I'll get these Schottky diodes if they are ok. https://www.jaycar.com.au/diode-1n5822-schottky-40v-3a-d027-pack-10/p/ZR1023
None of the three diodes in the product image correspond to the 1N5822 diode, so I guess that's a generic image.
Under the specifications tab we have a "maximum forward voltage of 40V". Of course that should be reverse voltage.
The actual forward voltage drop at 1A is 0.4V @ 25degC, and 0.3V @ 125C.
ISTM that this diode should be fine as a bypass diode. However, it may be inadequate as a blocking diode under certain operating conditions. For example, if a series pair of panels were producing 36V at MPPT or 42V when open circuit, then this would "challenge" the blocking diode in a shaded pair.
To add both bypass and blocking diodes for 6 panels you will need 12 diodes in total. We have plenty of Schottky diodes here if you want some, no charge, just PM an address to me so I can send them off. They are these RS component items https://au.rs-online.com/web/p/rectifier-diodes-schottky-diodes/9033450/
as you can see on the listing, minimum purchase is 500 units. I don't think we are likely to use 500 of the things in this life time, so we are happy to help out anyone who has a need for them.
T1 Terry
-- Edited by T1 Terry on Thursday 14th of November 2019 02:28:19 PM
That smart diode looks good. However, at AU$6 each x 6 panels, the cost is equivalent to 2 extra 20W panels. I think they would only start to make economic sense when they are priced at around $1, even in the larger panels.
Whenarewethere said
07:28 PM Nov 15, 2019
I don't have the space for 2 more panels & I'm not building it to a budget. It's only the cost of a handful of cappuccinos!
PetenSue said
07:41 PM Nov 15, 2019
And I just park my caravan in the sun and wow, my batteries get charged. Magic !! Simple as. Nothing like over complicating things. I didnt even have to add a picture. Regards Pete.
dorian said
08:59 AM Nov 16, 2019
PetenSue wrote:
And I just park my caravan in the sun and wow, my batteries get charged. Magic !! Simple as. Nothing like over complicating things. I didnt even have to add a picture. Regards Pete.
Thank you for providing us with the benefit of your experience.
dorian said
09:10 AM Nov 16, 2019
I found two other smart diodes, but the TI one looks best:
LX2410A, Microsemi, 10A IDEALtm Bypass Device, 12.5A, 95mV at 10A and 110°C, 12.5µA of leakage current up to 33V of reverse voltage, DFN:
Therefore, what in particular has set the AE Solar Smart Hot-Spot Free Mono Series as a new focal point in industry innovation? Bypass diodes. However, not the typical 3 or 6 bypass diode configuration in conventional solar panel designs of today.
Based on a standard 60-cell module design, the AE Solar Smart Hot-Spot Free Mono Series incorporates a bypass diode at each solar cell. The result, up to 80% more power when shaded compared to standard solar panels and the ability to mitigate the effects of detrimental solar panel hot-spot.
I had the same idea, but I rejected it because the voltage drop would have been too great. For example, if 10 cells were shaded, then their combined voltage drop would be 4V (= 10 x 0.4V).
However, here is a paper which uses smart diodes:
Photovoltaics in the shade: one bypass diode per solar cell revisited:
So I'm guessing that the AE Smart panel uses smart bypass diodes rather than regular Schottky types.
-- Edited by dorian on Saturday 16th of November 2019 10:25:28 AM
T1 Terry said
02:02 PM Nov 16, 2019
There were panels on the market many moons ago that used this technique, so it's nothing new. The area the panel covered to produce the same output as a panel that didn't have the bypass diodes meant the gains were not enough to make up for the lost harvest area, so they eventually disappeared from the market.
So long ago I can't remember the manufacturers name, but they were well known in the early days of RV solar.
T1 Terry
dorian said
05:44 PM Nov 16, 2019
T1 Terry wrote:
There were panels on the market many moons ago that used this technique, so it's nothing new. The area the panel covered to produce the same output as a panel that didn't have the bypass diodes meant the gains were not enough to make up for the lost harvest area, ...
I don't understand. Where were the losses? Was this in the days before ideal diodes? AFAICT, TI announced their smart diode in 2013.
Whenarewethere said
08:09 PM Nov 16, 2019
Thank you for all the links, I'll have to get my head around all this stuff. But it will be an interesting exercise to how far a small array can be pushed.
