That probably explains it then. Our whole house gets heated to 21 deg in the morning and just the living area again at night. TRVs are all at maximum. If I had set it to 19 the heating would hardly have come on. That extra 1-2 degrees obviously makes a difference. I may reconsider/buy some jumpers in the winter 😉
@kev-m, we run our system to 21C just about everywhere and the difference in our house, from a running efficiency, between 19C and 21C is huge. But 19C is too cold for my wife, so we run it at 21C.
I'm back to considering a solar diverter to heat ourhot water tank. I think I've been quoted £570 to install - but I guess I need to try and work out if this would be worth it, or if the £570 would effectively cover most of the hot water spend for whilst we intend to stay in this house.
We only have a 2W solar set up, so its fairly small, and at the moment we are exporting any excess to the grid.
We also only have a small tank (166L) and we're soon about to become a family of 3, so I'd imagine our hot water will begin to increase, and I'll probably need to adjust the timings for when its heated again.
I'm also not sure how much kW is required to heat the thank - and if we'd even generate enough to fully cover it from our solar panels.
Would welcome any thoughts from this community, I've attached an image from the tank
Good value, made in uk, 10 year warranty, fit and forget. An electrician shouldn’t charge more than £100 to fit. It doesn’t have all the data details of some competitors. But if you got a young family, you’ll soon run out of time to be data checking. So that’s £300 fitted and quicker ROI.
Had mine 7 years. Simples.
Daikin Altherma 3H HT 18kW ASHP with Mixergy h/w cylinder; 4kW solar PV with Solic 200 electric diverter; Honda e and Hyundai Ioniq 5 P45 electric vehicles with Myenergi Zappi mk1 charger
I agree with Julian should you go down the power diverter route, buy one and get a friendly electrician to install it.
Do you mind if I ask a few questions, so that I can better assess what would be best in your particular situation?
Do you have a meter showing the output (kWh) from your solar PV system? If so, it would be useful to record the generation on a daily basis, so that you know how much energy is available. Also record your imported energy at approximately the same time each day.
How are you heating your hot water at the moment? Is it by immersion heater?
Because you have a 2kW solar PV system you may not have that much excess energy that is being exported. Julian and I have 4kW systems, so we will actually have more than twice the excess of your system. Let me explain.
At this instant in time (14:44 on 28/5/21) our solar PV system is generating 1127W, of which 11W is being exported, 273W is being used within our home and 843W is being diverted to our immersion heater to produce hot water.
Assuming that your system is generating half the power, this would give, generation of 563.5W, 11W exported, 273W used within home, which would leave 279.5W to be diverted.
If you are heating your hot water using an immersion heater, then it would probably be more efficient, and cost effective, to use the excess generation from your solar PV system to run your ASHP, and use that to produce hot water. Maximum generation should normally occur around midday (clouds permitting), so you could try setting your ASHP to heat your water between 11:00 and 13:00 for a few days and see what results you get.
It takes approximately 1.2Wh of energy to heat 1 litre of water by 1C. So to heat your tank from cold (say 15C) to 60C, would require:-
1.2/1000 * 166 *45 = 8.964kWh
Obviously it probably won't be too often that you use all the hot water in one go, but with one of the small, noisy variety on the way, you will no doubt be using more hot water.
If you wish to investigate your options further, then please provide more information about your systems and lifestyle, so that I can suggest further tests which may be useful.
Just want to make sure I’ve understood correctly, we do have a solar inverter which tells us how much kWh we are generating, but its live and changes constantly – it doesn’t show how much we have generated per day, at least I don’t think it does.
That said, we have a little box on the wall next to the inverter which may show us the import meter (the builders never actually told us what was what) I’ve attached an image of it – do you think this is a record of our solar import kWh?
I can see how much we have exported though, its 335kWh since the 12th March 2021.
Currently, our hot water tank is currently heated by the ASHP at 3 times a day.
A friend of mine is an electrician so I could get him to take a look, just not entirely sure he’d know what to do.
The photo shows your solar PV total generation meter, which is a record of how much energy your system has generated since it was commissioned. It is indicating that your system has generated 2627.36 kWh since it was installed.
If you take the reading from this meter each day, after the Sun has gone down, and subtract the previous days reading, the result will indicate how much solar PV output you have received today.
