15000W LF, 48volt to 240 volt, what wattage?

Having just had a davidpoz YT clip pop up <foilhat>yeah, sure, google doesn't follow you around at all, it's entirely co-incidental that it threw that up after I did some searches on the topic in the larger internet .... </foilhat>, and I wonder if he used an autotransformer across the solark's 240V output would he get a better experience than coming-a-gutsa when his wife exceeds the 120v rating of the unit.  He'd still need to pay attention to load distribution of course but it would be more forgiving.

An autotransformer would solve the load distribution issue, but it won't help surge loading...

But after shelling out $8k on a unit that at a glance deceptively appears as a 12kw unit ("for that much money it'd BETTER be 12kw")...adding another couple hundred for a transformer seems to add insult to injury.

For that price, we could MAYBE make a Genetry Solar 12kw inverter in the U.S.A.  MAYBE...not sure.  But if stacked against a GS 12kw manufactured in China (and priced accordingly), I betcha nobody would buy the U.S. one--making it a complete loss to try in the first place.

Oh, but I digress 😉

An autotransformer would solve the load distribution issue, but it won't help surge loading.

Do not use  with a Powerjack  inverter .  Last year I try one time until   the  surge of the heat pump  exceed  the 5000 watt of the autotransformer and  the  back EMF blow up all the FETs  instantly .  It  was a bad idea  to improve a Powerjack  and will never try that again .   

Ok, I have kind of made my mind up what I'm doing now.

The UPower inverter if it is 3kw should be ok for running my (just under 2kw) washing machine & dishwasher one at a time.

<img class="ipsImage ipsImage_thumbnailed" data-fileid="982" data-ratio="42.56" width="679" alt="48volt-inverter.jpg.700525f5b8c58e0f7399c490cfdb9873.jpg" data-src="/monthly_2021_12/48volt-inverter.jpg.700525f5b8c58e0f7399c490cfdb9873.jpg" src="/applications/core/interface/js/spacer.png" />

So I will have two inverters one LF and the other HF. I'll run them on two separate circuits, HF for the house, and LF for the kitchen. I'll charge the batteries on a separate mains charger, run via an automatic transfer switch.

<img class="ipsImage ipsImage_thumbnailed" data-fileid="981" data-ratio="121.86" width="279" alt="automatic-transfer-switch.jpg.49746932ae4de7ae55c986d4c40241cc.jpg" data-src="/monthly_2021_12/automatic-transfer-switch.jpg.49746932ae4de7ae55c986d4c40241cc.jpg" src="/applications/core/interface/js/spacer.png" /> 

When the batteries get low the mains power cuts in, powering the kitchen and charging the batteries.

The idea is to switch the inverter on only when I do some washing, or the dishes. 

My other thought is to sell this u-power inverter back on ebay and get a 6kw Power star, as from what I have read over the internet they are all a load of **** ; but the power star is at least reliable, and they now have their new lifepo4 charging system, which kind of future proofs it.  

<img class="ipsImage ipsImage_thumbnailed" data-fileid="983" data-ratio="47.85" width="606" alt="6kW-power-star.jpg.3c3acec6eb5f93efbcf7786d0eef6cd3.jpg" data-src="/monthly_2021_12/6kW-power-star.jpg.3c3acec6eb5f93efbcf7786d0eef6cd3.jpg" src="/applications/core/interface/js/spacer.png" />

Thank you all for your input

Oh, before I go, am I correct in thinking that only one charger can be used? If so how does it all cope with a charge controller and a mains charger?

Can you recommend a 48volt charger.  

Cheers.

36 minutes ago, Bear said:

and get a 6kw Power star,

Might wanna research that a tad more carefully......

PowerStar W7-based inverters are notorious for extremely high no-load current. 

All (cheaper) Chinese LF inverters come from the same exact basic design.  That includes PowerStar and Power Jack.  Plus Solinba, Aims, Sigineer, etc., etc., the list goes on and on.

Am guessing you're based in the UK?

