Author Topic: powerjack charger overvoltage  (Read 7060 times)

0 Members and 1 Guest are viewing this topic.

phri

  • Newbie
  • *
  • Posts: 8
  • Country: au
powerjack charger overvoltage
« on: February 09, 2016, 10:51:20 PM »
I recently got a solar system with a 5 kW inverter installed. The solar inverter is sometimes pushing mains up to above 250 V. My 10,000W powerjack stops then charging the batteries and this seems related to the high voltage, as turning the solar off starts the charging again. This is a bummer as I intend to timeshift my usage with this configuration.

What can I do to make the powerjack accept the grid with pv inverter? (SMA 5000 TL)


joestue

  • Hero Member
  • *****
  • Posts: 1759
  • Country: 00
Re: powerjack charger overvoltage
« Reply #1 on: February 10, 2016, 12:44:04 AM »
Find a 12-24v (preferably toroidal, as these are much higher efficiency) transformer and buck the line voltage.
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

phri

  • Newbie
  • *
  • Posts: 8
  • Country: au
Re: powerjack charger overvoltage
« Reply #2 on: February 10, 2016, 07:58:48 AM »
I don't see how I can solve a slight overvoltage with a transformer. I need to lift the high line voltage protection of the powerjack by maybe 10-15 Volt but don't know how

dnix71

  • SuperHero Member
  • ******
  • Posts: 2513
Re: powerjack charger overvoltage
« Reply #3 on: February 10, 2016, 08:32:14 PM »
I wouldn't do that. I had inverters that don't play well with the solar MPPT. If the voltage got too high, the inverters shut down to protect themselves. I suspect your solar inverter is pushing too high.

253v is the standard upper limit for a nominal 240vac line. If you have measured correctly then your inverter has not violated standards. Your (Chinese) Powerjack inverter is probably expecting 230vac (the European standard). 230v is close enough to operate a 240 appliance, so the inverter's output is universal. The usual lower limit for 240v or 230v is 216v and the upper limit for both is 253v.

https://en.wikipedia.org/wiki/Mains_electricity  Skip down to the discussion on voltage by country and note the changes. It's a mess for anyone wanting to make an inverter. Australia made changes in 2000.

If your solar inverter is really pushing 250v+ it will shorten the life of some of your appliances or cause them to use extra current when operating.

phri

  • Newbie
  • *
  • Posts: 8
  • Country: au
Re: powerjack charger overvoltage
« Reply #4 on: February 11, 2016, 12:08:13 AM »
I start measuring: output pv 5kW voltage 253-257V, with one string (2.5kW) it's 247V, cable?? Solar inverter and PJ are both in my shed on the same subboard. This is wired up with 30meter 4mm to main switchboard, seems undersized now. I can't understand how that past the inspection 14 days ago. Might be a case to go back to installer of solar system.

joestue

  • Hero Member
  • *****
  • Posts: 1759
  • Country: 00
Re: powerjack charger overvoltage
« Reply #5 on: February 11, 2016, 04:05:41 AM »
I start measuring: output pv 5kW voltage 253-257V, with one string (2.5kW) it's 247V, cable?? Solar inverter and PJ are both in my shed on the same subboard. This is wired up with 30meter 4mm to main switchboard, seems undersized now. I can't understand how that past the inspection 14 days ago. Might be a case to go back to installer of solar system.

what is the voltage at the panel upstream?
My wife says I'm not just a different colored rubik's cube, i am a rubik's knot in a cage.

mab

  • Sr. Member
  • ****
  • Posts: 428
  • Country: wales
Re: powerjack charger overvoltage
« Reply #6 on: February 11, 2016, 02:53:19 PM »
two thoughts:

1. a 10,000w powerjack as standard might struggle with 5kw continuous without a bigger transformer (see Oztules / clockmanFra Powerjack exploits) - their ratings are a bit optimistic and it may be struggling if you're pushing 5kw through the standard transformers. That's asssuming you're not using the bulk of the PV output as ac before it reaches the PJ of course.

2. can you tweak the max output volts in the SMA software settings so it backs off a bit before it upsets the PJ?

phri

  • Newbie
  • *
  • Posts: 8
  • Country: au
Re: powerjack charger overvoltage
« Reply #7 on: February 11, 2016, 06:45:20 PM »
I actually tried to use the PJ build-in charger and this shut off at too high AC voltage from the grid-tie.

