D
Deleted member 91418
Guest
While I'm turned off by their products, that write-up is very informative!
Help
- Thread starter Turnergang
- Start date
They are around- multivoltage ones that can handle up to 48v battery banks like this one have a 100v PVmax rating...
D
Deleted member 91418
Guest
I do like that! If those terminals were different, I wouldn't hesitate to jump for one.
Yes...
BUT...
By having the Vmp as close as possible to the battery charge voltage- you are one of the ones I mentioned before- trading a higher 'peak' output for less total daily generated power...
Unlike a high voltage MPPT (which starts charging basically at dawn and runs to dusk), a 'voltage matched' PWM with a 17vor 18v Vmp, will only start to charge once the panel voltage rises above the battery bank voltage- and depending on the panels orientation, may be several hours later than a panel running on a MPPT, and shuts down much earlier to boot... even the same PWM with a panel with a higher Vmp (20-22v) will start earlier and finish later than that low Vmp panel- yes its peak will be lower, but its total power generated per day will be higher (and the MPPT total power generated higher again...)
In terms of total power per day generated, it is high voltage MPPT, low voltage MPPT, slightly higher but 'voltage matched' Vmp on a PWM, and coming in last in performance is a 'lower voltage matched' PWM..
You still get the same issue- you are throwing away anywhere from 25% to over 75% of your panels possible output power by staying with PWM over MPPT...
I know panels are cheap these days- but buying a 400w panel and only getting under 100w out of it seems pretty pointless to me...
D
Deleted member 91418
Guest
But after having a Victron this past week not being able to hold up on horrible roads, I need a controller capable of holding cables down as tight as possible... such as ring terminals. I haven't found a single MPPT that uses ring terminals, therefore for my situation I am limited to PWM. Now I could just stick to smoother roads, but our job sites go on surfaces that make wash-boards look like a freshly-made piece of highway. If I was only doing campgrounds or Walmart parking lots, then I could see it making sense.
While I do support the fact MPPT is a lot more efficient than PWMs (I'm certain everyone does by now), It's common for my system to be fully topped-up before 1PM with PWM. For those with larger systems, however, I always say go for MPPT; it WILL make a huge difference in every aspect.
While I do support the fact MPPT is a lot more efficient than PWMs (I'm certain everyone does by now), It's common for my system to be fully topped-up before 1PM with PWM. For those with larger systems, however, I always say go for MPPT; it WILL make a huge difference in every aspect.
You are comparing a low voltage parallel connected MPPT with a low voltage parallel connected PWM- most of the time your MPPT would have been running in PWM mode anyway (they really need about 5v minimum over the charging voltage before the MPPT circuitry kicks into life), and with your 34v Vmp and a 28.8v charging voltage- you only have 5.2v- for much of the morning before the peak, you would have been operating in PWM mode...
so zero difference apart from a few hours in the middle of the day (maybe- depending on other factors like location , season etc, you may never get into MPPT mode all day...)
That is why it is important to try and get as close as possible to the PVmax rating (I prefer to leave a 20% margin for safety for those rare, but not that uncommon times when panels can briefly exceed their listed ratings by 10-15%)- so for my own 150v MPPTs for example, a series string that just under 120v is ideal...- the panels I selected here have a combined Voc of 114.7v with 3 in series- perfect...
And why I literally start charging at half an amp at sunrise, with no direct light on the panels at all...
Your low voltage PWM (or low voltage MPPT) won't start for an hour or two after that...
seneysolar
Solar Addict
You haven't seen Aussie outback roads- I drove a tilt-tray for several years after the mining boom collapsed here- and it wasn't uncommon for me to pick up both utes and caravans to take them home that had literally 'broken their backs' because of the corrugations on the dirt roads...
I've got a video of my panels charging the battery bank at the old campsite while I was building the shed
before sunrise...
No visible sun at all, just running off the 'skyglow' you see just before dawn...
Not a lot obviously- a pulse of about half an amp once a second or so- you can see the voltage rising until the caps inside the charge controller are charged, then it dumps that into the battery bank and starts charging them up again...
(less than a minute long...)
Pre sunrise and charging...
D
Deleted member 91418
Guest
While Australia doesn't have roads made of ice, we certainly haven't had any chassis frames break. That looks nasty! Every time I get an oil change, I also get inner and outer tie rods changed, along with all four shocks just because oh where we get sent to.
That's exactly what happens in the office trailer.
D
Deleted member 91418
Guest
But... I do think we got off course from what the OP had asked lol.
Similar threads