T1 Terry said
01:43 PM Nov 17, 2019
dorian wrote:
T1 Terry wrote:
There were panels on the market many moons ago that used this technique, so it's nothing new. The area the panel covered to produce the same output as a panel that didn't have the bypass diodes meant the gains were not enough to make up for the lost harvest area, ...
I don't understand. Where were the losses? Was this in the days before ideal diodes? AFAICT, TI announced their smart diode in 2013.
Finally got the better of me, I had to Google "AFAICT" to find out what I meant :lol: I have 2 of these early panels with the bypass diodes between each solar cell/module glued to a sheet of fibreglass and glued onto the poptop of my kombi. they are early semi flexible panels and originally came off the roof of an ex hire Kia transit van The panels are 6v so there are 2 in series, the pair cover an area of 1490mm x 740mm and produced a stunning 64w when new. I haven't actually measured their output for a while, but I can't imagine it has improved with the passing of the last 15 yrs. No doubt the manufacturers name is on the underside of these panels, but I'd have to destroy the panels to get them off the fibreglass, so that's not happening. As a comparison, the semi flexible 100w 12v nom. panels I have here measure 500mm x 1000mm and I'd in no way claim these were the cutting edge as far as area to output ratio.
Maybe the theory doesn't match the reality, but the reality is a fixed thing, so the theory must be missing a few figures in the calculations ......
T1 Terry
After a rethink, it might be only 10 yrs they have been on the Kombi roof, before that we had rigid panels mounted as assort of aerofoil over the roof up front that acted as shade over the windscreen yet had enough clearance behind to allow the poptop to be raised and lowered. They had been recued from a rubbish bin at a CMCA rally in Tassie some 16 or more yrs ago and finally shattered after coping a wave of water thrown up by a truck travelling in the opposite direction. With each of us travelling at around 100km/h, the impact was all too much, but they had been there for probably 5 yrs so they had done a great job. Considering the panels were probably circa 1960's or at the latest '70s, so the technology was not even close to todays, they outperformed these semi flexible shade tolerant panels on the poptop now by a country mile.
-- Edited by T1 Terry on Sunday 17th of November 2019 01:43:41 PM
-- Edited by T1 Terry on Sunday 17th of November 2019 01:52:08 PM
Whenarewethere said
10:03 PM Nov 18, 2019
Found these diodes which hopefully are ok for blocking diodes.
None of the three diodes in the product image correspond to the 1N5822 diode, so I guess that's a generic image.
Under the specifications tab we have a "maximum forward voltage of 40V". Of course that should be reverse voltage.
The actual forward voltage drop at 1A is 0.4V @ 25degC, and 0.3V @ 125C.
ISTM that this diode should be fine as a bypass diode. However, it may be inadequate as a blocking diode under certain operating conditions. For example, if a series pair of panels were producing 36V at MPPT or 42V when open circuit, then this would "challenge" the blocking diode in a shaded pair.
Datasheet:
https://www.vishay.com/docs/88526/1n5820.pdf
Thank you for the information.
To add both bypass and blocking diodes for 6 panels you will need 12 diodes in total. We have plenty of Schottky diodes here if you want some, no charge, just PM an address to me so I can send them off.
They are these RS component items https://au.rs-online.com/web/p/rectifier-diodes-schottky-diodes/9033450/
as you can see on the listing, minimum purchase is 500 units. I don't think we are likely to use 500 of the things in this life time, so we are happy to help out anyone who has a need for them.
T1 Terry
-- Edited by T1 Terry on Thursday 14th of November 2019 02:28:19 PM
This link is easier to work with:
https://au.rs-online.com/web/p/rectifier-diodes-schottky-diodes/9033450/
T1 Terry
Has anyone had experience with these smart bypass diodes. They are over the top for my panels but they have a very low voltage loss.
https://au.element14.com/texas-instruments/sm74611kttr/hot-swap-controller-30v-to-263/dp/3008488?ost=sm74611&ddkey=https%3Aen-AU%2FElement14_Australia%2Fsearch
Data sheet:
http://www.ti.com/lit/ds/symlink/sm74611.pdf
That smart diode looks good. However, at AU$6 each x 6 panels, the cost is equivalent to 2 extra 20W panels. I think they would only start to make economic sense when they are priced at around $1, even in the larger panels.
I don't have the space for 2 more panels & I'm not building it to a budget. It's only the cost of a handful of cappuccinos!
