Can solar panels make a clock radio run fast? « Alternative Technology Assn Forums

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Can solar panels make a clock radio run fast?

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Started 2 years ago by fozzy
Latest reply from molly_chick

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fozzy
Member

Hi All,

Sorry for a dumbish question, but I had my PV System installed last week, a 1.5 kW system from Eco-Kinetics and this week I have noticed that one of our clock radios seems to gain time through the day. It may just be a co-incidence but I thought I would ask.

We noticed at the start of the week that it was running 10 minutes fast so we reset it to the correct time. In the past two days it has gained around 5 minutes each day during the day but doesn't seem to gain any thing over night. Another clock radio seems to be working fine.

It's not really much of an issue, but I thought if it is the solar system causing that to happen then it may be doing undesirable things to our other electronic equipment.

Any thoughts?

Posted Thursday 15 Apr 2010 @ 2:54:55 am from IP #
rockabye
Member

Clocks running on mains power are typically synchronised to the AC mains frequency of 50Hz. If for some reason your power supply is running at a different frequency, say 52Hz than the clock timing will be affected. This is unlikely in my opinion, but possible.

It may be that the inverter is introducing noise to the AC circuits in the house. Basically it is a very smart switch mode power supply with lots of computer circuitry that may be causing the problem. Normally on board filtering of these circuits would prevent this from happening but you may have a faulty one.

Be interesting to know the brand/model of your inverter.

My Powermate Lite can tell the actual frequency of the AC mains when plugged in so that is one way of checking.

Posted Thursday 15 Apr 2010 @ 3:14:12 am from IP #
ghostgum
Member

If your PV system can change the grid frequency, then you must have the largest PV system in Australia by far!

More seriously, there are several methods for trying to get clocks to run at the right speed.
1. Old direct wired clocks would use the mains frequency. The power authority makes sure that there are the right number of nominally 50Hz cycles in each day, even if the frequency varies slightly during the day.
2. More modern clocks (including battery power clocks and watches) use quartz crystals to keep time.
3. Some clocks synchronise from external sources, such as NTP over the Internet or GPS or other radio time signals.

I'd check whether the clock speed is different between daylight and night time. Your PV system is only going to affect the daytime.

In any case, I think it is likely to be a clock problem, independent of the PV system.

Posted Thursday 15 Apr 2010 @ 3:21:55 am from IP #
rockabye
Member

Excellent suggestion ghostgum.

Another is to take the clock to a relative or friends house and see if it 'fixes' itself.

Or use battery clocks, you will save power as well.

Posted Thursday 15 Apr 2010 @ 3:24:51 am from IP #
fozzy
Member

Thanks for the replies.

The inverter is an Oelmaier PAC2S. The clock radio is a Sanyo that is probably about 9 years old.

The main reason I asked is because I have only noticed it since the panels were installed, and for the past two days it only seems to have gained time through the day, not during the night.

The PV system can't change the grid frequency, but when the meter is running backwards, doesn't that mean that all the power I am consuming is coming directly from the inverter? In that case couldn't the frequency be different from the grid, or is that not how it works?

Posted Thursday 15 Apr 2010 @ 3:35:51 am from IP #
fozzy
Member

Hi All,

I'm stumped by this. I've tried a few things to test it out and I still have the same problem. We have two clock radios in the room so it is easy to see if they are gaining time relative to each other. I have tried the problem clock in 3 different powerpoints in the room and I have the same problem. I check the clock at around 7am and 7pm. The problem clock gains around 5 minutes through the day but doesn't gain any time through the night.

I periodically check the display on the inverter and whenever I check it reports the mains frequency as 49.9 or 50.0 Hz which seems ok.

I'm going to get another clock, but I can't work out why it would only gain time through the day.

Posted Tuesday 20 Apr 2010 @ 2:52:02 am from IP #
David robinson
Member

I'm no expert on this but from reading the posts I would conclude that the PV system is affecting the clock which is why the clock is only affected during the day (see Ghost Gum's post)

Posted Tuesday 20 Apr 2010 @ 3:59:38 am from IP #
rockabye
Member

I'm think there is a likelihood of noise being injected into the house wiring from the inverter. A quick search of the web suggests this also.

A lot of opinions but here are a couple.

