Designing new 12VDC Off Grid system. Many questions. (Midnite 150)

[vk4akp]

I have a new question.

It looks like I will end up with 6x 250Watt panels. Giving 1.5KWatt total.

I was going to split these as 2 strings of 3 panels in series each. (VMP 90.3VDC).

But the online calculator says 1.2 Classic 150's required and in red "Excessive"

Now I don't mind it being excessive because it will be located in a far from perfect location. (Flat mounted / no tilt, & shading issues).

But my question is will this configuration "Not hurt" the Classic 150?
Will it just harvest at it's peak capacity at any point where more then 96 Amps are available?
With this panel configuration, Max ability for a Battery @14.4VDC is 104.2 Amps.

.-.-.

[Halfcrazy]

1.2 times the Classic will not hurt it you will just go into current limit.

Ryan

[vk4akp]

Hi Guys,

Still collecting bits for my solar project, but I'm getting closer. 

Batteries.
Latest items obtained are 3x deep cycle lead acid batteries. (Panasonic_VRLA_LC-XA12100P [100Ah 12VDC]).
These are second hand ex government about half way through their life.
http://www.panasonic.com/industrial/includes/pdf/Panasonic_VRLA_LC-XA12100P.pdf][url]http://www.panasonic.com/industrial/includes/pdf/Panasonic_VRLA_LC-XA12100P.pdf[/url]

Eventually I still want to go to Nickel Iron cells but for now these will get me started.

I'm just wondering if it's OK to Parallel up two of these batteries to give me 200Ah combined?
Or is that a bad idea due to mismatched characteristics of each individual battery?

Panel wiring and voltage into the Midnite?
Also I'm currently shopping for MC4 connectors and "Y" cables.
Eventually I'll run all 6 panels in parallel to keep the volts down to under 40 VDC but for now is there much loss in the conversion process if I run all the panels in series for easy initial wiring?

~TNX~
Ken
.-.-.

[vk4akp]

BUMP BUMP BUMP

HUmm.

Is Midnite Solar still trading?

Your forum says no new posts since my last visit?

And messages seem to go unanswered.

Latest my way is I am looking at a Powerstar W7 (12VDC 3000/9000Watt inverter charger) to add to the system.
Just wondering if anyone has had any experience with these?

.-.-.

[TomW]

BUMP BUMP BUMP

HUmm.

Is Midnite Solar still trading?

Your forum says no new posts since my last visit?

And messages seem to go unanswered.

Latest my way is I am looking at a Powerstar W7 (12VDC 3000/9000Watt inverter charger) to add to the system.
Just wondering if anyone has had any experience with these?

.-.-.

This is a fairly old thread. 8 months on most forums is an eternity and posts fall off the edge as it were.

Midnite is still very much alive and kicking.

Maybe nobody knows the answers you seek?

This forum is quite active, several posts every day so you should see some "new posts". Perhaps you need to flush your cookies for the Midnite forum? That is usually the cause of "no new posts"

Sorry, I have never even heard of that inverter but 9KW at 12 volts will need huge cables for battery connections when it peaks at nearly 800 amps.  Just a general observation.

What do you mean by "messages go unanswered"? If you mean posts here on the forum it is likely nobody knows the answers. If you mean personal messages to members they may not know the answer, either.  If you mean email then maybe they got missed?

Good luck sorting it out.

Tom

[Vic]

Hi Ken,

Nice to see you back here.

RE MidNite,  there are numerous posts per day here.  All is well,  alive and active here,  as I see it.

Folks who make 12 V  Inverters with specs like this (was unable to find any real hard specs) should NOT be trusted in my opinion.

As Tom indicated,  the currents involved to make even the 3 KW are huge -- around 300 Amps.  It is very difficult for an inverter to handle these large currents internally.  At 12 V,  the voltage drops are very significant inside the inverter,  let alone the cables and effects of these high currents on the batteries.

Generally,  if you need these power levels,  a 48 V system is in order.    Just my opinions,  73 - GL,  Vic

[vk4akp]

Hi, Well it's good to see you guys are still going. I love your products. It's a big shame the classics can't be distributed in Australia at a more affordable price.

I wonder why when I log in it says no new posts since your last visit. Oh well.

OK, Yes I've been searching and searching on these Powerstar W7 inverters and have come up with some YouTube video's that are saying they have terrible standby current usage and a Energy Matters forum thread where they have tried to replace the standard transformer with a toroidal. These people found that the more you loaded the thing up the more the sine wave tended to turn into a very dirty looking square wave.

This is a shame as they are at a reasonable price.

OK And I understand what you are saying about the larger inverters at 12VDC.
Unfortunately at this point I don't want to go to a higher DC voltage system as most of our devices will be running from 12VDC.

