Janma

We all know that in SA there are two types of electricity supply. Single phase and Three phase. What most people don't know is that when it comes to how the "earth" is supplied there are also different ways. (All legal and above board). One of which is tapping a wire off the neutral and supplying it as a earth wire to the consumer.
When you have a 3 phase power supply you will have 4 (or 5 wires) coming from the municipality. 3 of them are the live phases, one of them is Neutral. The three phases (live wires) will have 230 Vac relative to the Neutral wire. Remember Voltage is always measured between two points. In this case a Live phase wire and Neutral. In the distribution network the Neutral is always considered as the reference voltage (0V). But by convention the Earth (the planet) can also be used as a reference voltage 0V. It would be a very bad thing if the Neutral wire would be at a much higher voltage than the earth... So what Eskom does is they earth the neutral wire that come out of the generator. They also earth the neutral at various points in the distribution network. This is to ensure that the voltage difference between neutral and the real earth is very close to 0V. So in theory there is nothing wrong with splitting the Neutral wire into two, one they give you is labeled earth and the other is labeled neutral. (This is fine because the neutral is suppose to be earthed further up stream in the distribution network.) In an ideal world this would be the end of the story.... but..
Here's a little test you can do. Take a volt meter and switch it to measure mV. Now take the two leads about a meter apart and see what it measures. It will most likely never be 0V. The further apart the two points you measure the higher the voltage can be..  Depending from how far you are from the point where they earthed the neutral and how well its earthed you may find that there is a voltage difference between the Neutral and the real earth at your property. Typically this should be a small voltage difference.
The thing that really mess things up is when they steal cables.. If they break the neutral cable before they break the live cables you can potentially get hundreds of volts on the neutral wire and serous voltage differences between a given live and neutral wire!  This is because breaking the neutral cable they've effectively disconnected it from the ground.
In many cases (such as yours) the earth wire that you get from the municipality is nothing other than the Neutral wire. In addition to them bonding it to the earth, it is also connected to all the metal fittings in your house and all the other houses, all these fittings are connected to the earth really, so they all pull down the voltage of the neutral/earth back down to 0V relative to the earth. The problem comes in when its not done this way and the neutral is not bonded to earth properly in the distribution network...
If your sparky picked up that there is a high voltage between the earth/neutral supplied by the municipality/eskom and the real earth it could point to a wiring fault on the local distribution network. If I were you I'll contact the municipality and ask them to check it out.
Normally your appliances (inverter, fridges etc) would not be affected. They only really use the live and neutral to operate, they only care about the voltage difference between those two wires. The problem comes in with the earth wire you get from the municipality, if its connected to the metal casing of the fridge for example and you touch it you might not like it very much.
In theory the earth you get from the eskom/munisipality should be at very close to 0V relative to the earth and it should be perfectly acceptable to use it in your DB and for grounding your PV panels etc. It should be okay to connect it to your own earth spike as well. In your case I would not do that until the municipality had a look at why the earth/neutral is at high voltage.
 

At long last.. I've completed the wiring and installation. I switched on the system this morning and by 6:23 am the GTI started producing power. By 7:20 am it stated limiting so it was already matching my consumption. Very happy indeed.

Jaco I would suggest doing both. Have a wire running from the panels directly to an earth spike then have a separate wire connecting the earth spike to the AC earth in your DB as well.
Nope, I would not do that unless the inverter/charge controller's documentation explicitly instruct you to do so.

We did it. It has been a 5 year journey. I want to thank each and every member for making this possible.
To the future and sharing knowledge! . Find The attached. We will add the description tomorrow.
Magnum Opus.
Sincerely
Jason

in these and other cases pumping grey water to a holding tank at a higher elevation will in fact be the solution IF it doesn't damage the pump [dirt, hair etc] and doesn't start stinking to high heaven. regarding the latter the ionization process might be an option, something @SilverNodashi inquired about. from the holding tank the water can be gravity-fed even to the veggie garden as even the e coli will be neutralized by the positively charged ions; i mean some hospitals use it [ionization] to zap legionnaires disease in their water storage tanks. this report is very significant.
just had 13.5mm rain in vredenburg!
God bless
gabriel

