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I wrote this in a word document originally. Copy-pasted to the first topic attempt and only a fraction appeared after posting. Apologies. I am retyping the entire post in this topic. Joy. G'damn I hope this works.
*12V system
*20A MPPT controller/regulator, basic LED unit, un-programmable
*1 panel, 130W, 32.3 Vmp,
*2 betteries, 12V 102Ah, parallel, so 204Ah. Silver calcium (not ideal, I know that now!)
*Load: planned for worst case scenario (including fudge) of 420 daily watt hours, never came anywhere close to 250.
*Conditions: sunny South Africa, despite a listed insolation of 2.5 to 2.7 hours - who makes this stuff up?! Come gimme a visit NASA, and bring your sunglasses.
System has been in use for a year. Calculation outcome was:
*battery bank at 12V @ 20% dod: 175Ah
*panel wattage with MPPT: 252
*amps at 12V: 21
Straight off the bat, it's clear I never went with the calculated panel size. I had been given a 130W panel with a high Vmp and wanted to start experimenting, and I needed lights and music at an off-grid cabin. Sunking consistently makes it clear we'll pay for not following the numbers, and I was willing to pay for school fees.
I was also constantly put off of ever actually starting my solar energy experiments because of the numbers, which of course are super important. But for someone like me (i.e. the numerically challenged) , starting somewhere, albeit imperfectly, was necessary - I was willing to pay school fees and get practical experience.
The battery bank turned out to be a less-than-ideal paralleled set of 12V batteries. Yes, found out afterwards about the limitations of paralleling. I also found out afterwards that silver calcium batteries need to be charged at a 'boost' (that's what it says on my controller/regulator) rate higher than my un-programmable LED unit can allow. This means the batteries will not last as long as they could have, and their lifespan was already short because I'm using silver calcium with solar, which is apparently not good.
The cabin is visited infrequently for now, so the number of daily cycles is low. I am also using much less of the planned watt hours, so dod (when it occurs) is very low. I am curious to see how this plays off for battery life: insufficient charge and float rate vs. infrequent use and tiny discharges.
I swear the insolation numbers for my area are wrong. So sunny and clear here in winter, with an occasional cold-front that clouds things up. But even then I wonder if the panel's unusually high Vmp of 32.3, used on this 12 V system, is getting a higher voltage through to the batteries from earlier in the morning on those cloudier days. Speculation.
I am curious to see how the batteries are doing in another year's time. Dead you say. Likely. Here's hoping. FWIW, the silver calcium batteries were cheap and have worked well for a year so far, so maybe I should look at them as good learning tools.
An important take-home point form all this (although I'm sure other points will be raised, go ahead, I'm happy to learn) is: never purchase a controller / regulator that is not programmable. Sunking has frequently pointed out the need for maximum smoke settings, and this can't be done with many units.
On this CC/regulator note, two people replied to my failed V1 of this topic and said some MPPT units are fake. I really hope this is not the case with mine. It's a microcare 20A LED unit, if anyone would like to look into it for me. South African company, generally good rep.
I hope they're okay, because I plan to purchase two more units from them - digital display, programmable ones (I've seen them used in many installations). One for the newb system I have described so far, and one for a second system.
For the system I've described so far, I plan to set the new, shiny, digital display MPPT to max smoke and hopefully get a bit more mileage out of those dodgy silver calciums. When the batteries die, I plan to get a 250 watt panel to replace the present 130W high Vmp one - though maybe someone could tell me if this is necessary considering the high Vmp on the present panel. Anyhow, I've found out about the Trojan T105RE (6V, 225Ah) since then, so I'd put two of them in series to get me to 12V.
Okay, made my mistakes, now need to install a second system. Calculations as follows:
*Daily load watt hours: 1080 (over-estimated for fudge, despite no inverter being used)
*Insolation: 2.5 (alleged)
*24V battery Ah @20%dod: 225
*Panel wattage with MPPT: 648
*Amps at 24V: 27
Having made my mistakes, paid some cheap school fees, and tried to take in as much as possible from this forum and elsewhere, the construction will be as follows:
*MPPT 40A digital display programmable for max smoke
*2 panels, 320W each, Vmp 37.8 each, series
*4 Trojan T105RE (225Ah, 6V), series for a 24V system
*Step down device to power some of the 12V stuff I already have like lights, chargers, car stereo).
If I can't get the Trojans in South Africa, I know I can get 2V cells at 456Ah. But this means a 12V system, not ideal. And a 60A controller / regulator.
So hopefully I'm not as clueless as I was a few years ago when I joined. Although I'm sure Sunking will find a way to tell me that I am - I'd expect nothing less!!
Comments welcome.
Thanks to all the members who consistently contribute and make this site what it is.
