Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: clockmanFR on August 10, 2013, 08:58:41 AM



Title: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: clockmanFR on August 10, 2013, 08:58:41 AM
Presently at 48v with 1300ah batteries, (about 65Kwh).

Its sending the juice at 48v a couple of 100 meters so I am for ever installing very big cables to reduce cable losses.

My trackers are all sending max DC back to the MPPT controllers at 120vDc & 150vDc, so voltage drop is less.

Pros.
Could use a 120v Dc system to run most things directly around the house with out using an inverter.

Cons.
Internal resistance of batteries, is this a real problem?
Wiring at the power house will all need to be shielded like if Household mains supply, extra work.
Not many Inverters working at 120vDc in and 240vAc out. Name and model of Inverters?
Charging the batteries ?. need some controllers that will charge at 120vDc? or other solutions.

I like the principal of 120vDc but converting from 48vDc system?

If I was starting from scratch then 120vDc would be the way forward, but what about the appropriate equipment.

Biff runs a 120vDc system so I would be interested to see what he recommends.
 



Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 09:50:56 AM
Good morning Clockman,
                           I am glad to hear you are considering changing over to 120vdc.On the question of inverters,The chinese 120v x 2kw inverter are still available and is not that expensive.There are three different types of 120vdc UPS,s available,ranging from 5.2kw to 2.7kw .They are not that expensive in fact they would be cheaper than the 48vdc version except for the Symmetra rm which I blether on about now and then.
   Then the controllers (all chinese) are relatively inexpensive compared to all the other big names I have heard discussed on Navitron.In all the times I have been using the digital chinese controllers,I have yet to see one of them pack up,so they are good.
    Charging the batts would have been my biggest concern and in the 6 years + that my system has been performing I have never once charged my batteries from a dedicated power source.I have depended entirely on the wind and solar and my reserve 48 system and them my final 800ah x 12 volt system which is very seldom used.I toyed with the idea of setting up an engine to power a 2kw wind turbine lump and using that to charge the batts.
  I have 2 x 2kw dump load immersions fitted to two tanks in our house but lately, because it has been so hot and Diese and Nat sleep by the front door in the hall,I have redirected all the dump load to our big D/H/W/C upstairs and watched the voltage creep up past the normal 140max .Remembering what Rogerico had said about the internal resistance of the batteries,I let it go the whole day in very bright sunshine.We got our tank heated to the max with the recirculating pump working away yet the voltage never passed 146vdc.I have of course got all my eggs in one basket here whereas normally there would be a dump load of 4kw or a second dump load to take the heat should one of the immersions fail but as an experiment,it was rather successfull.The downside is that you need a big battery bank yet you can fill it quicker and grab more energy while the going is good(compared to 48v of the same weight or ahs)Then of course the wiring is much less of a problem and the high voltage travels much better with the lower amps,I think my max amps would be around 20 amps approx.! 120 vdc works well enough on elictric fires and immersions but you would have to find out about anything else.I used to blether on about only having a diesel bill of 100 ltrs but this past years the diesel cans have stayed full and the generator has just lay there unused and overgrown.I think that this is the way that one should judge the success of any off-grid system.
                                                                       Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 10:06:18 AM
In the early days when I set up the first bank,I was well aware of how dodgy 120vdc was under charge and it can arc so one has to be very carefull and just take more precautions than one would take with 220ac to be on the safe side.When I installed our forklift bank of 60 cells,i kept a further 10 x 100ah bank sitting ready in case I need to work on the forklift bank.Before working on the forklift bank,I would press a lever that connected the 100ah bank alongside the forklift bank and then pull the other lever which disconnected the forklift so that no charge would be going into the forklifts while I was in the area.This is about preventing a spark from igniting the gas so you would get that of any forklift bank maybe more so in 48vdc.
                                                                    Biff
                                   


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: marcus on August 10, 2013, 11:03:25 AM
Good call CM!

