How much can I practically/legally DIY, and other newb questions

[Joeboy]

Currently, I've got mine set to charge to 100% on Octopus Go (00:30-04:40). By the time I get up and make a coffee, the batteries (2xUS2000C) are down to about 90%. The sun hits the panels around 10:30, by which time the batteries are down to 70% ish. If it's a good day, by the time the sun goes down, the batteries are at 100% again.

That's the part I wasn't sure inverter can deal with, i.e. charging batteries from PV outside of time-of-use charging time.

I expect as the days get longer I'll reduce the overnight charge level to account for the panels starting to generate earlier in the day. If you've got a Sofar inverter you use 'time of use' mode and can set a charge level for the charging time, outside of that time it runs from PV and batteries, and any excess PV goes into the batteries, or if they are full, gets exported.

I definitely need another battery though, even on a sunny winter day I'm exporting loads to the grid and not getting paid for it! On a dull day, my current batteries aren't enough and I'm back on grid power by 6-7 pm.

Does it make sense to you to add another battery? On days where i go over battery capacity I probably use on average 1kWh, which is 20-30p extra a day. I guess once i have couple panes it will happen let's say 100 times a year, which means I need a US2000 battery to save <£50 a year. Having another battery would prevent getting close to battery limits around sunny days but still not sure it financially makes sense.

You could go the DC hookup route that a few here have done and install yourself?
I found that the more batteries we had the more we found ingenious ways to use the stored capacity plus of course the intangible of making the decision to be fully in charge (absolutely unintended horrendous pun). I do see the point though in Ducabi's sub £50 rationale though.

https://camelot-forum.co.uk/phpBB3/view ... =14&t=1194

I loathed running out of juice in the stack and going to the grid. Then again I am a control freak who views overly in terms of black & white.

[dangermouse]

I found that the more batteries we had the more we found ingenious ways to use the stored capacity plus of course tge intangible of making the decision to be fully in charge (absolutely unintended horrendous pun). I do see the point though in Ducabi's sub £50 rationale though.

I can see both sides ... On one hand I agree that it's hard to justify another battery on purely financial grounds. But looking to the future, I suspect buying energy is not going to get any cheaper, and having more storage capacity will allow me to reduce my gas (and grid leccy) usage and have a generally more flexible system.

[Joeboy]

I found that the more batteries we had the more we found ingenious ways to use the stored capacity plus of course tge intangible of making the decision to be fully in charge (absolutely unintended horrendous pun). I do see the point though in Ducabi's sub £50 rationale though.

I can see both sides ... On one hand I agree that it's hard to justify another battery on purely financial grounds. But looking to the future, I suspect buying energy is not going to get any cheaper, and having more storage capacity will allow me to reduce my gas (and grid leccy) usage and have a generally more flexible system.

It does and it will. Flexibility is a bit of a Grail place to be. My values used to be financial, then planet but tbh I'm now about as much independence as I can have in my power world. The first two reasons are still present but doing it for myself on as many of the 365 as I can is very important now. Almost a game but for real.

[ducabi]

You could go the DC hookup route that a few here have done and install yourself?
I found that the more batteries we had the more we found ingenious ways to use the stored capacity plus of course the intangible of making the decision to be fully in charge (absolutely unintended horrendous pun). I do see the point though in Ducabi's sub £50 rationale though.

https://camelot-forum.co.uk/phpBB3/view ... =14&t=1194

I loathed running out of juice in the stack and going to the grid. Then again I am a control freak who views overly in terms of black & white.

That's the long term plan. Then I may try to move some gas usage to electricity, e.g. water.

[NikoV6]

I found that the more batteries we had the more we found ingenious ways to use the stored capacity plus of course tge intangible of making the decision to be fully in charge (absolutely unintended horrendous pun). I do see the point though in Ducabi's sub £50 rationale though.

I can see both sides ... On one hand I agree that it's hard to justify another battery on purely financial grounds. But looking to the future, I suspect buying energy is not going to get any cheaper, and having more storage capacity will allow me to reduce my gas (and grid leccy) usage and have a generally more flexible system.

