never exceeds battery maximums. So if you have two 60 Amp controllers, say, and the batteries only can take 60 Amps altogether you put enough Watts on each controller for 60 Amps but limit each controller's output to 30 Amps. Thus on the best days you get 30 from each one using half their arrays' capacity totaling 60 Amps. On a bad day the extra panels can keep each controller's output higher than it normally would be if they had only half the Watts on them. This rather than an integrated management system like the FNDC.

    There's other ways to make use of excess panels if you want to do the work. Diversion loads, for example. The Classic's "Waste Not" function heating water. Et cetera.

    The trick is, as always, balance. Putting in a lot of extra PV and controller to get charging on one or two odd days every now and then is not worth the investment. It's like buying a battery-based back-up system for grid power that goes down for an hour every four years; a generator is a cheaper way to get the power.

    The opposite side of the coin is to go off-grid with a system whose power demands are so large that the PV can never meet them (even with turbines) and so you end up running big, smelly diesel gensets anyway.

    Neither makes sense.
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator
    Not quite as cut-and-dry as that.

    Multiple controllers (good ones) can be programmed to limit their output so that the combined total never exceeds battery maximums. So if you have two 60 Amp controllers, say, and the batteries only can take 60 Amps altogether you put enough Watts on each controller for 60 Amps but limit each controller's output to 30 Amps. Thus on the best days you get 30 from each one using half their arrays' capacity totaling 60 Amps. On a bad day the extra panels can keep each controller's output higher than it normally would be if they had only half the Watts on them. This rather than an integrated management system like the FNDC.
    Midnite calls this feature "follow me " or is it something else ? What is FNDC ?
    There's other ways to make use of excess panels if you want to do the work. Diversion loads, for example. The Classic's "Waste Not" function heating water. Et cetera.

    why could you heat water, when you already "enjoy" hot water all day long (thanks to 47C / 110F peak temperatures and non-insulated water storage) :p isn't there anyway to charge batteries with low self discharge rate with this "Extra power". These batteries will cover those "Bad weather" days
    The trick is, as always, balance. Putting in a lot of extra PV and controller to get charging on one or two odd days every now and then is not worth the investment. It's like buying a battery-based back-up system for grid power that goes down for an hour every four years; a generator is a cheaper way to get the power.

    The opposite side of the coin is to go off-grid with a system whose power demands are so large that the PV can never meet them (even with turbines) and so you end up running big, smelly diesel gensets anyway.

    Neither makes sense.

    In that case, we should follow Photowhit advice
    Photowhit wrote: »
    But only to the limit that the battery bank can handle, 13-15% perhaps more in some AGM batteries.

    I think going upto 20% or less is way to go. :-)
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    drraptor wrote: »
    Midnite calls this feature "follow me " or is it something else ? What is FNDC ?

    "Follow Me" co-ordinates multiple Classic controllers so that they agree on charge stage, set points, battery Voltage, and temperature. It does not limit the current output (although that can be programmed in Classics). FNDC is Outback Flex Net Direct Current: http://www.solar-electric.com/oupoflsymo.html It monitors and co-ordinates multiple charge sources.
    why could you heat water, when you already "enjoy" hot water all day long (thanks to 47C / 110F peak temperatures and non-insulated water storage) :p isn't there anyway to charge batteries with low self discharge rate with this "Extra power". These batteries will cover those "Bad weather" days

    Not everyone has those temperatures available. Water heating is just one example of what surplus power can be used for.
    In that case, we should follow Photowhit advice

    I think going upto 20% or less is way to go. :-)

    As a rule, yes.
    But we were discussing how to handle large amounts of surplus power potential from extreme over-paneling intended to charge on bad weather days.
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator
    "Follow Me" co-ordinates multiple Classic controllers so that they agree on charge stage, set points, battery Voltage, and temperature. It does not limit the current output (although that can be programmed in Classics). FNDC is Outback Flex Net Direct Current: http://www.solar-electric.com/oupoflsymo.html It monitors and co-ordinates multiple charge sources.

    Except for "co-ordinating multiple charge sources" Midnite's system seems to be more economical with all better features.
    Not everyone has those temperatures available. Water heating is just one example of what surplus power can be used for.
    Those of us who have such hot climate, need extra air conditioning
    As a rule, yes.
    But we were discussing how to handle large amounts of surplus power potential from extreme over-paneling intended to charge on bad weather days.
    that is why we need batteries with low self discharged rate, something equivalent of "pumped storage"
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator

    I have found my diversion load, a former Car radiator fan converted over to a pedestal fan, now I need some kind a speed control for that. It is consuming ~10-11A at full speed, I want to reduce/control/regulate that what device I should use ?
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Okay... You don't 'need' a diversion load with solar, do you have a wind generator as well?

    If this is just a miss understanding in terms, this might be an opportunity load. Opportunity load defined as a load we run to our benefit when our batteries are charged, but the energy from solar doesn't need to be generated, it can just not be created as determined by your charge controller, the potential is still there. If your system discovers a load the charge controller will draw just enough energy from the array to run the load and keep your batteries at float.

    You can add your system information in a signature line, like mine...which needs updating...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    Re: What 4 bad weather days in row looks like without a generator
    Photowhit wrote: »
    Okay... You don't 'need' a diversion load with solar, do you have a wind generator as well?

    If this is just a miss understanding in terms, this might be an opportunity load. Opportunity load defined as a load we run to our benefit when our batteries are charged, but the energy from solar doesn't need to be generated, it can just not be created as determined by your charge controller, the potential is still there. If your system discovers a load the charge controller will draw just enough energy from the array to run the load and keep your batteries at float.

    You can add your system information in a signature line, like mine...which needs updating...


    Thanks. The correct term should be Opportunity load to describe the fan.

    I have learnt a lot from this forums and you guys, Thanks NAWS 8)

    As for signature, I like to keep it simple but that might change in future. ;)


  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator

    Photowhit, I think that diversion load may be the (more) correct term for an over-panelled system. It would actually need to be 'managed' in the same way as wind if one had 2 or more CC's charging the battery. Assuming that you want to take advantage of the PV you have installed as opposed to the 'just let it be wasted' scenario.

    I am planing to over-panel my system (relative to summer input/use) for 2 reasons:
    1 winter isolation is quite low at 52* N Lat.
    2 we have been getting far more cloudy and/or drenching wet days in the last few years

    A diversion of excess PV for hot water would be a good thing for SWMBO...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Re: What 4 bad weather days in row looks like without a generator
    westbranch wrote: »
    Photowhit, I think that diversion load may be the (more) correct term for an over-panelled system. It would actually need to be 'managed' in the same way as wind if one had 2 or more CC's charging the battery.
    But solar does not need to be produced, unlike wind you can simply not generate it.
    westbranch wrote: »
    Assuming that you want to take advantage of the PV you have installed as opposed to the 'just let it be wasted' scenario.

    I'm not sure why you would think that. If you are utilizing the extra PV energy that could be put to use, you better be using it with a load that you would not normally run.

    Hence an opportunity load.

    A diversion load defines a load to dissipate energy that must go somewhere, like a wind generator, in that case you can NOT shut it down and need someplace for the energy to go once your batteries are full, hence a diversion load. This can be something useful like heating water but often is just raw resistance heating air to create a load.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.