Faster Charging For Solar Generator With DC Converter
- Thread starter dmholmes
- Start date
Not necessarily following the mppt route as some of the comments suggest.
If you increase voltage through any fixed resistance or battery the wattage will increase.(limited to the pv max)
Not sure if this is such a good idea specially if the panel is a Jackery one made for those units as in the video.
Just buy 3 generic panels for the same price!
Being the sceptic I am could acheive the same result shown in the video by adding a 30watt load to the system at any point.
If you increase voltage through any fixed resistance or battery the wattage will increase.(limited to the pv max)
Not sure if this is such a good idea specially if the panel is a Jackery one made for those units as in the video.
Just buy 3 generic panels for the same price!
Being the sceptic I am could acheive the same result shown in the video by adding a 30watt load to the system at any point.
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Hi @dmholmes ,
Having twice watched that video you linked, the creator seems very credible to me and if the charge controller of the solar generator reports a faster charge rate, what's not to like?
The convertor he links beneath the video is "currently unavailable" at Amazon, but they have this unit in stock, which appears to be identical - at a great price:
I have a Bluetti EB240 that does not come with a "car charging" cable, because its MPPT requires a minimum input voltage of 16V.
Hobotech's video review of the EB240 recommends the purchase of a 300W sine wave inverter that can be plugged into the 12VDC power outlet of your vehicle, and from there, one could use the 120VAC transformer that's included with the solar generator to output 5A at 42VDC for 210-Watt charging, as displayed on the EB240.
To me, that seems horribly inefficient - converting 13.8V DC from your vehicle's alternator to 120VAC, then from there, converting 120VAC to 42VDC to charge the EB240, but that's Hobotech's advice for car-charging the EB240, as seen in this video:
So, thanks to you, I've ordered the convertor I've linked above and will follow-up later with my findings.
Having twice watched that video you linked, the creator seems very credible to me and if the charge controller of the solar generator reports a faster charge rate, what's not to like?
The convertor he links beneath the video is "currently unavailable" at Amazon, but they have this unit in stock, which appears to be identical - at a great price:
Amazon.com: MeterMall Protable DC-DC 600W 10-60V to 12-80V Boost Converter Step-up Module Car Power Supply : Electronics
Buy MeterMall Protable DC-DC 600W 10-60V to 12-80V Boost Converter Step-up Module Car Power Supply: Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
I have a Bluetti EB240 that does not come with a "car charging" cable, because its MPPT requires a minimum input voltage of 16V.
Hobotech's video review of the EB240 recommends the purchase of a 300W sine wave inverter that can be plugged into the 12VDC power outlet of your vehicle, and from there, one could use the 120VAC transformer that's included with the solar generator to output 5A at 42VDC for 210-Watt charging, as displayed on the EB240.
To me, that seems horribly inefficient - converting 13.8V DC from your vehicle's alternator to 120VAC, then from there, converting 120VAC to 42VDC to charge the EB240, but that's Hobotech's advice for car-charging the EB240, as seen in this video:
So, thanks to you, I've ordered the convertor I've linked above and will follow-up later with my findings.
Hi,
Can you please elaborate? I'm probably just revealing my noob ignorance, but I'm not able to correlate your post to the context of this thread.
Oh, wait, just guessing, are you saying that no step-up converter would be needed if a higher Voc panel was used?
If so, that's probably applicable to the OP's video link, but in my case, I'm trying to use a 13.8V vehicle power jack (only with the motor running) to charge via an MPPT that requires an input of 16V, minimum.
Trusting that your experience surely exceeds mine, which setup would you imagine is more efficient:
1) Hobotech's recommendation of plugging a 120VAC 300W sine wave inverter into my 13.8VDC car jack, then using it to charge the EB240 with its switch-mode brick-style AC adapter...
or
2) Plugging this step-up booster into the 13.8VDC car jack and adjusting its output voltage and current pots to maximize the charge rate Watts displayed by the EB640?
Amazon.com: MeterMall Protable DC-DC 600W 10-60V to 12-80V Boost Converter Step-up Module Car Power Supply : Electronics
Buy MeterMall Protable DC-DC 600W 10-60V to 12-80V Boost Converter Step-up Module Car Power Supply: Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
Thanks!
RCinFLA
Solar Wizard
- Joined
- Jun 21, 2020
- Messages
- 3,564
I do not know for sure if that Solar Generator is running an MPPT controller but based on an improvement by putting a voltage boost switcher I assume it is an MPPT controller. MPPT controllers need some overhead above battery voltage to operate properly.
