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B17-5 and B17-3 / Re: MNB17-5 Surge Capacity and Load Regulation Capability?
« Last post by boB on August 09, 2020, 06:29:03 PM »

The differences between large load changes with the grid and with an inverter with batteries is because an inverter, being solid state and limited power or current at the output voltage and the immense capability of the grid which really is a voltage source except for your home wiring resistance and the transformer at the pole of course.

An inverter, comparatively is a small source that is being regulated by feedback from its output and possibly, in addition, a bit of feed-forward regulation based on the battery voltage.

An inverter cannot respond in the exact same manner as the grid, which does not have to respond to anything, based on its relatively small load changes.

BUT, most of the industry tries to make regulation as fast as possible with load changes so that the voltage doesn't sag, droop or overshoot very much.

A typical tell-tale indication of poor regulation is dimming lights.  The less they dim and brighten with  abrupt changing of loads, the better.  At least, the less noticeable they dim-brighten, the better.

Some inverters are awful and some are great at this regulation.  We will always strive to be as great as possible.

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B17-5 and B17-3 / Re: MNB17-5 Surge Capacity and Load Regulation Capability?
« Last post by boB on August 09, 2020, 05:50:50 PM »
Basspig, check out this short history...   There is a lot more to be added, especially regarding local pacific northwest audio companies and relations with the inverter industry up here but it's  a good start.

https://www.midnitesolar.com/pages/frontPage/nwHistory/history.php

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B17-5 and B17-3 / Re: MNB17-5 Surge Capacity and Load Regulation Capability?
« Last post by Basspig on August 09, 2020, 04:54:31 PM »
boB, what a surprise to see someone here who knows my friend Bob! I used to have a lot of PL gear in the 1970s. Sold most of it in 2007 and reinvested in industrial amplifiers from QSC. I'm what you might call an extreme audiophile. Designed a lot of speaker systems since 1968. The setup I built in 1982 are pretty much the same today, except having updated the LF drivers and adding a lot more amplifier power. The main array is 112dB efficient below 40Hz. The system will hit 132dB with only 6 watts of amplifier power at 8' from the array. At times I've hit levels in excess of 150dB and it's like sitting in the front seat of an IASCA competition car audio system. There's just something about having your whole body shaking to a 32' organ pedal stop. :-)

Class D seems to be the way to go. That's like a 3-state PWM sinewave inverter. Low source impedance is important to keeping the power from getting dirtied up by even a single poor power factor load. The output of my Northstar 13kW genset is nice and clean until I turn on the Carver M500 in my recording studio. The glitches seen on the scope in the shop in another room are drastic.

Reliability is of course important. Resiliance to nasty spikes like motor start loads (well pump, 86 amperes LRA) and accidental shorts (yesterday I was starting repairs on a Carver Lightstar amp for a customer and the output transistors are shorted and customer says it pops the breaker) Fired it up to find out which channel was popping which breaker and when I found it, it nearly shut down the generator. Oh, yeah, we've been plunged into the early 1800s here in the northeast as our power company has barely any crews to repair lines after a widespread outage. Going on a week with no power and me tethering off my 4G phone!

Gas is out. I've seen too many homes blown up due to a leak. When I was working in Middletown at a radio station about a decade ago, a gas fired power plant was in the early phases of testing when it blew up. Damage for miles around from the shockwave! No gas for me.


mike90045: A split system would be great for redundancy, but would require significant rewiring of the panel. Presently, I'm feeding my genset into the panel with the main breaker off. I plan to run off grid with the genset replaced by a big inverter.

I've been told on the solar-electric forum that I would need $400,000 worth of batteries to accomplish my power needs! Tesla batteries are intriguing, but dangerous. They would have to be installed in a concrete bunker, just like my genset currently is, away from the house. But 4500Wh can be had for $1400. Ten of them would provide decent power.

When I'm not using the sound system, our power draw is a static 4kW. That's all the computers, lights, test equipment in my lab, and recording studio gear running.

On the A/C front, I've installed my first Mr. Cool DiY unit in April. I'm flabbergasted, because it seems to be giving me something for nothing in that it is cooling my studio very well for no more energy than a couple of light bulbs. I really found this out on generator power. My conventional LG air con really bogs down the generator when the compressor kicks on. But the mini split I installed doesn't affect the generator pitch or sound when it comes on, any more than if I turned on a 150W flood light. And it cools as well as the LG and does so silently. So I'm all for converting the rest of the house to these mini splits and that will eliminate the big load in summer.

We're so suffering under the high electric rates here that I told my wife to hang the laundry outdoors and stop using the dryer. That saved us $150 a month right there, but the very next month Eversource kicked in a whopping 30% rate increase, so that nulled out any savings. We'd be looking at $1000 electric bill if we used the dryer this month.

