Graham Chiu

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since Jan 01, 2018
Wellington, New Zealand
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Recent posts by Graham Chiu

Thanks Phil.  Is there an explanation anywhere on what all these curves mean?
8 hours ago

Joseph Michael Anderson wrote:
4) if you can time your power usage to use 30-40% of your battery by the morning, your panels,at peak can get them recharged right away,  better than draining the batteries in the evening and having them sit at less than 100% charge overnight.  

Currently it looks like the batteries for the main house get to less than 10% at about midnight

and the rear flat hits 1% at about the same time which is sad considering the flat is empty since no one can live in it while there's no code of compliance, and the only thing running is a half size fridge

I'm very new at this so I'd appreciate a strategy of maximizing the use of the panels, and batteries, and minimizing the export back to the grid.  Normally we pay 29c/kWh imported, and get back 8c/kWh exported.  The batteries aren't getting fully charged yet in the morning but we've had some cloudy mornings this week so far.
9 hours ago
Thanks for the calculator link.

I tried various degrees of tilt for the azimuth of 45 deg, and found that best was 23 deg giving estimated production of 7,641 kWh/year vs 7,408 kWh/year at a tilt of 41 deg which is my lattitude.
9 hours ago
I asked a solar company to install some panels that were supposed to be split between my house and my daughter's to be built house.  The panels were going to go on my roof as her roof was going to be shaded for much of the day.  Now my roof has a 10 degree pitch using a vertical seam metal roof with the seams running  NW to SW.  Initially I asked for the panels to be flat mounted against the roof to reduce the wind on the roof, and that's what my contract says.

But the installers have rack mounted them at an approximate 40 deg angle facing north east.

I think 12 panels (300W) are mine, and 8 panels are the daughter, and we have 14.4 kWh of lead carbon batteries (8 batteries) shared between us, with two Solax hybrid inverters.
My location is about 41.3° S, 174.7° E

Now this my 3rd day with the system active, and it's just after 4 pm, and I expect by 5:30 pm the solar production will drop to neglible levels as the sun will then be behind the panels.  The whole morning was a miss as it was clouded over until midday.

So, my question is,  does one get more sun light with the panels as flat as possible (allowing some inclination for self cleaning), or is the production higher with the panels pointed north thereabouts (in the Southern Hemisphere).  The other consideration is that with a large amount of solar generation the batteries can only be charged at a certain rate and excess is exported to the grid.  So, wouldn't I have been better off with lower peak production spread over the day?
1 day ago
As an aside, has anyone tried putting a heating element around the single skin chimney before it becomes double skin.  Heating the chimney might get the draft established.
1 week ago
So, with the colder weather you have a greater thermal gradient between your outside chimney and the inside of the house, so the thermosiphon starts working.
Sounds like the simplest thing to do to permanently fix this problem is put a fan on the chimney to increase the draw irrespective of the outside temperature.  The trouble is, those fans can be kind of expensive.
Or, you can try using your hair dryer to drive the fire where you feed the fuel when you start the fire.  That might increase the heat enough to establish a decent draft.
1 week ago
So it looks like you're just twist tying some wire to prevent it from unfolding?  If I'd known that worked, I wouldn't have gone to the bother of buying metal mesh to wrap around mine!  
1 week ago
Thomas, what are you using to hold the wool in shape?
1 week ago