# Interest group forums > Energy and Resource Conservation Forum >  Solar systems

## Isetech

After a couple weeks without electricity, load shedding, Tariff increases and a few other issues experienced resulting in darkness has made me realise that it is time to invest, yes invest in solar.

I have been involved in a few solar audits, which have resulted in really expensive upgrades, due to a lack of research into the customers usage, or just bad design. 

Before you go price hunting, which seems to be another issue with these systems, people try make a plan and cut costs, by not doing time of use energy audits. Instead they go for a one size fits all. If you have a R150 000.00 to waste on a system, that might do what you require, go wild. 

Something that I try tell all my customers, be it in a house, commercial building or factory, create a solid foundation then build on it. 

A couple of examples of why I say build a solid foundation: 

A CCTV system, dont get a "twister" (a name for installers who dont use junction boxes or mechanical means to secure joints, they just twist and tape) to do the foundation work, why, because when you decide to upgrade or add in devices etc, there is a good chance the connection will be twisted, the wire will be the cheapest tinned copper, there will be no camera boxes and no structured wiring layout, etc etc. 

An electrical installation, there is a good chance the twin+E is plastered directly into the wall, so if you want to add a switch or light point, you will have to cut the wall again or stick the wire to the wall, the Db will have no spare pipes in the wall and there is a good chance it will already to full to capacity, there are just so many issues we encounter which result in expensive solutions. 

I have found the same with solar/ PV (whatever you want to call it), if the installer has cut costs it could mean that the panel supports are screwed directly into a rectangular tube with rooking screws, no earthing, no surge protection, the type of wire is not suitable and not double insulated, the batteries inside the box are not what you were quoted, the electrical wiring is not up to code, the list just goes on and on.

This applies to anything, do the foundation right and build on it rather than cut costs and fit a  cheap crap system installed by a dodgy installer or supplied by some salesman only interested in making a quick buck. 

Make sure you understand what you looking for, do your homework, understand that unless you are prepared to spend a lot of money, there is not such thing as an off grid system.

Understand the difference between a backup system and a hybrid system. 

IF you decide to include a generator in the backup system, which is recommended if you want to your system to function without the mains during blackouts or long power outages or  days of rain. Make sure the generator is designed to charge the battery and keep the lights on or setup correctly. 

One the most common problems I come across, people panic buy during load shedding or long power outages. they rush out and pay premium price for crap which is just not suitable for their application, and boy do suppliers know when to load prices.

 I cant tell you how many generators are rusting in garages around the country, most wouldnt start if there was an outage. LED backup lights with dead batteries, because they have been left unplugged or not charged since the last outage. Fortunately for supplier people have credit cards and funding to piss against the wall, so there is a huge market to dump stuff. 

Here is a basic video of units of one of the systems we will be supplying and installing.

https://www.youtube.com/watch?v=IzD0...hannel=Sunsynk

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## Isetech

Installing a backup system without solar power in SA will NOT save you money unless you are on a time of use tariff, in fact your bill will increase due to standby power used by the system, losses and power required to recharge the batteries.

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## Isetech

I get this question a lot, can I use a UPS for load shedding, the simple answer would be no, why? because if you use a good quality UPS designed for computer backup, they are designed for a specific application, to allow sufficient time to shut down the computer (normally a couple of minutes). You could over spec the UPs by some crazy figue, but it would not be considered be a financially viable option. 

Most people dont know this, a UPs can save the information, close the program and shut down the PC, that is why it pays to buy a decent UPS for your computer or server. Some have software for you to monitor the battery SOC. 

The reason I mentioned this, so that people dont get confused with a UPs for a computer and a backup system for your house/office or factory. 

I am not going to go into modified and pure sine wave units, they each have their place in the market, personally I would rather just go with a pure sinewave unit.

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## Derlyn

Well, it seems as if I'm joining the PV crowd.

A good friend of mine passed away recently. Hi's wife is selling up and moving to a smaller place.
She asked me if I wouldn't please come and remove the solar system and it's mine, mahala.

I have just returned home from taking down.
Nothing special, but they have been using it for a couple of years for lighting and TV during loadshedding.

2 inverters.  A 1440 Watt Mecer and a 1000 Watt CB solar inverter.
4 x 100 Watt panels.
6 x 100 Ah batteries and a 20Amp regulator.

I'm gonna be playing some games here soon.  :Smile:  :Smile:

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## Derlyn

Ok, the questions start.
My small setup. 4x100watt panels connected 2 x 2 series panels connected in parrallel.

Micro Care LED 20A MPPT controller.

Tested 8.6 Amps from panels. Pass.
Voltage from panels. 41V.  Pass.

Cannot get more than 1A charge from controller. Boost led flashing continuosly. 

Any suggestions or ideas ?

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## Alfred M

Boost led flashing Mppt charger is in float mode your batteries are most probly fully charged what is the battery voltage of each 12 v battery individually

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## Alfred M



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## Derlyn

Ok, so the charger/controller I inherited was faulty.

Replaced it and getting a more respectable charging current.

I am playing games.
I have 2 inverters.   1. Mecer 1450W    2. CB Solar 1000W

I decided to check what each inverter draws from battery with no load.

Mecer 1,1 Amps         CB Solar 3 Amps

Mecer draws about a third of the current that CB solar draws.

In all the spec sheets I can find, the power consumption of the inverter itself is nowhere to be found, so I would not know if the CB solar is faulty or not.
It does what it's supposed to do, but I know it's drawing 2 more amps from the batteries than the Mecer. 

Does anyone know whether this is normal or not ?

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## Justloadit

I would put it down to the PWM to Sine wave filter and booster transformer, the higher output power, has a lower impedance in the boost transformer and filter, thereby drawing more energy from the battery to function.
60 to 100watts on standby is average for that type of inverter.

The higher the battery voltage the more efficient the inverters become, because the standby power becomes lower, as the switching devices have lower loses due to the lower current required.
As an example, in all the inverters, they use a IGBT, which has a fixed voltage drop of 1.25V, so at 12V to get 1000watts through the device, will yield a current of 83Amps, and a loss off 104W - that's 10% of the power you are using, now if we use say 48V as a source, the same 1000watts requires 20.8A yielding a loss off 26W, a huge difference. Not only that the power cables are smaller, and cheaper for the same output power.

This is the reason for any inverter, use the highest DC voltage you can buy, as the loses of the inverter gets lower meaning you get more time from your batteries to drive your load.

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## Derlyn

Thank you brother for that detailed reply. I also learn't about the IGBT transistor ( never knew such a thing existed ).

Like I said, I'm busy playing games with something that I have not been involved with before and enjoying every moment.

Trying to get as much out the batteries as possible without going past the recommended amount of discharge and also not using mains power to charge the batteries. Only panels.

I can see this keeping me occupied even more than what ham radio did.

Like a kid with a new toy.

Enjoy your day and thanks for the info.

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## Derlyn

My experiment for tomorrow.

Connect both inverters to same battery bank.

Connect identical loads to each inverter ( about 500W ) and then measure how much current is drawn by each inverter from the batteries.

The one with the lowest current will be my choice.

The other one goes on Gumtree 😁

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