hi @SilverNodashi, i used to collect my grey water in a 260l drum prior to having it flow [gravity fed] via hose pipe into a section of garden [all indigenous by now, no grass anymore] - this changed as from yesterday... most grey water now flows via 50mm>40mm>15mm pipes into the garden directly. the 15mm black [class 3 plastic] pipes are laid every 500mm off the 40mm pvc with small valves in order to control flow. the 15mm pipes are closed at the end and have small holes in order to let the water through to the plants.
gone is the schlepp of moving around a very low pressure hose pipe from bossie to bossie, all that needs to be done now is open and close some valves every other day.
the washing machine run-off goes into the wife's vegetable garden and the dish washing water runs to eight trees [well, they are just seedlings at this stage...]
the first couple of liters of cold water in the shower is caught in buckets for flushing the toilet...

I spoke to one of the Victron guys earlier this year about it and he said they didn't have immediate plans to accommodate the South African regulations. So I'm not sure, but that's directly from them. 
Yes you're right it doesn't make it a bad inverter, it's just our regulation that doesn't accommodate it. And, perhaps, the regulation is like that to accommodate the "less knowledgeable people" in the industry? What I'm hinting at, is that Solar / renewable energy is still a fairly new concept, on this scale, in South Africa. The knowledge is still limited. So to protect everyone (linesman, industries, importers, etc) they are probably a bit more strict, at this stage, till everyone is comfortable with these products?

Update: I've just returned from a site visit and instead of 50 people using the system, there are now 90 people using it daily. They have used 244000l of hot water in just over a month (no water restrictions there!) so we are pretty chuffed that the system has held up with the added demand.

The Axperts, also made by Voltronic, had this issue and it was fixed by a firmware update. @superdiy, maybe you're thinking of them, but maybe all their products from that period (2015?) had this issue. It may have been a desperation fix for some issue, and I'm blanking on what that was. Overcharging batteries comes to mind, but I can't see how the two are related. 
Edit: maybe it was overheating due to fan failures, that they fixed with coating some fan connectors. Still makes little sense. 

It's quite a while now that I look at the Ingecon Sun Storage 1 play 6kw as a hybrid inverter option. It does however have one or two drawbacks. You need to have a 96 V battery bank and the inveter cannot run without batteries like the Infini's. It also have only one MPPT compared to the two of most 5 kw inverters. I would also like to hear from someone who has got experience with the product. Where did you get your price from Hein?

Hi Chris,
I agree. You are talking about a ground loop. These can pose a serious problem. You do not want multiple paths to the ground which will cause a loop. Yes any lightning strike close to it would cause a current to flow in the loop, frying any equipment in attached in the loop.
Lighting will induce a current in any conductive loop within the magnetic field flux. In my case I have a rater large irrigation system with a central controler. There are wires running from the controller to all the irrigation valves. These + & - wires form loops from the controller to the valve and back, very narrow ones but still they are loops. Any magnetic field flux through that loop will cause current to flow through it. But there is a trick, if you twist the wires around each other and you look at them from the side you'll see that that some places the + wire is on top and the - at the bottom, then other places the - will be on top and the + at the bottom. This will work like small loops. 50% of the loops will have the + wire on the top and the - wire at the bottom and 50% of the small loops will have the - wire at the top and the + at the bottom. Depending on the direction of the magnetic flux it will cause a current to flow either clockwise through the loops or anti-clockwise. But since the 50% of the loops are one way round and 50% the other way round the current cancel each other out. They use the exact same principle in Ethernet cables (twisted pair) to minimize interference of induced currents.  

