30-day solar update

I’ve been recording energy use and PV solar system output on my spreadsheet for 30 days now, so here’s a short summary.

Here’s my average daily use for last year for comparison:

Household use excluding hot water heating: 5 kWh—cost $1.26 per day
Off-peak (at night) hot water heating: 5 kWh—cost $0.83 per day
(Water is less because it’s on a lower rate)

Total use: 10 kWh—cost $2.09 per day
Add in service charge @ 92 cents per day
Total cost = $3.01 per day
(This is calculated on today’s prices—there have been 3 price rises since the beginning of last year).

Last 30 days on solar:

Household use excluding hot water heating: 2.2 kWh—cost $0.55 per day
Off-peak (still at night) hot water heating: 4.1kWh—cost $0.68 per day
(It’s lower because I’ve been more frugal with hot water)

Total use: 6.3 kWh—cost $1.23 per day
Add in service charge @ 92 cents per day
Total cost = $2.15 per day

So I’ve saved $0.86 per day on solar compared with last year’s consumption.

But—

The solar panels have generated an average of 13.4 kWh per day.
Since I’ve only used 6.3 kWh of this, 7.1 kWh per day has gone to the grid.

(Note that when the energy supplier FINALLY comes out and reconfigures the meter to show what has gone to the grid, I’ll be able to read it directly from the meter; no messing around with the spreadsheet).

So, that 7.1 kWh exported is worth 8 cents per kWh as credit = $0.57 per day.

So take that off the total cost of $2.15 per day and you get $1.58 per day.

Compare that with last years consumption of $3.01 per day and I’m saving $1.43 per day.

That’s worth $522 per year which (on this year’s bills so far), equates to about 6 month’s worth of energy bills, i.e. it looks like I’ve cut my energy costs in half. It will be even better if and when I can get the hot water heating changed from night to day.

Another way of looking at it is to express exported credits as a percentage of the daily supply cost (92 cents) and so exports covered 62% of that in the last 30 days.

Interesting things to note:

In the last 30 days there have only been 5 days when I used more power than the panels generated. I recorded the weather on those days as ‘heavy cloud/rain’.

Highest generation occurred on a ‘sunny all day’ day, and was 21.9 kWh.
Worst day was 3.8 kWh which I recorded as ‘heavy cloud all day’.

I’m constantly amazed when it seems like a dud day, with intermittent cloud, even rain showers, and the panels still produce over 10 kWh per day. Once the sun comes out, it doesn’t take long for the kilowatts to build up, especially in the afternoon, which is when the 12 panels on the west-facing roof spring into action (the remaining 8 panels are on the east-facing roof).

My system is a 3.9 kW system. I don’t expect 100% efficiency so never expect the output to reach that, but the other day I just happened to check the inverter as I was passing by, and it was reading in the high 3’s. I kept watching and got a shock when for a brief instant it went over 4 kilowatts. I didn’t think that would be possible, so I Googled (as you do) and found this:

Solar panel output is affected by cell operating temperature. Panels are rated at 25° C. Output can vary by 2.5% for every 5° variation in temperature.

If the panels are cool due to cloud cover and the sun bursts through the cloud, it is possible to exceed the rated output.

Which is exactly what happened. How cool is that!

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A project worth supporting

I’ve long been a fan of Linda Cockburn’s blog since reading her book, Living The Good Life, which is about her attempts, together with partner Trev and son Caleb, to go 6 months, living off what they could produce and without spending a dollar. They were living in Queensland at the time and have since relocated to Tasmania, built a strawbale home, and developed a huge food garden which fills me with envy every time I see a picture of it.

Linda has a new project, to produce a video helping people meet the challenges of a changing world. Her post about it is here. The Peak Challenge site is here, where you can read about the project and pledge a donation to help Linda finish it.

I’ve pledged to help fund Linda’s efforts. Whatever she does, she will do it far better than I ever could.