If you would care to provide details of the make and model (there should be a label on it somewhere) of your solar inverter, I will see what information I can find. It is normally possible to interrogate modern equipment to obtain additional information. If it is one of the latest systems there may even be an app.
What times during the day does your ASHP heat your hot water? What is the make and model of your ASHP?
Do you have a smart meter for your electricity supply? Is your electricity supply meter accessible?
Perfect, funny enough I was doing exactly that back in January/February, and for the 16 days I did track it, the difference / we were generating 2.7kWh per day – I’ll start tracking it again, given the brighter, longer days we will be generating more.
Our inverter is a Solis Mini 2000 4G model, the ASHP is LG Therma V air to water heat pump
Presently I heat the water three times a day, 5am-7am, 11-3:30 and 6-8pm. This has been working for us and we always have hot water when its needed, even if the 5am-7am is not an effective time to heat the tank, it does mean we have hot water for the morning shower.
And yes to both having a smart meter and an accessible supply meter.
If you have the operators manual for the Solis inverter then look at pages 27 and 28. It gives details of advanced settings, from which you will be able to access the stored data, daily, monthly and yearly production. Don't worry about the warning that you have to be a trained technician, you are only viewing the data, not changing any settings. I am surprised that the manufacturer has decided to put this data in the password protected area, since it is information that the user would probably like to see. If you don't have the manual then just google it.
Are your solar panels South facing?
What information can you extract from your smart meter? Does it give past electricity consumption? The reason that I ask is that, if you can compare solar PV generation with electricity consumption, it may be possible to estimate how much excess solar energy that you are exporting back to the grid. On sunny days, with higher solar production, your electricity meter should indicate lower consumption, the difference being due to the fact that you are using more of your solar production in your home, and hence are not importing as much energy from the grid. Though of course this will not be the case if it was cold outside, and your ASHP was running more frequently.
Whilst our smart meter does not show how much energy was exported during the day, it is possible to see the instantaneous value which will be negative if the solar generation is greater than the energy consumption in your home. This may give some idea of your base load, how much energy is used during most hours during the day. In our home the base load is in the region of 100W to 300W, dependent upon whether the fridge and freezer are running along with our two laptops and router etc. If you know your normal base load it is possible to estimate how much of your solar generation is being exported.
If you decide against a solar diverter, you may be able to get paid for the electricity that you export. Maybe someone on the forum knows the procedure for registering?
Looking at the manual for the i-boost+, your friendly electrician should have no problem installing one, though if he has problems you can always get in touch. I installed my own, which is an immersun unit, though it does the same as an i-boost+.
This winter and spring has been a lot colder than last year, and it's really interesting to see the correlation between ambient temperature and ASHP consumption.
Our next step in this journey is to now drop our consumption. The new K3s have definitely addressed our cold rooms, and everything is now coming to temperature. I think that we'll try and drop the flow rate to 40C, and see if that helps.
I dropped ours to 40C on May25, 2021, but the outside temperatures have gone up and I haven't seen a considerable difference, but let's see what happens.
This winter and spring has been a lot colder than last year, and it's really interesting to see the correlation between ambient temperature and ASHP consumption.
Our next step in this journey is to now drop our consumption. The new K3s have definitely addressed our cold rooms, and everything is now coming to temperature. I think that we'll try and drop the flow rate to 40C, and see if that helps.
I dropped ours to 40C on May25, 2021, but the outside temperatures have gone up and I haven't seen a considerable difference, but let's see what happens.
The Energy House at Salford University came up with some interesting insights. This is a full size typical poorly insulated old house they have built in a controlled environment. They are also working on an Energy House 2.
A cut/paste of some of their findings, not with an ASHP, but I thought was interesting regarding weather.
I can relate to their findings with our house with Rain.
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We were quite surprised by the extent of the findings,’ says Richard. ‘We found that the addition of thermostatic radiator valves [which control the temperature in each room according to different needs throughout the day], reduced heating bills by 40 per cent’.
The house is always throwing up new surprises.
For example if it's windy outside, heat loss from the home will increase by 5-8 per cent.
But if it's rainy the loss shoots up to 20 per cent. And if it's windy and rainy, expect a massive 30 per cent heat loss.
And do not underestimate the power of curtains. Drawing the blinds at dusk can reduce heat loss by 13-14 per cent and curtains from 15-17 per cent, Richard reveals.
