Building Reserve and Using KWH

[bcroe]

. A non vented electric clothes drier would be the
other item, except they are pretty small. Bruce Roe

Today I see a 7.4 cu ft heat pump hybrid unvented electric clothes dryer, seriously considering
getting one. There have been small unvented ones, but this one is full sized. I always hated
blowing all that heat outside, and the vent leaks plenty of air the rest of the time. Whirlpool.
Bruce Roe

[bcroe]

. Here's a peek inside......dual MPPT.....hinge on side.

That looks great, I went and opened the cover of my unpowered standby Fronius for the
first time, and it looks just like that. Apparently 2 inverters the same size, I knew they
shut one down to increase efficiency for light loading. The whole thing made possible by
the development of the microprocessor (control) and power MOSFET transistors (muscle),
not to mention economical solar panels. I had used them and IGFETs, but now I guess
silicon carbide transistors or the like have taken over.

Just amazing how something that light and cool running can handle that much power.

I looked at the bottom section, looks like the fuses are connected to the plus red leads, so
I guess that means it is set for negative ground. I think this one came with fuses, my
originals had shorting slugs. Bruce Roe

[DanS26]

So, show us the pictures. Does it hinge open just like the bottom section? Bruce Roe

Here's a peek inside......dual MPPT.....hinge on side.


IMG_0684.JPG

[bcroe]

Being cautious is good, a 60W incandescent light bulb should bleed them in a timely manner

Incandescents are more efficient bleeders, because the resistance drops as they cool
for near constant current. For our 400VDC stuff you might need this. Bruce Roe


PVtestLt.JPG

[Mike90250]

Generally, those big caps, are on the battery wiring, and the controller internals bleed residual voltage down in half an hour, which is why inverter cables spark at initial hook-up.

Being cautious is good, a 60W incandescent light bulb should bleed them in a timely manner

[bcroe]

I couldn't help myself and opened up that big upper transformer box a few months ago just to see what was inside. Lots of big caps that I don't think one would want to short with screwdriver before removing. Bleeding those big boys off with a resister would make a lot of sense.

IMO very beautiful engineering inside.....I especially liked the active cooling design.

So, show us the pictures. Does it hinge open just like the bottom section? Bruce Roe

[DanS26]

...............When they do fail, I will no longer hesitate to pull them apart and see if DIY repairs are possible.
My hope is to replace all hard stressed caps, being prepared to do the same later for the ones
on line. Could be the failure will damage beyond repair. Meanwhile, I have one backup inverter
mounted close by, all I need to do is move over the power wiring (conduit already connected) to
put it in service...........

I couldn't help myself and opened up that big upper transformer box a few months ago just to see what was inside. Lots of big caps that I don't think one would want to short with screwdriver before removing. Bleeding those big boys off with a resister would make a lot of sense.

IMO very beautiful engineering inside.....I especially liked the active cooling design.

[DanS26]

I called Fronius awhile back about their SunPower badged inverters. Talked to a knowledgeable tech.....he said that the upper units are exactly the same as all similar rated inverters. The bottoms are usually wired for negative ground and are normally converted to positive ground at the field location for SunPower panel installations. The only real difference is the operator/installation manual put in the box to guide installers on how to wire for positive ground. Some factory orders will specify positive ground be made before leaving the factory but that specification only affects the bottom unit.

I found negative ground in the box so I have confidence that the unit will work when needed and without modification but I will probably only need the top unit anyhow..........if the capacitors are still good......

[Mike90250]

Capacitor shelf life
As long as they are well manufactured and stay hermetically sealed, they should have a 30+ year shelf life. But if supplied by the lowest bidder.......
Operating life is dependent on Voltage % of max voltage and temperature, well designed gear should run at least 10 years, maybe more. My XW just hit 10 years, and I have a spare in box ready to go.

Capacitor forming. used to be needed with old aluminum paste caps, started off at a low voltage, and slowly ramped up over a period of hours to re-form the oxide layer that insulates the foils. Modern ones don't need it for a couple years. Might not be a bad idea to fire up the inverter, applying the DC voltage over a period of a couple minutes, and let it idle for half an hour before you pack it away for several more years.

[bcroe]

Bruce you said you keep a couple of Fronius 7.5 inverters as backups. I found a Sunpower badged Fronius 7.5 inverter on E-bay recently and went for it cheap. It came new in box both top and bottom unit absolutely spotless. Since Sunpower panels are/used to be positive ground I was a little concerned about the internal wiring in the Fronius inverter. But lo and behold it was still wired for negative ground.

But I do have a concern about the shelf life of the capacitors in this unit. My understanding that these electrolyte capacitors have an 8 to 10 year shelf life is left unused. Does this concern you?

I had not considered the issue of positive ground operation. That might affect the wiring of the
1 GFI fuse on the Fronius, I have no idea how the inverter makes that change. Guess my array
would not care if it was turned upside down.

The backups are labeled SUN POWER, and I can see some differences. They have a
disconnect switch coming out the bottom, not on my originals at that position. Perhaps I
should investigate more, even try running them one day. At least, I should not need to do
any high line voltage setup, the PoCo has tamed it and local increase is quite small.

