Solar Panels UK - is it worth it?

[thewishy]

Yeah, if you're looking at the web dashboard for your inverter (or the mobile app), the data is only transmitted every few minutes so you get inconsistencies in what's shown at low loads. It annoyed me so I went down the Home Assistant route with my Fox setup.

I'll add that any hybrid inverter takes a short time to sync with load, typically a fraction of a second. The best way to see what's happening is the IHD of your smart meter. Likely over the course of the day, you'll have a fraction of a kWh from grid, and a fraction to grid for the time between the load change being detected and the inverter ramping/dropping the output to match.
Giv recently introduced a new firmware with supposedly faster response times, although I've not really seen much different to those totals

 

[Avendit]

If you want zero costs you need an export tariff. My givenergy seems pretty slow. My bill in June and July (billed midway) was still about £23 including standing charge and I’d been monitoring carefully as the first full months since commissioning and I don’t recall any significant grid pull, just the lag from the kettle going on or slow at reacting to solar changes on a cloudy day. This is with 38p peak and 8p off peak

View attachment 957280

I would like a way to set it to be more cautious if I know I have excess solar to let it export more to give a buffer. Probably wouldn’t make much difference though

I can set my target export - currently on 0w. Could move that up or down to prioritise export or other devices over the battery. It's a key feature my car charger is missing .

 

[yessuz]

yeah, there is some grid pull and I understand that.
it was basically first day when whole system is fully operational - so fascinating to watch

other than that - look at your bill, it's more than half for standing change alone. grid consumption is 30p a day

 

[phil4]

Yeah, if you're looking at the web dashboard for your inverter (or the mobile app), the data is only transmitted every few minutes so you get inconsistencies in what's shown at low loads. It annoyed me so I went down the Home Assistant route with my Fox setup.

I don't think you can beat slapping a few CT clamps on the various parts and monitoring with a few seconds update frequency. A Zappi is pretty good for this if you want dual purpose. All feeds easily into HA.

 

[The_Cable_Guy]

that the bit that get me, if your bill is £150 a month, £40 of that is standing charge which you cant get away from, so at best on your best days you sell back to grid and you recoupe you standing charge, and hope that it balances out over the year due to the winter months when generation is much much lower.

Has anyone done clacs/figures with a yearly breakdown vs without solar/batteries.

Obviously this is very dependant on your usage/array size/storage size/FIT & buy/install cost.

I think im going to do batteries only for a few years, and charge purely at night and run off batteries during the day, i think repayment period is about 2.5 years, then when they have paid for themselves i will fit solar.

 

[phil4]

Obviously this is very dependant on your usage/array size/storage size/FIT & buy/install cost.

That's the problem, and you forgot use in that list.

Everyone seems to think everyone else's system works like theirs. You see this most with the Flux evangelists. Some solar arrays are huge, and home use negligible. Some it's the other way around. So you really need to juggle home use, battery size and solar array to find something that works for you. If you happen to be able to export lots, then you can use export tariffs and flux to negate standing charge. But that's a big if.

 

[Pete UK]

If you want zero costs you need an export tariff. My givenergy seems pretty slow. My bill in June and July (billed midway) was still about £23 including standing charge and I’d been monitoring carefully as the first full months since commissioning and I don’t recall any significant grid pull, just the lag from the kettle going on or slow at reacting to solar changes on a cloudy day. This is with 38p peak and 8p off peak

View attachment 957280

I would like a way to set it to be more cautious if I know I have excess solar to let it export more to give a buffer. Probably wouldn’t make much difference though

Is that import figure perhaps including the calibration discharge and charge from the grid?

On my GivEnergy system I’ve been billed less that 10p most days - usually it’s around 5p (2-8p); on 3 days you can see I was messing about charging the car where I used extra above that, due to one inverter only discharging at 600w ( fixed by GE!) and/ or the batteries getting to zero (or at least one battery in a pair getting to zero and stopping the pair discharging, hence the grid pull). I’ve dialled down the Tesla wall charger to 26A (~6kW) while charging from solar/batteries which then fully covers the charging and most peaks and all background drain.
If you’re charging the car at 32A that’s a full 3.7kW from each inverter (7.4kW), so the background base load has to come from either excess solar, or the grid during that time. So if you’re charging at max and a cloud goes by (or more likely it’s dark!), anything above 7.4kW will come from the remaining 1.5kW (3kW) Solar (x2 hybrids) or get drawn from the grid. Maybe it’s this?
6.8kW seems like a lot still !
I’ve found that due to the car charge starting and stopping there is a bit of a lag where you draw from grid as well. Ovo ‘smart charge’ seems to do a lot of small charges for a minute or two and then stop. It’s quite annoying but I think this is how it is calculating and re-calculating how to meet the target percentage by the “ready by” time.