An MPPT controller has a buck switching downconverter. This requires a minimum input to output voltage overhead to stay within a reasonable switching duty cycle and have feedback control stability. In addition to that overhead, the MPPT algorythms require the ability to detect a peak V x I product loading on the panel. In order to find this peak it must be able to see a drop off on low and high side of true MPP point. This requires the ability to allow the voltage to rise above MPP point. It cannot drop below battery voltage or above available panel voltage. If the MPP point cannot be detected by drop off on both sides most MPPT controllers just revert to PWM mode of operation, assuming panel voltage is above battery. (just on-off through connections switch between panel and battery)
There are many MPPT algorythms used by different MPPT controllers. They all require overhead voltage, some more then others.
A panel is a series stack of silicon cells. Its Voc and Vmp is dependent on the number of series cells within the panel.
To be confident to run an MPPT controller to a 14.6 vdc battery the minimum Voc of panel should be about 21 to 22 vdc. This generally means a panel with at least 36 series connected cells. A 32 or 33 cell panel will not reliably produce enough voltage to run an MPPT controller when it get warmed up by sun.
Although rare, there are controllers that run boost or buck-boost switcher to allow lower voltage panels to charge a 24v or 48v battery but they have a bit worse power conversion efficiency.
An MPPT controller has a buck switching downconverter. This requires a minimum input to output voltage overhead to stay within a reasonable switching duty cycle and have feedback control stability. In addition to that overhead, the MPPT algorythms require the ability to detect a peak V x I product loading on the panel. In order to find this peak it must be able to see a drop off on low and high side of true MPP point. This requires the ability to allow the voltage to rise above MPP point. It cannot drop below battery voltage or above available panel voltage. If the MPP point cannot be detected by drop off on both sides most MPPT controllers just revert to PWM mode of operation, assuming panel voltage is above battery. (just on-off through connections switch between panel and battery)
There are many MPPT algorythms used by different MPPT controllers. They all require overhead voltage, some more then others.
A panel is a series stack of silicon cells. Its Voc and Vmp is dependent on the number of series cells within the panel.
To be confident to run an MPPT controller to a 14.6 vdc battery the minimum Voc of panel should be about 21 to 22 vdc. This generally means a panel with at least 36 series connected cells. A 32 or 33 cell panel will not reliably produce enough voltage to run an MPPT controller when it get warmed up by sun.
Although rare, there are controllers that run boost or buck-boost switcher to allow lower voltage panels to charge a 24v or 48v battery but they have a bit worse power conversion efficiency.
That Bluetti eb240 has a 10A MPPT 68Voc charging ~ 40V battery.
RCinFLA
Solar Wizard
- Joined
- Jun 21, 2020
- Messages
- 3,564
Looks like Jackery is just a bad design. Panels shown is 32 cell panel but looking over the sketchy Jackery spec it appears to have six LFP cells in series for about 20-21 vdc battery supply. So it has to have a boost circuit internal to charge from lower voltage panel or a 12v car cigarette lighter output. If it was designed correctly there would be no need or benefit putting a second boost switcher externally. It likely is not MPPT loading on panel.
The prospect of taking an external random boost switcher designed to work from a voltage source input supply and have it work from a current source PV panel is iffy.
Assuming it started with full sun, at Voc clamped, and external boost switcher soft-starts with a low enough startup surge current not to collapse panel voltage causing switcher to reset/start over, and output voltage and current limiting is not set too high to collapse panel voltage it might work.
As soon as a cloud goes by the house cards may fall and you would have to go through the sequence again to get it running.
The prospect of taking an external random boost switcher designed to work from a voltage source input supply and have it work from a current source PV panel is iffy.
Assuming it started with full sun, at Voc clamped, and external boost switcher soft-starts with a low enough startup surge current not to collapse panel voltage causing switcher to reset/start over, and output voltage and current limiting is not set too high to collapse panel voltage it might work.
As soon as a cloud goes by the house cards may fall and you would have to go through the sequence again to get it running.
I've built a fan-cooled, 5A, 12V-to-48V converter that works great for charging the EB240 from a vehicle's 12V power jack, while driving:
Bluetti EB150 and Power inverter 500w 4.2 AMPS
I'm newer than a newbie here... We are thinking about getting the Bluetti EB150 solar generator, as we heard many good things about it. To charge it we know A/C is most preferred and of course via solar panel, however we also have a Power inverter rated at 500w at 4.2AMPS Can we charge the...
diysolarforum.com
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I just got into solar/power stations two weeks ago, so please forgive me if these are really stupid questions, I am trying to learn, but have already possibly made mistakes on my purchases. Trying to figure out the right course going forward from here.