Yesterday I tried it the other way, AC coupling of the SMA grid tie to the output of the PJ, works great. At least up to 2.5kW grid tie.
As the The PJ is fused at 20A I didn't want to feed all the 5kW PV in the inverter, this is easy in my configuration as I have 2 identical PV strings.

I am aware of the PJ limitations and read up on the build of Ozrole, very impressive, although seems a lot of work, and I figure that I have enough juice from a 10kW original unit. I might get a second one later and split the loads over both units.

No way I can tweak the SMA, you need a service password for that.

clockmanFRA

  • Hero Member
  • *****
  • Posts: 952
  • Country: fr
    • Renewable Energy creation
Re: powerjack charger overvoltage
« Reply #8 on: February 12, 2016, 03:38:27 AM »
Are you off Grid, or grid tied?

The PowerJack boards give sufficient criteria for the SMA to function.

The PowerJack output voltage normally climbs high when the batteries are full, as the PowerJack is just a dumb charger, ie it can not control or do any charging rates, it just belts the lot into your batteries.

What battery Bank size? If the Ah is to small you may be cooking them.

With my PJ 15kW boards, 48v, 230vac, 50HZ, at 1.7kw of PV going into my 1000ah battery bank the AC voltage goes from 230vac to 237vac in Bulk Charging mode.

I use a Midnite Classic 200 controller, Auxiliary Contacts, that I am using on 3kW of PV that DC charges the battery bank to control the AC Coupling GTI's.
The Midnite controller says 'battery full going to Float' relay operates and shuts down the SMA GTI's on a fail safe mode.

However, I do have the SMA GridGuard codes, as I have five SMA SB's all the Toroid version, some New but old stock but very cheap price. And I can alter the SMA internal shut down voltages in a sequential pattern depending on what the battery state of charge, and loads on the AC Mini Grid my OzInverter is maintaining.

I start backing off, shutting down the GTI's at 244vac.

Another option is to off load, load shedding, ie, the PowerJack gets high voltage then switch on a AC load to use up the excess, but then if you are also Grid tied ?.

I doubt that your PJ 10000 will cope with 2.5kW load for long as it will just get hotter and hotter and the PJ board will shut down. 
Its the Toroids, PJ's are normally woefully inadequate for what PJ say they can do.

Here we build are own toroid monster, get them right, get the very important cooling right. Now your talking.

My 6kw to 15kW OzInverter, and yes it will do 6kW for some time but the fans are going some, cost me a total of about $900, but then I bought most of the bits, some folk scavenge and get the cost down.

In my opinion AC Coupling is the way forward as I do not need to increase my battery Bank size, as my fine tuned SMA GTI's will come in and out on my Mini Grid when required.

I trust this helps.



 
 
Everything is possible, just give me time.

OzInverter man. Normandy France.
http://www.bryanhorology.com/renewable-energy-creation.php

3 Hugh P's 3.7m Wind T's (12 years) .. 5kW PV on 3 Trackers, (8 yrs) .. 9kW PV AC coupled to OzInverter MINI Grid, back charging AC Coupling to 48v 1300ah battery

phri

  • Newbie
  • *
  • Posts: 8
  • Country: au
Re: powerjack charger overvoltage
« Reply #9 on: February 13, 2016, 06:09:26 PM »
ClockmanFRA thanks for the detailed response, you must have a large off grid system. I have been reading for many hours on this forum, and it's a amazing resource, however some stuff is still unclear to me.

I am grid tied, but want to play with off-grid: start with time shifting: use PV energies from batteries at night. For this I want to use the PJ with AC coupling of some of the pv I have installed. This is also a learning exercise for me as I look at grid independent aquaponic/aquaculture systems.

I have a spare inverter; one of those Inspire 2.5kW (I should have bought 2 to use for a homebuild). I want to AC couple this unit to my 10kW PJ, I have a battery bank of 48v / 200Ah AGM. How much PV/GTI power can I safely AC couple to my Powerjack without cooking the batteries/damage the PJ? For the sake of sizing what % of the energy generated by PV will be available for useage at night? I reffer to losses in transitions and storage

Elegant solution with your GTI chain. I think of automatic grid-tie GTI when batteries are full, however don't fully know impact on batteries if I switch over based on charge voltage.