My tiny 24v bank is starting to show signs of age and I need something bigger anyway, but was wondering whether to go 'high' voltage or not.

the big 'cons' for me are:
the cost of a new 120v battery - the smallest Ah I've seen in traction batteries makes for a very big (for me) 120v battery.
my existing solar panels are only in matched sets for up to 48v  :(.


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 11:24:45 AM
Hi Marcus,
           You need to check your vmps and see if they can be configured to any above 120volts and below 150 volts.
        I have a pair of panels with a vmp of 66v going into a 48bank successfully for the past 5years.really good job,these same one can be let loose on the forklift bank without the controller and they drop off about 58.9 volts.
   So you dont have to be absolutly spot on with the figures,however if you aim too low your batts will suffer,slightly high and your controller will redirect it to your water heaters.
  I am no expert,I am just going by what I see here in the ground.I have two 120volt arrays,a 48v array and a 12v array.The 24 volt one has been dismantled because I no longer need it.Its all brilliant stuff
                                                              Biff
               


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: w0067814 on August 10, 2013, 01:42:04 PM
Remembering what Rogerico had said about the internal resistance of the batteries,I let it go the whole day in very bright sunshine.
                                                                       Biff

Biff,
Can you link to this for those of us with poor memories?

Thanks,
-Tim


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 03:16:25 PM
Seems like an awful lot of work to save on a few quids (or francs) worth of cable CM  ??? The sanity of switching 120v DC appliances in the house also seems questionable to me and I'm not particularly 'elfin safety' minded. Fine if you're starting from scratch but to convert a perfectly good 48v system after honing it for a couple of years  ??? Surely you must have better things to do  ;D

Without a doubt if you don't have to ever charge your batteries quickly with an external charger and are happy with UPS's or Chinese inverters then 120v is the way to go. However if you've spent all that time and effort developing what seems to be a reliable 48v system with dump loads and UFH I question your sanity  :hysteria I'd be inclined to make some use of 'AC coupling' if you're worried about cable runs.

Good luck, Paul


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: Tinbum on August 10, 2013, 04:22:53 PM
I'm sure it won't be cheap but how about the new TS-MPPT-600V from Morningstar when its released. I'd be interested in it but my battery bank is 48v and its only rated for 60A. (I don't quite understand why they rate it on current and not power).


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 04:36:12 PM
I'm sure it won't be cheap but how about the new TS-MPPT-600V from Morningstar when its released. I'd be interested in it but my battery bank is 48v and its only rated for 60A. (I don't quite understand why they rate it on current and not power).

I looked at that with interest, it is available now in the US but I think with a similar price tag to Xantrex's version, so around $1200 http://www.altestore.com/store/Charge-Controllers/Solar-Charge-Controllers/MPPT-Solar-Charge-Controllers/Xantrex-MPPT-Solar-Charge-Contollers/Xantrex-XW-MPPT-80A-Solar-Charge-Controller-up-to-600V-DC-input/p8992/  :o


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 04:47:40 PM
(I don't quite understand why they rate it on current and not power).

Because it's the current that creates the heat (in the circuit) and not the power  ???

Just guessing  ;D


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: Tinbum on August 10, 2013, 05:07:59 PM
Looking at the Morningstar data sheet, the power when into 120v battery bank is yet to be decided. Your link looks interesting but it only does up to 48v battery bank but does do 80A. Very expensive!!

With all these things their is so much flexibility.  I use a Trace inverter at the moment but I don't like to see the Morningstar MPPT on absorption when I could be using the wasted DC solar power for heating either the DHW, the buffer tank or the kids pool. That will finally change when I finally get the sunny backups installed, but then the batteries will be some distance away from the 'DC' PV panels.