It does and it will. Flexibility is a bit of a Grail place to be. My values used to be financial, then planet but tbh I'm now about as much independence as I can have in my power world. The first two reasons are still present but doing it for myself on as many of the 365 as I can is very important now. Almost a game but for real.

I agree, being as independent as possible is our goal too. We have no gas here so everything is electric! Keeping a leaky welsh cottage warm with an ASHP can have our 13.5Kw battery flat (bar 20% backup) by early afternoon on a poor day. We are toying with the idea of taking total battery capacity to around 27Kw to ensure we stay off peak rates as much as possible

[ducabi]

I agree, being as independent as possible is our goal too. We have no gas here so everything is electric! Keeping a leaky welsh cottage warm with an ASHP can have our 13.5Kw battery flat (bar 20% backup) by early afternoon on a poor day. We are toying with the idea of taking total battery capacity to around 27Kw to ensure we stay off peak rates as much as possible

I've looked at your spec and I wonder how you manage to keep house warm by early afternoon with such battery capacity. During freezing in Dec we used up to 120kWh of gas a day in late 80s build with no cavity wall insulation. Maybe I could half it by doing some improvements but 60kWh is still a massive battery storage if I wanted to remove gas.

[Stinsy]

I've looked at your spec and I wonder how you manage to keep house warm by early afternoon with such battery capacity. During freezing in Dec we used up to 120kWh of gas a day in late 80s build with no cavity wall insulation. Maybe I could half it by doing some improvements but 60kWh is still a massive battery storage if I wanted to remove gas.

A few things:

1) Your boiler is at best 80% efficient. So that 120kWh of gas turns in to 96kWh of heat.

2) The HP has a CoP, so to produce 96kWh of heat it would require 24-32kWh of electric.

3) You can squeeze maybe half of your heating requirement into the cheap period as the HP starts up and gets the house up to temp in the cheap period and is therefore only ticking along keeping it warm from battery power.

[ducabi]

A few things:

1) Your boiler is at best 80% efficient. So that 120kWh of gas turns in to 96kWh of heat.

2) The HP has a CoP, so to produce 96kWh of heat it would require 24-32kWh of electric.

3) You can squeeze maybe half of your heating requirement into the cheap period as the HP starts up and gets the house up to temp in the cheap period and is therefore only ticking along keeping it warm from battery power.

1) My boiler was replaced couple years ago, so based on it's spec it's over 90%.

2) I know about the ration but I can see many people complaining about huge bills after switching to HP? I know it's mainly due to bad house insulation but if it was much better then they would have much lower gas usage too.

https://www.examinerlive.co.uk/news/loc ... y-25802491

[Stinsy]

The people I see are shocked at how little energy their HP consumes compared with their previous gas boiler. The inference being that their gas boiler was clearly much less efficient than assumed.

There are a few reasons why a HP might be costing more that you expect. Sometimes an undersized HP is fitted and the backup resistive element is being used excessively. Back when gas was 2p and electric was 15p the CoP couldn't make up the 7.5x difference. Now that Gas is 11p and electric is 35p the CoP of a HP can make up the difference.

[Joeboy]

I can see both sides ... On one hand I agree that it's hard to justify another battery on purely financial grounds. But looking to the future, I suspect buying energy is not going to get any cheaper, and having more storage capacity will allow me to reduce my gas (and grid leccy) usage and have a generally more flexible system.

It does and it will. Flexibility is a bit of a Grail place to be. My values used to be financial, then planet but tbh I'm now about as much independence as I can have in my power world. The first two reasons are still present but doing it for myself on as many of the 365 as I can is very important now. Almost a game but for real.

I agree, being as independent as possible is our goal too. We have no gas here so everything is electric! Keeping a leaky welsh cottage warm with an ASHP can have our 13.5Kw battery flat (bar 20% backup) by early afternoon on a poor day. We are toying with the idea of taking total battery capacity to around 27Kw to ensure we stay off peak rates as much as possible

Do everything you can to plug air leaks and insulate. There is absolutely no point in heating the world from your house. I say that tongue in cheek but it's the sort of thought I had when I got to grips with my own house and felt the cumulative difference of all the little works. Every little bit you can do in this regard matters..