Yesterday was my best yet, in Gauteng, how was yours? Just wondering...

Us Too. 40.788kw for the day

 

https://pvoutput.org/list.jsp?id=46371&sid=42296

Its these clear days with high UV. I have a built in UV sensor on the top of my bald head, so I can tell when solar production will be good!

I've never seen anything like that - though I note I get to 100% SOC earlier of late. I guess I need to burn more electricity 🙂

I am only doing about 5kWh a day  need more load....

55 minutes ago, Alejandro said:

Just wondering how much cheaper gas?

Hi , I am interested in your comment. How would you apply gas to replace Solar. We know about Gas geyser and Stove, but how to apply gas to lights, tv, aircon, swimming pool pump and borehole remains a mystery to me? 😜

54 minutes ago, Alejandro said:

Just wondering how much cheaper gas?

@plonkster has said that gas per unit costs the similar to Eskom per unit. And then you gas prices fluctuate as do their availability.

18 minutes ago, The Terrible Triplett said:

 has said that gas per unit costs the similar to Eskom per unit. And then you gas prices fluctuate as do their availability.

Everyone has to do their own math. What I did was through some internet research (TM) I found out that the calorific content of LPG is 46.1 MJ/kg, and if you divide that into 3600 (joules in a watt-hour) you get around 12.8kwh per kg of LPG.

Note that natural gas has a slightly higher energy content than LPG. We don't get natural gas by pipeline where I live, so I didn't bother to work it out.

That means a typical 9kg bottle of LPG has the equivalent of 115kWh of energy. It costs around R230 or so for a refill, which pretty much puts the price per unit of energy at R2/kWh. Cape Town charges me R2.02/kWh right now (below 600kWh) and R2.74/kWh above 600kWh. So already very similar in cost.

What makes it break down however is that gas is particularly inefficient when you're heating anything other than a room. Especially when cooking. The efficiency I'm talking about is how much of the energy makes it from the burning flame through the utensil and into the food you're cooking. An induction stove plate is by far the most efficient at that, a proper flat-plate electrical element with a right-size utensil is next... and gas is about half of any of the other. So the equivalent cooking cost with gas is more like R4/kWh.

Water heating does slightly better, but again: heating water electrically is pretty darn close to 100% efficient. Gas is nowhere near that.

So in my opinion, the only reason to go for gas is independence: So your not tied to grid power for hot water and food.

It's also cheaper to buy gas for the next few decades than installing a larger solar system. If you are hell-bent on not running your stove and geyser from grid power, gas might be an option.

And finally, gas burns much cleaner than coal (which we use for power stations). So that would be the third reason to do it.

Agree with everything Plonkster said except the comment: "It's also cheaper to buy gas for the next few decades than installing a larger solar system"

You got gas to come in at around R2/kWh - solar is much less, even with storage. And the solar cost would be fixed whereas gas is likely to go up. Financially gas makes no sense, especially compared to solar.

Edited September 20, 20196 yr by PeterP

Agreed, currently gas is equivalent to eskom, but solar gets cheaper so quickly, and fossil will only get more expensive, so do it now. You wont go wrong. I used to use gas for cooking and making coffee etc, but with solar and an induction plate gas gets used less and less.

Edited September 20, 20196 yr by DeepBass9

1 hour ago, DeepBass9 said:

... with solar and an induction plate gas gets used less and less.

Funny ... I was contemplating gas stove / oven as we have no stove, just induction plates and we don't seem to "get" the hang of them.

And we've had them for years.

Maybe we need to "get" the hang of the induction plates rather than gas. 

Will speak to SWAMBO.

Edited September 20, 20196 yr by Guest

15 hours ago, PeterP said:

Agree with everything Plonkster said except the comment: "It's also cheaper to buy gas for the next few decades than installing a larger solar system"

Yeah perhaps that requires some explanation. It's a bit like that time I bought a house in the neighbouring town, which added an extra 30km to my commute. The reason was that for the difference in house prices, I could buy a car AND 5 years of work-commute fuel 🙂

In the end it would have been cheaper to buy a house in Stellenbosch... but as it also turned out... work wasn't always going to be in Stellenbosch.

Similarly, for the 100k you'd spend extra on a solar installation so you can run the stove electrically... you can buy a heck of a lot of LPG. I agree with you that given enough time (and certainly now that solar is even cheaper than it was 5 years ago when I first did the math) solar is cheaper, but I can absolutely support the decision to move at least your cooking needs to LPG, even if it isn't cheaper.

What do you mean? A generator that works on gas?

2 hours ago, DeepBass9 said:

What do you mean? A generator that works on gas?

Hi DeepBass9, they are also available in SA, I looked at buying one  about a month ago, but after reading up on it, I decided against it.

1. Its got a lower efficiency than an equivalent  sized Petrol generator. 
2. Its got a very small gas tank and needs refilling quite often. 
3. There is very little people that can fix it when something goes wrong. A petrol generator you can just about take to any guy to repair, but from what I have read, when the gas parts start giving problems, you'll need and experienced guy to fix that.   

EDIT: I Just contacted the Supplier to get an idea of price. These were discontinued, they didn't give a clear answer why...

67.9KW/h yesterday in Somerset West from my array with a peak of 9KW at noon. Need to clean the panels. Getting there though...

Did a capacity test on my batteries - discharged to near zero (watching lowest voltage on a cell) so I had something to fully use my solar potential (charge batteries and supply loads).
Batteries fully charged at around 3 o'clock including finished absorption cycle !

Batteries took around 45KW/h to charge fully, the rest went into normal loads.

 

On 2019/09/26 at 7:26 AM, Jaco de Jongh said:

Hi DeepBass9, they are also available in SA, I looked at buying one  about a month ago, but after reading up on it, I decided against it.