We all know that in SA there are two types of electricity supply. Single phase and Three phase. What most people don't know is that when it comes to how the "earth" is supplied there are also different ways. (All legal and above board). One of which is tapping a wire off the neutral and supplying it as a earth wire to the consumer.
When you have a 3 phase power supply you will have 4 (or 5 wires) coming from the municipality. 3 of them are the live phases, one of them is Neutral. The three phases (live wires) will have 230 Vac relative to the Neutral wire. Remember Voltage is always measured between two points. In this case a Live phase wire and Neutral. In the distribution network the Neutral is always considered as the reference voltage (0V). But by convention the Earth (the planet) can also be used as a reference voltage 0V. It would be a very bad thing if the Neutral wire would be at a much higher voltage than the earth... So what Eskom does is they earth the neutral wire that come out of the generator. They also earth the neutral at various points in the distribution network. This is to ensure that the voltage difference between neutral and the real earth is very close to 0V. So in theory there is nothing wrong with splitting the Neutral wire into two, one they give you is labeled earth and the other is labeled neutral. (This is fine because the neutral is suppose to be earthed further up stream in the distribution network.) In an ideal world this would be the end of the story.... but..
Here's a little test you can do. Take a volt meter and switch it to measure mV. Now take the two leads about a meter apart and see what it measures. It will most likely never be 0V. The further apart the two points you measure the higher the voltage can be..  Depending from how far you are from the point where they earthed the neutral and how well its earthed you may find that there is a voltage difference between the Neutral and the real earth at your property. Typically this should be a small voltage difference.
The thing that really mess things up is when they steal cables.. If they break the neutral cable before they break the live cables you can potentially get hundreds of volts on the neutral wire and serous voltage differences between a given live and neutral wire!  This is because breaking the neutral cable they've effectively disconnected it from the ground.
In many cases (such as yours) the earth wire that you get from the municipality is nothing other than the Neutral wire. In addition to them bonding it to the earth, it is also connected to all the metal fittings in your house and all the other houses, all these fittings are connected to the earth really, so they all pull down the voltage of the neutral/earth back down to 0V relative to the earth. The problem comes in when its not done this way and the neutral is not bonded to earth properly in the distribution network...
If your sparky picked up that there is a high voltage between the earth/neutral supplied by the municipality/eskom and the real earth it could point to a wiring fault on the local distribution network. If I were you I'll contact the municipality and ask them to check it out.
Normally your appliances (inverter, fridges etc) would not be affected. They only really use the live and neutral to operate, they only care about the voltage difference between those two wires. The problem comes in with the earth wire you get from the municipality, if its connected to the metal casing of the fridge for example and you touch it you might not like it very much.
In theory the earth you get from the eskom/munisipality should be at very close to 0V relative to the earth and it should be perfectly acceptable to use it in your DB and for grounding your PV panels etc. It should be okay to connect it to your own earth spike as well. In your case I would not do that until the municipality had a look at why the earth/neutral is at high voltage.
 

Jaco I would suggest doing both. Have a wire running from the panels directly to an earth spike then have a separate wire connecting the earth spike to the AC earth in your DB as well.
Nope, I would not do that unless the inverter/charge controller's documentation explicitly instruct you to do so.

So I got the Geywerwise MPPT system.
 
So far I am impressed. Working well, even in winter. We using a 1kw  array (6x170W 85V panels in parallel) making roughly 5kw per day for the geyser. 
I have the geyserwise set to only 45 degrees on AC, and timers are from 6am to 9am and 7pm to 9pm. 
AC element goes on for 45min max on a day where we both take long showers at night. Most days AC element doesn't come on and infact I left the breaker off for 5 days with no noticeable cold showers.
The DC element heats the water up by around 20 degrees a day. We have a 200L geyser. We "use" around 3-6 degrees per shower. 
So on a typical day geyser is around 48 in the morning. At around 6:30am geyserwise senses enough light and turns DC element on. DC element heats water at +/-3 degrees per hour peak and at 5pm temp is around 65-70 degrees. By 8pm when we shower geyser has lost 3-4 degrees (We haven't installed a geyser blanket yet). After showers geyser is 50-55 degrees and by 6 the next morning its in the high 40s and the DC element turns on again. The only time the AC element comes on is if we had long showers the night before and the temp drops below 45 degrees at 6am.
 
I have ordered some 40amp DC SSR to play around with on our 100L kitchen/out building geyser.
 
