Question >>> home energy monitors

A question about : Question >>> home energy monitors

If a basic home energy monitor (of the type sometimes given away free of charge by electricity suppliers) with a clamp-on line sensor is connected to a solar home, will the monitor register just the kW / kWh of electricity provided to the home or will it be confused by the quantity of electricity exported?

Best answers:

• Hi Sterling..
  I have an Eon monitor clamped around the in/out cable(so to speak). The basic model only shows what you are importing(Wh/kWh), which will reduce to zero when you're exporting(works for me) Is that what you wanted to know?
  Which monitor are you looking at?
• As they typically clip on just the import cable (your side of the meter) they will only show import.
  I've got a current cost/Eon monitor that only registered import.
  I've also got an Owl with Intuition PV, a Wattson Solar and I've got a GEO Solo PV that came with the solar install.
  So far, out of all the toys I've got, I've still not found my gadget nirvana!
  I keep looking at Openenergymonitor.org but they keep moving goalposts! I'm waiting for a release date for their RasPi based emonPi standalone solution, which should be next month.
  I've also contacted one of the forum members who built his own version several months ago, waiting to hear if he is going to market his.
• Thank you, tunnel, Eric and theboylard for your answers.
  I think that the answer then is that the meter will read the net current flow (always positive) >>> import minus export.
  So my current position is that I can see my solar generation at the Enphase site >>> public view here:
  https://enlighten.enphaseenergy.com/...2614?preview=1
  I can read the export dump to the immersion via iBoost.
  I can only read my import via the main mechanical meter.
  So there is some information that I am missing.
• I have an old owl monitor on a cable. It shows how much I am importing or exporting but does does not say whether it is positive or negative.
  So if it reads 2kw I might be importing 2kw or exporting 2kw. It can't tell.
  I have a second basic monitor (Ј10 off ebay) on the inverter cable which tells me how much I am generating.
  By looking at the two I can generally make an educated guess as to whether I am importing or exporting, though it is by no means ideal.
  If I spend Ј80 on an owl pv it would tell me if the number was positive or negative but I have not felt that was worth it.
• I wired our house to include a 'split load consumer unit' so that almost everything in use is fed by the RCD side of the CU. Only exceptions are smoke & burglar alarms (negligible usage) and a couple of lighting circuits (obviously not used when SPs are generating). I was therefore able to reroute the cable that supplies a live feed from the non-RCD side of the CU to the RCD side and can therefore measure power in use with a clamp on sensor around that cable.
  My Wattson meter therefore uses one sensor on the inverter cable to measure generation and another (described above) to measure most of the consumption and since the Wattson allows an additional input on the consumption side I've got another sensor on the feed to the UPS (which of course is fed from non RCD side of CU). The net reading of the Wattson should therefore be reasonably accurate
• .... and if either the customer or the installer thought about the problem before the installation the inverter could have been connected to a separate small CU (garage type) with the metered supply split by a Henley block - you would then have the ability to spot measure generation, consumption or a net figure as required with any simple clamp based monitor just by locating the clamp appropriately (or perm whichever combination you want !)
  Regarding accuracy of the OWL, they're probably just as accurate as any other clamp based monitor if setup correctly .... We can check accuracy by balancing reported generated power to reported total power consumption and check the accuracy at the meter (ratchet wheel balanced) so I know how accurate our OWL monitor is, however, I'd still only use a monitor as a monitor, they're not meters - but you've already got enough of them for what you need (generation & import) , and if you really need to measure export accurately it could be done without too much expenditure (~same cost as a TGM & a little labour) ...
  HTH
  Z
• The Geo Chorus II was expensive but I've been pleased with it's performance. It uses sensors to count the import & export meter pulses in addition to a clamp on the meter tail.
  The generation & import figures are 100% accurate. The only time it's slightly inaccurate is when it uses the clamp sensor to calculate the solar use during export.
  When pv generation is low (

• My import meter flashes in both directions, it's an Ampy. I've been suspicious that it's counted export as import before, but i've monitored it several times and can't catch it in the act.
  I have asked to have it changed, but as it's only 4 years old they won't hear of it.