Solar Panel Q&A

[BillyStubbsTears]

3:30 am tonight, the Octopus Agile tariff is 1p per kWh!

[Superspy]

Awesome.
Everything you've described is exactly how I've been operating with mine, only I opted not to go for the Agile tariff and just went Economy 7 instead - 18p/KWh every night between 12:30 and 7:30. At the time when I signed up the peaks of the agile tariff just weren't worth the risk, and the lows (on average) weren't really beating the E7 rate - clearly things have come back down!

You'll likely find that in a month or so none of it will matter as the huge majority of your usage will come straight from the panels - you'll be generating so much between 5am and 9pm your battery will still have juice in it the following morning when the sun comes up.

As you've said, the daily gains might be relatively small but if you're willing to put the effort in it could mean the difference of a year or more on the payback timescale. Not to be sniffed at.

I've just checked my numbers and between generation, export and E7 I'm now up to over £500 in savings since mid-September, and that's without me being on an export tariff until November, so I missed out on a significant chunk of export payments there. Overall I'm really pleased at saving 500+ over winter!


It'll be really interesting to see how things goes in summer for me in terms of savings, as obviously using the energy is more financially beneficial than exporting it, and I'm a little different to most in that my circumstances mean I use more leccy in summer than I do in winter, so I'm expecting the overall savings to be massive.

[BillyStubbsTears]

The amount of electricity we've used today would normally cost us just under £5. Today I reckon it's cost us 23p.

[Superspy]

Fun game isn't it?
We've generated 9.5kwh today, even with the weather being crap. Still got 70% in the battery so will be charging very little tonight... tomorrow could be a zero cost day...as was last Wednesday.

[Superspy]

I've just bit the bullet and signed up for Octopus Flux in place of my E7 import / Outgoing Agile combo. The more I thought about it the more it made sense to have a shorter cheap charging window over night but be in a position where the export price is always higher than the cheaper import. It means, rather than having to wor k out how much I should charge the battery at night I can just fill it, and anything I generate the day after goes back to the grid for a higher export cost (albeit not much, but that's not the point).

In another few weeks when overnight charging becomes completely irrelevant, the flat daily export rate of 22p is significantly higher than the average agile export rate for most of the day.

[BillyStubbsTears]

15.5 kWh produced by our system today and it's not even the equinox and it's been cloudy all afternoon.

I'm fascinated to see what it will produce on a clear June day.

[BillyStubbsTears]

5am tomorrow morning, the Octopus Agile electricity price is -0.3p per kWh.

They are paying me to take electricity off them.

[drfchound]

22.9 kWh produced by my solar today.

[Superspy]

21,17,20 for me over the last 3 days. Haven't bothered charging the battery much over night this week so starting to see the saving figures flip from an E7 based bill reduction towards an Export payment.

[BillyStubbsTears]

15, 17, 15kWh for us. We are less than perfect position with a tall and wide chimney stack on the house next door that throws shadow over our roof from about noon. It'll be better later in the year as the sun gets higher.
Very happy with that output from a 4kW system though, given that it's been broken sunshine with a lot of cloud. I'm expecting to get into the high 20s in June.

We haven't got the DNO authorisation for feed in payments yet, but to my way of thinking, filling up the battery to full at last night's rates is a no brainer once you do get feed in.

I filled up our 9.6kWh battery last night for less than 4p. Then the 12kWh our panels have produced so far today could all be sent to the grid at 15p/unit on Octopus Outgoing. That'd be basically free electricity all day and the thick end of 2 quid back.

Like I say, it's not going to buy you a Caribbean island, but marginal gains like these will add up significantly over months and years.

[SydneyRover]

the other solar panels .......

''Concentrated solar power is an old technology making a comeback. Here's how it works''

https://www.abc.net.au/news/science/2023-04-06/concentrated-solar-power-technology-comeback-electricity-mirrors/102184372

[BillyStubbsTears]

So today is going to be my first day totally off the grid (1). 20kWh produced, even with a fir bit of cloud around noon.

I'm chuffed to bits with this system. It's madness that we don't have them on every house in the country.

(1) There's the odd bit of energy dribbles in from the grid when demand in the house suddenly surges (eg toaster going on) because it takes the inverter a few seconds to respond and feed the demand from the panels or the battery storage. But over the whole day it's added up to less than 0.1kWh.

[Superspy]

Yup, you'll see a lot of that now we come into Summer. October will be the first month with a lower generation than March was.

First 7 days of April look like this for me:

Import from grid: 27.79 kWh - approx £6.40
Export: 75.16 kWh - approx £16.53

I've dropped my direct debit with Octopus to a quid a month.

The reason my import is still relatively high is because the Flux tariff means you can charge the battery over night still and never be any worse off because the export rate during the day is equal to the import rate over night. If I didn't charge the battery instead I'd export less, but the delta (about £10 last week) would be the same.

[BillyStubbsTears]

Our figures for the first 7 days of April are

Import 37.2kWh. Estimated cost about £6.70 at estimated Octopus Agile average price of 18p/unit (almost all overnight charging)

Export to grid: 16.5kWh, but still not registered for feed in tariff.

[BillyStubbsTears]

Octopus Agile tariff overnight is as low as -5p per kWh.

There are 3 hours tonight where they will be paying me to charge up my batteries and run washing machine, dishwasher etc.

[albie]

Looking at he bigger picture, an interesting 15 minute talk on energy costs and futures;
https://youtu.be/EAU5D8hqIUI

The importance of who controls the transmission infrastructure is clear.

[BillyStubbsTears]

Update from our system.

Just got the first monthly bill since installing the panels and battery. We've used pretty much exactly the same amount of electricity as the same period last year. We are heavy users as we have electric induction hob and oven, and several computers on for long periods of the day, as well as electric blankets to cut down gas central heating costs, so we've used about 400kWh in a month.