One thing to note with the Titanium PTC element: We got the 2200W AC/DC version. When the AC side comes on, it initially draws 4kw and over the space of 30 seconds it slowly decreases to the 2.2kw stated spec. Must be something to do with PTC chips resistance

We all know that in SA there are two types of electricity supply. Single phase and Three phase. What most people don't know is that when it comes to how the "earth" is supplied there are also different ways. (All legal and above board). One of which is tapping a wire off the neutral and supplying it as a earth wire to the consumer.
When you have a 3 phase power supply you will have 4 (or 5 wires) coming from the municipality. 3 of them are the live phases, one of them is Neutral. The three phases (live wires) will have 230 Vac relative to the Neutral wire. Remember Voltage is always measured between two points. In this case a Live phase wire and Neutral. In the distribution network the Neutral is always considered as the reference voltage (0V). But by convention the Earth (the planet) can also be used as a reference voltage 0V. It would be a very bad thing if the Neutral wire would be at a much higher voltage than the earth... So what Eskom does is they earth the neutral wire that come out of the generator. They also earth the neutral at various points in the distribution network. This is to ensure that the voltage difference between neutral and the real earth is very close to 0V. So in theory there is nothing wrong with splitting the Neutral wire into two, one they give you is labeled earth and the other is labeled neutral. (This is fine because the neutral is suppose to be earthed further up stream in the distribution network.) In an ideal world this would be the end of the story.... but..
Here's a little test you can do. Take a volt meter and switch it to measure mV. Now take the two leads about a meter apart and see what it measures. It will most likely never be 0V. The further apart the two points you measure the higher the voltage can be..  Depending from how far you are from the point where they earthed the neutral and how well its earthed you may find that there is a voltage difference between the Neutral and the real earth at your property. Typically this should be a small voltage difference.
The thing that really mess things up is when they steal cables.. If they break the neutral cable before they break the live cables you can potentially get hundreds of volts on the neutral wire and serous voltage differences between a given live and neutral wire!  This is because breaking the neutral cable they've effectively disconnected it from the ground.
In many cases (such as yours) the earth wire that you get from the municipality is nothing other than the Neutral wire. In addition to them bonding it to the earth, it is also connected to all the metal fittings in your house and all the other houses, all these fittings are connected to the earth really, so they all pull down the voltage of the neutral/earth back down to 0V relative to the earth. The problem comes in when its not done this way and the neutral is not bonded to earth properly in the distribution network...
If your sparky picked up that there is a high voltage between the earth/neutral supplied by the municipality/eskom and the real earth it could point to a wiring fault on the local distribution network. If I were you I'll contact the municipality and ask them to check it out.
Normally your appliances (inverter, fridges etc) would not be affected. They only really use the live and neutral to operate, they only care about the voltage difference between those two wires. The problem comes in with the earth wire you get from the municipality, if its connected to the metal casing of the fridge for example and you touch it you might not like it very much.
In theory the earth you get from the eskom/munisipality should be at very close to 0V relative to the earth and it should be perfectly acceptable to use it in your DB and for grounding your PV panels etc. It should be okay to connect it to your own earth spike as well. In your case I would not do that until the municipality had a look at why the earth/neutral is at high voltage.
 

Hi Chris,
I agree. You are talking about a ground loop. These can pose a serious problem. You do not want multiple paths to the ground which will cause a loop. Yes any lightning strike close to it would cause a current to flow in the loop, frying any equipment in attached in the loop.
Lighting will induce a current in any conductive loop within the magnetic field flux. In my case I have a rater large irrigation system with a central controler. There are wires running from the controller to all the irrigation valves. These + & - wires form loops from the controller to the valve and back, very narrow ones but still they are loops. Any magnetic field flux through that loop will cause current to flow through it. But there is a trick, if you twist the wires around each other and you look at them from the side you'll see that that some places the + wire is on top and the - at the bottom, then other places the - will be on top and the + at the bottom. This will work like small loops. 50% of the loops will have the + wire on the top and the - wire at the bottom and 50% of the small loops will have the - wire at the top and the + at the bottom. Depending on the direction of the magnetic flux it will cause a current to flow either clockwise through the loops or anti-clockwise. But since the 50% of the loops are one way round and 50% the other way round the current cancel each other out. They use the exact same principle in Ethernet cables (twisted pair) to minimize interference of induced currents.  

