Midnite Solar Rosie HF Inverter 27kW Surge Test

[robby]

It's kind of Amazing to see and for the OP that knows what is happening I get his excitement.
Unfortunately as a viewer it was not as satisfying. It would have been nice if something showing some actual Power or Amps was being displayed. If you get that opportunity again please show us the real time power being consumed.

 

[Hedges]

Beta -
You said,



Did you get a measurement of the AC surge delivered to the compressors and lights?
What kind of motor do they have?

Reason I ask is some types of motors can happily start a bit slower if voltage sags, while others can't.
So I'm asking if 6.8kW rated Rosie did in fact deliver 27kW, or that's just what surge would have been if powered from grid.

At least some DeWalt compressors of that style apparently have brush-type motors.
Those are far easier starting.
Customers need to see how Rosie performs with induction motors, in particular how large an induction motor deep well pump it can start.

1.6 HP Continuous, 225 PSI, 15 Gallon Workshop Compressor

www.dewalt.com

D55168_1 | ServiceNet

1

www.toolservicenet.com

Robot or human?

 

[Midnite Beta Tester]

It's kind of Amazing to see and for the OP that knows what is happening I get his excitement.
Unfortunately as a viewer it was not as satisfying. It would have been nice if something showing some actual Power or Amps was being displayed. If you get that opportunity again please show us the real time power being consumed.

The video was spur of the moment. A rare chance to get some video at the end of a day when only a couple employees were in the factory building where the show booth is stored. It was "quiet" and the Rosie had just been wired in recently. They won't just stop production "making noise" so somebody can grab a video without interruptions.

The booth is designed to be interactive. If you are at a solar show and stop in, you get to do exactly what I did. Bring your test equipment, scopes, meters etc. and they will let you take any measurements you desire. You can do the same at their factory. About a month ago I did request a scope be used to determine the surge of the four pumps. I wanted to know real numbers. The B17 in the booth was used and 15kW was the surge number, 7.4 kW running.

The booth is not really a test bed, they have other areas specifically designed for that purpose. But it's there and the opportunity the other day to play with a Rosie and spank her with all available loads, and grab a short video was something I could not pass up. As I say in the video, Midnite had not spanked a Rosie as hard as I did. 4-8 hours continuous with 6.8 kW loads? Yes, many times. Long term thermal stress testing. But to the best of my knowledge they had not yet done any big surge load tests. Rosie's head engineer, Andy, will probably freak out when he see's the video. You did what? There are no restrictions as a Beta tester, that would defeat the purpose.

The Beta program doesn't have any monetary rewards. As Tecnodave stated: The "outside view" is what the good companies want and seek out. The rewards are being part of the process. Trying to "break" stuff is fun! It's more fun when you fail to break anything. That means the engineers did it right. But bugs do show up, and feedback and suggestions are taken seriously. Getting your hands on a product before it hits the market falls under priceless fun!

Sorry, long post! Next trip up to Midnite I will plan to bring my test gear and do another video with all possible measurements observed and recorded. Discovering what Rosie's max surge capacity is, how long at specific loads etc. is on Midnites list and mine!

 

[Hedges]

There are no restrictions as a Beta tester, that would defeat the purpose.

Well, maybe no EMP testing, and no using a cheater cord to backfeed live mains?

But I still suggest measuring actual surge current and voltage wave form (which you plan).
And, try larger and larger induction motors (not brush-type as I think those air compressors are) until you find what it can't start. Starting a deep-well pump hundreds of feet away is probably the most stressing real-world test. I'm not sure how unloaded motor would compare.

 

[BMcL]

Rosie will be a nice addition if they can offer it cheaper than the Outback Radian.
I don't really understand how Rosie and Sol-Ark can make a lightweight high-surge capacity model
and the others have to use a heavy transformer to accomplish the same thing ?
I'm leaning toward the heavy low frequency design if the price is the same.

 

[Tecnodave]

Each type has their own advantages, high frequency inverters are smaller, lighter and more efficient generally but when driving hugely inductive loads such as a induction run deep well pump the start surge will stall a poorly designed high frequency inverter and what is not widely known is when a huge transformer load or a large induction load the low frequency inverter transformer can “recycle that reflected power” which is caused by the out of phase current and voltage of the unbalanced load back into the inverter main transformer and recycle that out of phase power back to the load. High frequency inverters generally use small torid transformers which cannot absorb and use that reflected power and that is wasted. So in the case of highly inductive loads the low frequency inverter has a distinct advantage and results in higher effeciency driving that highly inductive load even though overall effeciency of the low frequency inverter is less than that of a typical high frequency design.