Two good posts

I just read two good posts in my feed reader. I don’t have time to comment on them so have linked to them. I hope you can find the time to read them. Some of you may already be reading these bloggers, anyway. I hope so.

The first is from Linda Woodrow at the Witches Kitchen. It will really get you up to speed with gas—liquid petroleum, liquid natural and coal seam. Hands up if you know the difference and how they are produced. No hands? Then this post is for you.

Next is from Gail Tverberg at Our Finite World. Gail writes about peak oil and financial stuff and really knows her onions. Most people don’t ‘get’ what is happening around the world or why. Gail is the one to put you in the picture.

OK, off to get dinner. Happy reading!

Growing potatoes from real seed

Just a quickie to say that after my last post about planting sprouted potatoes, rabidlittlehippy sent a useful link via the comments box. Just in case some readers don’t read the comments, I’m relinking to it here.

It’s a really good piece of info about growing potatoes from real seed…..yes, potatoes flower like any other plant and set viable seed. I think I remember reading that the famous (American) variety Russet Burbank, was developed by planting real seed (by a Dr. Burbank, no less).

Last year, I was sent some seed of Pink Fir Apple potato by a member of the Ozgrow garden forum. I sowed it and it germinated and I had a dozen or so seedlings. Somehow I didn’t get time to pot them up and they grew for a while, being intermittently watered and unloved in the seedling tray, until finally giving up on the terrible gardener they’d been lumbered with, and dying. When I started to pull them out, I found a few small tubers. They’d tried so hard, I figured I owed them something and so I put the tubers into some pots and left them in the polyhouse.

A couple of days ago I noticed this (don’t blink, you’ll miss them):

Little green leaves. Those tiny, tiny tubers have started to sprout! (those orange globules aren’t tubers…that’s slow release fertiliser.)

I’ve promised them this time I will look after them.

More mini cuttings

I’ve written about taking mini cuttings here, here and here. I’m still trying various varieties and now I can add two more: silver beet and cucumber. I was surprised at the cucumber; it didn’t seem that it would grow new roots up the stem like tomatoes do, and it didn’t. They grew out from the cut bottom edge. I can’t imagine that this will make for a very robust plant, since roots like that will easily break off, but I wouldn’t normally want to increase cucumbers by this method anyway. It’s just nice to know it can be done.

Treating silver beet this way, though, IS useful. A single silver beet seed is actually a composite of many seeds and several plants will appear from sowing one seed. Usually the recommendation is to thin to the strongest. Now I can snip off the extras with scissors and put them in as mini cuttings.

When a potato does this…..

…..I make a small space somewhere in the food forest, place it in a hole, cover it with a pile of chook poo compost and a bucket of leaves and leave it to itself. It’s great fun digging up the progeny. Growing your own potatoes couldn’t be easier!

I’ve finally been able to harvest a decent-sized pepino:

And there are two more to come:

In the past, the rabbits or possums have taken them when they’ve been on the ground like this. When I saw these three rapidly expanding, I protected them with apple socks and thought I’d better put a wire cage over them as well. It’s done the trick. I’m going to enjoy these on my breakfast mueslii.

I bought the apple socks from Green Harvest. They call them apple pouches but they’re actually little nylon sockettes. They’re great to slip over fruit to keep birds and possums off. I wouldn’t want to do a whole tree with hundreds of fruit on it, but they’re OK to do enough of the best (and low-hanging) fruit to get a useful harvest. Here’s the persimmon with its socks on, a couple of seasons ago:

I managed to collect and eat every one. No problems with possums, blackbirds or parrots. Persimmons are really vulnerable because they lose all their leaves before the fruit ripens, so you’re left with a naked tree covered in bright orange fruit that can be seen by every bird for miles around.

Solar update

The new solar PV system was connected 24 days ago and I’ve been taking readings from the electricity meter and the inverter for 22 of those days and recording the whole lot on a spreadsheet.

