The Solar Thread

My installer has 40kWh of battery storage and uses that to force charge on an EV tariff and heat the hot tub every day.

He uses 60+kWh a day…

@footflaps we had both the old and new elec meters showing after moving to octopus. Eon next hadn’t decommissioned the old elec properly. Took 5 mins on the phone for octopus to fix and while I was on the phone they booked an engineer to fix the not transmitting ‘smart’ meter.

Ah, interesting, thanks Daffy. I’m struggling to find anyone that wants to take my money – the industry seems very in demand! I haven’t researched but I wonder if there’s a restriction in the FIT terms to siphoning off the PV kw into a battery when I’m meant to be pushing it out to the grid.

I’ll have another go as it would remove worries we have of power outages also, we have a small PHEV battery and an even smaller e-Moped battery that would benefit from such an install. I guess the sooner I do it the quick I get the benefits.

Interesting video about the new Octopus Flux tariff here:

Not that dissimilar to Octopus Agile, same shape, just fixed rather than dynamic…

We top up our battery every night between 3 and 5 am (unless it’s over 60%) and then either top up on solar or just run the battery down during the day.

Not used any electricity in peak evening hours for months now.

On a ‘bad’ day, with no solar at all, and only a 60% charge, battery runs out around 11pm ish when we’re only using 0.2 kW or so.

Well, the sun is down on the second wettest March on record and we’ve done okay. 366kWh generated. 46kWh Exported. That’s partially due to my silly self limiting expansion pack (stupid 65A max), but also my wife refusing to make use of the sun as she’s “too busy to put the dishwasher/washing machine on whilst working from home” Grrr!. There were around 3 really sunnt days where we generated about 26-27kWh and the batteries can only store 19ish, so we were never going to use it all.

We’ve apparently only imported 102kWh. So, £33 + the standing charge should see me under £50. £130 paid back…It’s a long road to recovery!

322kwh here compared to 460kwh in 2022.

114kwh exported mostly as we only had one battery till about the 10th and my firmware was updated.

Imported 120kwh

Signed up to flux this morning as every rate except the peak is lower than OVO has just put their rates up to.

Although thanks to powermove our bill was 30 quid for march

Array size?

335kwh generated from 6kw array in the south east

50kwh exported

140kwh imported

My app annoyingly doesn’t aggregate months, just daily totals.

Not sure how accurate the numbers are from the app or how efficiently the battery provides generated electricity.

Aberdeen 5.3  array

4kw array Aberdeen

It’s definitely been sunnier in Aberdeen than in the south.

129kwh on a 3.2 array (small usable roof space) 5kwh battery. I’m happy with that as it was only installed on the 16th of this month. South Northumberland.

6KW south facing in a deep Welsh valley

304 Kwh generated in March with no export (only marginally better than February & 275 kwh and that was 3 days shorter!)
132 kwh imported from grid

so 304 @ 59p = £179 saved this month. Looks like there is a potential saving of well over £2K over the year.

59p a kwh sounds high?!

I assume welshfarmer may be on three phase business rates other wise 59p/kWh is having pants pulled down

.

Single phase, but business rates. My contract came up for renewal at just the wrong time. 59p was best I could get. I was getting quotes of over a £1.10 a unit in December when I had to renew. At the time there was no guaranteed rate relief for businesses and prices were going up daily (sometimes twice a day). I took what I could get for a 1 year contract. And there are no dual rate tariffs for small business users either 🙁

With the value of hindsight I could have stuck it out on a variable rate tariff which would have been nicely reduced with the business relief, and then looked to get a new contract now that the prices are back down to around 35p a unit.

7.2kW install on an E/W roof in Sunny Leeds… well I say sunny, it wasn’t particularly this month.
Install only went live on 5th March, so not a full months data.
However in the period 5-31st March we generated 307kW and put 170kW into the batteries.
Import from Octopus was 135kW which is a lot less than we would normally use and some of that was me testing our the forced discharge on the batteries.
We are on Octopus Flux import and just waiting for Flux export to go live in the next week or so.
Being new to solar, I am impressed how even with a fair bit of cloud you can generate a lot, and the E/W aspect works really well too, so south facing really isn’t important so much.

358kW from our 5.6kW array in March. Had a Raspberry Pi issue whilst we were away so lost almost 3 days of readings plus had snow cover for almost 2 days so final “recorded” result was 358kW, without the Pi dropout probably around 390kw, thats off 5.6kW array.

@daffy

Our manufacturer recommends force charging to 100% regularly as this keeps the batteries in best condition. General consensus from those on the vendor facebook page (many of whom seem well informed) is to set the minimum SOC at 10%, force charge occasionally to max then let the BMS do its thing.
In my view when you consider the battery charge is constantly on/off during the day (possibly 00’s of times) as the battery use against solar gain constantly changes then I think this must be the greatest risk to battery longevity. Anyway will be interesting to see how this pans out over the next few years across all manufacturers.

I have changed my overnight charging schedule and reduced it to 45 mins. (8.7kW battery and 5kW inverter) previously I aimed to have 100% when our Eco7 finished at 7:30 and some days I was feeding back more than we were using (only 1p difference in cost) but if I charge and wake up to 50%, even with the early morning kettle and toaster etc it can easily be 100% by late morning and only drawing around 300w so at some point it is fully charged well before the teatime rush.