Thank you for providing us with the benefit of your experience.
I found two other smart diodes, but the TI one looks best:
LX2410A, Microsemi, 10A IDEALtm Bypass Device, 12.5A, 95mV at 10A and 110°C, 12.5µA of leakage current up to 33V of reverse voltage, DFN:
https://www.microsemi.com/document-portal/doc_download/135254-lx2410a-datasheet
https://www.mouser.com/datasheet/2/268/ds_lx2410a-1592826.pdf
SM74611, Texas Instruments, Smart Bypass Diode, 15A, forward voltage drop of 26mV at 8A, TO-263:
http://www.farnell.com/datasheets/1857934.pdf
http://www.ti.com/lit/ds/symlink/sm74611.pdf
MP6914, Ideal Diode for Solar Panel Bypass, Integrated 5.3mO 30V Power Switch, SOIC8E:
https://www.mouser.com/datasheet/2/277/MP6914_r1.0-526360.pdf
Here is a commercial panel that uses one bypass diode for each solar cell:
REVIEW | AE Solar Smart Hot-Spot Free Mono Series 280 -- 310W:
https://review.solar/ae-solar-smart-hot-spot-free-mono-series/
https://review.solar/wp-content/uploads/2019/05/AE-Solar-Smart-Hot-Spot-Free-Mono-Series-280--310W-Datasheet.pdf
I had the same idea, but I rejected it because the voltage drop would have been too great. For example, if 10 cells were shaded, then their combined voltage drop would be 4V (= 10 x 0.4V).
However, here is a paper which uses smart diodes:
Photovoltaics in the shade: one bypass diode per solar cell revisited:
https://www.onlinelibrary.wiley.com/doi/10.1002/pip.2898
So I'm guessing that the AE Smart panel uses smart bypass diodes rather than regular Schottky types.
-- Edited by dorian on Saturday 16th of November 2019 10:25:28 AM
So long ago I can't remember the manufacturers name, but they were well known in the early days of RV solar.
T1 Terry
I don't understand. Where were the losses? Was this in the days before ideal diodes? AFAICT, TI announced their smart diode in 2013.
Thank you for all the links, I'll have to get my head around all this stuff. But it will be an interesting exercise to how far a small array can be pushed.
Finally got the better of me, I had to Google "AFAICT" to find out what I meant :lol:
I have 2 of these early panels with the bypass diodes between each solar cell/module glued to a sheet of fibreglass and glued onto the poptop of my kombi. they are early semi flexible panels and originally came off the roof of an ex hire Kia transit van The panels are 6v so there are 2 in series, the pair cover an area of 1490mm x 740mm and produced a stunning 64w when new. I haven't actually measured their output for a while, but I can't imagine it has improved with the passing of the last 15 yrs. No doubt the manufacturers name is on the underside of these panels, but I'd have to destroy the panels to get them off the fibreglass, so that's not happening. As a comparison, the semi flexible 100w 12v nom. panels I have here measure 500mm x 1000mm and I'd in no way claim these were the cutting edge as far as area to output ratio.
Maybe the theory doesn't match the reality, but the reality is a fixed thing, so the theory must be missing a few figures in the calculations ......
T1 Terry
After a rethink, it might be only 10 yrs they have been on the Kombi roof, before that we had rigid panels mounted as assort of aerofoil over the roof up front that acted as shade over the windscreen yet had enough clearance behind to allow the poptop to be raised and lowered. They had been recued from a rubbish bin at a CMCA rally in Tassie some 16 or more yrs ago and finally shattered after coping a wave of water thrown up by a truck travelling in the opposite direction. With each of us travelling at around 100km/h, the impact was all too much, but they had been there for probably 5 yrs so they had done a great job. Considering the panels were probably circa 1960's or at the latest '70s, so the technology was not even close to todays, they outperformed these semi flexible shade tolerant panels on the poptop now by a country mile.
-- Edited by T1 Terry on Sunday 17th of November 2019 01:43:41 PM
-- Edited by T1 Terry on Sunday 17th of November 2019 01:52:08 PM
Found these diodes which hopefully are ok for blocking diodes.
https://au.element14.com/on-semiconductor/fsv1045v/rectifier-schottky-10a-45v-to/dp/2473428RL?st=45v%20diode
On page 2 of the PDF they note Solar Panels.