Solar Power Thread

[phoneJunky]

Thermosiphon vacuum tubes. If I remember correctly the termosiphon part means it circulates the water through natural convection and the vacuum tubes are the newest technology. Heats up pretty well.

 

[Sinbad]

Ja mine boiled again today

If money was no object, I'd go for a pumped split indirect vacuum tube system, controlled by a geyserwise max

 

[Freaksta]

Heh, money is not unlimited Unfortunatly!

 

[Paul_S]

Thermosiphon vacuum tubes. If I remember correctly the termosiphon part means it circulates the water through natural convection

Any solar heating system can circulate water as long as the heating portion (solar panels) are installed below or at the same level as the geyser.
If the geyser is below the the solar panels a pump is necessary to force the circulation of water.

and the vacuum tubes are the newest technology. Heats up pretty well.

Evacuated tubes have been used in solar heating for decades.
The Chinese started mass production at the beginning of 1985.

 

[phoneJunky]

Any solar heating system can circulate water as long as the heating portion (solar panels) are installed below or at the same level as the geyser.
If the geyser is below the the solar panels a pump is necessary to force the circulation of water..

And that is basically what thermosiphon is.

Also remember to go the indirect route if you get very low temperatures in your area and if so then your system also needs a pump to push the warm water back into collectors, otherwise your collectors might break. But all the quotes I got had that in.

Evacuated tubes have been used in solar heating for decades.
The Chinese started mass production at the beginning of 1985.

Okay, but I thought the flat panels were used more frequently until recently. Or that is what the people that quoted me said.

But in anycase here is a guide:

Buying a Solar Geyser Guide

 

[Arthur]

(As an aside, as per the OPs intention, this thread is for solar PV systems, as in electricity from solar radiation, not solar thermal hot water heating.)

 

[phoneJunky]

(As an aside, as per the OPs intention, this thread is for solar PV systems, as in electricity from solar radiation, not solar thermal hot water heating.)

Sorry, some one just asked for advice regarding this, but I think it is covered now.

 

[abudabi]

Someone at work told me grid-tied net metering is now allowed in JHB. Anyone around that can confirm this?

 

[Sinbad]

Someone at work told me grid-tied net metering is now allowed in JHB. Anyone around that can confirm this?

Not that I'm aware of

 

[Paul_S]

How will the municipalities do maintenance with grid-tied systems? Are the systems able to detect the loss of municipal power and stop supplying to the grid automatically?

 

[abudabi]

How will the municipalities do maintenance with grid-tied systems? Are the systems able to detect the loss of municipal power and stop supplying to the grid automatically?

Yup.. just like that

 

[abudabi]

Not that I'm aware of

Aw man... was getting my hopes up.

 

[Arthur]

How will the municipalities do maintenance with grid-tied systems? Are the systems able to detect the loss of municipal power and stop supplying to the grid automatically?

Yes. One of the fundamental requirements of a grid-tied SSEG is that it automatically disconnects from the grid if the grid is not energized. This is referred to as islanding in the literature.

Correct islanding is vital to ensure safety of electrical workers doing maintenance, for example.

 

[Sinbad]

Yes. One of the fundamental requirements of a grid-tied SSEG is that it automatically disconnects from the grid if the grid is not energized. This is referred to as islanding in the literature.

Correct islanding is vital to ensure safety of electrical workers doing maintenance, for example.

Also to stop you overloading your installation as you try to feed the whole Street

 

[wetkit]

@Arthur, so how is your system running?
Any issues or problems?

 

[Rouxenator]

Had someone from SolarTech visit me and said they could put up a heat pump for R14k or solar geyser for R17k. Both prices are after the Eskom rebate. The claim is that in summer I would not even need the electric geyser bit of the solar thing.

Is this a good deal or bad deal?

 

[spiff]

Had someone from SolarTech visit me and said they could put up a heat pump for R14k or solar geyser for R17k. Both prices are after the Eskom rebate. The claim is that in summer I would not even need the electric geyser bit of the solar thing.

Is this a good deal or bad deal?

depends on the manufacturer / guarantees / warranties etc.


have read here:

http://mybroadband.co.za/vb/showthread.php/451029-solar-geyser


I bought a solar geyser a year or so ago ( http://www.agssolar.co.za/) and it was the best R16k I ever spent. never once used eskum power during summer - water was consistently heated to 99 degrees (reduced to 65) never ran out of hot water.

with winter here the temp has dropped to between 45 -55 but is still hot enough to enjoy a decent shower. I am considering installing a heat pump because of its efficiency as apposed to an electric element.

 

[Arthur]

@Arthur, so how is your system running?
Any issues or problems?

Hi wetkit. The system is chugging away without issue or problems. However, the lower sun and shorter day has drastically reduced daily power generation. I was a nett importer of energy in May, for the first time this year.

So far in 2013, monthly power generated by the 12kW PV array, in kW:

Jan: 1804 (31 days). Daily Avg: 58.19kWh
Feb: 1723 (28 days) Daily Avg: 61.53kWh
Mar: 1688 (31 days) Daily Avg: 54.45kWh
Apr: 1373 (30 days) Daily Avg: 45.77kWh
May: 1151 (31 days) Daily Avg: 37.13kWh
June mtd: 509 (17 days) Daily Avg: 29.94

TOTAL SOLAR POWER YTD (17 June): 8248kWh

The biggest problem with my system - as anticipated - is that all but one of the PV arrays are sited in areas with tall trees to the east and west, meaning longer times in shade. The lower winter sun and shorter days mean I'm getting far less sunlight on the arrays than in summer, and this considerably affects the amount of power generated in winter especially.

Two of the three arrays are pretty much in shade now. The PV array is still generating 2.04kW and the house pulling 0.8kW, with 0.8kW being exported (some also to the batteries, but the balance lost in translation, so to speak). Here's a summary on the MLT home screen from about 2 minutes ago:

 

[spiff]

http://mybroadband.co.za/vb/showthread.php/546447-Eskom-suffers-another-shock


Right so after reading the above article I foresee electricity becoming "seriously" expensive

either PV has to become shyt cheap very soon or my idea of a diesel generator + batteries will become viable sooner than I thought!

just out of curiosity - has anyone ever used a diesel generator to charge up banks of batteries during the day, ready for use at night? instead of PV cells?

what are the pro's & con's?

The pro's are you can be independent of Eskom.
The cons are the cost of fossil fuels make the exercise very expensive.

A modern diesel generator uses between 0.28 and 0.4 litres of fuel per kilowatt hour produced.
Using the 0.28 figure, at the current price of diesel that works out to R2.89 per kWh excluding the losses in charging the batteries which is a tad higher than the ~ R1.20 per kWh consumers are paying municipalities for electricity.
What would be funny is if/when the electricity tariffs pass the R3/kWh mark and people start using diesel generators at home to go off the grid.

Even if electricity hits R3/kwh it will still cost less to use eskom than Diesel.
Your batteries will cost you at least R500 per month in maintenance.

 

[Rouxenator]

PV is still prohibitively expensive. Right now thermosyphon solar geyser systems are the best way to cut your Eskom costs. You should be able to recover your expense on it within about 2 to 3 years depending on the costs of electricity.