The Solar Thread

We don’t work from home, Mrs f is disabled so doesn’t work and I’m out all day. We’re also fairly low power users, from March to early October our general energy import per day will be around 3-4kWh the rest is covered by the solar panels.
Based on that requirement I’d be looking at around a 5kWh battery using an 80% DoD. Assuming we can charge the battery fully for 75% of the year that’s 274 days, that’s 1096kWh at 4kWh a day. At 50ppkWh that’s £548 per year, £5480 over ten years.

I’d be happy to self install and then it’d be worth it but I can’t because a g99 application is required (probably fast track) and for that you need an mcs certificate which obviously I can’t provide so it’s have to use a registered installer.

Trying to work out just how much we might be able to generate. We have a South facing roof which is great. Unfortunately, half of that is a cross gable roof over the master bedroom which does nothing, not even extra usable loft space.

Our Solar power system went in today: opted for 10 panels split between south facing (6) and east facing (4) roofs (house is three bed semi-detached) with a system power of about 3.7-ish KwH, Inverter and one storage battery.

System was switched on at lunchtime, I’m not sure about the overall power generation yet (will check tomorrow) but according to the system app the battery was at 100% charge by about 4pm and the house was being powered from the panels alone for most of the afternoon. After sunset we were using about 65% power from the battery/35% from the grid when the electric oven was on this evening. Once the cooker was off the house was running fully on the battery supply so that’s the lights, fridges, freezer, TV and our usual plethora of USB chargers/smart speakers etc. We’re not running the immersion from the system yet but might get this set up later on although it probably means a new hot water tank too.
Some excess power was getting sent to grid earlier. The SEG isn’t set up yet, I feel that the monetary value of this will be minimal (read: pathetic) anyway but its money in the bank so we’ll do this as soon as the documents come through to allow this to be set up.

Battery is down to about 75% charge now so I reckon it should easily last to sunrise.

I’m interested to see how this all works as the days get shorter but so far so good.

Mine has been in just over a week, I’m one 5kw battery down it’s due to be replace this week hopefully. So far pleased with results. Can’t apply for SEG yet as I’ve no paperwork yet.

I’m interested to see how this all works as the days get shorter but so far so good.

Can you get on a time based tariff like Octopus Go? Depends on the size of your battery but filling the battery up at 7.5p per kWh for 4 hours with a little solar top up might get you most of the way through a winters day. Worth doing the sums.

You can’t move to Octopus at the moment. They’re not accepting new customers.

You can move to Octopus right now. You just need to call them up. The regulations don’t allow for suppliers to refuse new customers but they don’t have to make it easy for you to join.

according to the system app the battery was at 100% charge by about 4pm

I very much doubt the battery would have been supplied with a low charge.

I called last week and again yesterday. On both occasions, they agreed to call me back. So far they haven’t.

I very much doubt the battery would have been supplied with a low charge.

Typically, you are supposed to store Lithium batteries at around 60% charge, so my guess is it was at around that level when installed.

Can you get on a time based tariff like Octopus Go? Depends on the size of your battery but filling the battery up at 7.5p per kWh for 4 hours with a little solar top up might get you most of the way through a winters day. Worth doing the sums.

This is exactly what we’re doing and have sized our battery according to around 90% of the usage cycle at 13-16kw. We’re at the low end of that due to availability.

Mine has been in just over a week, I’m one 5kw battery down it’s due to be replace this week hopefully. So far pleased with results.

@ Bruneep – what size system have you got and where are you?
Some of those numbers don’t make much sense.

You can’t move to Octopus at the moment. They’re not accepting new customers.

I moved to Octopus Go two weeks ago. I was an existing Octopus customer so maybe not a completely new customer. The only thing that held up my Go onboarding was them having to switch me from the Octopus Outgoing export tariff to the standard export guarantee. Once that was done the switch to Go took a couple of days. I suggest talking to them as I’ve found them very helpful on the phone. Its understandable they are going to be snowed under with people wanting to switch to Go but things may have calmed down a bit after the price cap announcement.

Aberdeen, despite the gloom merchants the sun does shine here on south facing roof 😎

5.3kw array

3.6kw inverter

1 5kw battery had 2 fitted one is faulty awaiting a replacement.

What’s not making sense to you?

My bills are making sense just now

Yesterday

because your original image showed ~7400kWh of use…

because your original image showed ~7400kWh of use…

…. and 140kWh generation in what,8 days?