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 05:17:07 PM
Right enough Tinbum,

http://www.morningstarcorp.com/en/support/library/TSMPPT600V-ds-Eng.pdf I'd forgot about that bit Supports nominal 48 or 120 Vdc batteries


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 06:27:26 PM
Hello again,
           I would agree,if your are happy with your 48volt system then thats fine but you can only do so much with a 48volt dump load.
     On the other hand,the 120vdc x 2kw chinese controllers come fitted with massive big resistors to act as dump loads,so all one has to do is bypass the big green resistors and direct it to the immersions.no call for mppt or anything like it.Add another array,great,,add another controller and bypass the resistors again in route to the second immersion,ect.There is no magic or board costing 500.00 to replace.The money involved in these controllers and inverters is much less expensive and a lot easier to understand and they are extremely reliable.
    mppt controllers are kind of risky.Thats the conclusion that I have come to.Once you fit the buxxers you cannot diddle about with them or you will upset them and bad things happen.
                                      Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 06:36:16 PM
Hi Tinbum,
           If you go into the solar pv threads and look for "Solar pv direct to the battery,,temp"  by Rithym you will find Rogerico,s contribution on the subject,I have found the same thing happen in 48volt and 120volt. Its intresting.
                                                                                   Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 06:39:41 PM

    mppt controllers are kind of risky
                                     

Can't argue with that Biff  8) but there's nothing to stop you dumping AC with a decent inverter, it's what I do (have been for eight years) and you don't have the issues of switching DC. You cannot easily use a thermostat to control DC immersions like you can with AC. Horses for courses really.


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 06:56:16 PM
Hi Paul,
      You need that fancy inverter with the ac out and they dont come cheap.EricW had a little board that clockman got going.I honestly would not mind something like that If it was not too complicated.What I have at the moment is pretty good but I think a relay on the AC side would help things as well,I actually have another ac immersion on the water heater in the hall and maybe I could bring that into action when I fit my third and final 120v array. another 1140watt. I have been reluctant to install it because the results from the present setup more than meet our demands on sunny days and you can only heat so much water but a dump on the ac side means we could trigger an electric fire or a storage heater or underfloor heating like clockman.
                                                                                      Biff
                                                                                                           


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 07:04:38 PM
You could always just turn the array off Biff, that's what I do with my hydro turbines if there's too much power. No point cooking the dump loads or running hot water into the septic tank once all your needs are satisfied.

Cheers, Paul


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 07:51:07 PM
Good point Paul,
                Thats what I had in mind for the mobile array,I would have to have a heavy switch between the incoming live from the array and the live connector on the controller.I wonder is there some kind of soft landing switch that would be suitable for reconnecting when the sun is bright.Something like the soft start up you get now on some grinders.
         I suspect that if I was foolish enough to try and connect in bright sunlight i might blow the blocking diodes on the panels.I can connect 56 volts and lower by pushing a fuse home but 120 volt (180v before going into the controller)is just too wicked.I will just have to find a way round it but switching off the array is the simplest and best idea like you say.
                                                              Biff
                   


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 08:07:04 PM
You should have a DC breaker capable of breaking at full load anyway Biff and it's the sudden amperage that wrecks the contacts not the voltage.

Cheers, Paul


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 08:31:12 PM
The only emergency disconnect I have are anderson connectors,
                               Fine to disconnect in sunlight but not to connect.I also use a large blue tarp to cover the arrays if I need to disconnect or connect .I have a healthy respect for these things.Everything at 48v and below is fused but the 120 volt depends on the controllers,which come already fused internally and easy worked at.
  Have you any idea of the type of breaker that would suit,?
                                                                     Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 10, 2013, 08:56:15 PM
I use these http://compare.ebay.co.uk/like/130873544226?var=lv&var=sbar&_lwgsi=y&cbt=y&lpid=66&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=66 Biff up to 25amps, which at 120v is 3kw

Cheers, Paul


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 09:08:53 PM
Thank you for that link Paul,
                      Those will do just nicely. :crossed.
                                      Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: clockmanFR on August 10, 2013, 09:35:07 PM
Paul, I am happy with my system at 48vDc.

