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.


12 Responses to “First week on solar power”

  1. L from 500m2 in Sydney Says:

    That’s all terribly exciting. I love the way that power minimisation becomes a game after the panels are installed. I noticed with with my parents when theirs were installed too. My usage is embarrassingly high. I hope to rectify that.


  2. Frogdancer Says:

    Use your thermomix as much as possible. Very energy efficient. 🙂


  3. narf77 Says:

    I am intimidated by how organised you are Bev ;). I, myself am the queen of lists and I fully appreciate your sterling efforts. I agree, get that hot water system kicking in to daylight power ASAP. Pretty soon you won’t be complaining about a lack of sun, you will be lamenting where the moisture has gone but your solar system will be humming and your electricity costs will be negligable. Gotta say this is exciting reading about the possibilities. Here in Tassie, where even in summer you get cloudy skies I am thinking that it might be smarter to harness the roaring 40’s that are constantly with us and install a wind turbine. Our hot water system is “alternative energy” ready and at the moment is completely heated by Brunhilda’s sterling efforts. We have a back up gas hot water system and our cooktop and bbq that we use constantly for cooking through summer are both gas. Cheers for sharing your adventure with us Bev, it’s great fun as well as injecting hope to those of us who really want to damn the man and get off the grid eventually :). The roaring 40’s and the rooster both say “Hi!” 😉


    • foodnstuff Says:

      We are having roaring 40’s here at the moment. I’ve had one huge tree down already (but thankfully not on the house).


  4. Penny Says:

    My parents installed a 2kw system some 2 years ago. It was a big purchase given they are now 80 years old. Since installing the system they have not had a bill and because they are away for part of the year they have managed to generate a credit. Their electric hot water system under the roof consumes more than half of their daily use. I didn’t know that the hot water could be heated during the day. It is something worth considering. Our other thought was to insulate the tank in the roof to reduce heat loss. I also read in ReNew that panels can be attached directly to the electric hot water system. I am not technically minded and could have misunderstood but if it is possible, it would be great.


    • foodnstuff Says:

      I bet they are/were getting paid a good tariff for it. I’m hoping for no bills, but don’t expect it to happen. Saving anything will be a bonus.


  5. Africanaussie Says:

    i have just spent a huge amount of time reading posts – you have a mine of information here! I was interested in your yakon – I tried to grow it before but it rotted away in the wet season. I live in the tropical north (just north of Cairns)- so we have a wet season and a dry season.


    • foodnstuff Says:

      It originates in South America, but I don’t know in what climate. I remember reading that it needs about 800 mm rainfall. I have to water mine in summer, otherwise the large leaves wilt badly.


  6. Liz Says:

    Great post. Its motivated me to go and check exactly what our energy usage is. I’m sure it could be a lot lower.


  7. Dr Green Says:

    It is a good idea to keep a tab and make note of readings to see how much you are actually gaining from solar versus the regular energy systems.


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