I recently added 10 recessed lights to my home. Since the addition, when the new lights are on, the digital clock on the coffee pot gains about 5 minutes per hour. Is this coincidence and only a problem with the time keeping componentry of the clock, or could the clock be a symptom of a serious electrical issue?

http://en.allexperts.com/q/Electrical-Wiring-Home-1734/2010/4/digital-clock-gains-time.htm

"The problem with electronic clocks is that, if they are poorly designed, they can have much less noise immunity than their mechanical counterparts. The clock on the classroom wall won't care about a 10 microsecond spike on the power line, but a "red" clock may see it as an extra cycle. Lots of spikes, and you have a clock running amok. The new streetlights were probably injecting noise onto the power lines. (Notice that the clock always runs fast---a noise source can't remove cycles, only add them.)

http://ask.metafilter.com/75780/Time-Glitch

I doubt whether it is a serious problem but it would be interesting to talk to other users with the same model inverter to see if they have noticed a similar problem.

The coffee pot example is probably from a lighting switch mode supply inducing noise into the AC line.

If it is the only AC clock affected then it is possible there are aging capacitors that a failing to filter the noise.

Posted Tuesday 20 Apr 2010 @ 10:35:00 am from IP #
BuiDoi
Member

You could try making sure that the circuit used by the CLOCK has a number of other Electronic Appliances on it also, so that they might ad some filtering to the line.
Otherwise you could look at buying a "Mains filter" from Jaycar or similar, and see if it corrects the problem.
It's possibly 50cycle harmonics ..

Posted Wednesday 21 Apr 2010 @ 12:45:37 pm from IP #
Bergen
Member

This isn't a uncommom problem. It caused by the PV inverter. In some extreme cases we had to replace the inverter with a high quality inverter to fix the situation. It's caused by poor power filtering within the inverter.

Posted Thursday 22 Apr 2010 @ 6:08:34 am from IP #
fozzy
Member

Hi Everyone,

Thanks for your informative posts. I think you are right about the inverter adding noise. I'm not sure that it is that big a deal or not, but I have let Eco-Kinetics know and asked them to inform Oelmaier.

Posted Friday 23 Apr 2010 @ 3:28:33 am from IP #
LanceTurner
Key Master

Yep, a simple filter would be the best solution, so long as it is a proper LC (inductive-capacitive) filter and not a simple spike arrester. Alternatively, if you are a bit of a diy'er, add some extra filtering inside the clock, won't be hard if you know what to look for...

Posted Friday 23 Apr 2010 @ 4:55:19 am from IP #
Baz
Member

Hi Fozzy, not sure whether you have resolved your problem bit I have encountered exactly the same problem - I had a system installed last week and my clock radio starting running faster - 5-10 minutes per day. I thought this was a coincidence until last night when my TV turned on all on its own. So I looked into the PV system a little closer.
At my company we have an expert on inverter technology and he informs that there are two possible causes.
1. the earthing conductor from the inverter is inadequately sized and high frequency signals from the inverter are not diverted to earth but remain in the electrical system and affect the clock radio. This can be checked by unplugging the clock radio and coiling the cable around a pencil and then plugging it in with the coil in place (you can remove the pencil). The coil acts as an inductor and the high frequency is blocked. If high frequency was the cause then the clock radio should run ok.
2. there may be a voltage difference between the earth and neutral. You may need an electrician for this but a meter across the neutral and earth should prove this. There should not be any voltage across the earth and neutral. If there is the installing electrician should be called back to rectify,

I'll be checking my system in the next couple of days and will post an update - in the mean time let me know if you resolved your problem and how.

Posted Thursday 3 Feb 2011 @ 11:59:28 am from IP #
thatmosis
Member

Just to add insult to injury, we have several battery powered but mains (solar) charged items in the house.I have found that the times for charging are rather increased in our home compared to a home on direct power. This has been tested in several homes in the area and in Brisbane. The mains powered charge is usually less than when we charge them at home. Not worried as we have plenty of Solar Power but an anomaly non the less. An example. Our cordless vacume cleaner takes up to 16 hours to recharge fully here but less than 12 hours in Brisbane. We have had our Solar checked and we put out 240vAC constantly through a 2500w Techronics Sine Wave Inverter that runs every thing in the house quite well. Any suggestions?

Posted Thursday 3 Feb 2011 @ 11:33:02 pm from IP #
rockabye
Member

Yes this is a common problem with sinewave inverters. It appears to relate to the peak to peak voltage/current from the inverter being lower than the AC mains voltage. This occurs with the old linear style of battery chargers in particular. The result is a lower DC voltage output and consequently a lower current flows increasing the time it takes for a full charge to occur. Further reading suggests this may be particularly evident in half-wave rectification often used in cheaper devices.