However, I am always being asked what battery system voltage is best,? and if I started from scratch now knowing what I now know, what would I use?

At present I reply that there is sufficient charging/controllers/inverters at 48vDc. But to be real efficient then 120vDc system would be advantageous.

But honestly, Charging/controllers & Inverters seem pretty thin on the ground at 120vDc.

Biffs Symentry Inverter sounds okay, any others you know off Biff? 


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 09:43:47 PM
Yes C/M,
           There are two other types but I have only one other which is 2,700watt x 120v.I will post the name and model tomorrow.These are not that expensive,work out around 150.00 a time.I keep one or two in case something goes wrong(you never know).The symmetra is more or less bullit proof and gives lovely clean power.
       Paul,
            I bought 5 of those fused breakers and paid just under 11 euros each,now you might think I got stung there but I could not find anything like that before and it is money well spent.So thanks again,
                                                              Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: billi on August 10, 2013, 09:51:18 PM
My priority  , would be simplicity  nowadays

The base  is the Inverter and a tough battery  ,  and i am very happy with those two components  i have (ok my charge controllers are great as well , but i would reduce charge controller costs today )
PV i can pick up somewhere  today for 300-500 per kw  and our 4 kw PV runs our house easy for 9 month a year , so another  4 kw  would do the 12 month trick and lots of hot water and some heating and perhaps electic driving later ..........

Keep on rocking.... oh i mean  focusing on the production side.... in a free world (ok, not so free  ::))


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 10, 2013, 10:26:36 PM
I would agree 100% Billi,
                    Simple controllers,simple inverters and a layout that can be easily understood and remembered ( ;D)
                                                                  Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 11, 2013, 07:40:16 AM
Paul, I am happy with my system at 48vDc.

However, I am always being asked what battery system voltage is best,?

The answer should then be, 'it depends what you want from it'. If you want a reliable 'off grid' system that can be left in the hands of numpties then it has to be a 'proper off grid inverter' that will make all the decisions for you. One that will start a generator to 'load share' or when your batteries are low, and most importantly charge them quickly and correctly. If on the other hand you're enthusiastic, capable, on grid or don't mind watching meters or being careful about what you switch on then go 120v. It's certainly cheaper and more efficient when it comes to cabling and second hand UPS systems but you won't have the flexibility of the many dedicated controllers the use of 'AC coupling' or be able to charge your bank quickly.

Cheers, Paul


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: Tinbum on August 11, 2013, 11:53:55 AM
Hi Tinbum,
           If you go into the solar pv threads and look for "Solar pv direct to the battery,,temp"  by Rithym you will find Rogerico,s contribution on the subject,I have found the same thing happen in 48volt and 120volt. Its intresting.
                                                                                   Biff

Yes I'd seen that previously, but good reminder. Personally I think the probable reason for the failure of the Morningstar will be due to overvoltage. 4 panels in series at a VOC of 33v is too close to the max of 150v that the controller can handle. (I did it with similar panels, Suntech 250S-20/Wd, but the controller survived so now I have 4 strings of 3 panels).


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: clivejo on August 11, 2013, 11:55:40 AM
DC in higher voltages is a dangerous beast.  It seems to develop a "momentum" in cables and can jump/arc switch gear.  I remember my dad telling all kinds of weird accidents which happened on the 120v DC Lister gen set.   whistle


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: Tinbum on August 11, 2013, 12:05:34 PM
It made me laugh when my first lot of PV was installed by a so called PV installation company- Never again but that's another story.
They said they would have to turn the power off (remove DNO Fuse and break all the seals!!!) to connect it up. I asked why. They said for safety.
I then saw them working on the live DC cables, approx 600v that's so much more dangerous!! I guess ignorance is bliss.


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: camillitech on August 11, 2013, 06:16:14 PM
Somewhere on our new ship is an inverter that converts 400vdc into 230vac for the transitional lighting.

