A cloud free day

Today was the best day I’ve seen for our solar system in a while, it’s cloud free, the temperature is moderate – not excessive.

We broke 5kWH instead of the more desired, 6 – 7 I anticipated based on the design of the system and the figures we were provided. We’ve had pretty much cloudy days and rain for a while.

Our Solar Hot Water system is showing better signs of life today too, having previously exhausted all the hot water when our granny flat resident assumingly sucked it all down in one day last week.

I’ve been playing with an Arduino, and some DS18s20 sensors to capture temperature data, but, in the process have caused two sensors to break, so waiting on the replacements to redo that – the plan will be to check the accuracy of the sensors of the hot water system, and gather an idea (using temperature sensors and piezo transducers) of consumption of house and of the flat over time.

I’ve had a CurrentCost CC128 (and a plug for Grant at Smart Now for his fantastic service) in for a good while now (about a month I think), because part of switching to solar meant time of use metering from Energy Australia. The Current Cost meter gives us amazing power over our consumption in that sources of waste are very easily identified. The general rule is: If you aren’t enjoying the consumption / it isn’t necessary, off it goes. The server is getting an upgrade to a Intel D510 atom setup as a result – 10W compared to the 100W base it has now has got to be good.

Time of use penalizes high usage during the 2pm – 8pm period weekdays, while gives us a good off peak rate for our usage in the 10pm – 7am time frame, which is just a matter of adjusting to – Don’t bother using washing machine, or oven til later at night – works well!

We consulted Energy Australia for a quote on the metering for the flat, I was hoping to have that seperate so we could get a solid idea of our own consumption, and not so much as billing for the flat seperate, just an idea of our own relative to the bill.

They wanted close to $600 for it – stuff that.

The clamps are easy to install behind the panel, but I won’t detail that here for obvious idiot prevention reasons (and it’s actually illegal, apparently, for someone not licensed in NSW to go behind a panel – meh). I’ve got a house clamp – covers two house circuits, lights and stove, a clamp around the flat (which has a 400V fuse..), and one on the Off Peak feed to the hot water system.

The device captures data transmitted to it wirelessly (using the 433Mhz range) and the other end attaches to my server (which is always on) so I can graph and monitor it using rrdtool and the bash script I put together, shouting the data over the broadcast address of the network, along with a gnome, python applet in Ubuntu.

The Aurora Inverter has RS485 attached to it, with Cat5e cable attaching to an RS485 to RS232 adapter, and responds to queries of it’s usage / generation.

At this time, 5.16kW out to the grid and as the graph below shows, unaffected by cloud cover today. The result could have been better, the peak should have been closer to 1.52kw, but barely broke 1.0 for some unexplained reason. The graph shows input to the Aurora Inverter, so output is of course, less.

<img class="aligncenter size-medium wp-image-822" title="Power Graph" src="http://www.tocpcs.com/wp-content/uploads/2010/08/usage_power-300×78.png" alt="" width="300" height="78" srcset="http://www.tocpcs.com/wp-content/uploads/2010/08/usage_power-300×78.png 300w, http://www.tocpcs.com/wp-content/uploads/2010/08/usage_power go now.png 781w” sizes=”(max-width: 300px) 100vw, 300px” />

The Hot Water is also of interest because of the rain performance issues. The temperature on the roof was peaking at 70oC today, and the tank (measured at the bottom, not the top, was 58oC.

The thermostat is set to 65oC, so there should be very little work by the electric element required, and therefore a reduced amount consumed (in theory – I will check).

The purpose of the monitoring of the hot water is to determine how it responds to temperature changes, and that will allow appropriate configuration.

It’s not unheard of for installers of solar products to get it wrong – in the case of the Apricus systems, putting too much compound on the roof or tank temperature sensors, meaning it thinks it’s colder than it actually is. I plan to test that theory by the return pipe, as it should get as hot as the water flowing through it (which I will test by the tempering valve, set at a poor 45oC – so I can check the pipe in relation to that!).

Update, our hot water normally heats up at 10.20pm, it did today (after the house has all had showers, etc), and it finished at 10.55pm (assumption here is that the temperature is spot on, and a less amount of energy used – cause the Sun heated the water). Our tenant in the flat isn’t exactly a conservative person, it would seem.

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