Bypass VS Blocking Diodes in a Solar Power System



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47 comments

  1. After testing for extended periods of time at a 'shade problem' location I have found the parallel consistently out performs the series setup, the bypass diodes may help a series setup but they are not as good, it would be interesting to see the exact efficiency losses for those diodes. I have found the bypass diodes are only about 80-85% as effective as a parallel setup in problematic location setups.

  2. Nobody seems to be addressing what a blocking diode does. If you have a 100 watt panel and a 50 watt panel you will need to install a blocking diode between the two different wattage panels.

  3. Hey Will- talking about bypass diodes. I did some testing to see what it takes for the diodes to turn on and found that when that when that loaded string of (shaded) cells output voltage drops to just less than .8 volts the diode turns on and allows current to fully bypass that that string of cells. The output of that panel or string of cells becomes zero but at least it allows current to continue to flow through the series circuit.

  4. Hello 🙂 I love your videos and have a question for a long time: If I connect 12v and 24v solar panel in parallel do I need a diode? Or I may have a problem with power output? Thanks again for your great videos.

  5. I just ordered forty 240w solar panels from santan solar today. Looking forward to starting my off grid living experience!

  6. hi Will thankyou for your great videos ,you said never use blocking diodes for a series string ,what would happen if you put a blocking diode after each panel in series ?apart from volts used by the diodes ,would they work fine?

  7. I don't understand it's like this is not working properly I shade just a fourth of one panel and my output drops to 25 to 40 watts from 300 if I shade just one cell on one panel it doesn't drop as much am I doing something wrong or are my panels not working properly. Thanks in advance

  8. I have a small diy system (2)100 watt panels connected to two separate controller/battery setups. The solar inputs of one controller leaks full battery voltage at night, back to the solar input of the other controller sharing the panels. Its madness 🙂 Im thinking an inline diode on the(+) leaky controller would solve my issue. Is it common for a controllers solar inputs to mirror battery voltage?

  9. Will. Now that you have basically explained everything a solar system has and how it works in 10 different ways. Would you please make a series or playlist on how to check for common faults and problems. It would be nice to teach people how and what to look for when having problems.

  10. I’m an electrical engineer, and with this video you’ve shown you know your stuff.

    You speak a different language than I would at work so it took me a while to come around after watching a number of your videos.

    Thanks for the great tutorials. They’ve saved me a ton of research when designing the solar system for my van build!

  11. Back in the Olden Days — LOL
    I used to teach classes to military and civilian computer tech personnel from several countries; some of the computer equipment, like card punches and readers used vacuum tubes. That was the "Olden Days."
    🙂

  12. Nice diode roundup Wil! Thanks. Would you recommend that if I have two MPP Solar units hooked together for split phase operation and I have east and west arrays it would be best to hook an array to each MPP rather than using a diode combiner?

    Mike I did see that crazy illusion with the black diamonds jumping all around. Funny they disappeared when you looked specifically at them.

  13. Good that you mention using multiple MPPTs instead of using blocking diodes as this maximises your output.

  14. Anyone notice the optical illusion when looking at the solar panel? Where all the cells meet in the corner, there is a diamond shape. I think it is the solder track. Anyway, if you stare at them, the white diamond turns black, but only in your peripheral vision. You can't look directly at one, you are always chasing the black diamond. Good videos…

  15. I have a 4P array of Renogy 100 watt (5 amp each, 20 amp combined) panels that are wired directly (no charge controller) to 384 18650 cells in 3S8P sub-packs (24 cells per subpack). The battery is never charged above 12.6v, or 4.2v per 18650cell. Although the panels produce 20v/20a all day, there isn't enough amperage to overcharge the battery cells. Thus, this self-charging, "amp-balanced" configuration runs continuously without an auxiliary charger (unless overcast for an entire day). I tested current back-drain by disconnecting everything except solar panels overnight; and, in the morning, there was no drop of voltage from the value recorded the night before. Conclusion: my solar panels must have blocking diodes as well as bypass diodes?

  16. I was under the belief that blocking diodes protected from reverse charge / current that could cause a coating on the solar cells to separate from its substrate, which would ruin the cell.

  17. Excellent explanation. I always wondered about the purpose of the diodes on solar panels. I suppose I should look to purchase extra diodes for my solar panels in the event of an EMP surge.

  18. So I have multiple solar panels all over my bus mainly because of my hatches, so I have one large one on the roof one on each side & one large one at the back window! They are all mounted on the inside of the bus except the roof one! So I have to make sure that no cell is shaded ! Now I get that I should have one MPPT charge controller for each panel so that when the sun is on the opposite side it won’t draw on the battery????? 👍 Cheers

  19. Does this mean that any inverter with 2 separate MPPTs will support a different string on each MPPT without one string adversely affecting the performance of the other? I have one 3kw array on my east-facing roof connected to MPPT1 in my inverter (Sol-Ark 5k), and bc 3kw is nowhere ner enough for my home, i'm planning to put another 3kw array on my west facing roof connected to MPPT2 in the Sol-Ark. Does the fact that an inverter supports separate MPPTs indicate that it uses blocking diodes internally to allow each to perform at it's best (given solar conditions) without adversely affecting the performance of the other?

  20. So I have a renogy DCC30S in my van and an auxiliary plug to chase the sun with. I am thinking of putting on a 50w solar permanently attached to my battery pack. Can I simply plug both positives onto the PV+ of the Renogy and it will take the power together or one panel?

  21. Excellent explanation. I am familiar with water pipes. Bypass is the same in water open all times just like an overflow pipe so water will flow at any direction. The blocking diode is like the backflow prevention. It only allows for one direction.
    What are thoughts on combiner boxes with solar system with sun trackers (with the assumption of the system in two different sides on the east and west side)?

  22. I have a curved roof RV with the utilities in the middle. My plan is to use 4 CIGS solar panels in two rows parallel and in series.
    Driver side has two panels in series going along the outer edge and the passenger side has two panels in series along it's edge. The middle of the camper is vents, AC units, TV antenna, etc..

    After watching this video I'm concerned about having the one side shaded by the hardware on the roof while the other is facing sunlight. Would it be best to use the diode as explained or get two of these: Victron Energy SmartSolar MPPT 100V 15 amp.

    I assume if I bought two victron's I would have to manage them separately. Is there an MPPT on the market that can accept two solar inputs and balance the charge to the batteries?

  23. Done learnt me sumtin new today 😜. Seriously, another great explanation of basic circuits that everyone uses but no one ever really thinks about. 👍

  24. San Tan Solar panels. I live in STV,AZ..are they good back yard array.? Can you run AC off it?

  25. Hey there. What if I tell you I have found out a way how to charge your batteries at night? Need your attention and I offer my help

  26. I reuse shottky double diodes, they look like transistors, from computer power supplies as blocking diodes, since I do parallel connections of multiple strings with different angles and different solar panels into my grid tied inverter with limiter. It has max 90 volt input, so only 2 panels put in series each string.

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