For the first 7 days, I was tweaking the system, e.g. by turning off the hot water system and doing a daytime water heating boost, but I gave that away and went back to normal, i.e. normal daytime/evening  use in the house and off-peak water heating at night (although I am being more careful with hot water use (shorter showers…ugh…do love my hot shower).

So the results that follow are for the next 15 days of normal use.

OK, first up—last years usage figures, which have been fairly typical over the years. I’ve calculated this at current supply charges for comparison (there were 2 cost increases last year and another one at the beginning of this year).

Average consumption per day (2012):
House         5 kWh  costing $1.26 per day
Hot water   5 kWh  costing $0.83 per day
Total consumption = 10 kWh per day, costing $2.09 per day
Add in supply cost of $0.92 per day = $3.01 = total cost per day

15 days on solar panels:
Average consumption per day:
House         2.0 kWh costing $0.50 per day
Hot water   4.6 kWh costing $0.76 per day
Total consumption = 6.6 kWh per day, costing $1.26 per day
Add in supply cost of $0.92 per day = $2.18 = total cost per day

You can see that consumption in the house has dropped by more than half—that’s energy coming from the sun—and water heating is marginally lower (shorter showers).

(Note that heating hot water at night, even though on the off-peak rate, is now more expensive than powering the house—how can I get the sun to shine at night?)

Now, here’s where it gets interesting.

The solar panels have generated an average of 13.3 kWh per day (just over twice what I used), meaning I exported an average of 6.7 kWh per day to the grid. The inverter gives me this reading at the end of every day, before it shuts down.

The current feed-in tariff (what I get credited for exporting to the grid) is (a lousy) $0.08 per kWh. Yes, you read that correctly—8 cents per kWh! And they sell it back to me at 25 cents per kWh. My electricity! Nasty them!

So I earned the magnificent sum of 6.7 x $0.08 = $0.54 per day for the electricity I exported to the grid.

54 cents per day credit. Not exactly an overseas holiday in there.

Take that off the daily usage cost ($1.26) and you have $0.72 per day

Add in the supply charge ($0.92 per day) and the all-up cost is $1.64 per day.

Go back to the 2012 figures and compare that to $3.01 per day.

Savings of $1.37 per day. ($3.01 minus $1.64)

Is that good?  Well…

It’s worth $500 per year. Still no overseas holiday, but better than nothing (an iPad maybe?).

The catch is in that supply charge. No matter how much energy I save or how much energy I export to the grid, I can’t avoid that supply charge and I can’t afford to go off-grid.

Here’s another way I looked at it.

Express the daily export value (54 cents) as a percentage of the daily supply cost (92 cents).

54/92 x 100 = 59%. So what I’m exporting to the grid is saving 59% of my daily supply charge.

That’s not including what I’m saving in powering the house by the sun (in the daytime).

Oh, well, that’s better…..

I should mention that I’m calculating the daily export to the grid by subtracting what I’m still taking from the grid from what the panels generate. The meter isn’t actually reading this yet. I’m waiting for the energy supplier to come out and reconfigure the meter to read the export. Until then, I’m not actually getting that 54 cents credit—they’re getting the power for free. Nasty them again!

I’ve got a nominal 40-day wait from the time my energy retailer puts in the request to the energy supplier to reconfigure the meter, until they actually come out and do it. It’s day 33 and I’m counting down. If nothing happens in the meantime, when I get to day zero, angry phone calls will ensue.

I should also mention that when the meter IS reconfigured, it looks like I will lose the night-time water heating and go onto a time-of-use tariff. I’m still not sure about this, so I’m waiting to see what the Powers That Be will say. I really WANT the water to be heated by the sun anyway, it’s just that there will surely be a change in the tariff and it certainly won’t be downwards.

Warm? Really?

They’re saying we had the warmest September on record. Well…I don’t know what happened to it once October hit. We had a week of freezing (well, cold), gale-force winds that saw a lot of trees and branches come down around Melbourne and culminating (at my place, anyway), in a humungous hailstorm that had me panicking about what to save first…the chooks or the solar panels. The solar panels came through it OK and when it had passed, it was hilarious to watch the Girls trying to pick up pea-sized hailstones in the belief that this was some new kind of treat that Mum had thrown at them.

