Will sunlight damage the electronics?

Starting about 25 years ago, the local power company started a program whereby they installed these boxes to home AC units and electric water heaters, supposedly to reduce peak demand on the grid in times of high demand. A few years later, they returned to remove those units and install different untis (different brand/model), saying that the originals never gave them the control of peak demand they needed. Then, about 7-8 years ago, they again returned to remove all vestiges of the control boxes, saying that they were too expensive to maintain; frequent failures caused many service calls to replace them. The end result was that the boxes never gave the power company the relief from peak demands that they hoped; in all a waste of time and money.

To your question, it's unknown from your observations whether the innards would be damaged by sumlight intrusion. There could be a UV EPROM inside that could possibly be erased if sunlight got to it on a continual basis, however, most EPROMS have a label covering the window that protects the contents. Constant UV exposure from sunlight could possibly damage the markings on components, but they will likely be OK. Most plastics and glasses are fairly good blockers of UV. If you're concerned about the esthetics of the label on the box, paint it or cover it with a piece of tape. That will not harm the box.

The green LED is probably on to indicate to a service guy that the unit is operational (not in an error condition). Without specific info on the unit, it's impossible to know its exact purpose.

--
David
masondg44 at comcast dot net

Wonderful idea. If the AC units are creating an excessive load, just turn them off remotely. Beats investing in grid infrastructure.

Sylvia.

The problem is getting people to buy into this idea. It usually is under a different tariff than "normal service". And, utilities often don't price those tariffs rationally. People are hesitant to let someone else turn off a "comfort feature" if they aren't getting something "significant" for their potential inconvenience [1]

The same is true of ToU tariffs. Its as if the utility

*wants* the benefits that these tariffs offer *and* wants to figure out how to get more money from the subscriber at the same time! [1] Though often load shedding can be implemented as load *shifting* so you don't really feel any significant "loss". E.g., most hotels/motels have their HVAC systems arranged on a staggered schedule. So, even if you turn the "heat" (ACbrrr) on in your room *now*, you might not actually *get* that until your "timeslice" comes along.

SDWOTN.

(Sarcasm does not work on the net.) You might be serious. If so, I think you're right. The infrastrucutre would be generators. Very expensive.

Most homeowners don't really need air conditioning anyhow. They should open the windows and buy some fans. My greatgrandparents didn't even have electric fans.

In a way, I shouldn't take this money for putting a switch on my AC. I only use it for 2 or 3 weeks most summers anyhow, so they probably don't cut down the load when they radio me. Last summer was the least hot of my life, and I didn't use the AC at all.

D, it was pretty easy to get me to sign on. They pay 10 or 15 dollars (I forget which) dollars a month during the summer for the AC and since I almost never use the AC, it's defitely a bargain. But I think a substantial percentage of people have signed up, 10, 20, 30 percent or more. I have one friend who uses it all summer who did.

They also pay maybe 5 dollars a month during the summer for the water heater. I don't know why, but I didn't like the idea of them fiddling with that. I think I thought it woudl come out ugly looking, even though it is in the basement, sort of like the AC did the second time (I had signed up 10 years ago during the previous round. I don't know if BG&E had the first round that Dave mentioned.)

I get the impression they only turn off the power for short periods two or three days a summer. Maybe 20 days at the most in a hot summer.

It was intended as sarcasm, but of course it's also a true statement from the perpective of power suppliers.

I have AC installed. It only gets used for a dozen days a year (and a few nights) at most. But at those times, it wouldn't be much fun without it. The problem with comparing the present situation with that in the past is that people in the past didn't have a choice, just as they didn't have a choice about dying from diseases that are now either easily treatable, or easily preventable.

Even fans are not so effective when the air is so warm that sitting in front of a fan feels like sitting in front of a fan heater.

Would I survive if I didn't have AC? Probably. Would I like it? No.