Low frequency types excels in the machine shop environment where there are many electric motors to be powered. This is exactly where a AIMS low frequency inverter shines....even though they have a whopping 200 watt idle current they are more efficient in that environment than a modern light weight high frequency type.

I can clearly see the difference in performance between two different inverters, both low frequency types as I have two stone antique Dynamote Brutus TB 32-24 inverters as well as a MagnaSine MS4024AE. Both of these have very large low frequency transformers but the Brutus transformer is much larger than the MagnaSine even though is rated for less power, the 3200 watt Brutus never stumbles on my deep well but the 4000 watt MagnaSine has difficulty late in the season when my water level drops below -300 feet or so. Borrowed my neighbors AIMS inverter, it had no problem at all pumping that deep well. but at 200 watts idle that is a lot of power wasted doing nothing. The MagnaSine idles at 20 watts plus another 12 watts of so as the fan controller is stuck on, The Dynamote idles at 96 watts and the AIMS at 200 watts. My Exeltech XP-600 high frequency idles at 8 watts.

There are differences in the designs that make certain inverters better than others for some uses.

 

[robby]

Each type has their own advantages, high frequency inverters are smaller, lighter and more efficient generally but when driving hugely inductive loads such as a induction run deep well pump the start surge will stall a poorly designed high frequency inverter and what is not widely known is when a huge transformer load or a large induction load the low frequency inverter transformer can “recycle that reflected power” which is caused by the out of phase current and voltage of the unbalanced load back into the inverter main transformer and recycle that out of phase power back to the load. High frequency inverters generally use small torid transformers which cannot absorb and use that reflected power and that is wasted. So in the case of highly inductive loads the low frequency inverter has a distinct advantage and results in higher effeciency driving that highly inductive load even though overall effeciency of the low frequency inverter is less than that of a typical high frequency design.

Low frequency types excels in the machine shop environment where there are many electric motors to be powered. This is exactly where a AIMS low frequency inverter shines....even though they have a whopping 200 watt idle current they are more efficient in that environment than a modern light weight high frequency type.

I can clearly see the difference in performance between two different inverters, both low frequency types as I have two stone antique Dynamote Brutus TB 32-24 inverters as well as a MagnaSine MS4024AE. Both of these have very large low frequency transformers but the Brutus transformer is much larger than the MagnaSine even though is rated for less power, the 3200 watt Brutus never stumbles on my deep well but the 4000 watt MagnaSine has difficulty late in the season when my water level drops below -300 feet or so. Borrowed my neighbors AIMS inverter, it had no problem at all pumping that deep well. but at 200 watts idle that is a lot of power wasted doing nothing. The MagnaSine idles at 20 watts plus another 12 watts of so as the fan controller is stuck on, The Dynamote idles at 96 watts and the AIMS at 200 watts. My Exeltech XP-600 high frequency idles at 8 watts.

There are differences in the designs that make certain inverters better than others for some uses.

A Doctor friend of ours had a very expensive system installed at her house about 10 years ago that revolved around a 4000W MagnaSine and AGM batteries. She has a love hate relationship with the Inverter. On one hand she loves the reliability but on the other hand she says the system only puts a tiny dent in her electric bill. About a year ago she upgrade to 10 KWh of LIfePO4 batteries and said that helped but not significantly. Then 6 months ago she told me the Magnasine had died and she wants advice on buying a new Inverter. I tried to steer her towards a Sol-Ark since I knew price was not an issue, but she ended up getting back the same model of MagnaSine.
Truly a pity as she has not heavy loads like well pumps. I told her that the reason she is not seeing any savings is that nobody is home in the day and her 10KWH battery bank is being nibbled by the MagnaSines idle power.

 

[Tecnodave]

MagnaSine MS4048PAE idles at 20 watts.........AND it is a low frequency iron core transformer type....

and why did she buy another one......it lasted what ? 10 years at least without a hiccup.....

Those people who need two 12,000 watt inverters also have a refrigerator that requires a 20 amp dedicated outlet...

that is 20 amps times 120 volts.....2400 watts

mine is 24 volt DC 41 watts.....

Im all solar, I do not use appliances that were designed for a nuclear power plant....

I did a career at one of the most pro nuclear companies in the world.....i’m not really proud of that...

but you are free to do what you want.......until the earth gets so polluted that life will cease to exist due to our own making...