I'd particularly appreciate links to topics where people have experience with changing settings to max smoke with the Trojan RE range - I've looked and not found first-hand reports.
Whazzatt
*12V system
*20A MPPT controller/regulator, basic LED unit, un-programmable
*1 panel, 130W, 32.3 Vmp,
*2 betteries, 12V 102Ah, parallel, so 204Ah. Silver calcium (not ideal, I know that now!)
*Load: planned for worst case scenario (including fudge) of 420 daily watt hours, never came anywhere close to 250.
*Conditions: sunny South Africa, despite a listed insolation of 2.5 to 2.7 hours - who makes this stuff up?! Come gimme a visit NASA, and bring your sunglasses.
System has been in use for a year. Calculation outcome was:
*battery bank at 12V @ 20% dod: 175Ah
*panel wattage with MPPT: 252
*amps at 12V: 21
Straight off the bat, it's clear I never went with the calculated panel size. I had been given a 130W panel with a high Vmp and wanted to start experimenting, and I needed lights and music at an off-grid cabin. Sunking consistently makes it clear we'll pay for not following the numbers, and I was willing to pay for school fees.
I was also constantly put off of ever actually starting my solar energy experiments because of the numbers, which of course are super important. But for someone like me (i.e. the numerically challenged) , starting somewhere, albeit imperfectly, was necessary - I was willing to pay school fees and get practical experience.
The battery bank turned out to be a less-than-ideal paralleled set of 12V batteries. Yes, found out afterwards about the limitations of paralleling. I also found out afterwards that silver calcium batteries need to be charged at a 'boost' (that's what it says on my controller/regulator) rate higher than my un-programmable LED unit can allow. This means the batteries will not last as long as they could have, and their lifespan was already short because I'm using silver calcium with solar, which is apparently not good.
The cabin is visited infrequently for now, so the number of daily cycles is low. I am also using much less of the planned watt hours, so dod (when it occurs) is very low. I am curious to see how this plays off for battery life: insufficient charge and float rate vs. infrequent use and tiny discharges.
I swear the insolation numbers for my area are wrong. So sunny and clear here in winter, with an occasional cold-front that clouds things up. But even then I wonder if the panel's unusually high Vmp of 32.3, used on this 12 V system, is getting a higher voltage through to the batteries from earlier in the morning on those cloudier days. Speculation.
I am curious to see how the batteries are doing in another year's time. Dead you say. Likely. Here's hoping. FWIW, the silver calcium batteries were cheap and have worked well for a year so far, so maybe I should look at them as good learning tools.
An important take-home point form all this (although I'm sure other points will be raised, go ahead, I'm happy to learn) is: never purchase a controller / regulator that is not programmable. Sunking has frequently pointed out the need for maximum smoke settings, and this can't be done with many units.
On this CC/regulator note, two people replied to my failed V1 of this topic and said some MPPT units are fake. I really hope this is not the case with mine. It's a microcare 20A LED unit, if anyone would like to look into it for me. South African company, generally good rep.
I hope they're okay, because I plan to purchase two more units from them - digital display, programmable ones (I've seen them used in many installations). One for the newb system I have described so far, and one for a second system.
For the system I've described so far, I plan to set the new, shiny, digital display MPPT to max smoke and hopefully get a bit more mileage out of those dodgy silver calciums. When the batteries die, I plan to get a 250 watt panel to replace the present 130W high Vmp one - though maybe someone could tell me if this is necessary considering the high Vmp on the present panel. Anyhow, I've found out about the Trojan T105RE (6V, 225Ah) since then, so I'd put two of them in series to get me to 12V.
Okay, made my mistakes, now need to install a second system. Calculations as follows:
*Daily load watt hours: 1080 (over-estimated for fudge, despite no inverter being used)
*Insolation: 2.5 (alleged)
*24V battery Ah @20%dod: 225
*Panel wattage with MPPT: 648
*Amps at 24V: 27
Having made my mistakes, paid some cheap school fees, and tried to take in as much as possible from this forum and elsewhere, the construction will be as follows:
*MPPT 40A digital display programmable for max smoke
*2 panels, 320W each, Vmp 37.8 each, series
*4 Trojan T105RE (225Ah, 6V), series for a 24V system
*Step down device to power some of the 12V stuff I already have like lights, chargers, car stereo).
If I can't get the Trojans in South Africa, I know I can get 2V cells at 456Ah. But this means a 12V system, not ideal. And a 60A controller / regulator.
So hopefully I'm not as clueless as I was a few years ago when I joined. Although I'm sure Sunking will find a way to tell me that I am - I'd expect nothing less!!
Comments welcome.
Thanks to all the members who consistently contribute and make this site what it is.
I'd particularly appreciate links to topics where people have experience with changing settings to max smoke with the Trojan RE range - I've looked and not found first-hand reports.
Whazzatt