2 hours ago, Sid Genetry Solar said:

extremely high no-load current

Self consumes 100 to 150watts? But what are my options, use an unreliable 3kw that over heats? I'd be waiting for it to permanently die.

I have a 3kw Power star but I didn't want to use it as it's only 24volts; but thinking about it, maybe the self consume will be less than it's bigger brother? Just a thought 🙂 

Yes, I'm from Devon in England.

For running loads like a washing machine or dishwasher, I think 24V or higher input would be best. The DC current at 12V would be very high with a 2kW+ load.

As others on here have said, it can be pot luck what you get when buying a uPower device. However I am currently using an '8kW' 24-230v uPower unit bought about a year ago and have had no issues with it yet powering various household loads simultaneously up to about 3.5kW.

With no loads attached it draws 0.9A from the 24v batteries, i.e about 25w if the batteries are fully charged (about 25.5v and a little more when charging (up to the 29.4 volt limit set on my charge controller).

This was the one I bought. It was £50 less a year ago.  https://www.ebay.co.uk/itm/373439121334 .

You may see some photos of the internals in my other posts. Based on the transformer type (ASL3) I wouldn't expect this unit to sustain more than 3.5kW continuous for more than 30 mins.

I also bought a secondhand 12v 2000w 'Powerstar LW' for travelling, where I don't want to carry a huge bank of batteries in the car and only need occasional mains power. However that unit draws a disturbing 3.5A at idle for such a small unit - i.e 3.5A x 12.8v = 45w for a fully charged 12v battery. This is partly because they use an old-fashioned square transformer rather than a toriodal one like PJ/Upower do. Generally, the larger the transformer of any particular design, the idle current is proportionately higher. Therefore I would expect a 6K to use 3x that which aligns roughly what Sid suggested.

Also the powerstar units are over-stated just as much as the upower/PJ ones are. Using a scope I have observed transformer saturation at less than half the rated power on both the upower and powerstar units.

Remember all these units are specified in 'Chinese Watts' which is an arbitrary value typically between 2 and 4 times the 'Real Watts'.

I also bought an old secondhand Victron 24v 3kW unit last year. This did what it said on the tin in terms of 'Real Watts' and idle consumption was slightly lower than the uPower, but it died from some impossible to trace control board fault after just a few weeks. Being quite old Victron were not able to repair or supply spares. These units are extremely expensive new.

As we can't buy GS inverters (which are undoubtedly the best value for money and meet their specified ratings) in the UK, the best compromise I have found so far is the PJ/Upower units. Just buy one that is rated at least 2x more than the highest load you intend to run..

It was the high amps that led me to the 48volt U_Power, and putting away the 24volt 3kw Power star.

I traveled 200 miles to get the power star, which was £500 new, £300 unused second hand, but I forgot the petrol, £80. And now don't even use it 🙂

Thank you for the ebay link, I bought mine £600 from the same seller (David).

https://www.ebay.co.uk/itm/373439123711?hash=item56f2b4d0ff:g:6KwAAOSwnidgDmtC

I have a feeling that our two inverters are the same although mine is 48volt. The fuse is a 25amp in mine (25x240=6000kw), what have you got in yours? I bet it's the same.

3.5kw is what you get, that's better than the 3kw that I suspected, but still not the 4.5kw that I measured with every kitchen appliance on. I know, put one on at a time, but mistakes are made. So, not having used an inverter before, what happens when we ask too much from them? Over heat and turn off?

38 minutes ago, Bear said:

It was the high amps that led me to the 48volt U_Power, and putting away the 24volt 3kw Power star.

I traveled 200 miles to get the power star, which was £500 new, £300 unused second hand, but I forgot the petrol, £80. And now don't even use it 🙂

Thank you for the ebay link, I bought mine £600 from the same seller (David).

https://www.ebay.co.uk/itm/373439123711?hash=item56f2b4d0ff:g:6KwAAOSwnidgDmtC

 

I have a feeling that our two inverters are the same although mine is 48volt. The fuse is a 25amp in mine (25x240=6000kw), what have you got in yours? I bet it's the same.