Most of the high draw 240VAC devices should come in at over 1KW but most likely under 2.5KW so I might look for 2x smaller inverters instead of just one big one.

What to look for and where is now the big question.
Looking on eBay just seems to reveal a lot of junk like the Power Jack range etc.

I'm also finding it hard to find a source in Australia for affordable DC breakers.
As specially a couple of big ones say 100Amps for the panel and battery disconnects.

.-.-.

[phonetic]

If wanting to use 12 volt system, the Xantrex Prosine 1800watt inverters  are used a lot in motorhomes & caravans, friends of ours have a 20 x 10foot shed with 2x200amp hour batteries, 4x190 watt panels & Prosine 1800 inverter..seems to work ok, can drive a microwave and toaster etc.
As suggested the Powerstar W7 inverters are CRAP!

[zoneblue]

Couple of things ive learned.

1. Stay away from cheap inverters. You want to sleep at night right?

2. Stay away from cheap breakers.  You want your loved ones  to wake up in the morning.

3. 12V at 3KW, thats just silly. If you have 12v gear thats an even better reason to use 24V. A 12 batt is gona range from 12v to 16v. 24v to 12v dc converters are so cheap and efficient, and you get exactly 13.8, or 12 if thats your desire, all the time. And freeing yourself from this 12v limitation means no more asking: it is 12volts  when you buy something. Adjustable converters you can run anything. Doubing the voltage means halving the current and quaddupling the power loss in cables. Better choice of inverters at 24v.

Btw who was it you found freighted down here reasonably? If you think 800 was bad for aus prices here in nz ours was 1100 and that was the lite!

[Vic]

Hi again,

One complicating factor in using DC/DC Converters CAN be that some are poorly EMI/RFI suppressed (if at all).

The quality of converters may have improved since I looked at them,  however.  Ken is a Ham Radio guy,  and switchers fairly often cause NOISE.

On the other side of the 12 V argument,  is what has already been stated -- direct battery voltage varies far too much for many devices,  not the least of which are 12 V HF Transceivers.  Have heard from some who were using "12 V" LED lights that were toasted by cool batteries,  etc.  Hammie transmitters often will not make nearly full output power directly from a fully charged 12 V battery which is not being charged at the time,  and quite often the transmit distortion increases strikingly even at 12.5 V DC input.  Believe we have said this before,  here.

Anyway,  here,  we have NO direct DC loads other than Inverters,  and anywhere  DC voltage is needed,  it is made from 120/240 VAC.

And,  Ken,  regarding the "New Post" indication,  here,  it seems to be often delayed by hours from when the post was made.

73  GL,  Vic

[Westbranch]

the other option is to have a small 12v battery that is kept charged by a ,say Morning star PWM, CC off the 24 or 48V battery...

[classicaussie]

Hi ken
Where are you  & where r u shopping in aus?
Wouldve thought local price would still beat import +shipping+ duty etc.

I got mine at a reasonable rate mayb i can get annother

Why dont you go 24v & make up a linear 12v supply off that rather than switching  for the noise factor. I assume a hammy could manage that.
Drop me a msg if you like to discuss how far youve got.

In victoria here

Cheers
Mark

[vk4akp]

Hi, Wow. So many posts recently all of a sudden. I'm starting to like this forum.

OK. I got a very good deal. I've had my Midnite Classic 150 sitting here for some time now still in it's box.
So things might have changed a bit since I purchased.
However all up including freight delivered to my door - AU$625.
To get this price I had to get them to use normal USPS postage though.
Most places will want to use very expensive freight companies.
However I have always found USPS to provide a perfect service.

I can see I'll have to put some more thought into things.
I would have thought that most 12VDC devices would tolerate a 12-16VDC range.?
However I can see the advantage of running a higher battery voltage and then converting down to get a good fixed exact 13.8VDC.
This does however make me wonder about the costs and reliability of 24 - 12VDC converters. As specially when we are talking high current for many items. HF Radio can draw 25Amps each for example on transmit.

I do currently have 2x 12VDC Panasonic Lead Acid deep cycle batteries. So I could run them in series to get the 24VDC.

However when I finally go to NiFe cells it would mean having to buy twice as many batteries.

Ideally way down the track a 48VDC battery back would be the go I feel for the heavier load stuff like big inverters etc.
But that's way off due to the costs involved.

Xantrex Prosine 12VDC 1800W model looks interesting in the mean time.
.-.-. 

[Halfcrazy]

Be careful of High battery voltage on the HF radio. Most of the ones I have seen have a 15v Zener across there leads that will short out at 15v dc. I would prefer to go 24v and use a dc to dc converter for the radios

Ryan

[classicaussie]

Yep that was a very good price all right.

Last time i checked my radio gear didnt like more than 15v

Good luck