Home solar update after seven years

The rooftop PV system we installed seven years ago has just passed another good round number – 16 000 KWh – having produced 4 000 KWh since my last update, in September 2016.

The daily average in that period is therefore 5.9 KWh/day, a little lower than the average of the first five years.  The drop in output is so small that it’s not really worth worrying about but three explanations come to mind, and all may have contributed to it:

  • We don’t bother cleaning the panels, so full-sun output may have dropped;
  • Our trees have kept on growing, so the panels may be shaded for longer, especially in winter;
  • The period we are considering includes two full Wet seasons but not quite two full Dry seasons (the month-by-month variation is shown here).

How much money are we saving now?

Continue reading “Home solar update after seven years”

Renewable energy – all the good news

Most of us know by now that we need to decarbonise the global economy – fast – if we are to have any hope of avoiding catastrophic climate change. Fortunately, the technology to do just that is booming, charging ahead so quickly that merely keeping up with the news is difficult.

Solar and wind power are demonstrating astonishing growth rates, with or without government incentives, now that their costs have dropped below the costs of new coal and (in many cases) gas; some time last year we even began hearing of cases in which it was cheaper to build and run new wind and solar power plants than just to run old coal plants.

Last year, for most of us, was the Year of the Battery. Tesla’s big South Australian battery did something its many little Powerwalls couldn’t, i.e., make battery storage seem like a serious option for the real world rather than just a cool idea. Bloomberg’s 2018 outlook report sees this continuing and allowing electric vehicles to undercut conventional, internal combustion engine cars on both lifetime and upfront cost by the mid-to-late 2020s.

The Green Path facebook page does its best to keep up with all this news but anyone wanting it all, and unfiltered, should bookmark or follow these sites:

RenewEconomy

Launched in 2012, RenewEconomy.com.au is an Australian website focusing on clean energy news Continue reading “Renewable energy – all the good news”

Eco-Fiesta 2017

This year’s Eco-Fiesta, a few days ago, was much like those of previous years: a lovely day in the park with all sorts of loosely ‘greenie’ and ‘alternative’ people and organisations.  I wrote enough about the 2014 and 2013 events that I shouldn’t need to present an overview this time, so I will dive straight in to the things which caught my attention.

Wildlife Queensland had a well-staffed stall featuring a great gallery of flying fox photos. These animals get a bad press and need all the support they can get.

North Queensland Regional Plan had a very boring stall (I’m sorry, but it’s true!) which tried to engage visitors in planning for our region, the local government areas of Charters Towers, Burdekin Shire, Hinchinbrook Shire and Townsville. It’s a state government initiative and welcomes online input here. I told them about our declining rainfall. What’s your concern?

The Beekeepers had their usual displays of honey and hives, Continue reading “Eco-Fiesta 2017”

What happens to a solar power microgrid in a hurricane

A news bulletin from Kiva:

As you may know, Hurricane Matthew, a category 4 storm, made landfall in Les Anglais [Haiti] at the beginning of October [2016].* In the run up to the storm, our staff members told the community that they should charge their electronics soon as they would have to turn off the grid. They then secured the generation site with sandbags and found safe spaces for staff.

After the storm hit, the community was devastated. As most of the houses in Les Anglais are made with straw or sheet metal, virtually all of those houses lost their roofs. About 30% of the community completely lost their homes and some have left the area to stay with family elsewhere. Even worse, about 90 people in the entire commune of about 30,000 people lost their lives.

Within a few days of the hurricane, humanitarian relief was able to arrive by barge and a week later the roads were opened up to allow relief by trucks. People are slowly starting to rebuild. Aside from re-building homes, much work will have to be done to restore agriculture in the area as many crops have been destroyed.

The microgrid fared comparatively well. About 40% of the panels were lost, but the battery bank, inverters and generator were left unscathed. The worst damage was to the distribution system and home installations. When roofs were torn off due to the winds, most of the wires, light sockets and outlets that comprised the home installations were blown away as well.

The community is eager for the grid to be up and running again and we are putting in place a plan to rebuild as the community is able to rebuild their homes. We anticipate this taking about 6-9 months to finish.

Kiva, if you don’t know it, is an international microfinance charity lending to small borrowers in (mostly) developing nations. They do good work – read more here – but my interest in this bulletin was how the solar power facility fared in the hurricane. The short answer: not too badly at all. In fact, it sounds like it could have been operational again, albeit with fewer panels and a severely limited distribution network, a couple of days after the storm passed.

That kind of resilience will be needed everywhere, and especially in developing nations, to cope with extreme weather events increasing because of climate change.

* More on Hurricane Matthew in Haiti: wikipedia

Home solar update

The 1.5 KW solar system on our roof has just passed a good round number in its total output – 12 000 kWh, or 12 MWh – and that’s a good enough excuse for another update.

We installed the system in May 2011 so it has produced an average of 6.26 kWh per day for five years. That’s a useful percentage of a household’s consumption: according to Ergon’s figures on the back of our power bill, the average consumption for a household like ours is about 20 kWh per day, so our panels are producing nearly a third as much as we use.

Of course, we use some of our solar power during the day and export the rest of it, and then use Ergon’s power all night, so our net benefit doesn’t quite reflect those numbers. I did the sums a year after the installation and came up with a figure of $700 p.a., with the expectation that that would increase if power prices increased. Using the same logic now for the five year period, we find:

  • Total produced = 12 000 kWh (6.26 kWh/day)
  • Total exported to grid ~ 5200 kWh, for ~ $2300 income
  • Total PV power used at home ~ 6800 kWh, for ~ $1700 savings
  • Total benefit ~ $4000

In 2011 I said:

All in all, making the best guesses I can for the unknowns, pay-back time for the whole project (PV system and switchboard) looks like being in the 5 – 8 year range. That’s perfectly acceptable … Of course, if the electricity tariff rises (hands up everyone who thinks it is going to fall? No, my hand didn’t go up either), pay-back time will drop accordingly.

The cost for the system was $3500. Even if my new figures on exports and savings are on the optimistic side, it looks like our system has paid for itself, just a few months ahead of the earliest date I anticipated.

That’s pleasing, of course. The thought that it will continue to  bring us that $800 p.a. benefit indefinitely is even more pleasing. So is the thought that we have done our little bit to reduce CO2 emissions, and that it has basically cost us nothing to do so.

Was there any downside?  Maintenance costs? Repair costs after the cyclone? None at all. It just sits there quietly on the roof, collecting photons and turning them into useable electricity, day after day.

For the record, the general tariff was 19.4 c/kWh when we installed the system five years ago, had risen to 30.8 c/kWh by July 2014 and has now (surprisingly) dropped back to 22.3 c/kWh. In May 2011 the “service fee” or “daily supply charge” was only $23 per quarter, whereas by May 2014 it had risen to 55 cents per day ($49 per quarter). It has continued to rise and is now $1.07 per day, closing in on $100 per quarter. The supplier is simply trying to maintain revenue in the face of flat or falling demand and the service fee is a favoured strategy – but that’s a topic for another day.