Current Cost Support Forum

Random thought..

Would it be possible to use a dev board to make an external temp sensor?

Could I then pair it to my Envi and bridge and upload the data on a different channel?

Discuss....

All help welcome!

Thanks,

In theory yes, it would deffinitely be possible, BUT it's hard to say how much work would be involved and it would depend on one's skill level.

The Dev boards contain a "PIC" microchip which is re-programmable if you know what you are doing. However the Analogue Dev board has been specifically designed to use an analogue input which could be driven from a thermistor of appropriate value or an analogue temperature sensor IC (LM335 for example) to provide that analogue signal. The Dev board would digitise this voltage into a number that could be received and displayed.

The Analogue boards output a value of 0-500 which represents 0-3 volts input approx. This could be scaled to some degree by the choice of thermistor value and it's pairing resistor value (forming a potential divider across the 3 volt supply) I guess this could be scaled to say 0 - 50 degrees C for instance in 0.1 degree steps. For example of you see 215 watts it might translate to 21.5 degrees C

Thermistors unfortunately are non linear in very simple setups like this but it would still give some indication of change to show it is possible. The LM335 or similar analogue temp sensor would be a better choice for linearity using an analogue dev board but you would have to consult the datasheet of the LM335 for it's connection pinouts and any additional components it may require for scaling (it's been years since i used them so i'm only guessing here.)

If a given person had some reasonable programming skills of course, then they could manipulate the firmware (software) inside the PIC chip to scale things more accurately or change the numeric values sent out, or better still connect it to a digital temp sensor IC and use a direct digital value in the first place. (again with some number manipulation in software but better results)

Anything is possible it just depends on skill level and the amount of time someone wants to invest.

Current cost could probably knock something like this out in no time at all given that they have the software source code to easily modify it.

Another product idea there CC !!

Although im a great supporter of hacking/repurposing, I think the effort wouldnt be worth it.
Suggest an existing open source project based on 1-wire /DS1820 etc.
OPENENERGYMONITOR has this facility, other Arduino projects, or even Weather-Display.

What was the reason/need behind the original question?

So, the reason for my original question is this....

At the begining of the month I had a PV installation at home. I'm using an optismart > Envi > Bridge to collect generation data. I've made my my.currentcost.com feed public so pvputput.org can collect the data and I can track it online.

On pvoutput.org there the ability to plot temperature from the same Pachube feed. Today, feed channel 0 is the temp of the Envi. I thought it would be very useful to have a temperature sensor actaully at the panels. I thought about hacking up the Envi to do it! Then I found out about the Dev boards and thought this would be ideal, to create a remote sensor that can transmit back to the Envi to report the panel temp, otherwise I'm sending the internal temperature of my study..

To get round this I've created a bit of a hack / work around, using a non-current cost solution. I have a maplins weather station which I have registered with www.wundergorund.com ( http://www.wunderground.com/weatherstat ... ENGLAND350) and if I disable the temperature feed from Pachube I can recover the temp from this instead.

It works, but I would like a 'currentcost only' solution to monitor : Internal Temp, External Temp, PV output generated, Energy consumed from Grid..... Then I will be happy!

_________________
Seeker
"The Truth is out there!"

Splendid...

I look forward to seeing your results. Reading your article, just one comment, it's quite a bit cooler here in the UK. My panels have spend the first 2 weeks of their life sub zero!

_________________
Seeker
"The Truth is out there!"

Well we don't get snow too often in the south of England. That said, since the panels were installed at the beginning of feb, they have even covered by snow for 3 days. A friend of mine jokingly suggested connecting them up to the mains to heat them up to melt the snow!

My roof is 30 degrees so it's at just the right angle for the snow to stick and hang around!

I'd actually be quite interested in tracking the panel temp vs the ambient temp and output, to understand how this effects efficiency in my location. But one step at a time!

Do you use pvoutput.org? My feed is here :
http://www.pvoutput.org/list.jsp?id=7314&sid=5871

Not to worry. In 6 months the snow will be a bad memory.

Had a look at your site. A bit light-on but it looks like you stopped publishing at 9am. Have you done a comparison to nearby sites?

I have 3 Pvouttput sites (all for the same PV system).
Site 420 LLoyds is from my Inverter using a home-brew system.
Site 1053 LloydsCC is from an Envi via my PC using PVoutput Integration Service. This has collected a year's worth of consumption data. Still needs to be calibrated against the billing meter.
Site 5378 LloydsBridge is from an EnviR and CC Bridge. Loaded hourly from Pachube using my own code

_________________
Seeker
"The Truth is out there!"