Newbie PV + Battery - Couple of questions please?

Hi I registered yesterday as a new user as it was suggested to me to get a 'feel' for GivEnergy tech and current issues/opportunities.

I'm commited go going down the PV + Battery route as I want to reduce my bills, reduce reliance on Gas if possible and generate green energy and help the planet a wee bit. I'd also like the ability to export back any excess to offset my bills potentially.

At the moment I've had some quotes for panels, battery & inverter and to me the GivEnergy quotes seem more exciting than the Pylontech/Solis/Growatt/Puredrive variants, but that is purely a 'feeling' based on specs/warranty etc (I work in technology so specs are helpful to me).

My install is probably going to be ~ 5kW PV (12 x 415W) panels + Battery (5 or 9/10) & hybrid inverter

Questions:

1. Is GivEnergy a good 'middle of the road' brand for inverters & batteries? Or are there too many issues currently? I'm seeing threads going into the thousands of replies on issues/firmware/beta testing etc

2. If the difference in a quote between a 5.2kW (gen1?) battery & 9.5kW battery (gen2?) is ~ £2000 then should I initially go for the larger due to future proofing and VAT considerations? I'm seeing lots of people saying they had wished for a bigger battery quite quickly after install.

3. Should I try to insist on a Gen 2 Inverter? Is newer always better here?

4. I'm confused about solar diverters, I get the idea of using excess solar generated electricity to heat my water insteasd of Gas, but would a smart immersion switch not allow me to do that better/cheaper? If on a future agile tarrif I would want to export to grid to make a bit of money, not just to keep diverting it to keep heating up my water. I think my background usage of gas is ~ 4kWhs per day to heat water twice a day for the 2 of us - showers in morning and hot water for dishes at night etc.

5. I assume I cannot reduce my CH gas consumtion at all unless I went full air/heat pump in future/at all?

Many thanks inadvance for help! Tony

Welcome Tony

As you are on the forums please check out the SOC issues threads. There is a ton of information in there that is worth reading before proceeding with givenergy.

Question 2, with the 9.5 battery you do not just get more power but you get 100% depth of discharge. The small units only give you 80% which is a good chunk of battery which is not available to you. IF you can afford to go for the larger I would recommend it.

Question 3, yes insist. Or at least have an agreement where they will supply a Gen 1 now to get the system in quicker if they will replace with a Gen 2 when available if they can not get one. The gain is how faster the gen 2 can charge / discharge your battery. A whole 1kw more than Gen 1.

Question 4, the best value you can get from your solar is to use it if possible. But do make sure you set yourself up for an outgoing tariff to make sure you get paid for the bit you can not use.

Question 5, can look at other heat sources. Saw some people on youtube use portable heaters to make use of their battery etc.

For me personally, I have been frustrated with givenergy in terms of fixing bugs. Their communications are questionable, speed of fixes not much better. When I had GE kit installed July 2021 I was happy with it all. It worked. But when I noticed the SOC issue which you will see in the other friends it has left me with bad feelings towards GE and it is going to take time for me to feel better about having their kit. The BETA firmware's are showing great promise and they do appear to be sorting everything out. But I think this is month 19 since the issue was first reported.

Do have a read of the soc issue and beta firmware thread.

Tony B My take on a few of your questions:

1. Yes, there are problems for some my AC3 & 9.5 hav behavd impeccably since installation. The problems are being sorted by GE.
2. Go larger. Size for winter and a solid load shift.
3. Yes, but you might be offered Gen 1 and later replacement as Gen 2 stocks are under pressure.
4. Solar diverter is very different to a smart immersion. If you ar rally using 4kwh per day just on water then it makes sense to get one as it can be set up to use excess solar which would toehrwis be wasted (unless you have a very good export tariff).
5. Correct, although there are electric boilers/heat stores/infra red radiators you can consider.

In the same position as you I opted for two batteries as I didnt want to wish i had later.
There is a good argument for the rate of return that one battery is better but i dont regret my decision and have the comfort of knowing that i have plenty of storage for repeated dull days.

I also am glad I went for the ac3 rather than the hybrid. having an eddi hot water diverter the eddi app can see what is going into the batteries with a dedicated ct clamp and it works faultlessly.
I have had no grid import since the 17th march and have also had 120 litres of hot water per day for the past few days. very little export as it all goes into the tank (250 litre tank)

On the GE support side, yes their track record is poor but the kit is good and having run the beta firmware for a while I have no complaints at all.

positor1 out of curiosity when you say no grid import, do you mean absolutely zero or are you ignoring the 0.2-0.7 that we see from being grid connected?

Thanks for the responses! So a bit of a mixed bag with GivEnergy then
Some people Ok (mostly AC connected?), some not (hybrid?)

Just had another quote today from a local installer and he said he is GivEnergy accredited but would not suggest them currently due to multiple charging and discharging issues. He then went on to suggest a smaller pv array, a smaller battery (Dryness) and a Solis 3.6 inverter so as to sidestep the DNO delay with SSES in my area. He even potentially suggesting no battery, just solar!

So I'm not sure I'm any the wiser!

cluelesscris Thanks for the response, so a couple of questions please if I may on solar diverters:

Especially the difference between smart immersion and solar diverter - the diverter is just turning on the immersion heater on with spare solar energy is it not? A smart switch would be doing this in exactly the same way (turning on the immersion) just differently by switching it on/off, timed or 'smart' and possibly using the pv, the battery or grid depending on the amount of energy needed to heat the tank? Or is that too simple a statement?