I usually plant my first crop of beans on the first of October and subsequent batches on the first of every month thereafter, up until about February. They normally take 2 months to bear and I have a continuous supply of beans until autumn sets in. I checked the soil temperature in the wicking boxes and at 10º C there was no way I was going to plant them just to see them rot away. I’m still waiting for some warmth.

I also have this tray of curcurbits (zucchini, pumpkin and cucumber) to put out:

I want to plant them on the hugelkultur mound but the soil temperature there is even colder than in the wicking boxes.

I’ve put out some tomatoes…ones I bought some weeks ago from the old guy at the Sunday market. I don’t know how he manages to get his tomato plants so big, so early, when my own seedlings are only centimetres tall. His tomatoes don’t have stems; they have trunks! I only buy from him when he has varieties I haven’t grown before and then I can collect the seeds and add them to my collection. I bought Golden Girl, Cherokee Purple and Black Krim. He reckons this one is better than Black Russian so I’m anxious to try it. It’s supposed to have a slightly salty flavour along with the typical richness of the black varieties.

Down in the garden, the salsify is flowering, so this photo is for Fran of The Road to Serendipity who sent me the seed:

If it sets seed, I’m going to broadcast some of it into the food forest as bee forage. The flower stems are taller than I am:

I have a nice patch of calendula growing in one of the veggie rings. I’ve been collecting and drying the flower petals in the hope of getting enough to make calendula ointment:

These red currants are setting fruit already. I didn’t know they’d flowered:

Oh, there they are. You wouldn’t call them spectacular. I wonder what pollinates them:

Postscript:

I wrote this post a week ago and it was left in ‘drafts’ in favour of the solar posts. So I’m happy to say that warmer weather has arrived (forecast 30º C today) and I’ve planted those beans and some of the curcurbits.

Postpostscript:

A question for all you computer geek WordPress bloggers. In the above post I’ve got two celsius temperatures quoted. You’ll notice the little degree sign º between the figure and the C. Can anyone tell me how to do this without leaving the blogpost edit page?

Here’s the roundabout way I go about it. Return to desktop leaving blog page open. Open Microsoft Word to a new document. Click ‘insert/symbol’ and find the degree sign. Add it to document. Copy degree sign to clipboard and close Word. Return to blogpost edit page and paste degree sign into place.  It’s giving me the irrits doing this. I know I could just type 30 C and everyone would know what I mean, but I’m a stickler for doing things right. I annoy myself intensely about this. I suppose it’s the scientific training.

Another week of solar living

I’m trying to understand how my new PV solar system works. I keep asking questions and thinking about it all.

The other day I tried boosting (turning on) my hot water system using the boost function in the new Smart Meter. The old meter didn’t have it (I guess this is why the new meter is ‘smart’). Normally the hot water system heats at night on a cheaper (off-peak) rate. I wanted to see if the boost function would use power from the solar panels rather than take it from the grid as happens at night. If this is the case, I could permanently turn off the heating at night, via the switch in the meter box, and just boost from the sun each day.

I read the meter before and after the boost. It didn’t show much of a reduction in what I normally use at night, so I wondered if the power used was actually coming from the panels or from the grid, because it seemed to be registering on a different circuit on the meter. I rang my energy retailer (AGL), who didn’t know what I was talking about. This, after putting me through to three other people who didn’t know either. Eventually I was put through to my energy supplier (United Energy), who said (quite angrily, I thought), “you don’t have a booster on your meter”. I told him I did and that I’d just used it. Humph! After a bit of to-ing and fro-ing he agreed that I did have a booster. So I explained what I was trying to do (they don’t like you trying to use less energy so they get pretty narky about it). He couldn’t answer my question either (or didn’t want to).

