Good, now my OCD is also at rest. 

Just an update on the generator story. I see my InfiniSolar has a generator input. It also has the output ports to auto start the generator. So the Infini can do this out of the box.

@jdp If I had to do it over i might have gone for the InfiniSolar. It looks like a good product! It seems to do everything my GTI does plus you can add batteries if you want and the generator. Not bad. Had I known... Who knows, maybe in a couple of years time I'll make the switch.

Nice, tidy install Janma. I am quite curious to know how your setup will perform over time, maybe some feedback after a while, please? I am also keen on some feedback specifically on the Microcare products. As you can gather, I am contemplating going the GTI route, at least initially due to the cost of batteries. Thanks and enjoy your system. 

47 minutes ago, Langeraat said:

Nice, tidy install Janma. I am quite curious to know how your setup will perform over time, maybe some feedback after a while, please? I am also keen on some feedback specifically on the Microcare products. As you can gather, I am contemplating going the GTI route, at least initially due to the cost of batteries. Thanks and enjoy your system. 

Hi Langeraat, good luck on your PV journey!

Thanks. I will keep you posted.

Some observations so far:

Last night I connected the very last MC4 connector and my system was fully wired up. I've spend days,weeks wiring, checking, double checking and getting everything ready. The whole family gathered for the long awaited "switch-on" of the system. I went through the startup procedure in the manual. To my utter disappointment and embarrassment nothing happened. Not even one light on the GIT turned on. I checked everything again. I knew that since it was dark it would not generate power but somehow I expected it to at least light up a LED or something. I started double checking the wires. The family eventually left after a while leaving me to figure out if something was wrong and if it could be fixed.  Eventually I started going through the manual. There somewhere "hidden" in the specs section under "Features" I saw and entry for "On/Off mode = auto"  Could this be the reason it did not want to switch on? There was no way for me to tell if it "switched off" automatically because there was not enough volts on the PV side or if I wired up something incorrectly. Only when the sun came up this morning would I know. Great was my relieve when the GTI started up at around sun rise!

The long and the short of the story: In my opinion Microcare manuals do not have a lot of information it them. Yes its got the specs and all that stuff in you need to design a system, but very little about operating the system. In fact, I promised my wife that I would write a small "operating guide" for the system and keep it right next to the GTI  (in the "server room" as she terms it). I think its very important that everyone in the house knows how to operate it and exactly what to do if something goes wrong!

Another observation:

I've  have picked that even with the Grid Tied Limiter there is still a small amount of back flow into the grid. I am one of the fortunate few that still have a very very old electricity meter (spinning disk). When I checked this afternoon I could see it spinning backwards ever so slightly.

The Grid Tied Limiter does have a couple of settings that you can use to compensate for this. You can adjust (using dip switches) the amount of electricity it should allow to be pulled from the Grid. You can set it to 0 Watts (This is my setting currently), 50 Watts or 100 Watts. If for example, If the system is capable of producing 2000 W (nice sunny day) and you have this setting set to 100 W and you load is only 500W, the GTI will be limited to produce only 400W of the 500W load, the remaining 100W will be pulled from the grid. (This is according to the manual). I suspect they've put this option in so you can "calibrate" the Grid Tied Limiter to prevent your system from pushing anything back into the grid?

I've also read that some of the prepaid meters do trip if it detects you are pushing back into the grid. So I guess you would then rather set the Grid Tied Limiter to 50W or 100W if you have one of those meters.

 

Thanks for the feedback. Always good to get actual product feedback straight from the proverbial horses mouth.

Why do you still have power going back ? The Infini does not do that. Is the setup correct ?

On 2016/04/30 at 8:32 PM, jdp said:

Why do you still have power going back ? The Infini does not do that. Is the setup correct ?

@jdp I am not sure why I still have power flowing back. But I must say its really not a lot. The wheel is turning backwards but very very slowly. The grid tied limiter is definitely limiting the power produced by the GTI.

I suspect it has to do with calibration. It might be that the grid tie limiter's or Wh meter's calibration is slightly off. This is the most likely explanation.

I have an efergy energy monitor. it measures the apparent power NOT the real power. It does this by only measuring the Amps that flow through the live wire and then approximates the power by just multiplying it by 240V (in my case) to get to the Watts. It assumes a power factor of 1 (volts and amps 100% in phase) It does not give accurate measurements when the power factor is < 1 (Volts and amps not completely in phase). Also It can not determine the direction in which the amps are flowing, just that it is flowing. So it can not distinguish between the GTI pushing power back on the grid, or the load pulling power from the grid.