I believe the inverters I bought were newer than mine, still sealed in the box. In operation a
switcher is really tough on the caps in the power conversion switching section, big currents
flowing in and out at the conversion frequency. Have seen that in many constructs here. That
is why some caps are rated for very low ESR. My Fronius are into their 8th year, running flat
out clipping all day long whenever the sun shines, they each draw the line at 100W more than
their rating. And at least keeping busy under clouds. So they have survived very well, but I
presume they may have aged a lot more than the ones sitting quietly on the shelf.

When they do fail, I will no longer hesitate to pull them apart and see if DIY repairs are possible.
My hope is to replace all hard stressed caps, being prepared to do the same later for the ones
on line. Could be the failure will damage beyond repair. Meanwhile, I have one backup inverter
mounted close by, all I need to do is move over the power wiring (conduit already connected) to
put it in service.

Meanwhile we are FINALLY seeing a run of pretty much sunny days, a dozen more this month
might set a record KWH reserve heading into winter. A bit over 100 KWH today under just a
bit of clouding. Reserve is helped a bit by my more efficient AC power wiring, only 1% loss
around a 600 foot loop. My DC losses are more than that at peak, but it does not matter since
the inverters are clipping anyway. At reduced (cloudy) levels, the percentage wiring loss declines
for both. Bruce Roe

[DanS26]

Bruce you said you keep a couple of Fronius 7.5 inverters as backups. I found a Sunpower badged Fronius 7.5 inverter on E-bay recently and went for it cheap. It came new in box both top and bottom unit absolutely spotless. Since Sunpower panels are/used to be positive ground I was a little concerned about the internal wiring in the Fronius inverter. But lo and behold it was still wired for negative ground. So into my parts supply area it went. Sometimes you just get lucky. I'll rip that Sunpower badge off if and when I have to hang it on the wall.

But I do have a concern about the shelf life of the capacitors in this unit. My understanding that these electrolyte capacitors have an 8 to 10 year shelf life is left unused. Does this concern you?

[DanS26]

The usual digital model is just a cost cutting and making it vulnerable to hacking. I
ought to try and find one of the older units, what is your model no? I already got a
set of replacement inverters for when mine blow up, do not want the later model.

I cannot believe all the software and monitoring swirling about so many small systems,
but I hardly ever hear of someone trying to make theirs work better. Bruce Roe

When one of the relays failed a couple years ago I opened the box to see how it worked. I thought it was well engineered and built with quality parts. There is a lot going on in that small package.

I did notice one interesting electrical aspect about the product that intrigued me. Some of the circuits were controlled by switching the neutral as opposed to switching the power. I even talked to an engineer in the company to verify that they really designed a product with a switched neutral. I think the new product design will fix that questionable feature.

Good luck finding one of these older Geyser units.....they don't break down very often.

[J.P.M.]

The usual digital model is just a cost cutting and making it vulnerable to hacking. I
ought to try and find one of the older units, what is your model no? I already got a
set of replacement inverters for when mine blow up, do not want the later model.

I cannot believe all the software and monitoring swirling about so many small systems,
but I hardly ever hear of someone trying to make theirs work better. Bruce Roe

Apps are easier to create than good engineering. A consequence of the great dumbing of America.

[bcroe]

"Thank you for contacting Nyle Water Heating Systems about the Nyle Geyser heat pump water heater. We are excited to tell you that the Geyser is currently out of production for a short period of time while we upgrade the controls to a new, digital platform. Water heaters with the new controls platform will become available in early 2021.............."
So it looks like they are getting close to releasing the new product design.

The usual digital model is just a cost cutting and making it vulnerable to hacking. I
ought to try and find one of the older units, what is your model no? I already got a
set of replacement inverters for when mine blow up, do not want the later model.

I cannot believe all the software and monitoring swirling about so many small systems,
but I hardly ever hear of someone trying to make theirs work better. Bruce Roe

[DanS26]

Perhaps I might run a Nyle 8 months a year, but with net metering a Nyle
could be on continuously. No time of day difference, just save energy. Too late for
this net metering year, should plan for spring.

Does the Nyle do anything about a moisture drain like a dehumidifier? Maybe turn off my
dehumidifier when it is operational? Now there is an energy opportunity. Bruce Roe

Yes it does dehumidify the air in my basement and I have it plumbed to the basement drain system. It keeps my basement very dry in the spring and summer. Some people collect the water and use it for mineral-less water purposes such as batteries or steam irons......it is basically distilled water.

If you run it in cold weather the heat it takes out of the air and puts into hot water has to come from somewhere....and that will be your furnace or other heat pumps. If you vent it inside and outside in the winter I think you would lose a lot of efficiency. I also do not want to dehumidify my interior air in the winter time. So a few good reasons not to run it in the winter.

I received this message from Nyle.......

"Thank you for contacting Nyle Water Heating Systems about the Nyle Geyser heat pump water heater. We are excited to tell you that the Geyser is currently out of production for a short period of time while we upgrade the controls to a new, digital platform. Water heaters with the new controls platform will become available in early 2021.............."

So it looks like they are getting close to releasing the new product design.