(http://lifeattheendoftheroad.files.wordpress.com/2013/08/026_thumb4.jpg?w=716&h=538)

Need to find that tomorrow and see what it's like http://lifeattheendoftheroad.wordpress.com/2013/08/10/it-is-very-big/


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: clockmanFR on August 12, 2013, 08:08:49 AM
Tinbum, No doubt about it, Morningstar MPPT's SHOULD say that the working voltage is 120vDc input and certainly not 150vdc max.
And even at 120vDc without the battery temp sensor connected all hell breaks loose, and the Morningstar say's OVERVOLTAGE, Fault, Batt temp sence, Auto disconnect, Help!  sh*tfan:.

Talking of loose, Er Paul what happens if you have some rough weather and the boat starts doing some slamming, does those nice 100ah 6v Yuasa's start jumping overboard!. Or do they pound that glassfibre enclosure to bits?

Its been a long time since skippering anything, but that lot on deck? and not secure, look like a accident waiting to happen. Or maybe its for the captains biccy warmer thingy.  :hysteria


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: stephendv on August 12, 2013, 08:11:14 AM
But honestly, Charging/controllers & Inverters seem pretty thin on the ground at 120vDc.

Biffs Symentry Inverter sounds okay, any others you know off Biff? 

There is this: http://www.ingeteam.com/en-us/energy/photovoltaic-energy/p15_24_44/ingecon-ems-home.aspx  which supports up to 250Vdc for some models.  Supports full AC coupling with their own brand PV and wind inverters.  It's a quality brand that you mostly see used in large PV farms; comes with 5 years warranty standard + 25 year optional extra.


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 12, 2013, 09:19:01 AM
I did not consider 2kw x 120vdc controllers to be a problem.
                                  If I went above 2kw I just added another Chinese 2kw hybrid controller to the system.I know that mine says that the solar input had a max of 600watt but because I did not have any wind turbine input I guessed that I could route through each controller and load each controller way above 600watt to its max and not worry about it.If I had any doubts,then I just connected any extra controller to the battery and connected the extra solar array output direct to the battery,bypassed the big 2kw resistors and power another immersion with its dump excess.
  It was the simplist way possible.It also meant that I did not have my eggs all in one basket.
 I will get the details of the other 120v UPS shortly.The Symmetra really is the best machine you could lay your hands on.It might want 200watts for itself but the quality of the electricity is fantastic,You really do see the difference on the big screens,etc.+ the fact that no matter wat happens the Symmetra is built to keep running regardless.
                                        Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 12, 2013, 11:15:02 AM
 Hi C/M,
MY other type UPS is called Powerware,
                                         series=EO3007i
                                        model=R300 XR-INT        input 120v @30amp,Output 2.700watt in 220,230,240volt in 50/60 hertz.
    There is also a third 120volt one but I cannot for the life of me remember the name.
     ON top of all that there is a French built one with a very french sounding name,Claud,,,,,. It is very old fashioned looking and I guess it would be The low frequency type the same idea as my Chinese Inverters.Symmetra and Powerware are modern Double conversion jobs,so a lot lighter and faster than the old heavyweight transformer types but in saying that,That French built one is supposed to be the Rolls Royce of them,The insides are certainly well put together(very impressive).It is only when you start looking for these things that you realise the hard work and definate heartbreak the designers and builders of these wonderfull machines must have suffered."Many are called but few are chosen"
                                                                                   Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: billt on August 12, 2013, 01:54:08 PM
Claude Lyons of Waltham Cross, Herts. maybe?


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: biff on August 12, 2013, 03:58:58 PM
Actually billt,
                Thats the very man  facepalm but I thought he was french and it been a few years since I did those enquiries.
                                                                             Biff


Title: Re: Upgrading from 48vDc to 120vDc, Pro's and Con's?
Post by: clockmanFR on August 13, 2013, 07:56:05 AM
Thanks Biff will add them to my 120vDc list.