Hi Janma
If you have a interconnected earth system it must only have one (or one set of earth spikes or grid). If the earth spikes are scattered a lightning strike sets up a earth potential gradient and current will flow up one spike through you equipment and down the other spike as this will be the path of least resistance.
 

I have an alternative suggestion: Eddy Currents. This ties in with the chair you were sitting on.
Physics: If you have a change in magnetic flux, any conductors in the immediate vicinity will have a current induced in them. This is why there is a rule that when using steel conduit, you must have both wires running in the same pipe (because the one cancels the other), otherwise the AC current (which produces a constantly changing magnetic flux around the wire according to the so-called right-hand rule) will induce current in the pipe.
In the same way, a lightning strike causes a small EMP wave when it strikes, and that induces eddy currents in all nearby conductors. I lost thousands of rands of network equipment once when lightning struck the building (6-story, so it likely had a steel core holding it up) and the little EMP wave induced currents in all the network wiring. I also lost a Modem (when we still used those) one day when a nearby lightning strike induced a spike in the overhead phone line. This I know because if it had been a direct strike, I'd have lost the computer too.
So back to your chair: It's possible that eddy currents induced in the chair is what got you. It's a wild guess, may or may not be the case. I'll just say I've seen a lot of damage from those things.

Second comment on earthing of the negative. Some things to understand.
1. On some inverters, usually the cheaper MSW ones, there might not be complete isolation between battery and grid. Remember also that neutral is tied to ground in your DB board. This happens with your so-called "transformerless" inverters, which has a non-isolating boost stage, or for the high-end GTIs (SMA et all), uses a high input voltage so no boost stage is necessary. With those inverters, your negative DC side ends up being connected (via the power electronics) to either live or neutral depending on what side of the AC-waveform you're currently producing. If you earth the negative, you literally short out the one bank of power FETs in the inverter.
2. Some inverters already ground the negative.
3. Charge controllers often have their current sensing in the negative line. If you ground both the battery and the PV line (or the inverter grounds the battery), you have just bypassed your current sensor and the MPPT cannot work properly.
Grounding is about picking up stray currents and shutting it down so you don't kill people. Your battery bank is at a fairly low voltage and unlikely to do that, so I see little point in grounding unless the inverter maker tells you to, and plenty of potential to severely f... things up if you don't know what you are doing :-)
Some video material, American grid, but still topical:
 

We all know that in SA there are two types of electricity supply. Single phase and Three phase. What most people don't know is that when it comes to how the "earth" is supplied there are also different ways. (All legal and above board). One of which is tapping a wire off the neutral and supplying it as a earth wire to the consumer.
When you have a 3 phase power supply you will have 4 (or 5 wires) coming from the municipality. 3 of them are the live phases, one of them is Neutral. The three phases (live wires) will have 230 Vac relative to the Neutral wire. Remember Voltage is always measured between two points. In this case a Live phase wire and Neutral. In the distribution network the Neutral is always considered as the reference voltage (0V). But by convention the Earth (the planet) can also be used as a reference voltage 0V. It would be a very bad thing if the Neutral wire would be at a much higher voltage than the earth... So what Eskom does is they earth the neutral wire that come out of the generator. They also earth the neutral at various points in the distribution network. This is to ensure that the voltage difference between neutral and the real earth is very close to 0V. So in theory there is nothing wrong with splitting the Neutral wire into two, one they give you is labeled earth and the other is labeled neutral. (This is fine because the neutral is suppose to be earthed further up stream in the distribution network.) In an ideal world this would be the end of the story.... but..
Here's a little test you can do. Take a volt meter and switch it to measure mV. Now take the two leads about a meter apart and see what it measures. It will most likely never be 0V. The further apart the two points you measure the higher the voltage can be..  Depending from how far you are from the point where they earthed the neutral and how well its earthed you may find that there is a voltage difference between the Neutral and the real earth at your property. Typically this should be a small voltage difference.
The thing that really mess things up is when they steal cables.. If they break the neutral cable before they break the live cables you can potentially get hundreds of volts on the neutral wire and serous voltage differences between a given live and neutral wire!  This is because breaking the neutral cable they've effectively disconnected it from the ground.
In many cases (such as yours) the earth wire that you get from the municipality is nothing other than the Neutral wire. In addition to them bonding it to the earth, it is also connected to all the metal fittings in your house and all the other houses, all these fittings are connected to the earth really, so they all pull down the voltage of the neutral/earth back down to 0V relative to the earth. The problem comes in when its not done this way and the neutral is not bonded to earth properly in the distribution network...
If your sparky picked up that there is a high voltage between the earth/neutral supplied by the municipality/eskom and the real earth it could point to a wiring fault on the local distribution network. If I were you I'll contact the municipality and ask them to check it out.
Normally your appliances (inverter, fridges etc) would not be affected. They only really use the live and neutral to operate, they only care about the voltage difference between those two wires. The problem comes in with the earth wire you get from the municipality, if its connected to the metal casing of the fridge for example and you touch it you might not like it very much.
In theory the earth you get from the eskom/munisipality should be at very close to 0V relative to the earth and it should be perfectly acceptable to use it in your DB and for grounding your PV panels etc. It should be okay to connect it to your own earth spike as well. In your case I would not do that until the municipality had a look at why the earth/neutral is at high voltage.
 