By far, my biggest load is dynamic and it's the sound system. The QSC amplifiers each can use 92 amperes of current at full output and I have multiples of these and other big amplifiers in my system. Fortunately, I rarely pop the 50A 240V breaker. I estimate the whole thing idles at around a kilowatt. I only turn it on for movies and once a month for loud listening sessions that last about an hour or less.

The other load is the well pump, which has a high surge current. When that kicks on, our UPS goes crazy when on generator power.

Grid tie is out of the question. I'm not dealing with permits and agencies. I'm doing this completely on my own, a little at a time. I built the whole house over many years, started in 1966, no permits, up here in the woods. Safety is a number one priority, as I can't get, nor afford homeowner's insurance, and it's worthless anyway, as my neighbors found out in 2018 when tornadoes destroyed their homes. I built for that, having lost my prior contractor built home to a tornado the year prior. It was also the Cold War, and I was planning to survive a nuclear attack. It turned out the robust construction was a huge benefit for my 150dB bass levels that I sometimes hit. Normally grid tie involves a lot of nasty contracts and the installers are sloppy and leave you with roof leaks. I just got done putting EPDM rubber down on my flat roof in 2017. And we sometimes get a lot of snow, which means I need panels that are at a slope so the snow slides off.

I cleared an area about 25x80' on the west side of my property. It gets full sun from 8am-noon. I was planning to start with 16 500W panels at $100 a piece from Alibaba, a 15kW split phase inverter, and a couple of Tesla batteries.

As far as I know, we have a flat residential rate here. I have a neighbor who shut off the main breaker when living overseas for long periods, and they still get a $200 electric bill. Highest rates in the nation, and they can't get the power back on after a tropical storm!

I know there's a lot of initial investment, but I see utility rates going nowhere but UP and rapidly so, while grid power is becoming less reliable every decade because of corporate greed and understaffing. So this latest outage has me thinking about getting SOMETHING up and running that will replace our genset and at least give us overnight power without the noise of the generator.

Is this rack mounted system on the market yet or available? Where can I get pricing?
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Lithium / Re: charge profile, choosing charge controller
« Last post by Glenn West on August 08, 2020, 06:54:07 PM »
Thanks guys.
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Lithium / Re: charge profile, choosing charge controller
« Last post by Vic on August 08, 2020, 05:57:41 PM »
OK,   perhaps my statements are a bit sharp  ...   sorry.

Was just trying to make it  clear that  our solar chargers are not really CC chargers. The Classic and the PT-100 behave the same in Bulk  --  producing as much current as is available at that moment,  up to the Limits of the controller

One could set the PT to 100 Amps CC,  but if that amount of current is not available from your PVs,   the PT will only put out as much current as the PVs can produce at that moment. The Classic is exactly the same,   except there is an output current Limit,  that is active in any mode.   And the Classic has the ability to set a Limit for the current that is actually going into the battery (with the WbJr),   which would not be useful for your Li batteries.

FWIW,   Vic
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Lithium / Re: charge profile, choosing charge controller
« Last post by Glenn West on August 08, 2020, 05:41:54 PM »
With my proposed solar system, at full output (how often that ever happen. lol) will be putting out 70 amps at 58v. 4k wattt solar. I have no roof top acs. All minisplit. Should charge up fairly quick at constant current. I could add 2 extra 400 watt panels as an awning, if I see a need.
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Lithium / Re: charge profile, choosing charge controller
« Last post by Vic on August 08, 2020, 05:13:43 PM »
OK Glenn,  Thanks   ...

So one can set Constant charge Voltage?   This would be like a second Absorb V,   guess
And if there is a Constant Current setting for the Bulk stage?  Bulk is considered a Constant Current stage,  but again,  with PVs as the power source (NOT the Grid),  that value would need to be set low to have any real effect.   As with clear WX and PV having a good view of the sun,  PVs are not CC sources.   There is that half-Sine curve of irradiance from the sun.

It seems,  that these two settings are of no practical use with PV charge sources.   A CV setting would generally  be just like Absorb,   gotta wait and wait for that voltage to be reached,   unless it was set quite low,   and then not much charging would generally not have happened.

OH,  and you are correct,  that from the MNGP display on the Classic,  the minimum Absorb time is 3 minutes.   Wonder why it is not even a smaller value   ...

IMO,  Thanks,     Vic
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Lithium / Re: charge profile, choosing charge controller
« Last post by Glenn West on August 08, 2020, 05:03:36 PM »
PT-100 does a cc/cv setting with remote which is constant current and volts. I may just use it anyway. I will already have the remote due to the inverters. Save me form having to buy a second remote.
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Lithium / Re: charge profile, choosing charge controller
« Last post by Vic on August 08, 2020, 04:29:01 PM »
Ok Glenn,   Thanks,

BUT,   what is being Set with that Bulk setting ?  Vic
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Lithium / Re: charge profile, choosing charge controller
« Last post by Glenn West on August 08, 2020, 04:22:48 PM »
PT-100 does do bulk and float. Use the remote for that. I am familiar with them. But I don't need that much controller though. That thing is a beast.
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