The solution is to use modern switch mode power supplies which don't suffer this problem. You can tell these because they don't weigh much compared to the old chargers which contained a heavy transformer. My electric bike charger uses one of these and the charging time is the same on either AC mains or Selectronic & SEA sinewave inverters.

More info here.

http://en.wikipedia.org/wiki/Rectifier

Posted Thursday 3 Feb 2011 @ 11:39:20 pm from IP #
alfresco24
Member

It seems the regulations and approval specifications for DC/Mains Inverters and Installation and Testing need to be tightened to recognise this as a real problem.
Time for someone to report this to local technical regulators and to get Standards Australia to do a better job of creating well researched standards spec's.

Posted Friday 4 Feb 2011 @ 12:47:32 am from IP #
thatmosis
Member

The inverter is one of the best on the market as far as I know and apart from this obvious problem or non problem works fine.

Posted Friday 4 Feb 2011 @ 4:59:00 am from IP #
rockabye
Member

Your inverter is fine. It's just a small compatibility issue between old technology and new technology.

Plenty of ways around it. Using a different type of charger, switchmode, is the simplest and easiest.

Posted Friday 4 Feb 2011 @ 5:11:19 am from IP #
swanning_it
Member

alfresco, I think you may be right!

Until fairly recently, there were no stand alone inverter standards by Standards Australia. AS/NZS 4763 (Safety of Portable Inverters) was released in 2006 as an interim standard, expired in 2008 as an interim standard and is currently still an interim standard with a 2009 ammendment. This is the most substantial inverter standard (80 odd pages in my copy), but I note it's become "unavailable". I did hear rumour that no (or very few) inverters could meet the requirements of this standard.

AS/NZS 5603 (Stand alone inverters-performance requirements), original draft documents (all of 30 pages) was first released in late 2007 and only became a standard in 2009.

They're the only two standards I'm aware of for stand alone inverters but even AS/NZS 4777.2 (grid connect inverter requirements) only dates back to 2001 (all 10 pages of it)!

I think the technology has beaten the standards. Also, Standards Australia were rumoured to be broke ($80m in the red the rumour had it) and apparently made redundant all their technical staff. I don't like your chances.

Posted Friday 4 Feb 2011 @ 5:50:43 am from IP #
Buzzman
Member

EcoKinetics are aware of some issues with the Oelmaier and are simply replacing any dodgy ones with new ones fresh from Germany.

Apperently one issue is a software issue which causes the internal clock to read incorrectly and/or fail.

This happened to my PAC2S.

It's since been replaced by Eco and now appears to be fine. I have not noticed any issues with my clock radio.

Posted Friday 4 Feb 2011 @ 6:05:39 am from IP #
rockabye
Member

Have to disagree. The quality DC/AC inverters we have had available in Australia for many years are well designed and engineered. Standards are valuable but should not replace ingenuity and functionality when it occurs. I agree the technology has beaten the Standards, Australian made inverters are great. Both my 11 year old Oz made units are still going great 24/7.

Posted Friday 4 Feb 2011 @ 6:12:24 am from IP #
swanning_it
Member

Standards are merely a way to establish a minimum bench mark for safety and functionability. They don't inhibit designers wishing to develop a better mousetrap, just a level of protection for comsumers from those who don't give a rats whether the mousetrap works well or is capable of taking your finger off!

For the record, I see lots of inverters, both Australian and foreign made and I still see absolutely dangerous ones on the market today. There have been deaths and countless electric shocks and numerous fires as a direct result of poorly built inverters.

Fair dinkum, some of you seem to have a real issue with consumer protection policies. It seems some of you genuinely believe that anyone advocating anything more than a "free for all" is out to rip everybody off and is part of some mafia-like organisation. Talk about your conspiracy crackpots!

Posted Friday 4 Feb 2011 @ 7:51:16 am from IP #
rockabye
Member

Australian Standards are generally of a high standard in my view. It is compliance with standards that can be an issue and there appears to be little enforcement in some areas. Sad to hear they may be broke.