Jaco I would suggest doing both. Have a wire running from the panels directly to an earth spike then have a separate wire connecting the earth spike to the AC earth in your DB as well.
Nope, I would not do that unless the inverter/charge controller's documentation explicitly instruct you to do so.

When it comes to lightning there are more than one way that it can damage equipment and people. I think all of us know about the direct strike between the clouds and the top of trees/houses or whatever. The reason there is a strike is there is a potential/voltage difference between two points (the cloud and the tree). Normally air is a very good insulator that prevents current from flowing, but there comes a point where the voltage difference is just to big that even air can't prevent the current from starting to flow. The amount of current that flows when this happens is enormous! You are talking kilo/mega amps flowing for a fraction of a second and then stops.
When current flows it causes an magnetic field to build up around it (this is what happens in a transformer). Now imagine how strong that magnetic field is when such a large current flows. The closer you are to the actual lightning bolt the stronger that magnetic field. If you have a conductor in that magnetic field and the field does not change nothing will happen, but when the magnetic field changes in strength or direction, it will induce a current/voltage in any conductor in side the field. This is how a transformer works. The current through the primary winding changes (AC) and that causes the magnetic field in the transformer core to change. The changing of the magnetic field causes a voltage/current to flow in the secondary coil even though its isolated from the primary coil. (Induced current will flow).  Those old iron core transformer based welding machines is a very good example of how strong an induced current can be - we weld metal with it...
Now lets see what happens when you have two earth circuits in your house that are not bonded together. The first is your normal AC earth that is connected to the grid earth. The second consist of an earth spike that has a wire running up to your PV panels. The key here is they are not connected. Now lets assume there is a lightning strike very close to your home, it causes a very strong magnetic field for a brief moment. This induces a voltage across the AC earth wire as well as a voltage across the PV panel earth wire. The voltages will NOT be the same (magnetic field is not the same everywhere and the wire lengths are not the same either).  There may be quite a big difference between the two (anything from a couple of volts to a couple of thousand volts or even higher). If someone were to touch the PV panels and the AC earth at that time, they may not be able to tell you how about how it felt afterwards...  The same applies to an inverter or charge controler that is in close proximity (electrically speaking) to the AC earth and the PV panel earth. If the induced voltage difference between the two earth systems is high enough it may find/make a path from the one to the other. That path can be via a cutter, inverter, or a person. 
Connecting the PV Panel earth, to the AC earth gives induced lighting voltages a controlled route through which to dissipate. Its better for that induced current to run via the wire connecting the two earths than through you or your equipment. That is the reason why you should ALWAYS make sure all the various earths are connected.
If it was a direct strike, you most likely would not have survived it. I might have been an induced strike as I've described above. The fact that you were wet (just out of the pool) and you were sitting on a metal chair made you a good conductor. If a lighting strike were very close it would have induced a current flowing through you and the chair. You were very lucky!