 

[DaveNN]

Mine moves in demand-battery supply/2 lumps about once a second. So whacking on the toaster and kettle in the morning takes a good 10-20 seconds to even out, then when they finish I export a decreasing lump for the same 10-20 seconds. But if demand is constant, then it matches really nicely. I call it arbitrage and it costs us about 20p per 24hr.

I've kind of given up relying on the data supplied from the laggy logger.
Yes, though, I see the same as you.
I don't have a SEG tariff, so use what it can.
I find that the smart meter remote display gives me all the instant info I need.
Otherwise, I walk 10ft and look at the inverter display.

What I do get is the below.
It could be the battery charger/inverter monitoring the grid but , over a month or so, adds up to a few quid.

Anyone any suggestions?

 

[Drew57]

The Octopus Home Mini can be used to check what the actual house load is in real time (updates every 5 seconds) via the Octopus app. The inverters & Zappi apps/web browsers provide useful solar, consumption, charging and export data with 2-5 minute time lags whereas this is equivalent to having the IHD permanently available on the phone.

 

[DaveNN]

The Octopus Home Mini can be used to check what the actual house load is in real time (updates every 5 seconds) via the Octopus app. The inverters & Zappi apps/web browsers provide useful solar, consumption, charging and export data with 2-5 minute time lags whereas this is equivalent to having the IHD permanently available on the phone.

View attachment 957395

If only the ruddy thing worked
( for me, anyway)

 

[Pete UK]

I've kind of given up relying on the data supplied from the laggy logger.
Yes, though, I see the same as you.
I don't have a SEG tariff, so use what it can.
I find that the smart meter remote display gives me all the instant info I need.
Otherwise, I walk 10ft and look at the inverter display.

What I do get is the below.
It could be the battery charger/inverter monitoring the grid but , over a month or so, adds up to a few quid.

Anyone any suggestions?

Something using 3kw is kicking in at about 3am.

 

[DaveNN]

Something using 3kw is kicking in at about 3am.

That's my battery home storage being topped up to 70%...it's the tiny amounts during the day when I'm on battery which is strange.

 

[DaveNN]

The Octopus Home Mini can be used to check what the actual house load is in real time (updates every 5 seconds) via the Octopus app. The inverters & Zappi apps/web browsers provide useful solar, consumption, charging and export data with 2-5 minute time lags whereas this is equivalent to having the IHD permanently available on the phone.

View attachment 957395

Got mine set up, totally fine now.
Except that I'm pulling this ...even though I'm on battery only.
It's buttons, of course, more an interest than an issue.

 

[Drew57]

Got mine set up, totally fine now.
Except that I'm pulling this ...even though I'm on battery only.
It's buttons, of course, more an interest than an issue.

Inverters usually draw a small amount of grid power when running.

Mine only show 0kWh when the house batteries are full and solar is still generating, once that finishes & they are discharging then ~35Wh is displayed on the Home Mini unless the house load exceeds 3.6kWh or something like the kettle/toaster etc gives an initial high reading for a few seconds.

My house normally uses around 20-30p/day plus standing charge unless a car has been charged via IO.

 

[Fursty Ferret]

Except that I'm pulling this ...even though I'm on battery only.

That is quite a lot. Possibly worth bring up with your installer. FWIW mine uses about 50W, not 1kW.

 

[GRiLLA]

That is quite a lot. Possibly worth bring up with your installer. FWIW mine uses about 50W, not 1kW.

11 Wh in 30 minutes, 0.5KWH a day, about 15p ?

 

[DaveNN]

It's pulling 11wh .

At this moment I'm generating 3kw, nothing imported nor exported.
2.65kw into the batteries, the rest into the house.

 

[DaveNN]

11 Wh in 30 minutes, 0.5KWH a day, about 15p ?

That's about it, yep....less really as I'm averaging 8ppkwhr over a month.
It's shown on my bill as this tiny but nigh on constant pull off the grid.
Let's be candid, it's buttons.

 

[Pink Duck]

My 8 kW Solis inverter consumes under 1 W overnight, for reference. Freezer bursts to 130 W, fridge to 40 W.

 

[DaveNN]

My 8 kW Solis inverter consumes under 1 W overnight, for reference. Freezer bursts to 130 W, fridge to 40 W.

There is something going on but all I can do is switch off both the controller and inverter and see what happens.
We have a few fridges and freezers, I'd say they pull 300watt or so.