At this moment I don't want to modify the SMA 5kW GTI as it's a new unit, that's why I have the second GTI.

A battery installation of 1000Ah/48v must ties up many $$$$$ I would love that too, but can't justify.

My PJ can't start my 2.8kW pool heater (heatpump) as the inrush current of the compressor courses a voltage dip which makes the internal relay of the heater to fall off. So that's clear not 10kW (or 40kW). Will I have the same issue if I use an AC which have build-in inverter technology? 

PaulJ

  • Full Member
  • ***
  • Posts: 111
Re: powerjack charger overvoltage
« Reply #10 on: February 13, 2016, 09:35:38 PM »
"Will I have the same issue if I use an AC which have build-in inverter technology? "
No, they use dc motors, no huge inrush current.
I have an 8kW PJ bought as a backup in case the main (offgrid) inverter fails, runs the house including 2 aircons no problems.
Wouldn't push it past about 4kW continuous though, it does get warm.

Paul.

oztules

  • Hero Member
  • *****
  • Posts: 1477
  • Country: aq
  • Village idiot
Re: powerjack charger overvoltage
« Reply #11 on: February 14, 2016, 02:23:58 AM »
You will have no problems driving the inverter air conditioners.

............oztules
Flinders Island Australia

clockmanFRA

  • Hero Member
  • *****
  • Posts: 952
  • Country: fr
    • Renewable Energy creation
Re: powerjack charger overvoltage
« Reply #12 on: February 14, 2016, 04:52:21 AM »
How much PV/GTI power can I safely AC couple to my Powerjack without cooking the batteries/damage the PJ?

You will need to know the C10 charge rate of your AGM's, most AGM's have this written on them somewhere.

In my opinion AGM's need careful treatment, and they can not stand the abuse like FLA's, Flooded Lead Acid types.
 At only 200ah and 5kW of PV, !!!!!!!!!. In my experience, and this only my experience, others will comment further, 200ah then 2kW of PV is still to much. In my opinion, with 5kW, You definitely need AC load shedding, and a charging regime.

If it were me with such a low AH batteries, I would use the AC through a standard 48v battery charger to your batteries. I can also use a 100amp Eltek charger, (thanks Simon) as I can control what amps it gives out and the precise voltage it gives. see photo below....... And at night switch over using a big 2 pole change over switch to your PJ created grid running from your batteries.

Are you switching over from Mains Grid to the PJ created Grid or are you mixing. If you are mixing then you have done well getting the PJ to sync with the normal Grid. As 'oztules' has said, 1 in 5 times you get away with it, other wise its smoke.

For the sake of sizing what % of the energy generated by PV will be available for useage at night? I reffer to losses in transitions and storage



Others on here are better informed and will probably comment.

I have 63kw of storage but its never enough, but then my house is largish and my other buildings need power.
Yes all my batteries are AGM's and all are from Telecommunication installations after the service contract has expired. So I pay a little more than scrap price.

I sort through them and take good matching strings at a time. Life time before the lead plates short out on the interconnect internal link, only 8 mm clearance by the manufacturer, for me is a usable 8 years.

I am about to add another 2 strings 210ah, (see if Simon has any), as my oldest are struggling to hold 12.80v and in another 6 months they will fail. Just my experience after 10 years....... 

Your batteries will be your biggest investment, so they really do need looking after.

Eltek with mods.  Eltek set for a gentle 48v battery charge.  2 Pole 90 amp Change over switch.
Everything is possible, just give me time.

OzInverter man. Normandy France.
http://www.bryanhorology.com/renewable-energy-creation.php

3 Hugh P's 3.7m Wind T's (12 years) .. 5kW PV on 3 Trackers, (8 yrs) .. 9kW PV AC coupled to OzInverter MINI Grid, back charging AC Coupling to 48v 1300ah battery

Phred

  • Newbie
  • *
  • Posts: 8
  • Country: aq
Re: powerjack charger overvoltage
« Reply #13 on: March 15, 2016, 02:58:31 AM »
For this I want to use the PJ with AC coupling of some of the pv I have installed. 
The problem with this PJ needs to signal the SMA to shut down in the case the batteries being over charged. A rudimentary method be to have a battery sensor that signals a relay on the ac side of the SMA to momentarily disconnect from your mini grid. This will force the SMA  to shut down and go for a 1-2 min hiatus before reconnecting