What I do see is that the efergy meter is recording about 2 amps (480 Watts/240 Volts) going through the municipal connection. But when I look a the electricity meter its standing still (or very close to). What this tells me is that the 2 Amp AC current must be very close to 90 degrees out of phase with the Volts and therefor the power factor should be very low.

Would it be advisable to put in some PF correction devices or would it be fine to leave it as it is?

The assumption I am making is that the normal electricity meters (Wh meters) only measure the Real power (W = Volts * Amps in phase). Is this correct?

I like the efergy monitor and the app that I can install on my phone but I do not like the fact that its not accurately give me information about Real power, power factor, voltage, frequency etc. Any suggestions about what could provide me with more accurate measurements?

 

 

Have you measured it with a meter? It may not be a lot but still enough to give a unsuspecting municipal worker a jolt.

Quote

Any suggestions about what could provide me with more accurate measurements?

I use the Exsolar EM502 monitor (http://www.exsolar.co.za/products/monitoring-devices/advanced-energy-monitor-exsolar-em502/), it can measure the power factor of one circuit. In total it can measure three AC circuits and one DC. The CT's are directional and I use it to check my grid feeding vs. consumption on a daily/monthly basis.

Cobus

5 hours ago, cvzyl said:

The CT's are directional

CTs are always directional... problem is that unless you also have a voltage signal, the direction doesn't help, because with AC the direction changes 100 times a second anyway... it is only when you compare the phase angle between that signal and the voltage signal that you can calculate the power vector, and only then do you know which way it is going. :-)

9 hours ago, jdp said:

It may not be a lot but still enough to give a unsuspecting municipal worker a jolt

Anti-islanding should take care of that, not? When an islanding event occurs, it will stop pushing back those few watts.

I concur with others here: Likely due to power factor being far from 1, so a little bit of real power is flowing back while no apparent power is going back. The disc meters measure real power, because apparent power doesn't make real magnetism :-)

Thanks plonkster

I know very little about these things, only thing I now is that it gives me a positive or negative reading, something the Efergy monitors did not do. Not measuring voltage explains why.

C

Thanks Plonkster, Cobus,

I'll try to get a hold of a proper energy monitor so I can see what is going on. Its the only way to be sure.

I've also noticed that on the municipal energy meter its written that it consumes 2 Watts. Now that started me thinking. What if its been calibrated to ignore the 2 Watts that it consumes. Now when the limiter is effectively zeroing out the real power (Amps) that runs through it, the meter runs backwards showing 2 Watts in reverse. I might be wrong, but I'll test it.

The meter also gives the number of revolutions for each kWh it registers. So what I'll do is measure the rpm of the meter turning back and using that to calculate the Watts its recording. I suspect the answer will be 2 Watts.  If it is then it means the meter has been calibrated to show 2 Watts less than the actual. Since the the Limiter attempts to keep the load at 0 Watts it would explain why the meter registers -2 Watts.

I'll measure it and let you know.

 

22 hours ago, cvzyl said:

only thing I now is that it gives me a positive or negative reading

Short story long... If you take a two-channel oscilloscope, a step-down transformer, and a Current transformer, and you set the oscilloscope up to plot both the voltage waveform (from the step-down transformer) and the current waveform (from the current transformer), you would expect to see a sine wave for both, right?

For a load with a power factor of one, the current waveform and the voltage waveform will be exactly on top of each other, the will swing positive at the same time, and negative at the same time, and pass through zero at the same time.

If your power factor is not one (you have a capacitive or inductive load), the current waveform will sit a little to the left or the right of the voltage waveform, but it will still be more or less on the same side, that is both waveforms will be in the positive side or negative side at the same time.

Now... when you push back, you will see the two waveforms go so far out of sync that the current is going negative when the voltage goes positive. This is how you know that you're feeding back. And that is why in basic terms you cannot know which way the power is going unless you measure both the waveforms.

:-)

A quick update:

My system has now been running for just over a week and I am exceedingly happy with it. Its performing better than I expected it would. When I first moved into my house. I was consuming over 1000 kWh on average a month. After installing the solar geyser, fitting LED lights, installing the gas stove etc. my monthly consumption dropped to around 300 kWh. In the fist week of operation the Grid Tied system produced 52kWh. (It could have done more but the limiter restricts it to produce only what is consumed). Considering Sunday was mostly overcast its not too bad. If in one week it saved me just over 50kWh, It should be able to save me just over 200kWh a month, leaving only 100kWh drawn from the municipality

My wife  has taken a keen interest in the system. She asked me how she can schedule the washing machine and dishwasher to run during the day. (These are the two largest energy consumers that still run at night during the week). Unfortunately the ones we have can not be programed to start at a given time of day. I'll have to replace them if we want to be able to do that. It'll have to wait for the piggy-bank to fill up first :-)

Over the weekend I collected the inverter generator ( 3.5 kVA). Last night I completed the wiring for the generator and will test it this afternoon. (GTI will be switched off when running on generator).