When it comes to lightning there are more than one way that it can damage equipment and people. I think all of us know about the direct strike between the clouds and the top of trees/houses or whatever. The reason there is a strike is there is a potential/voltage difference between two points (the cloud and the tree). Normally air is a very good insulator that prevents current from flowing, but there comes a point where the voltage difference is just to big that even air can't prevent the current from starting to flow. The amount of current that flows when this happens is enormous! You are talking kilo/mega amps flowing for a fraction of a second and then stops.
When current flows it causes an magnetic field to build up around it (this is what happens in a transformer). Now imagine how strong that magnetic field is when such a large current flows. The closer you are to the actual lightning bolt the stronger that magnetic field. If you have a conductor in that magnetic field and the field does not change nothing will happen, but when the magnetic field changes in strength or direction, it will induce a current/voltage in any conductor in side the field. This is how a transformer works. The current through the primary winding changes (AC) and that causes the magnetic field in the transformer core to change. The changing of the magnetic field causes a voltage/current to flow in the secondary coil even though its isolated from the primary coil. (Induced current will flow).  Those old iron core transformer based welding machines is a very good example of how strong an induced current can be - we weld metal with it...
Now lets see what happens when you have two earth circuits in your house that are not bonded together. The first is your normal AC earth that is connected to the grid earth. The second consist of an earth spike that has a wire running up to your PV panels. The key here is they are not connected. Now lets assume there is a lightning strike very close to your home, it causes a very strong magnetic field for a brief moment. This induces a voltage across the AC earth wire as well as a voltage across the PV panel earth wire. The voltages will NOT be the same (magnetic field is not the same everywhere and the wire lengths are not the same either).  There may be quite a big difference between the two (anything from a couple of volts to a couple of thousand volts or even higher). If someone were to touch the PV panels and the AC earth at that time, they may not be able to tell you how about how it felt afterwards...  The same applies to an inverter or charge controler that is in close proximity (electrically speaking) to the AC earth and the PV panel earth. If the induced voltage difference between the two earth systems is high enough it may find/make a path from the one to the other. That path can be via a cutter, inverter, or a person. 
Connecting the PV Panel earth, to the AC earth gives induced lighting voltages a controlled route through which to dissipate. Its better for that induced current to run via the wire connecting the two earths than through you or your equipment. That is the reason why you should ALWAYS make sure all the various earths are connected.
If it was a direct strike, you most likely would not have survived it. I might have been an induced strike as I've described above. The fact that you were wet (just out of the pool) and you were sitting on a metal chair made you a good conductor. If a lighting strike were very close it would have induced a current flowing through you and the chair. You were very lucky!

If you don't mix the panels in the right way you will loose a lot of power.  Here's why
Lets take the case where you have two types of panels 300W and 200W that you want to place in the same string. Lets assume the following is true for the two types of panels:
V open circuit300W = V open circuit 200W V max power300W = V max power 200W Then it follows that
I max power300W > I max power200W But since you put them in series, the current that will run though both of them will be the same. The MPPT will search for volt and amp combination that will produce the maximum power for the string. So what would happen is that the I max power string will be somewhere between the I max power300W and the I max power200W In other words not optimal for either of the two types of panels. The 300W panel will never produce 300W and the 200W panel will never produce 200W
Now if you put the 300W and 200W panels in separate strings (parallel). The voltage over both strings will be the same. The 300W strings will then contribute I max power300W and the 200W strings will contribute I max power200W. So both strings will run optimally.
There is one other way it can be done in the case were the following is true:
I closed circuit300W = I closed circuit200W I max power300W = I max power200W Then it follows that:
V max power300w > V max power200W If the above is true, then you should mix the 300W and 200W in the same string. Make sure each string has the same amount of 300W and 200W panels (the strings must be symmetrical)
The problem comes in when the panel's specs do not match up on the Volts or the Amps. Then it becomes quite difficult to ensure maximum power out of the strings.
 
 

A hint perhaps. Google "Itead Sonoff"...
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