1. Its got a lower efficiency than an equivalent  sized Petrol generator. 
2. Its got a very small gas tank and needs refilling quite often. 
3. There is very little people that can fix it when something goes wrong. A petrol generator you can just about take to any guy to repair, but from what I have read, when the gas parts start giving problems, you'll need and experienced guy to fix that.   

Some plusses though, from what I've read:

One being a much cleaner fuel so they tend to go longer without maintenance or stand longer.

Another being the fuel itself doesn't go off or age like diesel of petrol.

In an application that you rarely use, but you want it to definitely work when you do need it, I think it might have a place.

2 hours ago, The Bulldog said:

67.9KW/h yesterday in Somerset West from my array with a peak of 9KW at noon. Need to clean the panels. Getting there though...

Did a capacity test on my batteries - discharged to near zero (watching lowest voltage on a cell) so I had something to fully use my solar potential (charge batteries and supply loads).
Batteries fully charged at around 3 o'clock including finished absorption cycle !

Batteries took around 45KW/h to charge fully, the rest went into normal loads.

 

bliksem - Lightning!!

2 hours ago, Dex_ said:

bliksem - Lightning!!

O_o lol a moderator must have changed this ?

1 hour ago, Dex_ said:

O_o lol a moderator must have changed this ?

Hahahahaah!!! Hulle moes gese het Weerlig!!!!  

5 hours ago, The Bulldog said:

67.9KW/h yesterday in Somerset West from my array with a peak of 9KW at noon. Need to clean the panels. Getting there though...

Did a capacity test on my batteries - discharged to near zero (watching lowest voltage on a cell) so I had something to fully use my solar potential (charge batteries and supply loads).
Batteries fully charged at around 3 o'clock including finished absorption cycle !

Batteries took around 45KW/h to charge fully, the rest went into normal loads.

 

@The Bulldog What size system are you running? That some good power that!!

 

On 2019/09/20 at 9:32 PM, Guest said:

Funny ... I was contemplating gas stove / oven as we have no stove, just induction plates and we don't seem to "get" the hang of them.

Please excuse my ignorance, but how are induction plates different from regular electric plates atop a stove? And do they draw significantly less power?

If not then the real problem is that they may draw a lot from the batteries very quickly - which is why such things are typically not backed up in a grid tied scenario.

I don't think I've ever pulled more than about 10.5 kw/h out of my solar in a day - but we have capacity to spare. I figure this is no bad thing. On a sunny day when we're both at work, the battery will be fully charged by 11:00 at this time of the year, and then the panels derate and do just enough to service loads. But this means that if it's an overcast day or there's some unusual load (say the lawnmower) then we have a time buffer to allow the battery a better chance of being 100% charged when the panels stop generating useful power.

Highest I've seen is about 3200. I have a theoretical peak of 3900, but half the panels face north and the other half faces east, so I'll never see that peak, even for a split second.

43 minutes ago, Bobster said:

Please excuse my ignorance, but how are induction plates different from regular electric plates atop a stove? And do they draw significantly less power?

An induction plate is cold to the touch even when it is on. What it does is induce eddy currents in the utensil placed on top of it, causing that to heat. A bit like this cool tool.

It only works with metal containers and better with some than with others. It does not use much less power, but because the heat is generated in the utensil (rather than below it) you avoid the transfer loss. So it comes out slightly ahead of a flat plate element in the efficiency stakes.

I still find that people grossly overestimate the amount of electricity they actually use for cooking. The average household that cooks a pot of vegetables, rice and meat (as is typical in South Africa) three or four times a week will end up using less than  10% of overall use in the month for cooking. If your cooking is around 10% more efficient, that means a saving of 1% on the total bill . If you go with gas instead, it costs about 10% more (assuming my previous estimate of roughly half the efficiency to be accurate). Unless you measure carefully the difference is almost negligible.

How many times have you heard people tell you that gas is so efficient, they've been using a single 9kg bottle of LPG for 6 months now? Well, as we know, energy is neither created nor destroyed, and with 115kWh in that bottle, the electricity bill would have been about the same, and possibly quite a bit less (due to efficiency). But since nobody (or few-bodies) does a before and after test, everyone just marvels at how awesome the gas stove top is 🙂

Edited September 27, 20196 yr by plonkster

2 hours ago, Gerlach said:

@The Bulldog What size system are you running? That some good power that!!

 

Total of 42 panels - mixture of 250W  and 275W panels. That's all I could fit on the roof. Oh wait - there's West facing... Plonkster seems to think that not a bad direction either. Could squeeze another string of 14 panels there I think.

Ready to feed in once COCT gives the go ahead (hopefully soon). Got a 150A three phase connection and they authorized just over 30KW of feed in. Not enough roof space to get to that number though. 

1 hour ago, plonkster said:

How many times have you heard people tell you that gas is so efficient, they've been using a single 9kg bottle of LPG for 6 months now? Well, as we know, energy is neither created nor destroyed, and with 115kWh in that bottle, the electricity bill would have been about the same, and possibly quite a bit less (due to efficiency). But since nobody (or few-bodies) does a before and after test, everyone just marvels at how awesome the gas stove top is 🙂

I think one of the best benefits of gas is the fact that you don't rely on eskom or time related availability of sunshine when you consider it as an alternative to rather than a cost saving measure. I think a further effect on saving is the idea of having an open flame burning in your house whereby you don't leave it sitting for as long generally as you would maybe be comfortable leaving a stove to run.

even so though, surely 115kW will cost you more than the ~190 it costs to fill a 9kg? (i do agree however on the whole that it isn't as massive a cost saving as people sometimes can make it out to be)

Edited September 27, 20196 yr by Dex_