At standard rates, if we'd bought all that, it would have cost £140 including VAT. We've actually paid £31.5. It would have been £19 if our registration for feed-in payments had gone through.

The breakdown is interesting. Of the 400kWh used, only about half has come from the panels (they've produced nearly 280kWh, but a big chunk of that has come on a few very sunny days when they've produced a lot more than we could use or store in the batteries, so we lost that back to the grid.)

The other half has been bought in at low tariffs and stored in the batteries on days when there was little sun. The average tariff for that bought in electricity was 15p/kWh - less than half the standard tariff.

Story seems to be that if you can manage your usage times and more importantly, spend a little time every day planning when to programme the system to top up batteries from the grid, there are very big savings to be made. Even in a month like we've just had, with a lot of very cloudy days.

It beggars belief that we don't have a more pro-active Govt approach to incentivise people to make the up front investment. We could give Govt funded interest free loans to encourage people to install these systems. The payback for individuals and the country over 20 years would be enormous.

[BillyStubbsTears]

Did I say it beggars belief?

Stupid me.

I forgot that the Tory party is full of this sort of shit for brains, masquerading as Very Serious People.

https://twitter.com/DavidDavisMP/status/1650460298350940160?s=20

Solar farms are a blot on the landscape. But not a word of criticism for oil refineries or massive fossil fuel power stations. d**khead.

[albie]

David Davis is part of a government which could add solar to all available roofspace on industrial units, and instruct new build housing to include solar provision.

The French are installing them over parking lots, providing cover and power to existing land uses.

Reservoirs could host floating solar, which has the advantage of reducing transpiration losses in high summer.

If they did these easy options, there would be a greatly increased generation capacity without other land use conflicts.

Solar on farmland can be combined with some crops and livestock.
It is called agrovoltaics, where the panels are raised on a frame above ground level. Some crops benefit from the partial shade given.

The post below Davis claim saying that fossil fuel back up is required is complete nonsense.....storage technologies are cheaper than retaining redundant fossil fuel as reserve.

[drfchound]

Albie, I have seen several field full of solar panels which has also had grazing sheep in them feeding off the grass.
As you say, the two can go together.

[albie]

Yes, it would be good if we had some politicians who have a science/tech background, or could do basic research before commenting.

Short video on Agrovoltaics here:
https://youtu.be/UeqGMPmYsdw

The World Economic Forum are also aware of the potential;
https://www.weforum.org/agenda/2022/07/agrivoltaic-farming-solar-energy/

We keep electing planks as decision makers, and that's a problem!

[drfchound]

I can’t see how that will end though.

[Superspy]

I'm hoping the solar farm in Marr goes ahead, but waiting to hear what happens when they put the planning permission in.

Anyway, update for me this month is as follows - approximate saving so far is £160, with a week of generation to go.

Octopus do their export payments and billing on the 24th, so basically between 24/3 and 24/4 I've been paid £64 in export, and saved about £16 based on being able to charge the batteries cheap. Generation between 1/4 and this morning is about £80. So it's looking like a £180 is saving this month when I run the final figures in a week.

As you say BST - few minutes of effort planning can make a big difference. It also helps that the Flux tarrif I'm on has paid me an average of about 24p a unit to export - means there's less pressure to save by using what is generated, albeit it's still not AS good, but a lot closer than previous export payment rates.

I'm about to start taking advantage of this even more though - just ordered myself an EV after test driving one on Sunday. I'm REALLY excited. Can't wait for it to arrive.

[albie]

Solar panel costs continue to fall;
https://www.solarpowerportal.co.uk/news/uk_consumer_solar_costs_dropped_by_13_in_six_months

With energy costs still too high for many, installing solar is a no brainer, IF you have the money for the purchase and a suitable roof.

A new Dutch panel gives a 50% reduction in weight, which is important for load bearing on certain types of roof;
https://solarge.com/en/producten/solarge-solo

[BillyStubbsTears]

Just a reminder that anyone who isn't on Octopus Agile for their electricity is choosing to be shafted by the big energy companies.

Even if you haven't got batteries to take the very best advantage, it's still a no brainer. The standard electric tariff at the moment is about 31-33p per kWh.

Octopus Agile's average rate for May so far has been 19p. From 12:00-16:00 today it's between 0-4p.

[Superspy]

I'm sticking with the Flux tariff. Paying a bit extra for the energy i do import is significantly outweighed by the higher export rate with the amount I'm exporting.

I got paid 90 quid in exports this month. Utilisation will be higher now though (and therefore lower export payments) I've got my pool heat pump set up, and the EV should hopefully be here in a couple of weeks or so.

[BillyStubbsTears]

SS. I'm sure that's the right tariff for you with the huge amount of feed-in energy you've been producing.

I'm saying that Agile is a no brainer for people without solar panels, even without battery storage.

Anyone using 10kWh/day who can switch half their usage out of peak times (put the dishwasher and washing machine  on at 2pm or the middle of the night, cook tea a bit earlier or later) can easily save £4-500 a year over a standard tariff.

[Superspy]

Yup, you just have to be willing to manage it properly.

[BillyStubbsTears]

Exactly.

For example, today if you were going to use a big oven for 2 hours at standard tariff, it would cost about £2 for the electric.

If you were on Agile and cooked at the time of the very highest tariff today (16:30-18:30) it would cost £1.75.

If you cooked at the time of the very lowest tariff (14:00-16:00) it would cost 50p.

Little bit of planning and flexibility and there's decent amounts of money to be saved. It's scandalous that the big energy companies are charging top whack 24/7. But they will while ever people accept it.

[Superspy]

Solar benefit split between usage, export payment and night-rate differential ended up being a touch over £250 for May.