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Hi Dave C, what was the model of inverter and battery you had installed? Is your system hybrid or just for making the most of an E7 tariff? Thanks

Hi Alshamal, thanks for the reply. I've got a bunch of questions of you don't mind... Does the Lux 3600 provide the easy option to charge itself at night and then to be the primary power source until empty at user selected times in the day? Does it also offer the option to automatically step in if there's a power cut? Is the Lux just the inverter, and were there options for the battery modules? Did you consider any other options for the battery? Or for the inverter? What was the approximate cost? Was that including installation? THANK YOU!

Thanks, ProDave. I've just moved to Economy 7 as the maths made a lot of sense even with the "extortionate" day rate. Before, I was paying 35p/kWh for every kWH under the EPG; right now, I pay 7p/kWh for 75% of my usage and 54.5p/kWh for the rest, averaging about 18p/kWh. Now admittedly that's skewed in my favour as so much of my usage is heating at this time of year (which I can do at night), but crunching the detailed stats for the whole year, I expect 63% of my usage to be off peak and my weighted average cost to be around 25p/kWh saving me around £800 in the year (from £2,800 for 8,000 kWh to £2,000, of which £350 is for 5,000kwh night units and £1,650 for the 3,000kwh day units): The thing about EDF's particularly skewed day/night rates is that it then makes it worthwhile trying to use a battery to shift a large predictable, and regular, chunk of the 3,000kwh at day rate to the night rates... 6.9kwh per day would be around 2,500 of them. Under my plan, I'd then have 7,500kwh @7p and 500kwh @54.5p total £800 annually for 8,000kwh, with weighted averaged cost of 10p/kWh... Does that stack up to you?

A bit late to this topic. I have an ASHP and have just got EDF to apply their E7 tariff to my account. (I have a new Smets2 meter so it was just a case of applying the tariff, no wiring or meter changes needed). I'm in the Eastern region so the difference is big: 7p /kWh at night (11pm to 7am, so actually 8 hours), 54.5p /kWh in the day. I'm lucky enough to have wet underfloor heating and a well insulated house, so it seems I can heat at night and last nicely to the following evening, combined with programming DHW and D/W, W/M and dryer running to nighttime I'm at around 75% off peak. Preamble over, I do still have 5-7kwh per day daytime usage as a minimum that I want to install a battery to benefit from the low rate. I'm looking at a Fox ESS option that comes with 2.6kwh scalable battery units. 3 of these would have usable capacity of 6.9kwh. Including their battery management system and an AC (NOT a hybrid/PV) inverter this looks to be £4,300k for the kit incl VAT. I know if I add *some* PV it would be zero-vat rated, (£3,600) but not sure the minimum approach, as the eco and cost benefit comes from using, say, wasted nighttime off shore wind or nuclear, and reduce the need for peak hour gas-based electricity. 6.9kwh per day is 2,518 kWh per year. Each kWh has a saving 47.5p/kwh, or £1,196 a year. Accepting energy and capacity losses I'd hope for £1,100 to be achieved. So a 3-5 year payback depending on finding an electrician to install and the VAT answer). This is entirely hypothetical at the moment - I'm not an electrician, and am yet to approach one, so interested on people's thoughts of the feasibility. I would also be interested to hear of any other options versus this: - 3x Fox ESS HV2600, with brackets plus - BMS plus - AC1-5.0 A/C inverter. The 5kW inverter feels generous, but the saving for a 3.0kW option seems small for the added limitation on running appliances (e.g. oven plus microwave plus kettle plus)