This the the generation from my 3.9kWh system for the last 3 full weeks:

2022-36 67.600kWh 05/09/22 – 11/09/22
2022-35 85.800kWh 29/08/22 – 04/09/22
2022-34 81.600kWh 22/08/22 – 28/08/22

I’m much further south (Chester) and haven’t had a weekly generation over 130kWh this year (early August) – so your 140kWh further north in mid September sounds rather “amazing”.

Edit: And my system here produced 6.9kWh on the 14th and my 3kWh system in N Wales produced 6.4kWh – yours apparently produced 15!!

There are 14 x 395 JA panels on roof

my daily import from grid is around 2kwh a day now,

so on day of install the inverter consumption was started at 7382.1kWh rather than zero there is the issue of funny numbers

There are 14 x 395 JA panels on roof

…. but it’s still a 3.9Kwh inverter – that’s the maximum it can ever output.
(All standard PV systems in the UK are limited to >4kW output – anything over that requires permission from the local DNO)

I might be wrong, but the generation just looks huge!

Yup a 3.6 inverter.

we have full sun today, maybe yours is under performing 😉

Many hybrid inverters include power drawn from the battery in their “generation” figures. You need to dig a little deeper into the stats to get the actual solar generation total or use something like Home Assistant.

I have 12 JA 395W panels split east/west in North Yorkshire and over the last week they’ve generated between 5kW (rainy day) and 15kW (mostly sunny).

Having to do everything from the website annoyed me so I’ve built an in-home display similar to that you’d get with a smart meter which shows stuff in real time (3D printed case still printing)

14th of September ?

My 3.6kw inverter produced 10kwh

I’m 10 miles inland from bruneep

My roof is much steeper than his.

So as bruneep says the sun doth shine on Aberdeen.

My 3.6kw inverter produced 10kwh

So 33% less! (Steeper roof will help now also)

Given he has 30% more panel area than me it seems logical.

7.5kWp S and W array here with two inverters totalling 6.5kW, in Chester just like you sharkbait, and the best I’ve seen during August was w/c 8th Aug with 205kWh generated (I think that may be my best solar week this year) so 140kWh in September in Aberdeen is going some.

Edit: Just realised my second array was’t connected until 1st Sep so that 205kwh was generated from a 5kWp array and 3.75 kW inverter. Maybe 140kWh could be possible in sunny Aberdeen

I have 3 quotes and I’m close to asking one of them to proceed but I have not looked into tariffs. I’ll have a battery I’d like to charge overnight but with no EV I’m not eligible for EV tarrifs

I’m with Shell at the moment after previous supplier went bust.

If Octopus aren’t taking new customers what options do I have?

Does anyone know or can they find out the lead times on either the Powerwall 2 or the new LG RESU 10h or 16h Primes?

I ordered my Powerwall 2 back in September 2021 with an April 2022 delivery date. This was postponed twice and the Powerwall was finally installed beginning of this month. I noted that Tesla sent a load of Powerwalls to the Ukraine and whilst it would be churlish to complain that may have had something to do with my delivery date getting pushed back. I seem to remember the LG RESU which was the other option was almost immediate delivery.

We are 100% electric and have a 10KW inverter and just over 13KW of panels. The roof is not optimal so the the base generation is spread out over more of the day and tends not to clip.

We are in Aus so generally a bit sunnier than good old Blighty and currently averaging about 40KWH over the last month which I expect to increase as the angles improve as we approach Summer. The major difference is we pay 22c per KWH and get 9c feed in so vastly different pricing to UK. I cant make a battery look viable here, as much as I would like one.

I’m in Warrington, about midway between trail-rat and sharkbait. On 14 September my main array (2.15kWp) generated 5.1kWh; so that’s about 2.4kWh/kWp (or just 2.4h/p?). The 15kWh bruneep made would be 3.8h/p (if inverter limited), which is much better, but East coasts are often sunnier than West coasts.

does anyone know what the optimum angle of solar panels is from a money-saving perspective? It seems that (south of england) the optimum angle from a generation perspective is around 35-40 degrees, but if you don’t have unlimited battery storage, most generators will be pushing at least some electricity back to the grid during the summer (so the value is extremely low) vs not consuming energy from the grid in the winter (so the value is high).