 

4 hours ago, Janma said:

Unfortunately the ones we have can not be programed to start at a given time of day. I'll have to replace them if we want to be able to do that. It'll have to wait for the piggy-bank to fill up first :-)

Once could use one off these timer switches (plug) to schedule it 

Hi Manie, the timer switches should work well with the "electromechanical dial type" washing machines and dish washers. I still have a tumble dryer that I can set up that way.

Unfortunately it does not seem to work so well with the newer electronically programmable ones.  Once the power is cut to the machine  the program you set is erased. It also does not start a cycle unless you press the start button. :-(

The other options I guess would be to have a arduino or RPi power a small servo motor that will actuate a "finger" device that press the "start" button on the machine.. It would be fun to build it but unfortunately I do not have the time to play..  Also I don't think my wife will like the idea of such a "contraption" attached to her washing machine as much as I'd like it

 

Lol yes very true, the new ones does not have the dial , so its going to be hard to do that. Lol maybe you must put n nice red light there by the washing machine when the pv produce a lot, the red light will shine nice and bright and then your wife will know she can start the washing   (Just joking) 

Well done on your setup, guess Eskom will not make a lot out of you anymore 

Janma I had the same problem. that is why I looked at switching things on and off from AICC, The way around was as you say build a micro controller rig that is wired into the kit. Now that I am on Infini I no longer have that problem and may not even get to the automation parts as I don't need it.

@jdp Thanks, if I had to do it over again i would most likely go with the infini 5kw. For now the microcare GTI will have to do. I must say I am happy with it and it is performing better than I expected.

If I move as much of my energy consumption to during sunlight hours it would not be a bad thing, even if I go for the Infini later. It's always more cost effective and efficient to consume the power you are generating immediately rather than storing it for later use. In the end you would need a smaller battery bank or lower DoD to run only the bare minimum at night. Well, that's my thinking anyway.

With GTI eskom is your battery. You just have batteries for load shedding.

On 2016/04/08 at 4:05 PM, Janma said:

Yes, the plan is to only change the batteries during the day while the grid tied is producing power. But that is still some time away. For now I'll be happy with just the grid tied during the day.

When I started investigating PV solar options I stumbled upon the MLT drives Powerstar system. What a nice piece of kit! but expensive! I just could not justify spending that amount of money on the system, but liked the idea that it could manage all the energy sources. Municipal feed, Generator, Solar, wind whatever and then manage the flow of energy from source to load. If money was not an option I would do something like that. The problem I had with it is that if you want to do this kind of thing with a "central power management system" that should be able to manage ALL the load (Lots of amps going trough it, large battery banks = lots of money.) Also if that one piece of equipment breaks the whole system is down. It also needs to be sized so that it can handle the entire load all the time.

 

The other thing I looked at was to only do it for a subset of the load. The moment you want to power ALL the loads in the house the battery bank gets really large! So to keep the size of the batteries small enough one would only put the "Essential" loads on the inverter. Something like this:

In this case the inverter is smaller (cheeper) the battery bank is also smaller (cheeper) but the PV you attach to it can only ever power the essential loads. If you have underfloor heating installed you would not want to attach that as a load to your inverter.

That's why I like this option:

 

The PV via the Grid Tied inverter can be used to power any and all load in the house (Swimming pool pump, geyser, underfloor heating etc). If its large enough and the sun shines you have power. The PV has a life expectancy of 25 years. ROI of that part of the system is quite good (over time it will pay itself off). The batteries on the other hand is the "expensive part" as you would have to replace them every so many years. The thing I like about this AC coupled system is that you can "choose" the size of of the essential load and thus the size of the inverter/battery bank. You also "choose" the size of the PV/Grid Tied side of the system.  The smaller the inverter/battery bank side of the system is the better the overall ROI for the system. For now I will not have an inverter/battery bank, just the GTI and therefor optimal ROI. (Or so I'd like to belief ;-) )

 

If I may ask why do you have 2 "inverters"? or rather 2 different cct's

On 2016/04/10 at 1:01 AM, plonkster said:

Its a Triac with an opto-isolator for isolation :-) About R20 worth of guts... :-)

SSRs usually have very small leakage currents (typically few micro-amperes) while they are off.  I am not sure if it can effect any kind of sensing of GTI or any other devices, but it is just an aspect to consider before using them.