It's fair to take the money. The infrastructure required to support extreme peak loads (which is not just generators, but transmission gear as well - lines, switches, transformers, the works) is only used infrequently. If the need for it can be obviated by persuading people not to use it, then there is a substantial cost saving. Although you may only use AC for two or three weeks in the summer, it's likely to be the same two or three weeks that other people are using it.

That actually makes more sense. It encourages people to have tanks with a decent capacity so that turning them off at times of high load has no impact. My own hot water is heated overnight at a lower tarif anyway.

I think I thought it woudl come out ugly looking,

I can't even see how that would help them. ACs run on thermostats. Turn them off for a while, and they'll simply run for longer when they're turned back on. So unless they're left off until the peak load drops (ie, because the outside temperature has, or at least the sun goes down), there'll be little or no net saving.

The real problem power suppliers face is that consumers are not subject to the true costs of supplying the power. Indeed, those consumers who cannot afford things that create high peaks, like airconditioning, are subsidising those who can. In Sydney, where I live, time of day metering is being introduced, which at least charges more during period where demand tends to be higher, but even they don't ramp up the cost during heat waves. As an AC owner, I'm not complaining, but it doesn't seem at all equitable.

Sylvia.

There's not much point in having a comfort feature if it's likely to get turned off at the time of greatest need.

I'd only go with it if the saving were enough to finance a petrol generator to supply the power instead.

Well, they probably do.

Sylvia.

If anything, exposure to heat, if it is in full glare of the sun all day, will damage the electronics. I'd imagine they thought about that before hand though....

-B

It's not "turned off", per se. Rather, it is *deferred*. I.e., maybe 10 minutes later your ACbrrr will kick in instead of at the (slightly) earlier time when the thermostat called for cooling.

Chances are, a normal user wouldn't really perceive the fact that the ACbrrr kicked in "late" -- the house may rise some fraction of a degree beyond the thermostat's set point? But, the *idea* of this is unnerving to many people: "Oh, I am going to be *so* uncomfortable!"

OTOH, if they were to raise their thermostat's setpoint that degree (or two?) all the time, they would probably not notice the difference.

Defeats the purpose. The utility can produce electricity far cheaper/cleaner than you can.

The point of ToU and load shedding is to let the utility cut back on peak loads. This lets them use things like nuclear energy (good for big, steady loads) instead of having to fire up coal/gas generators to respond to short term fluctuations in the load.

The (new?) tariff here borders on ridiculous. You'd have to shift 2/3 of your load to off-peak to break even.

But, as I've commented elsewhere, as soon as the AC is powered up it will stay on for longer to bring the temperature down again.

There is an energy saving, but it's very much a second order effect, arising form the slightly higher average temperature.

I'm not so sure that's necessarily true for extreme peak loads. They not only have to generate the power, which is likely to be done using diesel or some such, but they also have to deliver it to me, which involves transmission infrastructure which is only used during these extreme peak loads, but which is there all the time.

Sylvia.

It's generators plus distribution facilities. Like most utilities (e.g., phone, gas, etc.) the systems are not designed for "everyONE to use everyTHING" at the same time. There is some probablistic/statistical analysis that goes into determining what sort of "typical" loads will be experienced as well as "bad cases" (not *worst* case) that are "likely".

Power plants, distribution systems and even the number of "work crews" are determined by these magic numbers. Once you start moving beyond a few standard deviations from the norm, things get brittle. E.g., the ability of the power plants to respond to changes in demand, the ability of the

*lines* and substations to handle those loads, the availability of crews to respond to faults, etc.

Additional generating capacity can be brought on line by burning more fossil fuels. This is expensive and also bad for the environment.

Most utilities are like diesel engines: they have a sweet spot where they like to run. Push them much beyond this and they get cantankerous.

Shirley you jest? We break 100F in May and that usually persists through mid October. July and August see this a *slight* reduction in temperature -- as the humidity then climbs to over 90 percent (90F at 90RH is quite uncomfortable -- I don't care how many fans you have!). And 110+ is *hot* even when the RH is only 10% (should we give up swamp coolers as well as AC?)

