Wednesday, October 28, 2015

PV upgrade year 1 results

It's been a year since we upgraded our PV system. We re-roofed our house and I thought it would be good opportunity to review the pros and cons of upgrading. We had a 1.1kW Kaneka thinfilm system with a 1.7kW SMA inverter, with some room for more panels. We are lucky enough to be getting the 40 cents Feed in Tariff (FIT) on top of the miserly 8 cents Synergy pay us for any power fed to the grid. So, my main thought was what will our power bills be after the FIT ends in mid 2020? Based on the current power prices (+5% price rises) they actually worked out to be quite high, mainly because of the low price for power fed to the grid. It would be nice to think that common sense would prevail in this area (eg parity with prices we pay them), but I doubt this will happen any time soon. Anyway, I'm not a big fan of paying bills, especially thinking of the future when I'm retired. So we looked into an upgrade.

I got some quotes and advice on upgrading. It turns out you can keep the FIT as long as you keep your original inverter. It also turns out that you can overload most inverters and we decided to upgrade to a 3.1kW system. The panels are REC 260PE's, with six facing due North and six facing due West. Spreading them in two orientations means that we will also use more PV power in the home, which is best post FIT. The system cost $4,650 installed with new racking, etc. We were lucky enough to sell our old Kanekas for $900 to someone who wanted to expand his system and needed the same panels to be compatible with the existing ones. All up this took the price to $3,750. Here are the first year's data:

To sum it up we had a yearly bill of -$612 (credit), the Business as Usual (BAU) bill (ie no PV) would have been $630 so we saved $1,242. This makes the payback time roughly three years, after that we'll have three more years of FIT and then we'll still have small to negative bills for the next 25-40 years. Apart from the economics, getting more PV is better for the planet too. Remember, business as usual is not an option if we are to keep the planet from cooking...

Here's the N facing set:

And the West facing set (on the garage roof):

Overall we're chuffed with the new system. Comparing the old system's generation to the new one is interesting. Theoretically a 3.1kW Kaneka setup would have generated 11.9kWh/day (based on last 6 year's data) compared to the 9.7kWh of the new system (although our roof would not be large enough!). I think the reason for this is threefold. Firstly, I think there is something the experts call clipping happening. This is when the panels generate more power than the overloaded inverter can handle and some power is wasted. Secondly, the West facing panels would be generating less power than the North facing ones due to low morning generation. Thirdly, I think the Kaneka panels are better suited to Perth's heat and produce more power than mono and poly crystalline panels. I have seen this effect at our local Primary school where two systems side by side are located. The smaller thinfilm system (2kW) produces significantly more power than the larger (2.3kW) monocrystalline system.

That's all folks. Food for thought if you're in the same boat as us.

Saturday, October 24, 2015

Home grown chamomile tea

A miracle has happened in our garden. I know, another one! A chamomile plant self seeded in the veggie patch. I've been wanting to get one for a few years now but just never got round to it, so now ones got me. I asked google and facebook who have both confirmed that it is indeed a chamomile plant - probably a Roman Chamomile. It must have self seeded from my tea going into the compost.

It has cute little daisy flowers on a small shrub about a foot tall. If it is indeed a Roman it should be perennial, I'll take a few cuttings and see.

So to make tea, all you need to do is pick and dry the flowers (not the leaves or stalks). It's easiest to kind of rake them off the plant between your fingers. Do this when it's sunny and the flowers are dry. Ideally they should be at their peak, but if they are a little old, that's okay too. There are few things more satisfying in life than sitting in your own garden, picking your own tea.

I then dried them on paper towel under a net cover to keep off bugs and dust. (Not sure why I used paper towel, surely a clean cloth would work just as well).

Its taken a few weeks for them to dry and they look and taste amazing. The flavour is a lot stronger than the tea I buy in bulk but I think that must just be because it's so fresh.

The plant itself is wonderfully productive for such a little thing. I collect about enough to cover the large cake holder in the picture and I've harvested it four times and I suspect there will be much more to come! 

In the evening after Quin is in bed and the dishes are done we often share a little pot of chamomile tea together as our wind down ritual. It's something to chat over and relax with. And now this lovely little section of our day has just got better with the satisfaction of zero food mile, home grown tea!

