https://www.ozervnews.com

The two controllers seem to work absolutely fine when paired up. It is interesting to see when one is putting out more than the the other, usually indicating some shading from the satellite dish. Wind the dish down and the outputs are virtually identical again. My two sets of panels do slope towards each other slightly so when the sun is quite low there will be a noticeable difference in output.

With regard to the solar harvest experiment, a total harvest over a month or so was always the plan, along with which setup would begin delivering a useful charge at first light and continue later into the evening. My money is on the series wiring, but I am happy to be proven wrong.

Cheers

Chris

How much are we wagering here If you had a PWM controller up against an MPPT controller I'd back the PWM controller to be the first putting out current and the last to stop charging in the evening

T1 Terry

To do the solar harvest comparison, you need to be able to measure the input for the day on each set up and do the test over a few days or longer.
Have you had any issues with the two controllers working together? We have finally managed to get more than one Victron MPPT controller to work on a system, but only because they are now Bluetooth and can communicate with the Victron 712BMV and each other, it appears that they take the battery voltage from the 712BMV as being the correct voltage so there is no conflict with one controller still charging while the other is testing the battery voltage.
We are in the process of installing a Victron 250/100 MPPT controller, 250vdc max open circuit and 100 amps max output. These things are huge compared to the 100/50 units and mega expensive, but still cost effective compared to 2 x 100/50 controllers if you add in the additional cabling and DC circuit breakers required if we went down that path. This converted bus will have 2kW of solar on the roof and a 12v 400Ah battery, so it will still clip the solar output at 100 amps through the middle of the day, but the full 100 amps should be available for longer each day. We used 4 B&S cable from the controller to the junction box and on to the battery so it will be interesting to see if there is any voltage/current fluctuation through the day.

So what does this mean for my bus...???

vik...???
Fixed up the quote bit for you Vik, if you put the bit you want to quote in between the brackets made by the " symbol in the header bar they come out as the bit you want an answer to rather than just part of the text

T1 Terry

Brucie2 wrote: ↑Thu Jun 04, 2020 8:16 am Hey Vik!!
Is your bus still for sale? Might have a cashed up buyer.............

Yep...

https://www.dailymotion.com/video/x3vg1nr

$180,000.00

vik...

T1 Terry wrote: ↑Wed Jun 03, 2020 12:56 pm How much are we wagering here If you had a PWM controller up against an MPPT controller I'd back the PWM controller to be the first putting out current and the last to stop charging in the evening

T1 Terry

I won't get into another debate regarding PWM vs MPPT but I am working on the principle that the potentially 60 + volts with the series configuration should reach 16 - 18 volts and start producing some viable current before the 20 volt paralleled configuration. Only time will tell.

Chris.

nut17 wrote: ↑Thu Jun 04, 2020 1:04 pm

T1 Terry wrote: ↑Wed Jun 03, 2020 12:56 pm How much are we wagering here If you had a PWM controller up against an MPPT controller I'd back the PWM controller to be the first putting out current and the last to stop charging in the evening

T1 Terry

I won't get into another debate regarding PWM vs MPPT but I am working on the principle that the potentially 60 + volts with the series configuration should reach 16 - 18 volts and start producing some viable current before the 20 volt paralleled configuration. Only time will tell.

Chris.

I think I'd go along with that line of thinking, about the only thing that might make a difference is the additional heat generated converting the 60v plus down to 13.6v compared to 20v down to 13.6v. The only downside of such an experiment, the array you connect in parallel will require a junction box on the roof and 6 B&S cable run down to the circuit breaker and MPPT controller

T1 Terry

Well we finally took delivery of the new Winnebago on November 4th and have been spending time performing my upgrades since getting back home to Hastings on Nov 25th. So far I have fitted a 400 AH LiFePO4 battery bank, Votronic battery monitor, twin 40 Amp MPPT SRNE solar controllers, and have got the first three 200 watt panels on the roof and connected to one of the controllers. I will have to wait until Jan 5th before I can install the remaining three panels as I do not have enough of the UV stabilised roof top cable on hand to complete the wiring.
I have also installed - but yet to connect a 60 amp Renogy DC DC charger and will also install the Projecta 50 Amp Intellicharger as a back up in the remote chance that I may need to hook up to the mains. The Iluka was supplied with a BM Pro electrical distribution and charging system but has been relegated to basic tank monitoring and some basic switching duties only now.

Nice.
Bernie.

Wow, those 40 amp MPPT controllers are monsters, what voltage will they handle from the solar?

Sure looks a neat set up, well done. We usually power up the BM Pro power system from the lithium battery so it can still do its thing, easier than eliminating it because it at least holds all the fuses and separate circuits and we tap out the DC start battery isolation part so we can power the DC to DC charger from there, saves a separate ignition switch power source wire being run. There is a little battery charger in there as well and we either control that via a "Finder" 12v powered 240vac switch that we control with our BMS ... or we just leave it unplugged if a better battery charger is installed.
Looking forward to hearing how the MPPT controllers get along together on the 400Ah battery.

T1 Terry

Hi Terry
The SRNE controllers are good for up to 100 volts. I am running three 200 watt OSDASOLAR PERC Mono crystalline Solar Panels into each controller. They have an OCV 22.6 volts so in series fall well within the maximum 100 volts. They are not fan cooled so need to have a significant heat sink to dissipate unwanted heat when they are working hard. They do have a dedicated LiFePO4 setting as well as fully customised settings. I am sticking with the lithium setting which charges a little high to 14.4 volts but has no float. I have HA02 active cell balancers on my battery pack.
I have done as you suggested and have the BM Pro unit hooked up to the Lithium battery to continue the low current 12 volt power distribution duties and pump switch. All seems to be working fine. The ILUKA was supplied with a Camec instant hot water service which I got Apollo to remove and fit the Swift 20 lt hot water storage gas / 230 volt unit in it's place. They have stuffed up the install resulting in gas only operation at this stage. I want the 230 v facility to function as we will power this via solar - battery - inverter for a large part of the year. It has a 1000 watt element.

I used a pair of identical controllers with our last caravan but only had two 200 watt panels in series to each controller. These were 24 volt panels with an OCV of 46 volts. Getting closer to the 100 volt maximum.
https://fazcorp.co.nz/collections/mppt- ... -ml-series

Cheers
Chris