Your comment is akin to telling folks in Chicago that they don't really need *heat* in February -- just put on another sweater! I've been outside in -26F with windchills below

-80; a sweatre just ain't gonna cut it! :>

And *their* greatgrandparents didn't even have *horses*! ;-)

Sure seems like *you* are one of those who "don't really need air conditioners". Can't you live without it for those two weeks? :>

We used to program EPROMS with UV light. Most synthetics degrade in UV unless designed not to.

I've never been able to do THAT! :)

Exactly. Every year there are deaths attributed to "lack of adequate cooling". But, its usually "not anyone *you* know" so it tends to get ignored. Just like folks freezing to death.

The problem with "excess heat" is there aren't many ways of "shedding it". And, once your body starts to overheat,

*you* usually aren't qualified to think about how to fix the problem (it muddies your thinking).

Exactly.

A smarter solution is to have "on demand" water heaters. Silly to keep 40 - 80 gallons of hot water available 24/7 just in case you *might* need it. This solution is a throwback to days when heating water was a slow process and you didn't want to "inconvenience" the user. :-/

Hotels use the same approach with their in-room HVAC units: they aren't all "enabled" at the same time. In years past, a simple time sharing scheme was used: some portion of the units were enabled for N minutes; then, another portion for the next N minutes; etc. The point being that the units could bring the room to "the desired temerature" (on average) when used for only a fraction of the time (i.e., they didn't need to run at 100% duty cycle to work properly).

Nowadays, technologies like ZigBee are being deployed to allow for smarter management. E.g., instead of blindly enabling some portion "now" and another group "later", just let each unit that *wants* power *request* power. And, force it to wait until that request is granted (by some centralized smarts that is tracking who it has "granted" power to at the present time). So, if you get lucky, only X% of units will *want* power at any given time. If more than X% do, then you have to decide how to limit the actual number of units to that percentage (i.e., you are back to the original solution) knowing that

*eventually* each room will achieve its desired temperature.

Some (US) businesses are charged based on peak demand. Stated simplisticly, if you use electricity at an X KWHr rate for 10 minutes and don't use *any* thereafter, you are charged a rate proportional to X *regardless* of your TOTAL energy consumption during that billing period (month)!

Things like ToU and Peak tariffs lead to some incredibly inefficient solutions that waste energy -- but, "save money". E.g., businesses "make ice" overnight to run their air conditioning systems during the following day. The cost of making the ice is artificially cheaper than creating the same "cooling" during the day (when it is actually

*needed*)

I don't know how the things work, but it could be possible in the event of complete power failure, to do progressive start ups. Starting all the refridgerators is bad enough. You might even try to control whose air is on and whos is off, so all on is not a possibility.

Heat will damage electronics. UV protection will be providd by any material preferably tinted.

greg

Sure! As long as you want them "programmed" to their erased values! :>

Actually, I think EPROMS under normal sunlight will erase in a very short period of time (like a day?). This is not the same as "under fluorescent light"...

Let me give a real world perspective on the use of EPROM's. I was involved in a product that needed a ROM to hold some basic logic. To be sure that the code was right, EPROM's were used because of the neat ability to quickly update the device by UV erasure and reprogramming. We probably had about 100 of these for testing and debugging the product.

Now we want to go into production and the required volumes ranged into the multiple thousands of pieces. Two factors come into the decision making. First, those ceramic packages with a window are not cheap. Second, EPROM's and their programming are also not inexpensive. The best economy is a mask made ROM in a plastic package. Here the problem was the start of cost of mask making and the delay in getting real chips of the line.

We settled on a stopgap compromise and started production with EPROM's that were in plastic packages. The design was frozen and we knew that erasing would not be an issue. Then when hard programmed devices became available the transition was easy. You have to look at the economics of this scenario to see if the savings are there. If you want 50 to 100 thousand of these it worked well.

As they always say "YMMV".

Charlie

[attributions elided :> ]

Yes, but not *much* longer. All you are doing is shifting (in time) when the house will be "as comfortable" again. E.g., if you had opened the front door (to carry a large piece of furniture in/out) you would similarly have disrupted the comfort level in the house for a short period of time. (if you've ever "moved" in the summer time, you'd understand :> ) But, that comfort level is once again restored, ultimately -- *later*.

