Powering up for the collapse

4 10 2010

I’ve been meaning for ages to talk about our solar power system, but simply never seem to find the time.  But since my last posting on this poor neglected blog, a few things have happened, like me landing a consultancy job selling solar power to people in my area.  Yes… a real job!  Sometimes it feels like I’ve rejoined the Matrix…

Some five years ago, when our house project was barely up (a roof but no doors windows or cladding!) we put 20 US64 amorphous solar panels on the roof (1.28kW) with a German inverter by the name of SunProfi 1500E.  Yes, it’s 1.5kW, and the E stands for Emergency, which means we have battery backup for when the grid fails and we have to endure a blackout.  Or not in our case, the system automatically and instantaneously switches to battery power when this happens.  To be honest, the battery backup is a real indulgence.  First, we started out with a tiny 17Ah battery bank (the more Amp hours the more energy you are storing) which very quickly turned out totally inadequate.  It was soon removed and replaced with a second hand 100Ah set of batteries which cost us the princely sum of $100 and a bottle of rum.  So far they were the better value for money, because they lasted maybe 18 months or more, but they eventually curled their toes up and died.  So, a replacement set made in China and bought on eBay arrived, for a grand total of $1300.  Gel cells…  never again.  They barely lasted long enough to run out of warranty, and the problem with this inverter is that it will not work at all without batteries, and if they are dying, prodigious amounts of solar power is wasted trying to keep them charged up, instead of feeding the grid.

new 500Ah battery bank

Luckily for us, my new boss is one of the few solar people around here who isn’t one of those greedy business people who jumped on the rebates bandwagon to sell grid connected PVs for a quick buck, he actually knows solar, and has been in the business for thirty years….  some people even consider him a guru of sorts!  That’s why I chose him to work for.  And he deals in and knows batteries very well.

Out of the blue, he bought an entire telephone exchange worth of backup batteries for a song.  Not gel cells, and not piddly 100Ah jobs, these were the Rolls Royces of lead acid batteries, 500Ah Yuasa, which, he claims, have been known to last as long as 34 years…..  pretty amazing.  So I bought a set of 24 (2 volts each to make 48V) for barely more than the last set of crappy Chinese batteries.  So far so good.  They are all housed in a brand new little cubby I entirely built out of salvaged materials, looks like it’s always been there!

new PVs

new PVs, old system at the back

One thing I have learned from rejoining this industry after a 15 year period of retirement, everything’s changed.  The incentives to screw panels to one’s roof are now hard to ignore, let alone resist.  So we decided to top up our old system with a totally new one, 2.2kW of, this time, monocrystalline Chinese made PVs with a 2.8kW Chinese inverter.  Yes, China is taking over the world…

I estimate that now we have reduced our consumption to around 3 kWh per day, we will be feeding so much excess energy into the grid during the day that we should make two to two and a half grand a year profit out of the panels…  I now firmly believe that ten years from now, there will be people with panels, and people without power. Or at least people who will not be able to afford the power they currently take for granted.  Only time will tell, but at least we are ready.


Since first writing this entry, Energex connected us up to our new “smart meter” which automatically works out how much imported energy we need to be charged for, and how much excess we get credited for. After our first month of “smart metering” , said meter is reading -284, 59.  This means we had to buy 59kWh @ 21c = $12.39, and we sold 284kWh @ 52 c = $150.28 for a nett profit of $137.89.

It’s a bit disappointing.  The inverter is playing up, misreading the grid voltage and cutting out constantly, and we’ve had cloudy days after cloudy days.  Still, it’s nice to know we’ll never have another power bill!

It was funny how Energex sent a team of two metering experts all the way from Brisbane (140km) to make sure we were unable to charge the batteries off the grid at 20c, only to sell the energy back to them at a profit for 52C!  As if….  the energy contained in those batteries is worth way more than theirs, and as I told the poor unsuspecting guys, I wouldn’t sell it to them for two buck a unit even if I could!  They drew a wiring diagram of the entire setup, insisted on running the house off the batteries with the panels turned off for more than half an hour, just so they could watch the batteries NOT being recharged when the grid was turned back on.  I expect the exercise would’ve cost Energex at least $1000…  a lot of kWh even at 52c!!


The inverter which was playing up eventually died.  My mistake, I should have followed my intuition and bought a Xantrex instead of supporting the firm I worked for… that’s right, I no longer do.  They no longer sell those inverters either.  It was replaced under warranty, and so far so good seems to work just fine.  How long for is the real question.  After two quarters of this and appalling solar weather, we got our first cheque for just over $500 from the Utility Company.  Hopefully we’ll do better now the inverter is working as designed, and the rain might hopefully go back to “normal”, if Climate Change allows this to actually occur.  At least we will never ever have to worry about any more power bills.


After some two years of faithful service, the backup batteries have been sold because the device that was connected to them started curling its toes after eight years of duty.  See here for details…….