Hi,
I have just discovered this forum via a link from another forum and it looks very interesting. I guess this is the best place to introduce myself and what gear i have, get direction to which section to ask what questions in and generally feel my way round.
I currently have 12 x 80w Solarex panels, a Plasmatronic PL20 with 250amp shunt, a BZ250MPPT controller and BZ250MPPTHV controller and a voltage sensing relay with direct feed to the shunt (J Car kit) feeding 800ahr of AGM batteries @ 12v nom.
Currently I am experimenting looking for the most efficient charging method and using the stored energy to do experiments with running household appliances from modified sine wave and pure sine wave inverters, again looking at efficiency v cost.
Questions needing direction:
What's the best form of battery charging, pwm, mppt or direct with simple voltage control?
Efficient battery bank design?
Converting excess solar power into a viable engine fuel, hydrolysis to create hydrogen/oxygen or to drive a hybrid electric set up?
My aim is to run my motorhome that I am currently building as much as possible on renewable energy while using common household appliances.
Sorry about the length of a first post, maybe not a good sign for the future

T1 Terry

Hi Terry, Welcome to the forum.

Looks like your not a newbie, and you know what your doing from the sounds of things. Nice setup BTW.

MPPT battery charging is the best option in terms off efficiency, however, if cost is an issue or they are reaching a full state of charge on a regular basis, simple voltage control would suffice.

In terms of battery bank design, usually the higher the voltage the better. For high power use, dont run a 12volt system. Go for 24volts minimum or even 48 volts. Just make sure you have the proper equipment to match the batteries, like 24 or 48v inverters and regulators.

Converting excess solar energy into hydrogen seems like a great idea, however, i wouldn't know where to start . I come from an electronics background rather than a chemistry background. I think if i experiment with setup like this on a larger scale all i would achieve is a huge explosion and a pile of mess . Keep us informed, this is an area im sure has huge future potential.

Show us some pictures of your home. sounds like you got heaps of rooftop area for the panels.

Just a quick question. How have you got your solar panels configured. Are they in series/parallel strings or just parallel.

Hey your long post is welcome. the more freaks the better .

Hi Tony B and thanks for the welcome,
For the current experiment I have 3 sets of 3 x 80w solarex panels, there is one more panel that short circuit amps are measured to give a reference of solar output (There is name for it but I can't remember it)
I will try to post the results of my 4 hr test here, unfortunately it's on another forum and it's currently running at glacier speed with regular SQL errors.


Unfortunately 4 hrs into testing the BZ250MPPT regulator stopped charging, I thought it may have been a because all the battery inputs were connected to the same place so i separated the inputs the different areas of the battery bank. At this stage I made a fatal error and accidentally reversed the battery connection momentarily but that was enough for the smoke to come out of the box. I contacted the BZ company in the states asking what components would need replacing and the answer was, buy a new one.
Basically the BZMPPT unit with the parallel panels rated worst, the BZMPPT with the panels in series rated a poor second and the PL20 rated best. After the smoke came out of the 2nd BZ unit I connected those 3 panels connected in parallel to the PL20 shut via a relay and controlled them with a J Car kit voltage control circuit. Surprisingly, this out performs the other 3 units particularly in poor light such as early morning and while raining. I have seen the direct connected panels putting 0.4amps in while the MPPT is putting out nothing and the PL20 0.2amps.
These BZ units are relatively cheap but to date I have found their output to be disappointing. I am planning to reconfigure the panels to the BZ250MPPTHV controller to 24v nom and see if the output improves.

T1 Terry

Here is a link to the bus/motorhome project that the panels are going on http://s419.photobucket.com/albums/pp27 ... -C_photos/ as you can see, it's still a work in progress.

T1 Terry

Great comparison Terry. It looks like the PL20 is the most efficient unit.

Have you tested the standby current consumption on these units?
Itll be interesting to see what the BZ units consume in standby.
I have a feeling they may have a larger idle current draw compared to the plasmatronics unit.

Wow, doesn't look BZ provide much support for there models. You should pop the blown unit open, post some pictures up here, maybe i can see whats blown. Ill try and help ya out.

Im looking forward to you results after yo configure the HV unit to 24volts.
Itll be interesting to see the improvements HV brings, if any.

Tony B

BTW: Looks like your motorhome has got huge potential . Keep us posted.

Hi Terry,

It could be useful to record the Panel output volts, the battery volts and the regulators 'mode' (if known) at each measurement.

It's certainly not a good look for the BZ MPPT's based on those numbers. I understood that MPPT worked relatively well for low light situations?

Could the common battery be an issue?

I'll be keen to see the Fatmax put through it's various paces.

PS Is there any difference with the various PL20 modes e.g. Pulse Width Modulation or slow speed switching?

Wahroonga Farm wrote:I'll be keen to see the Fatmax put through it's various paces.

I might actually take Terry up for his offer and send him a high power Fatmax unit for testing.
Itll be good to have a controlled comparison of these units.

Sweet

T1 Terry