The big (psychological) problem with load shedding is that folks don't feel like they have any control over it so they assume it will be uncomfortable, etc.

OTOH, if the technology was implemented as an *auction* (I am merely trying to make a point) in which the utility could alert participants:

"Hi, we need folks to shed some load. We are currently offering $X for you to shed Y load for Z minutes"

and then respond to folks who have accepted this offer by adjusting their *new* "bid price" (up or down):

"Due to the overwhelming acceptance of our previous offer, we are now only willing to offer $x (i.e., x < X) for you to shed Y load for Z minutes"

or:

"Hmmm... we haven't had many takers of are offer at $X so we are now sweetiening our offer to $XX for Y load for Z minutes"

Then I suspect most folks would probably complain that watching for these "offers" is too tedious: "Can't you give me a SWITCH that I can throw that says "I am willing to accept ALL offers of $X or more?" (which, in effect, is what the tariffs do -- except you have to make this commitment up front!

The goal isn't to save energy (though I think the laws of thermo say you *do* save in this case). Rather, the goal is to get you to *shift* your energy consumption (in time).

The infrastructure is sized for some percentage above nominal. Of course, going too far *beyond* that causes things to *break* (hence the blackouts that become newsworthy).

But, things like diesel/coal/gas fired plants that are there

*deliberately* to respond to these short term fluctuations in demand could, theoretically, be eliminiated if the demand could be "leveled".

Nuclear power plants, for example, like to put out a steady amount of power (can we *please* not let this discussion digress into the pros and cons of nuclear power? :< ) which doesn't lend itself to rapid response. If you had power source that was ecnomical to operate and had this characteristic, then you would have a big incentive to coerce users into adapting their usage patterns to match.

Also, it is important to define what crteria you actually want to optimize. E.g. "efficiency" can be defined in a lot of different ways -- many of which are inconsistent with each other :-/

The AC has to run long enough to pump out the heat that's flowed in during the time it was turned off. Heat is ariving in the building at a rate that's largely a linear function of the difference between inside and outside temperature, and the energy required to pump it back out is a slimilarly linear function. So to calculate the average energy consumption - ie power - you just look at the rate at which heat is flowing in. That rate is minimally altered by deferring the turn on of the AC. As I've observed, the rate is slightly lower because the average difference between the inside and outside temperatures is slight lower. On a very hot day, which is when this load shedding mechanism is likely to be most used, the saving will be modest, because the change in average temperature will be a small fraction of the total temperature difference.

All you are doing is shifting (in time)

But the demand cannot be levelled by short term adjustments to things like airconditioner demand. The overall demand is higher on hot days. Deferring an airconditioner load by ten minutes won't alter that. Getting people to defer their airconditioner loads until night time would be better, but of course that's not going to happen, at least not until and unless airconditioners based on a large cold sink become the norm. That might be a bit of an own goal anyway, environmentally, because the cold sink would have to be kept cool against the possibility that the day following would be hot. There would always be some leakage, so the overall energy consumption of such systems would be higher, even if they were running on cheaper power.

I suppose it could be argued that some transient peaks arise from a disproportionate number of AC thermostats switching to on at the same time, but given the number of ACs around, I'd be surprised if that were really an issue - the probability of a significant deviation from the short term average due to such an effect would have to be very low.

While nuclear, and indeed coal, plants cannot respond rapidly to changes in demand, that is not the reason they are not used to handle peak loads. It's purely a question of economics. It is not cost-effective to have such plants lying idle - if that's going to happen, you don't build them, because they're too expensive to be used that way. You build less capital intensive plant for that purpose - typically gas or oil powered (though what we do when the gas/oil runs out isn't clear).

Sylvia.

Radio-controlled AC turn-offs are not meant to be energy saving. They're meant to be peak-load lessening. It's meant to prevent brown-outs because of too much load at one time.