Is it theoretically better to mount the panels steeper than commonly thought so to optimise for generation in winter instead of during the summer? you’d get less generation overall in terms of kwh, but maybe a more valuable haul?

Is it theoretically better to mount the panels steeper than commonly thought so to optimise for generation in winter instead of during the summer? you’d get less generation overall in terms of kwh, but maybe a more valuable haul?

Mines are 55degeees.

This benifits me early and late in season – I am making about double the predicted for a standard (30-40deg) angle roof in march and September…. And I’m clipped in peak summer. I’ve been making 430kwh/AVE since march. If they were at less angle I’d make more in peak summer but less in the shoulder seasons

My old man has an 8kwh array half mounts due south at 45 degrees and the other half laid flat on a frame for prolonging summer generation for the pool infrastructure and the many showers guests take.

When he only had the 4kwh array his generation started to decline at 3pm – with the flat panels they decline at about 6pm

Given he has 30% more panel area than me it seems logical.

Not really when the inverters have the same maximum output.

I’ll just leave this here for you to mull over

been a mix of sun and rain today, still happy the 5kw battery is charged up. Dishwasher been on and tea made for tonight.

Given he has 30% more panel area than me it seems logical.

Not really when the inverters have the same maximum output.

more panels providing a lower input due to solar capacity at any given time.

he has 30% more surface area collecting the lower quality sun light

its exactly how over sized east/west arrays work to provide peak power for a longer period….. The inverter only affects his peak output . he has a solis so he has a 7k peak input at 600v and and will clip peak output to 3.6K

post for @trail_rat seeing he is unable to master these things

Interesting seeing everyone else’s app readings for comparison to my system (still cant master the forum posting images thingy so cant show mine) but its very much entertaining my inner Nerd 🙂

Day 2 of my system running and the battery was at about 11% first thing. It was overcast for the start of the day but the solar panels have been working well and the battery was fully recharged by about 2:30pm.
My small-moderate-ish 10 panel system has yielded (is that right?) about 8kWh aginst a consumption of 6kWh (again, not sure if im reading things right…) so far today, the bit im so far intersted in is the generation/use vs what needs to be imported which is currently 67% from the system/battery against 33% from the grid. Thats pretty much what the survey estimated the system would give me on a normal day for the south coast so I’m pretty happy so far.

I need to let things run for a few weeks, sort out when to run the dishwasher and washing machine so it can use as much solar as poss (we tend to run the dishwasher late at night). SEG definatley needs to be sorted as the energy being exported to grid is not being paid for (will check Octopus for this) and the second battery will probably be added in the Spring when funds allow.

@bruneep  Your graph appears to me to show that you were, at times, exporting 4kW. How is that possible with a 3.6kW inverter? I’m not saying you’re wrong, I just don’t understand.

I have just received a quote from GenFit

9 grand for 15 Longi all black panels + 15 SolarEdge optimizers + Invertor etc
Also includes a Zappi EV charger as I wanted to find out what it would cost to supply/fit at the same time, that may be removed as I don’t have an EV car currently and not ordered one yet as I was hoping for more choice at not ridiculous prices as well as the utility price hikes making home charging a lot less inviting.

Details show annual estimated energy production to be 5.54 MWh and shows another small figure next to it of 4.53MWh. Will find out what that means.

Also how good are these estimates in terms of real world figures (ignoring weather). Placement on roof + some on garage roof seems about right based upon how the sun moves round but I have a 4 sided hip roof so panels won’t all be getting sun at the same time. Again, I will raise this with them.

Price includes scaffolding and I have no idea if it’s a good price or not. Very well laid out quote.

Will get 1 or 2 more.

^his export totals for the day are 8kwh, so about 2.5 hours worth of production if you look at it that way. Fwiw I can back up his figures as I’ve a similar set up. 12x385W JA Solar panels & 3.65kw inverter and getting similar daily figures (if not slightly less due to a. Less panels and b. Living in Glasgow).
Edit-ah yes, sorry just checked the graph, does seem a tad high given the inverter rating!

wookster

assiming that the company are MCS affiliated then the predictions are regulated by the MCS handbook

They cant just throw spurious numbers at it .

For me due to the aforementioned angle of my roof i am producing more than anticipated by the predictions due to the longer shoulders afforded by the higher angle panels.

Look at PVGIS and put your numbers in there to get your own figures for comparison.