3.5kw is what you get, that's better than the 3kw that I suspected, but still not the 4.5kw that I measured with every kitchen appliance on. I know, put one on at a time, but mistakes are made. So, not having used an inverter before, what happens when we ask too much from them? Over heat and turn off?

 

 

Yes looks like you got from same seller as me - he also called himself David. Out of interest, what transformer is in yours? It usually says on a white label wrapped around one of the AC output wires from the tranny to the control board.

In my experience, the mainboards and control boards in these PJ/Upower units are fairly indestructible as long as you don't use the charging function, nor have one of the batch with dodgy capacitors (black rather than brown) from a year or two ago. Sid has stated in other posts that bad timing of changeover from charge to inverter mode and vice-versa by the crap firmware in the MCU can result in the FETs receiving input from the grid via the transformer whilst simultaneously being driven by the control board in inverter mode for a fraction of a second which results in the FETs being blown up.

The main limiting factor of these units as inverters appears to be an undersized transformer exacerbated by an incorrect winding ratio.

As you approach the saturation threshold of the transformer (usually less than half of the chinese rating on the tin) the sine wave will appear to have 'flat tops' when viewed on a scope. Beyond this the transformer starts to become warm and at about 40C the cooling fan will come on and prevent it getting any hotter. I've never tried loading mine above 4kW (50% of it's chinese rating) but I would imagine if you go much beyond this the transformer will get very hot despite the best efforts of the cooling fan. When the transformer temperature reaches 70C (measured via a sensor glued to the tranny) the control board _should_ shut down the unit (I know this from experience this summer when the cooling fan failed to operate due to a loose connection - my own fault after modifying the unit).

However not everyone has been so lucky and some have not shut down when they were supposed to and released the magic smoke.

I did actually wind my own transformer which is capable of 4kW continuous without barely getting warm or having any deformation of the sine wave - you should be able to see it sitting on the bench next to my upower inverter on my post 'been making improvements to a upower inverter'. As you can see it is at least 50% larger mass than the one inside the unit. I have still not got around to fully building this unit - which I bought another set of PJ boards from David to build.

Yes looks like you got from same seller as me - he also called himself David.

David  sell on ebay  in the  USA  also  and  I am sure he work for PJ in China .  Helen  from PJ  also sell on ebay  .  I  buy  spare parts  by ebay  messages  to both  .    I   replace the rev 10.3  control board  with the new rev 11.1  board and now the  PJ  15kw  only  run  continuous  1/4  adv  power  at  4000 watt  .   The  rev 11.1  board now have a hard time  starting the 4 ton heat pump .    It  shut down the 15kw  before the FETs  blow up  with  red light alarm ON  very loud  and  always save the FETs .  I  do not use the  15kw  to run the 4 ton heat pump   now with the 11.1 control board  .  Thank you for the information from the UK .  

If the white goods are all modern types that use motors run via electronics rather than mains direct you may well find you can run them successfully off a decent high frequency inverter, Bear.  If you like, post the make and model of each and I will try a google search about them.

I live outside the USA too so a GS inverter is more or less not going to happen for me leaving me with a choice of crappy Chinese LF, crappy Chinese HF - but an intact wallet - or a really good but quite expensive Euro / US design such as Victron etc and a wallet with the clasp torn off.  TBH when (not if!) my current Chinese inverter goes bang I probably will end up with Victron.

Some new photos.

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1 hour ago, dickson said:

I   replace the rev 10.3  control board  with the new rev 11.1  board and now the  PJ  15kw  only  run  continuous  1/4  adv  power  at  4000 watt  .   The  rev 11.1  board now have a hard time

So is rev 11.1 a step forward or back?

So it works well at 4kw for some time?

I did look on ebay at an auction for 4 big yellow Sonny boy inverters, each 5kw continuous but I think they went for £3500 and about 200+ miles away. What really stopped me was Sonny boy do not answer any emails. Totally unhelpful.

Funny that grid tie inverters have moved away from transformers, to transistors.