I am going to be getting a Bluetti EB240 delivered next week, and I recently bought two Rich Solar panels. One is a 100 watt panel with :
Vmp: 18.60V
Imp: 5.38A
Voc: 22.80V
Isc: 5.78A
And the 200 watt:
Vmp: 20.40V
Imp: 9.80A
Voc: 24.30V
Isc: 10.20A
The reason I have the two solar panels is I originally bought the 100 watt panel and a small 280Wh solar generator and soon realized this was not going to cut it for my needs, so I decided to buy a 200 watt panel and a Bluetti eb240 instead. Already received the 200 watt panel. But I was thinking I could still use the 100 watt panel in parallel to get more power in the morning and evening and cloudy days (since I would be current limited by the Bluetti during peak sun). Upon more learning though, I realized the 100 watt panel does not match the voltage of the 200 watt panel all that well, 22.80 vs 24.30. And I have also since learned the EB240 will not be at its happiest at 24.30 input voltage either. It wants over 40 volts.
So here are my questions:
1. If I wanted to run these two panels in parallel, could I use this DC booster to raise the 18.60 working voltage of the 100 watt panel to better match the 20.40V working output of the 200 watt panel? At the expense of amps, which I would have more than I need anyway... And then wire both from there in parallel. It seems like this DC booster would make them batter matched on the volts side for wiring in parallel. Or is the relatively small difference in voltage not a big deal, and I could skip this step... which brings be to the second part:
2. And then after I boost the 100 watt panel voltage, could I take the combined parallel output from the two panels, and add another second DC booster to raise the voltage to 40 volts, at the expense of my excess amps, to better match what the Bluetti wants for efficient charging, according to Will Prowse in the comments section of the video above about not charging the Bluetti from less than 40V input? I didn't know when I bought my panels that the Bluetti wants at least 40 volts to be in the most efficient charging range. But by boosting the voltage with my excess amps, could I use all the power that my two panels can output more efficiently?
3. If I cannot do #1, should I boost the 200 watt panel to 40 volts (or maybe even higher?) alone to increase the efficiency of charging the Bluetti? Or:
4. Should I have bought the 24 volt version of the Rich Solar 200 watt panel instead of the 12 volt one for the Bluetti? I still have time, until April 15th, to return both panels if I messed up on my purchase.
I want to charge the Bluetti as efficiently as possible, and try to figure out how to use both panels to charge the Bluetti, if possible. Otherwise, if I cannot use these two mismatched panels to charge the Bluetti, I will just use the 100 watt panel exclusively for the small power station (which I am keeping), and the 200 watt panel for the Bluetti. Or I will return the 200 watt 12V panel for the 24 volt 200 watt version. Depending on what you guys think.
Thank you for any insights!!! I am pretty new to all this!
I'd say, keep the 100w for the little one and use the 200w for your EB240. You should be good to go with that 12v 200w voc 24v. If I'm not mistaken the 12v panel is for a 12v system (Bluetti) and the 24v is for a 24v system. If you get another 12v 200w voc 24v panel, both wired in series adds the two voc voltages (48v), your still under the 66-67v max the Bluetti will take. I run two 12v 200w voc 24v panels in series on my Bluetti EB150, max input 60v, and they'll pull 320w of solar on a hot summer day. Also, test the 200w panel on your Bluetti to make sure it's working before you can't send it back.
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Thank you for your reply, Sun Tzu!! I really appreciate it! Glad to hear my single 200 watt 12 volt panel will work well with the EB240. I was afraid I had bought the wrong panel after reading Will Prowse’s comment about the Bluetti needing 40VOC minimum for its MPPT, in the comments on YouTube for the video linked here.
Can’t wait for the Bluetti to show up.
Shank, glad I could help. If Will said you need 40v to trigger the mppt then you'll need another 200w panel and wire them in series. That should do the trick. With a 2400w battery you want to pump in as many watts as you can get away with.
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Yeah that is what I was asking... if I bought the wrong panel because of what Will said about how he would not use a panel lower than 40 Voc to charge the Bluetti. Maybe one 24 volt panel would have been a better idea for the voltage with its 45.4 Voc. As far as I understood, it will charge with lower than 40 Voc, but won’t take in as much power as the panel is capable of at the lower Voc. Which is why I was thinking I might try this DC to DC boost converter in the video. And maybe use another booster to also use my 100 watt panel with my current 200 watt panel as well, with an additional booster. I don’t really have room for two 200 watt panels. I have the panels on a small balcony. Just barely enough room for the 200 and 100 watt panels.