This is 9am

First proper cloudless day in East Anglia for ages, been struggling to generate more than a few kWh for the last few weeks.

Looks like we’ll break 20 kWh today from a 3.8 kWh install, which will be a new record (Dec ’22 install).

Sunny day… by Ben Freeman[/url], on Flickr

It has been sunny the last couple of days. Annoyingly octopus seem to be taking an age to set up my export tariff. I notice they have a deemed contract for when they can charge for importing, I wonder if I can do the same for exporting..

Over the last 4 days we have drawn 17kW from the grid and exported 104kW.

An additional battery would remove need any import but at 18p per kW import and 15p export the £1,500 battery purchase would take a long time to pay for itself.

Monday the best days solar since install at 34.30 kW

Is that with Octopus @surfer ?

April has been good so far – 91kWh in the first 4 days. Yesterday managed to charge the house batteries and the car in a single day.

Is that with Octopus @surfer ?

Yes. On Eco7 at the moment but in the process of moving to Flux. I’d held off moving as our batteries dont have the facility to force discharge (do any?) but the rates even when exporting spare solar are very attractive. This is helpful to visualise.

Random question as I try to budget – is it cheaper to have integrated/whole roof array if you were going to re-roof a building anyway? Seems daft to pay for a whole roof of tiles then stand off a solar array…

61kwh so far this month for me in my small 3.2kwh array.

@surfer I can schedule my battery to force discharge on a schedule via my Solis Inverter it has three charge/discharge schedules. So far I’ve only used it for overnight cheap charging.
Solis integrate with Octopus in their app for pricing display so it’s not inconceivable that they’ll add Flux support via a firmware update.

@matt_outandabout – probably not cheaper, but certainly better.

Tiles and slates are only a few ££ and the cost of the trays alone will be £60-75 per panel. Then you’ll need additional fixings, metal work, etc.

Mine worked out about £2000 more for in-roof and there’s only around 250-300 tiles saved.

I think it looks better and there’s less likelihood of birds nesting or wind damage, I also get some light through the centre on the panel/tray. So my loft is now always light during daytime. In a full blue hue sort of way.

Quick question. We have an old set of solar panels on our home, installed right at the start (on one of the better generation tariffs). Anyway looking at how I can measure the amount of energy generated by the panels, since I am looking at getting some batteries installed to make better use of the energy that we generate.

Does anyone have some good examples? We have a basic inverter and meter, so it would need to be separate from those.

(I also know that before I install any batteries, I need to make suer that I don’t impact our generation tariff.)

is it cheaper to have integrated/whole roof array if you were going to re-roof a building anyway?

if you are re-roofing anyway go for inline. Avoids pigeons nesting or gathering underneath on-roof panels.

There was a saving in moving to online for us over a re-roof and on-roof panels. We had a high slate-breakage rate (crappy Victorian slates) and 18 panels installed so a fair amount of slate ‘saving’. And a neater finish imo.

@surfer I can schedule my battery to force discharge on a schedule via my Solis Inverter it has three charge/discharge schedules. So far I’ve only used it for overnight cheap charging.
Solis integrate with Octopus in their app for pricing display so it’s not inconceivable that they’ll add Flux support via a firmware update

I have Fox ESS batteries and inverter. It looks like they are adding this as a feature (although it doesn’t appear to work yet) Its unlikely I will export from my battery its almost all needed for self consumption in the evening and to get through to the charging window at 2am.

. I’d held off moving as our batteries dont have the facility to force discharge (do any?)

I can control charge and discharge times from Puredrive Batteries via the solis inverter app.

@bruneep which solis app is that one?
Is it Solis Cloud? It looks different to the UI have for the same functionality (Also Puredrive batteries)

@mickyfinn

That’s the web UI on Solis cloud I believe.

Or at least it’s the same as Solis cloud.

My app UI is horrific

1st was cloud app, this is mobile app.

I don’t think its that bad 😉 need to get remote access from solis via their customer support

Ah right that make sense I never use the actual web app just the mobile app. I should It’s looks nicer 😁

I can control charge and discharge times from Puredrive Batteries via the solis inverter app.

Are you able to “force” discharge to the grid? For example dump all of the storage in your battery? If so what is the discharge rate? is it based on your invertor so discharges at say 3.6kW

The Foxess app has a “feedin” option which was added a couple of weeks ago but it seems to work as follows:

Solar > powers Home > Grid (none goes to battery) as oppose to Solar > powers the Home > Battery > Grid

So it exports the unused solar (which actually suits me as dont want to force discharge my battery) as oppose to actually exporting the saved power in my battery.

Yes,  set the times you want it to discharge and the discharge rate can be set up to 100A

Discharge to the grid at 100A, that’s 23kW. I’m surprised your DNO would be happy with that. Is that a standard approval?

Our manufacturer recommends force charging to 100% regularly as this keeps the batteries in best condition.

That’s interesting. I had assumed the batteries were similar to EV batteries, and the recommendation from Volkswagen is not to charge above  80% unless you’re planning trip that requires it, as it shortens the battery life.

We have the Huaewei system, I can schedule charge / discharge (to supply the house) and also there is something called ‘force discharge’, which I assume just dumps the battery to the grid regardless of our usage, but never tried it as don’t see the point.