 

[Robin Gudgel]

MBT met Bob's and my dad probably 20 or 30 years ago? I had given my dad a Spectro Acoustics amplifier and preamp/equalizer. After it sat around a couple of years collecting dust, unbeknownst to Bob or I my dad sold the Stereo gear. MBT was the one who purchased the gear. It wasn't until a couple years ago, that we met him. It is true he comes up once in a while and does things like this for us. We have never compensated him although we should. Good beta testers are hard to find. I would like to point out that the 3K and 9K switches for the lights on the display are not additive. The lights are only 9KW total. MBT didn't know that. I seriously doubt he will be able to break the Rosie or a B17. We certainly can't anymore. We have been designing inverters since the early 1990's and have learned a thing or two. These inverters have some very special circuitry that allows huge excursions of current, but still protect the transistors from damage. One thing he doesn't show is what we built the display for. A single B17 inverter/charger module is only rated at 3000 watts. Each hot swappable inverter/ charger module is 120/240VAC. We have the 3000 watt light switch to demonstrate a single B17 module. We turn on 3000 watts of lights and then turn on all four air compressors with one flick of the switch. The air compressors are at about 80 pounds pressure, so it is a real good surge test for a 3000 watt inverter. Plugging in additional modules allow the compressors to start quicker. Both inverters have huge surge capabilities. It won't be long now until we start sending inverter beta units out. We still have things to finish though. Lots of lower risk features like external voltage sense, BTS, aux outputs, Canbus communications etc. The power stage is the hard part, so that is what we have concentrated on for the past 7 years now. We are pretty happy with the performance of both units. It has been a very long, hard and expensive project. We have an incredible engineering department. Once we think either one is ready we will be happy to send Will one of each. We want to make sure they are pretty much production ready though because Will is brutally honest and doesn't sugar coat anything. We wouldn't want it any other way.
Robin Gudgel
MidNite Solar

 

[Robin Gudgel]

The Magnasine is a fine inverter, but it doesn't do self consumption. She needs one that does that.
Robin Gudgel
MidNite Solar

 

[Tecnodave]

The Magnasine is a fine inverter, but it doesn't do self consumption. She needs one that does that.
Robin Gudgel
MidNite Solar

Ok......self consumption? Is that something only related to grid tie in systems. I do not have that capability, my Magnasine is a stand alone model, it does not sync with the grid nor does it backfeed its a MS4024AE is there some features in there that I have not found. This was not my top choice for an inverter but it came cheap with a problem that does not matter to me.

 

[Robin Gudgel]

The Magnum inverters are strictly off-grid with few additional features. Self consumption requires a bit more sophistication. The inverter will pwer loads in the house as much as your battery and solar will allow based on sunlight, state of charge and programming. It is seamless. Your loads will use inverter power if it is available and will use the grid when not enough battery power is available. You now must be dedicating a few circuits to your Magnasine, but if you are not maxing out the capability of the batteries and solar, then your batteries are just sitting there charged most of the time. The type of battery will have no affect on your electricity bill.
A self consumption system will essentially sell power back to your house, but not to the utility.
Does this make sense to you?
The OutBack Radian is one example of an inverter that can do self consumption.

 

[Tecnodave]

Ah, yes, but by that it must sync with the grid and use what solar and battery power and support it with grid power
So mine is either inverter or charger but a newer model can sync with the grid and do what you suggest that is the PAE models, mine is the forerunner of the PAE series, it is 120/240 split phase but is not stackable or grid sync. capable like my old Trace SW 4024 The AE models can not sync with the grid like the PAE. When i get down to low battery it shuts down and reverts to charge mode. I do have a small POCO feed only 30 amps 120 volt legacy system from the 1920-1930’s way too expensive to upgrade it to split phase so I do not even think about backfeeding. State law here requires me to draw power from the grid to maintain my occupancy here so I use a few bucks worth for yard lights. With our Public Safety Power Shutdowns my solar off grid is way more reliable than the power company

 

[SpongeboB Sinewave]

Ah, yes, but by that it must sync with the grid and use what solar and battery power and support it with grid power
So mine is either inverter or charger but a newer model can sync with the grid and do what you suggest that is the PAE models, mine is the forerunner of the PAE series, it is 120/240 split phase but is not stackable or grid sync. capable like my old Trace SW 4024 The AE models can not sync with the grid like the PAE. When i get down to low battery it shuts down and reverts to charge mode. I do have a small POCO feed only 30 amps 120 volt legacy system from the 1920-1930’s way too expensive to upgrade it to split phase so I do not even think about backfeeding. State law here requires me to draw power from the grid to maintain my occupancy here so I use a few bucks worth for yard lights. With our Public Safety Power Shutdowns my solar off grid is way more reliable than the power company

With self consumption mode, you should be able to allow some power from the grid to power the home.

