SilverNodashi

Price?

yea. my wife miss those "lights off evenings". Somehow it just too much trouble to walk over to the garage and switch off the inverter once in a while. Suppose I could do it now and then. I learned, a bit earlier this evening, that our suburb was without power all day long! Had no idea till someone on the whatsup group asked what time the power will be restored. Apparently there is / was a faulty cable somewhere?

And you also get to enjoy a nice romantic candle lit dinner every once in a while, for free

Rather see that as discount on your investment. AFAIK, COCT charge a monthly fee for grid tie as well. And you need to use more energy than you feed back before they pay out.

Mike, have you bothered using the Infinisolar inverters again?

your line fee is / was cheap. On the farm, we used to pay R1500pm, upto November when I installed a nice 9Kw PV array + 4x Axperst inverters

Another cost, which many fail to think about, is that a solar system adds value to your life. I'm not talking about direct savings from Eskom, alone. Think about this: My wife's office is at home, and every time she had to start the genset, or drive to a mall to work, she lost valuable time. And spent money on petrol for the genset (in 2008 we averaged on about R1200/pm on petrol!), unnecessary running costs on the car, unnecessary coffee + snacks money, etc. The time she lost with all of this is worth more than what was spent just to work. As an ex-IT support engineer, we used to charge R900/hour for consulting / support. So, 30 minutes TO the mall, 30 minutes to setup + shutdown & pay afterward, and then another 30 minutes back = R1350 LOST. And you can't claim that from SARS either. Her hourly fees are quite a bit less, as a webmaster / marketer, and art teacher. But it's still more expensive than trying to get working again after being disrupted due to downtime. Now, let's take it to the next level: Friend of mine has an engineering shop. We calculated one day, if they were "offline" for 4 hours, they lost about R40K, just on the jobs that stood still. Wages and other problems that arose from it also cost extra money. One client runs a restaurant. He also said they lost between R30k and R60k, everytime there was load shedding, depending on which day it happened. i.e. Fridays and Saturdays they lost the most. Their R250K "loadshed kit" was a no brainer. The mall didn't allow for solar panels or generators, so they got a nice big battery bank and couple 3 phase inverters to run their shop. Here you can't work on R/Kwh alone.

Interestingly I used to have the exact solar system running our gate motor, garage motor and 2x 10W flood lights - it worked very well for many years more than what they battery should have lased. Only difference: I had to upgrade to a 50W panel (the cost between 10W -> 20W and 10W -> 50W was marginal) due to a tree, in winter which shaded the panel till about 11am. The wires was already in place and I was too lazy to run new wires to a different spot, on a different roof. I used a cheap (R110?) 10A PWM charger (still have it. still use it to charge car batteries) . A couple years ago when I put up a big solar system, that same panel and charge controller was installed at my mother's place.

Can you solder? Check this out: https://www.robotics.org.za/index.php?route=product/product&path=237&product_id=1514 Or this: https://www.robotics.org.za/index.php?route=product/product&path=237&product_id=1200

Maar `n Tata met `n Toyota motor ry tog soooo lekker. Lexus is mos Toyota, is dit nie? P.S. I read to the end, where TTT said we derailed the thread to cars, again, before I made that comment!

There's a GSM shield as well

True. Another, much simpler, but more expensive approach: Centurion has a GSM intercom. I use one for something similar, but with the intercom itself disabled (took the speaker & mic out). I can phone it to do something, or SMS it todo something else - in this case switch on a pump on the farm. The nice thing about it, is that the intercom is connected to the solar battery so I can send an sms to the intercom and get a voltage update as well. This one has two relays, which can be open / close as needed, and I had one spare

75Kw is a bit small for a mine, unless it's a small mine. The figures are more or less on par. In this case, perhaps 1.8 bar. It's for a flat complex

You could also just use a 12V day/night sensor to switch on the DVR! Much cheaper, and with less work Put both the phone and the day/night sensor in a dark container and it will trigger as soon as the phone rings. Then, if you want to, add a "delay off" circuit and set it to 30 minutes or whatever you need to ensure long enough recording. Stick the DVR + CCTV on a 12V battery to make life easier as well. BUT, with the Arduino you now have the ability todo some other stuff as well.

Your observation is 100% correct, which is why, on smaller systems, standby batteries are fine. Eskom, is at this stage still cheaper and convenient enough to use at night. As said above, reduce your energy footprint, especially for night time usage and it will be fine.

haha, did you see what I said? 75Kw! That's a big, expensive installation. I don't think they'll have enough room for cheap lead acid batteries. we're looking at using 2V/4700Ah batteries

My neighbor duly measures his two battery banks (connected to 2x 5KW Microcare inverters) every morning, and every evening. Been serving him very well from day one and he occasionally drains it to 0, when it's cloudy / rainy, without any side effects.

I'm trying to convince a client, who wants to setup a 75Kw solar farm, not to buy "training batteries" as you call them. But now that I think about it, it may possibly not be a bad idea since it will cheaper on the whole setup and give them 2-3 years to save up for the right stuff later

On bigger systems, taking reading frequently (even daily!) will quickly help detect problems which you may not otherwise see / detect.

how's this project coming along?

Perhaps you should share a link to your feed so others can see how it works?

Why not? Is it purely taking too long to boil the water (due to the fact that it has a smaller element), or does it not reach boiling point (i.e. 100 degrees Celsius)?

Perhaps you can use the 2.2Kw kettle now?

I would use a "radio link" to open a engage with a buzzer closer to home. Something like this: http://www.communica.co.za/catalog/Details/P1929638763 Essentially it works the same as a gate / garage motor remote, but you can trigger it direcrly from the buzzer inputs. The receiver then connects to a relay to power a siren. This one has a built-in relay: http://netram.co.za/1869-codec-adaptive-wireless-relay-315mhz.html But you need a seperate 315Mhz transmitter, like this: http://netram.co.za/1148-315mhz-rf-link-kit.html but it has a 100m range outdoors. Similar kit with longer ranges can be acquired as well.

Yes. Earthing is a topic completely on it's own. Different areas (i.e. towns / provinces / mountainous / city / etc / etc) all have different earthing requirements. Sometimes you need to sink a spike 2m or more before you get good earth. In some areas you'll see an earth rod right around the roof, up the one wall, down the other wall, essentially creating an earth mesh around the house. In some cases you need to put a couple spikes in, 2m or 3m apart, in a square or rectangular fashion, and an earth wire joining them together. Together with that you get a Type I, a Type II, Type III and Type I + II surge arrestor. Again, each one is used in a different scenario, depending on where you live, what the lighting is like in the area, is there a lot of metal in the ground, what other taller / lower buildings are close-by, etc, etc. And then there's some calculations and measurements you need to make, to determine how far from the panels / combiner box / DB box the earth spike should go, this is referred to as separation distance, which again will be different from site to site, installation to installation. The most common question asked: Do you use 4mm or 6mm earth cable? 10m or 20m? It's REALLY simple, create a path with the least amount of resistance from your equipment to the ground. Look here: https://www.dehn-international.com/en/roof-mounted-systems-building-without-external-lightning-protection-system http://www.ee.co.za/article/lightning-surge-protection-rooftop-pv-systems.html