@batpred 

This is our current month, nearly 700kwh so far. About £10 of this is the standing charge also.

I can't see how I could save enough to make solar worth installing.

@bash 

my octopus estimate for my 8kwh system on intelligent flux with octopus  in addition you need to add in the units generated that I used myself  the system costs me £76 per month interest free over 10 yrs and even without the export payments I make on average £24 pm average just in using my own generated power

Posted by: @bash

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@majordennisbloodnok 

I know we have discussed this before but with export rates dropping and almost certainly dropping further the numbers to me favour storage over solar.

If you buy a heat pump storage is very important.

In this argument you'd end up having to buy your solar first, then buy a heat pump then almost certainly install a battery, so it's a much bigger investment.

Better to install your battery (with a hybrid inverter) first then the heat pump.

Only then consider solar.

I was convinced on solar and still toy with adding some.

However now that I have lots of storage, I cannot see the value, as I can import all my electricity needs for pennies per kWh.

How many units could I buy with that all solar money? That's what I keep asking myself and it is a lot!

I can't say you're wrong, @bash, or at least if I did I wouldn't be able to say it with any real conviction. However, I still maintain there's a case to be made.

The key is the issue of export rates available as well as off-peak import rates. Neither are set in stone, so we have to work on best guesses or historical data. Significantly, I don't think you can be cautious of export rates dropping whilst still using a reliance on pennies per kWh cheap import on the other side of the equation; either we have to accept that both export rates may well drop and cheap import rates may well rise or do a bit of back-of-a-fag-packet calculation based on their current relative prices. Consistency of argument whichever way we choose to analyse it.

I have 18 panels and they are 360W JA panels specifically. Dividing my rolling yearly sum of generated leccy by 18 means each panel last year generated 257kWh. If I were to install 18 panels today, I'd get more efficient ones and 550W JA units are approximately £94 each. Pro-rating the generation, I'd expect approximately 382kWh from each of them over a year. If we use your model of importing cheap to fill up the battery and then using that for home and heat pump, that effectively means each of those 382kWh from a panel is worth 12p to me since that's my current export rate (and yes, I realise that could change, but so as I said could the import rate in your model), which works out at just under £46. That's a paypack of just a smidge over two years. Even taking into account the installation costs on top of that, we're still looking at a pretty reasonable break even point.

To me, all this ends up just underlining that there's no single right answer that fits everyone's situation. I can't ignore the economics of what I've just laid out and similarly I can't ignore the practicalities of your line of reasoning. What does seem more reasonable, however, is the key point I believe @editor was trying to make in his podcast and that's about getting your leccy supply optimised before installing the heat pump; if you can put together an inverter/battery/PV/tariff package that effectively reduces the net cost per kWh you have to import from the grid, you're running your heat pump on energy that's much more financially competitive with gas and so you can end up saving significantly from the move from fossil fuels to electricity.

@majordennisbloodnok 

You are certainly correct, that each individuals circumstance and choice is relevant and needs to be considered.

They key point I try to say (hopefully not too often on here!) is I don't agree with the order of renewable installation that many including Mars advocate.

In an ideal world you'd have all 3, Heat Pump, Solar and battery.

However, if economics are very important you have to do your numbers and decide the priority.

The key for me is if you install a heat pump having access to cheap(er) electricity is vital.

What happens if you install your Solar first, then plump for a heat pump and the budget is gone, there is no money left for your storage.

As a Heat Pump owner watching that smart meter number growing is quite concerning in the winter, especially if your solar output has dropped to much lower levels.

There is no way I'd be as happy with my heat pump if I didn't have access to a home battery with or without solar!

Posted by: @bash

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However, if economics are very important you have to do your numbers and decide the priority.

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Bang on.

Posted by: @bash

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The key for me is if you install a heat pump having access to cheap(er) electricity is vital.

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Absolutely, which in most cases means questioning whether heat pump first is the right order.

Posted by: @bash

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They key point I try to say (hopefully not too often on here!) is I don't agree with the order of renewable installation that many including Mars advocate.

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Point taken and agreed, with the modifier that I don't believe @editor's priority order is necessarily set in stone but merely a means of giving newcomers a stake in the ground. My personal preference would probably be inverter and battery first (to unlock access to ToU tariffs and time shifting), followed by solar panels and then heat pump, but this then brings us back round to your point about doing numbers and deciding the right priority for one's own situation.

@bash I get bills of 700-750 in Dec jan and used to panic but after 4 years my pattern has never shifted so I just ensure sufficient is in my fund to cover that but I often come across users who have suddenly hit a high bill. If the system is well designed then Ave will sort it SL out - but no one ever seems to say that. I agree the use of batteries either as you do or as I do using the panels gives the cream on the milk which along with the COP gives a real benifits even to me with a 200 yr old long Scottish stone bungalow

@majordennisbloodnok 

Agreed, other than the comment about Mars's comment not being set in stone.

I watched the video he released a few weeks ago and can remember him saying to the question what should I install first "Solar PV every time" was his answer.

It is of course his opinion and I have a differing one, which is no problem at all.

Differing opinions from part of the healthy debate, so I am not saying I am right, or Mars is wrong!

@majordennisbloodnok 12p per kWh? Octopus giving 20p and on intelligent flux when they use my batteries to export between 3-7pm I get 30 (which I usually have charged on SP

Posted by: @sapper117

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@majordennisbloodnok 12p per kWh? Octopus giving 20p and on intelligent flux when they use my batteries to export between 3-7pm I get 30 (which I usually have charged on SP

Yes. I'm on their standard tariff Octopus Outgoing which is 12p per kWh at any time. I've only got a 6.5kWh battery so don't have the capacity to generate during the day, export at peak times and service the house load at peak times too. The size of battery is the only regret we have with any of our original install (heat pump, solar PV, battery, inverter) and we are certainly now looking at ways we might justify replacing the inverter and battery with something like an 8kW inverter with islanding capabilities and a beefy Fogstar battery (e.g. the 64.4kWh IP65 unit at £6,000). It's a pipe dream at the moment but we're well aware we're already in a comfortable position as we are and can plan ahead at leisure.

@sapper117 

I think bills of £700-£750 would be a bit of a shock to anyone, especially me!

It's why I installed battery storage first and added some more once I realised how brilliant they were for my finances, only then did the heat pump get ordered!

@majordennisbloodnok 

I saw that 64kwh battery for £6000 and I wanted one immediately, even though I already have 45kwh of Fogstar batteries 😆

Posted by: @bash

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@majordennisbloodnok 

I saw that 64kwh battery for £6000 and I wanted one immediately, even though I already have 45kwh of Fogstar batteries 😆

If you have a good (outdoor) location, a good few people re-use EV batteries with 400V capable inverters: https://github.com/dalathegreat/Battery-Emulator/wiki#supported-batteries-list