In fact, that is kind of the way to go because whatever inverter is doing the self consumption and looking at the current into/out of the main breaker panel may not be able to be perfectly "balanced" at 0 amps in or out of that breaker panel. Otherwise, a fast change in loads might try to make the meter spin backwards which they hardly do anymore. I think that Hawaii allows several 10s of back-feed per day without issues.

I'm not sure what happens with the smart meters these days when net energy is sold back to the utility in either cycles or seconds of time ?

Maybe somebody here has a good understanding of some of the utility power meters these days.

 

[Robin Gudgel]

Tecnodave, email me. I will make sure you get a Rosie to test at no charge. We are still months away, but you will get a real beta unit. The Rosie is very impressive. These high frequency inverters of ours are capable of “arbitrary power factor correction”. I’m a mechanical engineer and don’t fully understand this, but those words came from Andy.
Robin Gudgel
MidNite Solar

 

[Tecnodave]

Robin,

I am so totally honored to be selected for beta testing the Rosie, I had asked Andy several times but I knew the whole crew had their hands full designing the best solar gear in the business so I did not press the issue. As I have stated many times online, I do know top tier gear when I see it. My uncle broke me into ham radio on Collins gear, I did a career in high tech for some of the best out there so I for one do really appreciate top tier equiptment.

Never had a complete system shutdown in more than 20 years completely off grid, directly due to the quality of equipment that I have chosen.

I may have your email address at midnite but I PM’ed you here with my email addresses, phone numbers, etc.

David......

 

[Bud Martin]

Hi Robin,
Is Midnite Solar going to apply this robust HF topology to other inverter lines? I think it will be a great thing.

 

[Tecnodave]

Bud...

Just hearsay so far but i‘m hearing (from some pretty reliable sources) that the Rosie design is related to the B-17, I think the 5 slot B-17 is 10 kw, probably going to have some huge overload capability.

 

[SpongeboB Sinewave]

Bud...

Just hearsay so far but i‘m hearing (from some pretty reliable sources) that the Rosie design is related to the B-17, I think the 5 slot B-17 is 10 kw, probably going to have some huge overload capability.

Yes, the two inverter types are basically the same topology

I think that M BT may have to reduce his surge power level a bit BTW.... It's still good surge but will need a bit of downgrading. I'll let him respond.

 

[Midnite Beta Tester]

Yes, the two inverter types are basically the same topology

I think that M BT may have to reduce his surge power level a bit BTW.... It's still good surge but will need a bit of downgrading. I'll let him respond.

I was up at Midnite yesterday and talked to the guy that wired up everything in the booth. Like Robin said, the total incandescent lighting loads are 9kW. It was planned to have 12kW total but the guy building it said he ran out of space above the booth and the labeling was not updated. When I got there they were just getting started on taking the display/booth down and packing it up for the next show in Long Beach, Inter Solar North America. Wait! Can I get a few measurements first?

No time to get detailed numbers etc. That will have to wait for a planned visit when I can be present, not rushed, and in their normal testing area, lots of resistive and inductive loads available. Right now the Rosie's protection is conservative and limits how much she can surge. They only have 6-7 Rosie's fully functional. Robin said they are in the process of building a couple dozen right now for both in house Beta testing, remove protection and see where it blows up, and the rest for sending out to Beta testers.

I did get a few pics of her loaded up. Saw Robins post about the lights and brought along a portable load bank. Good for about 5+ kW. that gets back the "missing" 3kW of lights and adds 2kW more. So, my 5kW+9kW of lights+about 7kW of pumps = close to 20K+ running watts. I was trying for a different surge situation this time, just a big fat load, 14kW, more than double Rosie's rated continuous output, then turn on those pumps.......No problem! No hesitation at all.

Rosie pulled 467 Amps from the batteries at 43.56 volts. That's 20,342 watts on the DC side. She held that load for 10-15 seconds before shutting down! Wow! OK, now I'm a little nervous....will she come back to life? Yup! Big sigh....Robin said I can't hurt her...but still....One more time to make sure all is good. Did it again. Same result. 10-15 seconds, shutdown. Protection working properly! Now the crew is making some noise...ya done yet?

No, just a sec, gotta get a look at the AC output side....3rd run. Got a pic of the current, 76 amps, from one leg but neglected to pull back and include the volts. They were around 114-115. So that's 152 amps X 115 =17,480 AC watts. Not too shabby for an inverter rated at 6.8kW!

Look forward to having some more fun in the near future and gathering hard data. I really need to learn how to use the new fangled scopes. So many options, menus, sub menus....save waveform capture to thumb drive....analyze it on a PC....all coming soon.

Stay tuned!