Saturday, October 3, 2015

Fruit fly control

We had about 500 people visit us for Sustainable House Day and about 200 asked me about fruit fly control (mostly due to this article in the local paper).

Fruit fly are a huge problem in West Australia and many other parts of the world and people struggle to control them. These days few people want to use nasty chemicals which many commercial growers still use. People are also busy so they don't want time consuming methods. So, here's my solution: a chemical free, set and forget method I call 'Net and Forget'.

We have two types of fruit fly here, the Queensland and Mediterranean types. Here's an example of public enemy number one.

First things first. This method works best for stone fruit and apples, for citrus see lower down. The first thing you need to do is prune your tree to a maximum height of 2-2.5 metres. This makes everything you do on the tree easier: pruning, harvesting, pest and disease control, netting, etc. Fruit above 2.5m will rarely be harvested anyway and will fall to the ground and spoil. Using ladders is dangerous and not even I want to risk a fall for a few fruits. Fruit trees are very hardy so don't worry about hurting the tree when you prune. The best time of year is after fruiting in autumn.

So, now you've got your compact tree you can start on infrastructure.

You'll need the following:

Four 2m lengths of re-bar (steel reinforcing bar), 12mm gauge. Sold at your hardware store (cost $28).

Poly ethylene 25mm pipe, approximately 8-10m per tree. This is high density poly pipe which is strong and flexible. Sold as Vinidex PE pipe here in WA at hardware stores in the plumbing section (not retic). Costs $2/m in 25m rolls =$20/tree.

One nut and bolt larger than 50mm. Cost $2.

Fruit fly netting with 2mm mesh. These come in a variety of sizes and you'll need to measure your tree to find out the size you need. The best I've seen are from Green Harvest online, the 2.5 x 2.5m ones are great (cost $80). They're also sold locally at Dawson's and Bunnings.

Place the rebar half a metre into the ground so you have 1.5m protruding. These need to be placed around the tree in a square approximately 2m apart.

Then slot the PE pipe over one length of rebar and over to the other corner diagonally. Do this again with the other corners and you have a dome a bit like a tent.

Drill holes in the centre of the pipes to attach the pipes to each other with the nut and bolt.

This is your frame finished and you can leave it up all year if you want.

Then you throw the exclusion net over the frame and weigh it down at the bottom with some stones or branches. Now your tree is fully protected from fruit fly! You should put the netting on when all pollination has finished of course and do it soon since fruit fly can lay eggs when fruit is as small as a pea. When you've finished harvesting you should remove the net and store it ready for next year. Below is our apricot tree in the front garden.

If you think you may have fruit fly larvae in the soil under your tree place a trap inside the net for the first year, after that you should be OK. You can also do this for a week or so if you've trapped any flies inside your net. My favourite traps are Cera Traps and you can buy them locally at Dawson's or Bunnings or online at Green Harvest.

The cost of this system is hefty: up to $130 per tree. But the frame will last forever and the netting should last 5 years if you take care of it. So, over 20 years that's less than $20 a year. Think about the money you'll save on buying fruit too, how much do fresh organic apricots cost these days? Probably $20 a kilo, so if you get a kilo of apricots then you've made your money back.

One note: double grafted trees are not great for netting. One half often flowers at a different time to the other and it's very hard to net half a tree! For this reason I do not recommend buying multi graft stone fruits or apples.

A quick and easy method is to just buy the net and throw it over the tree canopy. Then tie it to the trunk and you're done. Any fruit which falls is caught by the net too. You will find that branches and leaves grow into the net and get distorted using this method.

What about citrus I hear you ask. Well, citrus are tricky because often you'll have flowers at the same time as mature fruit due to the slow ripening of citrus. This means you can't net them because pollinators need access to the flowers so you'll need to go for trapping. Again, I recommend Cera Trap, an organic and very effective type. Place a few of these around your garden for maximum effect. You can make your own traps with old plastic bottles with holes drilled into them and there are plenty of homemade trap recipes on the web.

Now, sit back and relax while your fruit ripen!