So, we're in the house and it only took from 20 Feb to 25 July, and (as of 31 Aug) it's really almost finished (few bits of 'snagging' type things but nothing major). The wood burning stove (ha! controversy starts here....) went in today. New A++ fridge-freezer to replace the one with half a foot of ice on the back wall. PV solar started generating on the 16 July. Obviously, the meter readings for the period we were out of the house tell me nothing, but now we're in I want to start monitoring our use properly again.

The only issue is the way in which usage gets complicated by the PV solar - we didn't get an export meter (another thing to pay for) so don't know how much we use of what we generate. I can compare gas (heating) with this time last year (heating off) but I guess I need to also calculate wood as an input/emission if I use that more for heating in the 'shoulder' months, and not just attribute a decline in gas usage to better insulation.

The company that fitted the PV solar provide a free energy monitor and my mother has also offered me one she has 'going spare'. However, both are pretty unsophisticated. The PV solar company also provide a slightly more 'all singing, all dancing' monitor that can feed data to your computer for analysis, etc....but you have to pay for this. Not sure if that is worth it.

A lot of my appliances have inaccessible sockets with accessible fuse spur switches, so are not easy to individually monitor using a plug in.

I'm interested in what tools other people use. Previously I was just reading the meters and logging the data on the carbon account (which I find pretty easy to use) and imeasure (until it stopped recognizing my username/password after an upgrade). Obviously just reading the meters is not going to work any more since we have PV solar and wood.

My intention is to reduce my personal CO2 emissions from 'housing' (i.e. space heating and electricity consumption) to < 0.5 tonne per annum before the kids leave home, and keep it < 1 tonne per annum when we halve the occupancy of this house (go from household of 4 to household 2), so really I just want to keep tabs on annual consumption and have a a more frequent mechanism to incentivize progressive reduction/finding any easy wins or big guzzlers.

Our inverter is an Eltek 2.0 HE-t.

I'm considering getting the Wattson solar plus monitor, which seems to monitor generation, total usage (and hence export) which given I haven't got an export meter seems worthwhile. It also has its own software (Holmes) in a Mac version.

The alternative is Current Cost - must cheaper, but not sure how it deals with the solar inputs and whether it just measures what we're importing from the grid rather than total use? Also, have read some negative things about the stability of the Mac software that you can use with Current Cost.

Not really sure...don't totally understand how these things work. Presumably to monitor individual appliances you need additional kit (at plug socket that talks wirelessly with the main unit?) - Wattson doesn't seem to offer this. A bit of further reading indicates that the software for Wattson is also not that great, a bit buggy. So the appeal of native Mac software is not that great if the software is not upgraded/bugs fixed.

This is their sales pitch/installation guide http://www.diykyoto.com/uk/aboutus/wattson-solar-plus

Since discovered that OWL also have a version with PV solar monitoring - but the disadvantage of theirs is that it relies on the set up having a henley junction block - which mine doesn't. The Wattson uses something they call an 'easifit' pack to get around this. http://www.theowl.com/uploads/downloads/Intuitionpvmanual.pdf

I've tried Efergy and CurrentCost Envi meters with with clamp sensors wireless to the display unit:
Positive of the Efergy was the battery-powered display. But it seemed to be about 20% off and had no way of logging the data. The CurrentCost is mains-powered (so can't be carried around) but does have a serial connection and outputs XML and also reports temperature. I do my own parsing of the XML output and storing of the data.

I also tried rfxcom.com's RFXMeter also with clamp sensors which reported wirelessly to the RFXreceiver I use to log temperature+humidity. I never really spent the time to work out how to collect the data reliably ...

But since my import and generation meters have 1Wh flashing lights, when they became available I replaced the CurrentCost clamp with CurrentCost OptiSmarts. This had the advantage that existing software just worked and I get the actual meter values instead of values whose accuracy varies over time depending on voltage and power factor. The only irritations are my old gas meter has no smarts! and though my import(+export) meter has what looks like two LEDs, only one flashes for import/export so I still have to guess whether I'm importing or exporting sometimes.

I'm still tempted to get the mains and PV rewired to a new DB which feeds the house DB through a third meter so I can record actual usage!

-- Chris

wattson solar plus recommeded
http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=9175&page=2#Item_13

<blockquote><cite>Posted By: SteamyTea</cite>How did you parse the XML data from the CurrentCost? I currently import it into Excel and then extract what I want, but it is a pain. Can you get it to timestamp every row of data?</blockquote>
I've got an ugly hack of a 102-line perl script that does way too many things:
- if required, sets up a RAM disk and restores the backup data
- configures the speed of the serial interface
- loops forever (or until restarted)
-- reads the XML records as they appear
-- selects the (few) items of interest
-- logs current data to a RRDB
-- fixes up the timestamp by merging the time on the record with the current date and working round the fact that the day offset changes when the hour=23 (!)
-- logs summary historic data to a text file (to act as a check on the RRDB and never removed)
-- backs up the data on RAM disk every so often (this last when I was trying to reduce disk wakeups!)

It's too ugly to show in public: I'll send it on request :-}

This all pre-dates the RFXreceiver and the XPL toolkit which now I believe support the CurrentCost: if I were starting over I'd probably start there!

-- Chris