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RE: Episode 131 - Are you a fear monger, Father?


G+_Chris W
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RE: Episode 131 - Are you a fear monger, Father?  First the LI batteries, now.. When talking about a solar array losing power because of a cloud, you said "..you'll actually start to decrease the Hertz"  which would cause appliances to "blow up".  No.  No.  and No.

 

First, the less solar-educated among your podcast audience will believe, because of your wording, that a low-powered solar installation will start to lower its frequency as the power from the panels drops.  This is, of course, totally wrong.  Solar panels make DC current, which is converted to AC by an Inverter, which is LOCKED at 60 Hz (in the US, 50 Hz elsewhere).  It cannot change, and will simply turn off if there isn't enough power for the load.

 

People a little more educated will know you were implying that the other generators on the grid would slow down when the solar station's power output dropped, and that is true, To A Point.  But (and this is a crucial point to the Non-Fear-Mongering public) It Will NEVER get to 40 Hz.  EVERY modern AC generator has a low-frequency cutoff.  Somewhere between 55 and 50 Hz, they will turn off, or trip a breaker, and some facilities set that trip point even higher.  More to the point, brown-outs are usually caused by the power companies dropping the voltage on purpose, to keep the frequency stable when the load is a little too high.  They know exactly what would happen if they let frequency drop too far, and they'd rather shut off the power than be sued for a few thousand refrigerators and air conditioners that suddenly don't work.

 

Oh, and they don't "Blow Up" either.. eesh.  Don't we have enough to worry about?  The absolute worst that could happen is a poorly designed unit might catch on fire, and that would be a rare occurrence these days.

 

How about we stick to the tech and leave the fear mongering to the politicians and insurance companies?

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No thanks. I'm not a troll, I just get offended when people in a position

to influence others step outside the lines of truth just for effect. And

the fact remains, commercial power can't get down to a low enough frequency

to hurt things without a minor catastrophe of things going wrong.

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"And the fact remains, commercial power can't get down to a low enough frequency to hurt things without a minor catastrophe of things going wrong."

 

Chris W -- That was the point of us discussing this... it DID happen. We were talking about something that is ACTUALLY HAPPENING RIGHT NOW on the island of Kauai. Their battery backup melted down. Since they are so tied to their solar array (80% of their power), they suffered enough drops in power frequency that it blew out appliances and some industrial equipment across the island.

 

I know... because I was actually living on the island when it happened.

 

Sooooooo.... now you know.... you're welcome? 

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Chris W does make some good technical points. While the context of fear mongering etc may be a bit out of the mainstream of the technical aspects of the discussion, his points are still valid.

 

So, As Chris pointed out, commercially designed setups do have some engineering design in them for protection. Not to say that a catastrophic failure cannot or will not happen, because they certainly do, however rare. Point being, hobbyist should not fear experimenting in this area if they are interested. Fr. Robert Ballecer, SJ having also pointed out rare but potential pitfalls is also good knowledge so that the hobbyist is at least is somewhat aware of the potential dangers.

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Yeah, as promising as solar electric is, it's still only a promise.

Lifetime is still going up, but an average of 20 years means, on average,

you will have replaced half your panels at the 20 year mark. So unless the

costs drop along with lifetime improvements, they'll remain the province of

people rich enough to help ecology while ignoring the costs. And battery

tech would have to improve with them.

 

One area of interest is used panels. Many municipalities and large

installations replace panels early to maintain peak output. Used panels

can be picked up for a pittance, if you can find them, and though they'll

have a reduced output, they should last several years, on average. If you

can find a source, don't pay for them sight unseen. There will always be a

bad panel here and there, but you don't want to get your panels and find

out half or more are completely dead, and no way to get your money back.

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I admit to being put off solar by the lifetime and battery issues, and not keeping totally current with the tech, but I also don't have $12 grand to spend on it. Most people would want to have a connection to the power company for backup, if not to recoup a few pennies selling their power back to the utility. Your setup requires a total disconnect. What do you charge to install an NEC mandated power transfer switch?

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The old Trace (now Xantrex) inverter I liked would do both, grid-tie and generator backup, and could parallel for over-power situations. But even if you don't do grid-tie, a power (bus) transfer switch would let you switch to commercial power if your system died.

I'd be interested in your views on grid-tie systems. Is your choice a personal preference or is there a hidden downside to them?

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