Next day Mario from MSJ Solar System rang. MSJ installed my PV system. In the course of the conversation I learned an important new fact. The voltage from the solar panels is higher than the voltage from the grid. That means that energy from the panels is ‘forced’ preferentially from the panels into my home rather than from the grid. The higher voltage wins out. But, if the appliances I’m using want more power than the panels are generating at that time, the extra will come from the grid.

I’m trying to visualise what’s happening. Supposing I could do an Incredible Shrinking Woman act and get myself so small I could actually get inside the wire taking power to the house and see the little electrons whizzing by; and supposing, if those coming from the panels were coloured green and those from the grid were coloured red, then I imagine if all my power was coming from the panels, I’d see a stream of green electrons hurtling by, but if my house needed a bit more from time to time, I’d see red electrons amongst the green. Every time the sun went behind a cloud the green electrons would diminish and the red ones would increase.

The fewer the red electrons, the lower my energy bills will be. I’ll drink to that!

It’s been a fortnight since the system was turned on. I’ve deleted the first week’s figures from my spreadsheet because I was playing around with turning the hot water heating off on alternate nights. I’ve stopped doing that and gone back to normal heating. I really need to see how the new system compares with the old system without any tweaking.

So, as far as power usage goes, over the second week of operation, I’m using pretty much the same for hot water as pre-solar days. Not unexpected. But daytime power use in the house has more than halved. Not gone away altogether because there’s still some night-time usage (lights, cooking, TV, etc) but it’s a start. If I factor in the excess generation (a credit) that has gone to the grid at the going rate of 8 cents per kilowatt hour, I’m saving about $1 per day. That’s over $300 per year which is a whole quarter’s worth of pre-solar energy bills (we get quarterly bills here).

Of course, it’s going on summer here and I don’t expect wintertime to be anywhere near as good, but time will tell. As I said in a previous post, I’m having a lot of fun with it.

First week on solar power

It’s been just over a week since my new solar system was turned on and I’ve been tweaking the system and my energy use to see how I can get the best out of it. I’ve been reading the inverter display and the smart meter daily and putting all the data on a spreadsheet which does the calculations for me.

Although the system is turned on and working I’m still not connected in the sense that although I’m using solar energy in the house and sending the excess to the grid, I’m not getting credited for that excess yet. That process looks like taking another month or two. My energy supplier is getting free energy until that happens, so they’re not going to be all that quick about it. In any case, on the appallingly low tariff that operates at the moment (only 8 cents per kWh), I’m hardly going to be losing a fortune.

I should explain for overseas readers, that in this country (in my state at least), we have energy suppliers and energy retailers. All this thanks to energy being privatised many years ago, when previously, energy was supplied by the state. Energy suppliers control the grid and own the infrastructure (poles and lines, etc), and energy retailers buy the power from them and sell it to us, the long-suffering consumers. You can change your retailer but not your supplier. Suppliers control the various regions throughout the state and you’re stuck with them.

In my house I have an electric hot water system in which the water is heated at night (off-peak) and the power used to do this is charged at a lower rate (16 cents per kWh). Energy used for normal peak day-time use is charged at 25 cents per kWh. Last year my average energy use from the grid, was 10.5 kWh per day, costing me $1.73 per day (excluding supply charges). My energy use is roughly 50:50—half used at night (therefore cheaper) and the other half used during the day—more expensive. So daytime is the time I need to use energy from the sun as much as possible. I’ve suddenly become Extremely Averse to using any power from the grid.

Over 7 days the system has produced a total of 85.1 kWh or an average of 12.2 kWh per day. There have been good days and bad days. Best day was 16 kWh and the worst (yesterday), was only 4.2 kWh. It was cloudy and rainy most of the day.

