PhilT

yeah mine's similar. With just the two of us and no visitors we easily get by with 40degC set temp but the sensor position is at around 25% of the height of the tank, so the water coming out of the top feed is much hotter.

Not necessarily. It's the battery discharge vs charge inefficiency which loses the most. I have separate AC/DC battery inverter and the losses from PV to battery feed are around 3%. A small price to pay for being able to use basic (and inexpensive) non hybrid HD Wave inverters that enable PV optimisers to capture a lot more solar on my 'difficult' roof. But you could go with something like an HD Wave with Storedge Hybrid module plus LG Res batteries, but I believe that would be considerably more costly

Need more detail. What exactly is reading 44, and what exactly is reading 52? I have the same as you and there is only one temp on the controller from the tank sensor. The tank sensor is near the bottom so will read a lower temp than near the top due to stratification.

To back that up, look at this very limited sample of users posting their results and you can see that the two most popular makes/brands are the best and the worst! https://heatpumpmonitor.org/ also your installation config can make a big difference. I have a good installation but my microbore + radiator refit will never be able to achieve greater than COP 3.5, whereas a new or complete re-build with UFH can get above COP 4.5

Would this be via Fixed Outgoing? What does it pay now - is it still 15p/kWh?

This is just your net imported energy. The huge solar and battery capacity you have relative to your tiny base consumption of only a few kWh per day (excluding those times when you ran your immersion heater) means that on most days your net imported energy is probably just inverter inefficiencies

Agree with everything said above, especially that the financials deteriorate significantly the larger you go, relative to your consumption. The situation in the market is so fluid that justication will vary from positive to negative with changes in tariff schemes, costs and export rates. If you can justify it, go for a small battery to start with (you can always add later), which will give you the most flexibiltiy to adapt to tariff changes and utilisation; a 3kW battery gives me near enough 200% utilisation i.e. it fully charges/discharges twice daily, programmed to user either low tariff rate or solar or both.

The "C" used in hobby packs is the multiplier of the Ah rating that the pack can safely discharge continuously, so a 5Ah pack rated at 120C can safely discharge at ( 120 x 5 = ) 600A, which would take around 30 seconds. The electric model car world speed record holder (over 200mph) would be using these crazy kind of packs, and that means wires like lamp posts!

Interested to know why some may like/prefer R290 to R32. Looking at the research literature, on paper R32 appears to be superior except for GWP, and has no onerous fire regs.

Large commercial storage batteries are very conservatively spec'd. For non critical applications such as radio control hobbies (airplanes etc.) the cell packs have "C" ratings as high as 120, which means they can safely discharge in 30 seconds!

Absolutely. The claimed "100% discharge" of the one I use, and its accompanying written guarantee, would be ludicrous if it didn't have massive hidden headroom built in

Battery dc in the region of 50v

I hope that black thing is a DNO cutout otherwise I don't have one either!

https://www.theheatinghub.co.uk/articles/hybrid-heat-pumps This might have been a good way to encourage large scale transition but, incredibly, they now don't qualify for any grant! Sadly I think it will be a slow burn based on a combination of homes' forced need for replacement of ageing equipment, an increasing gas cost relative to electricity, and improving HP technology/COP in conjunction with reduced up front cost through economies of scale

"Storage" is a requirement via declaration only, so you can tell a fib about having a battery and not have to back it up with an independently verifiable key such as an MCS number

it seems they do, they switched me to Cosy same day in Dec'22 then same day again to Flux in Mar'23. All provided of course that you meet the somewhat onerous conditions, smart meter, proof/declaration of heat pump ownership/MCS cert (Cosy), proof/declaration of MCS, DNO certs, DNO letter, PV + Battery ownership (Flux)

Your Luxpowertek app says that your system is capable of discharging at up to 180amps = c. 9kW

from the luxpowertek screenshots you posted in your other thread it looks like you have a 9kWh battery? The first chart suggests a utilisation of only around 50% which would make your battery well oversized for your application for most of the year. Can you get onto any export tariffs? With a battery that size you could be force discharging the other 50% to export via the Octopus Flux tariff at 24p/kWh standard rate or 37p/kWh between 4-7pm

Our installer told me that they update firmware remotely when due, a bit like our BT Router which happens occasionally overnight

you mean the power supply companies rather than the DNO. The latest average wholesale price they pay is around 5p/kWh so there is no incentive for them to pay us more than that. It's a bit like saying the supermarkets should sell us food at the same price they buy it

I was in exactly the same position and only went for an 11.2kW because we are planning on extending the house at some point, however the 11.2 coped so well in Dec when the night time temps got down to -11 I'm really glad I did. During milder times the compressor pauses maybe once or twice an hour when the heat requirement gets below the minimum continuous output (c. 30% of max power) however this doesn't seem to affect the recorded COP or efficiency in a measurable way

try contacting the supplier they responded to my email quite quickly. https://luxpowertek.com/contact-us also they sent me a user manual which includes a guide to using the phone and desktop app (section 2), I have attached it here Typical Application Instruction（LXP 3-6k Hybrid）.pdf

Your settings are in the default "self use" state, which seems to be working ok apart from one consumption spike not supplied by the battery just after 14:00 (which could be a blip). For what it's worth, my On Grid Cutoff SOC is set to 5% and Off Grid 3%, which is what the installer set based on advice from the supplier. Regarding a power cut, the installer should have put in a mains socket for you, connected to the EPS which you already have switched on (Power Backup "Enable" button in the settings, first section)

You need to click on the "Read" button first to populate all cells with the current settings, then take another screen shot we can have a look at

It looks like there's an issue with your settings - there's three x 2+kW consumption spikes, but no battery assistance in the first two, only the third one shows 100% battery support. Post a screenshot of your charge/discharge settings so we can see what's going on.