If it's any help,I've had a VPhase installed for the last 6 months - I didn't pay for it as such- was installed 'free' as part of a PV install.
Installation – It was possible on existing CU only because there was space andCU is a recent 16th/17th edition upgrade with several RCBOs. It was necessary to make a 3rd break in busbar so that the VPhase supplies the RCD block (upstairs and down stairs rings)and a block of mixed RCBOs (kitchen sockets, bathroom lights) and the non-RCD(smokes, downstairs lights), with the third (unregulated) block (most RCBOs)consisting of shed, oven/hob, PV and the feed to the VPhase.
The installation instructions for the VPhase state that it should not be usedto control any thermostatically controlled heavy heating loads (e.g. electriccookers, immersion heater, electric shower) and no heavy machine tool loads(presumably no big motors because of in rush currents?).
Out of the 40+ CUs I've seen in the last 4 months (when doing PV installations)there have only been 2 that would have allowed a fairly straight forwardinstallation.
Operation:
The spec says that the VPhase can regulate up to 20amps on a short termbasis, but I've never seen 4kW on mine before it bypasses. Practically, thismeans that any 2 high loads (e.g. steam iron + kettle) will send it temporarilyinto bypass. The VPhase is meant to be able to regulate at 8amps continuously(above this it gets too hot and goes into bypass). This seems about correct -on my unit it can regulate a 1.5kW load continuously, at 2kW after about 1 hourthe case temperature is 45+ degrees and the unit goes into bypass for about 10minutes then regulates again for about 40 minutes etc.
Losses in unit:
The spec says the VPhase losses are less than 1%. On my unit at a 2kWregulated load, the unit is consuming about 25W, so this seems about correct.However, it looks like it has a base consumption of about 10W-15W, so even atnight when the 'background' load is about 40W, the VPhase is consuming 25% ofthis.
Energy savings:
Equipment with universal electric motors in(vacuum cleaner, food processor, fridge etc) really do show reduced consumptionin the order of 18-20% (mains at 238-242V vs regulated 219-220V from VPhase).However, that's not the whole story. It's evident (change in pitch when switchbetween the 220 and 240) that the motors are running slower. It doesn't make much difference to how wellthe vacuum cleaner works, but although 'instantaneously' when the fridge/freezermotor is running it shows a 19% improvement, if I monitor the consumption overa week on 220V then on 240V the lower voltage only results in a 5% saving.Presumably because the fridge motor needs to do a certain amount of workcompressing the refrigerant and just runs for longer when the voltage isreduced.
As has been previously said, it makes no difference to any thermostaticallycontrolled heaters, they just run longer, i.e. takes exactlythe same number of Wattsxtime to boil the kettle or toast the bread. It looksthough like the microwave takes about 4% less energy to boil a cup of water at220V (takes a bit longer, but less than 10% longer and power consumption is 15%less).
White goods (dishwasher, washing machine)don't show a significant improvement <5%, I presume because most of energyused is in heating water, which isn't affected by voltage reduction - it's alsodifficult to do a consistent back to back test.
Lights - Most of my lights are LED, and Ican't discern any difference (either in brightness or energy consumption)running at the regulated 220 or 240V but the LEDs' consumption are close to theresolution/sensitivity of my test gear. The few halogens, consume about 15%less but are noticeably dimmer. Interestingly I tried an old (notelectronically regulated) fluorescent strip light and it showed both a 20%consumption improvement and no change in light output.
Electronic goods - Most of the stuff I havehas switch mode PSU (LCD TV, radios, computers, printers etc) and there's onlya very slight improvement running on a regulated 220V certainly less than 5%,seems to be about an average 2%.
Gas boiler - The peak electricity load (CHpump + flue fan) reduced by about 15%, it's possible that the pumps and fansrun longer to compensate, but I couldn't tell.
Conclusion: I've a fairly low electricityconsumption (8kWh per day, house occupied all day), and I make it that theoverall costs are somewhere between -£15 and +£5 (i.e. might cost an extra £5through to saving a maximum of £15), which equates to a maximum possible savingof about 3%. But, for example our lighting consumption is now 10% of that usedcooking, whereas before fitting the LEDs it was nearly the same and the newFridge Freezer uses 1/3 the power of the old one (which was the single biggestconsumer). So I would imagine it's possible if had an older F-F, lots ofhalogen/tungsten or fluorescent lights to see a saving over 5%.