Posted Friday 4 Feb 2011 @ 10:06:17 am from IP #
alfresco24
Member

sw_it: I've been involved with revising Australian Standards as well as making products that have to comply with them. Half the time I hate them for being pedantic and an expensive exercise in buying them, compliance, testing and certification. And, I get very pissed off when imported (as well as local) product go to the market without compliance and are obviously deficient in some way.
But that's not what we were talking about above.
If the relevant standard is weakly written then a test lab cant reject something that meets the mandated test regime. That's the problem.
I spent the best part of three months arguing with the local regulator and a test house over a piece of Australian made wire, meanwhile rubbish equivalents were coming in from China.
It seems as though you have very little understanding of these matters and very big monkey on your back about something we said?

Posted Friday 4 Feb 2011 @ 1:05:11 pm from IP #
swanning_it
Member

alfresco, you may wish to re-read my first post again, then tell me where my "misunderstanding" lies.

In fact, read my second post as well and you'll find I don't disagree with your sentiments (not even the part about having a big monkey on my back). What I was saying is simply that the inverters spoken about in this thread may not have had an Australian standard for compliance at all when they were bought. AS/NZS 4763 appears to have failed even to this day (unavailable) and more to the point, there is no legislated requirement for compliance, AS/NZS 4777 was only legislatively applied through AS/NZS 3000 in 2007 and AS/NZS 5603 also looks like there is no legislation for compliance with it either. So, for the inverters and their respective issues in this thread, depending on purchase date, they may not have even had a standard with which to comply or they may have had a standard with no legislative requirement for compliance and hence, no mandated consumer protection by way of the requirements of the standard. Exactly what you bemoan in your post.

There most certainly is a misunderstanding here, but I don't think it's on my behalf.

Posted Friday 4 Feb 2011 @ 8:49:14 pm from IP #
alfresco24
Member

Whatever...

Posted Friday 4 Feb 2011 @ 11:16:20 pm from IP #
emmarvee
Member

I had a 1.5 kW system installed and immediately 2 of the 4 clock radios began gaining 10 to 15 minutes per day. I added ferrite cores to the array input to the inverter (Clenergy SPH 15) and also to the output of the inverter to the mains, and this had no effect on the clocks. I ended up pulling the clocks to bits (both the same branded clocks, and about 4 years old) and added 2 x 1.5uF capacitors across the tranformer secondary windings to the centre tap, and this completely cured the problem. I aimed for a low capacitive reactance at around 100 to 150 kHz where I suspect most of the inverter switchmode noise is occuring, while having a relatively high capacitive reactance at 50 Hz. Good luck to those people handy with a soldering iron !

Posted Saturday 30 Apr 2011 @ 10:34:42 pm from IP #
rockabye
Member

Good suggestion MRV. Most problems are solvable with a little technical knowledge.

Where possible I only use battery clocks. They have no standby or phantom load impact and will improve your export figures. The digital/clock temp displays I use only need a battery change every couple of years. They also work in power outages.

BTW make sure you record your meters regularly and even post the data on pvoutput.org if your keen. In Adelaide postcode 5024 has couple of systems if you do a search.

Posted Saturday 30 Apr 2011 @ 10:48:56 pm from IP #
emmarvee
Member

Ta rockabye. As the clocks are quite low in power consumption, would not the cost of replacement batteries negate the advantages of the extra export ?

I will be uploading data to the website (which I have seen before) but the Import/Export meter doesn't get installed until the second week in June !

Posted Tuesday 3 May 2011 @ 3:46:14 am from IP #
rockabye
Member

Actually this is where I find the best results in analysing your electrical usage. My main experience over the years is in off grid solar applications where any tiny AC load can mean the difference between system success or failure. The main thing to consider in design after system loads are identified is TIME.

This situation is sort of like a dripping tap. A 5W load like an AC clock seems insignificant but multiply it by 24 hours and you have 120Wh per day. Still small but over a year it is 43.8kWh X 21c/kWh and now it is costing you $9.20 pa which means you buy the clock again every year. Of course a single battery clock powered by a 50c AA alkaline cell which lasts 2 years and isn't affected by power blackouts starts to look a lot better. If you are on a Net FIT a portion of that 43.8kWh is paid on my system at 44c/kWh.

That AC clock is likely to have poor power factor (PF) and actually require double the 5W used to 10VA being required to be generated. One clock is no big deal but all those AC clocks in Australia need Megawatts of power when added together. Round that up to 50kWh per clock and you are needing a MWh pa for every 20 clocks. Starts to add up doesn't it.

That old scottish saying about looking after your pennies and the pounds will look after themselves sort of fits here.

Posted Tuesday 3 May 2011 @ 5:19:57 am from IP #

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