Today looks like being more of the same. As I passed the inverter on the wall of the carport on my way out to the front gate to pick up the morning paper (in the rain, mind you), I checked the display and all it could manage was, ‘checking’. I expect it was thinking, “is there any use even getting up today?” I agreed with it. Normally at that time of the day (7am, even earlier), it’s showing a few kilowatts being generated. I’m amazed by the way it goes up and down like a yo-yo, even while I stand there watching it. When the sun goes behind a cloud the wattage plummets and then rockets up again when the sun re-appears. At the end of the day, when the system has almost shut down, the display tells me the total power generated for that day, then it re-sets for the next day. It also shows the total power generated since the system was installed.

So far, it looks like my daytime energy use has been more than cut in half. On a normal day all that is running constantly is the fan on the composting toilet, the microwave clock display and the bedroom clock. The fridge and freezer are on all day too, but only running intermittently, when their thermostats kick in the power. I use the desktop computer for an hour at lunchtime (eating lunch at my desk—I know, very decadent), and for another couple of hours after dinner (when the panels—in winter at least—won’t be generating). Most times, when I check the electricity smart meter during the day, it shows I’m exporting power to the grid.

Extra daytime use includes cooking (I make yoghurt twice a week which involves the Excalibur dehydrator running for 8-9 hours to keep the temperature constant while it’s curing), washing machine, vacuuming (not done very often as I’m severely allergic to housework), mulching, re-charging batteries (power tools, mobile phone, camera, laptop). There’s the shower fan too, so early morning or evening showers won’t be useful for saving power, but then I discovered that if I don’t turn it on the bathroom doesn’t really fog up, so there’s another saving to be had.

So, how can I change my usage times to make sure most of my power is coming from the panels? Here’s some of the things I’ve considered:

*Use the desktop computer through the day and use the laptop on the battery at night (recharging through the day).

*Cook in the middle of the day as much as possible. No more baking bread early in the morning; leave it till later. Evening meals will be a problem, especially during the short winter days, so investigate cooking less with the microwave and oven and more with the gas. I have bottled gas for the hot plates only, and at present a bottle of gas is lasting me 15 months, so it’s vastly under-utilised and it’s cheaper than electricity anyway. Time to hunt around in the cupboard for that old kettle. I can’t give up the toaster, though. Toasting bread on the end of a fork over the gas is not on. It was OK for camping trips but I refuse to do it now.

*Turn off the fan on the composting toilet at night. There’s never any smell, especially if the contents are well-covered with wood shavings and in fact the new fan, which I had installed last year is far more efficient than the old one and is drying the contents out too much, so that (I think) efficient composting is not happening. I’d been turning it off intermittently anyway. More energy saved there.

*Make sure I put batteries on their charger during the sunniest hours of the day, not just when I think of it.

*Use the mulcher only on sunny days.

*At the moment I’m playing around with turning the hot water system off every second night. I can do this because there’s a switch in the meter box. It means being very careful with hot water use and REMEMBERING to turn it back on again the next night. Even though it uses a bit of extra power to come back up to temperature than it would normally, I’m finding that it uses less power overall. I don’t know if I’ll continue with this, though. I need to talk to my energy retailer about getting the hot water system working through the day, so that the sun is heating the water, but I’ll wait until the system is up and running (with credits being added) and I’ve had one complete energy use bill of 90 days, so I can see what’s happening.

So, to sum up:

Last year my average energy use from the grid, was 10.5 kWh per day, costing me $1.73 per day.
Over the last 7 days total energy use from the grid averaged 5.9 kWh per day, costing $1.23 per day. (All prices have gone up in the last 12 months).
Energy generated by the panels averaged 12.2 kWh per day.
I’m assuming that the difference between what the panels are producing and what I’m drawing from the grid is what I’m exporting to the grid. In this case it averages 6.3 kWh per day. Costing that out at 8 cents per kWh (the current tariff rate), gives 50 cents per day, which is a credit (which I will get eventually).
So usage minus credit is 73 cents per day.
These are purely energy charges. None of this includes supply charges which are currently 92 cents per day.

Seventy-three cents per day sounds a lot better than $1.73 per day. I need to get that hot water heating out of the night and into the day and that should improve things a lot.

Time will tell. Having fun with it all, anyway.