Is heating water via electicity more or less efficient than gas (irrestective of whether I'm using 'free' spare solar, or battery?)

I assume that the gas water shedule is turned off in all cases once you have either a diverter or smart immersion switch?

On a diverter does the diverter divert spare solar (and I'm reading battery power too in places) up to the point where the water is heated? Then the rest of the spare can be exported still? Or is the the diverter not just going to keep heating the tank as the temp will fall as soon as it's stopped heating?

Sorry I got more questions there as I started typing!

Tony B Definitely not smaller you'll regret it almost immediately.

More the panels the better especially in the winter. Plus always worrying when an installer suggests side stepping the dno especially when you would like to export a little. But also a battery charges from your solar then discharges overnight giving you a longer period of self generated power.

A solar hot water tank diverter thingy notices you have excess solar that is going to grid and will grab that and heat your water at a slower rate. to whatever temp is set then you revert to exporting power.

THALL Thanks form the welcome and response 🙂
I'm not saying he didn't want to apply for the DNO entirely, he just wanted to go smaller as there is a 4 month delay with SSES deciding on G99 atm

But I defo take your point..

Right got it now, it looks at the export to grid above a certain limit and then determines to heat the water instead, once finished export ramps back up 🙂

...while self consumption takes first priority of PV energy... Told you I was a newbie!

Tony B Spot on.

So take my system
11.4 kw panels, single AC3 and 1x 8.2 and 1x 9.5 battery
ASHP, EV
Home uses pv first, excess goes to the battery up to 3kw then rest goes to the grid, unless my ev is plugged in, then its house first, then battery to up 1.4kw car will take as much pv as I can generate, if the house loads increase the car charge slows.

Basically house load first no matter what.

I have 8x400W panels, Solis inverter, a/c3.0 and an 8,2 battery. I've had no problems and have been really pleased with my kit. There seems to be no rhyme or reason to who gets issues!
I wish I could have fitted more panels on. If you have space- pack them on while you are paying for the scaffolding (if they use it - my lot just shinned up ladders!). Originally I was going to go for a 5.2 battery, but they didn't have any in stock, but did have some 8.2 (delayed order suddenly arrived). I jumped at the chance of a bigger battery and haven't regretted it. But consider where you are going to put it, as a big one can weigh 100kg, which is quite a weight to get into your loft. Mine is outside, but a garage is probably the best bet. If you get a small one, and then want to add another later then you will have to pay VAT. If you buy the battery as part of a solar system you don't. That can be quite a cost saving!.
I have an iboost. Like the Eddie it diverts solar power to heat your hot water immersion when the battery is full. I didn't use the gas boiler at all last summer. BUT, you need to do some sums about whether you get a better return from exporting your excess versus using it instead of gas to heat your water. It all depends how much you get paid for export . If you can get more than you pay per kw for gas it may not be such a good bet as it was when the SEG was just a few pence.
What ever you go with make sure you get your MCS certificate and a copy of the DNO letter from your installer (some people have withheld part of their payment until they receive this) as you need it to register for your SEG tariff. You don't have to get your SEG from the same company you buy your electricity from, but some offer their own customers a better rate. If you aren't tied into a good fixed rate take a look at Octopus energy as they offer tariffs specifically for EV drivers (Octopus Go/Faster) air source heat pumps (Octopus Cosy) and for solar/battery owners (Octopus Flux)
My system wasn't big enough to worry about G99, but I think if you agree for your export to be limited to 3.6 ish then it can go through pretty quickly. Take a look at some of the other threads on this as I think some of the rules and applications are changing in April

Karen Many thanks Karen - I appreciate the reply. I agree on all that you are saying!

Re DNO. From what I'm hearing from local installers I think for G99 SSEN are are saying:
Yes (unlimited): 10% of the time
Yes (Limited to 3.6kW): 85% of the time
No: 5% of the time

Any advice on who are the best SEG payers - is that going to be Octopus? I'm on a fixed price BG contract for the next year but it would be good to get paid for any excess I'm generating in the meantime.

Tony B Tony - this is a long term investment, so a while waiting for a DNO approval is time well spent - fill your roof with as many panels as you can!

As for GE or not - despite the doom and gloom you might pick up from reading this forum there are many happy users, self included - our system (with one minor loose conection issue) has behaved perfectly and saved us a ton of money over the past year and a bit. GE have been responsive and helpful when I have spoken to them. System is : 5.4kW panels, south facing, AC3.0, 2 x 5.2kWh batteries. Only thing I would do differently is to increase the battery storage capacity by 50%.

You will need batteries to increase your self consumption percentage - I reckon 50% without, 75%+ with. Our first full year was 75%. And I also have an Octopus Agile oiutgoing tariff which has made us more money.

My only hint - make sure you retain some payment to your installer until you have both your MCS certificate and post commissioning DNO approval - make them do the work chasing the DNO to get that.

wilfleek Many thanks for the reply - I appreciate it. Agree - I was going to say it's a big investment in our forever house so I can wait it out! I agree on hold back of some monies to be absolutely sure!

Seems people are saying that bigger is better in most cases across PV array, Battery & Inverter. But I'm hearing about lots of people have AC coupled inverters - are these not more inefficient with the number of conversions being done? And more expensive? And would I need hybrid & AC if I don't have micro inverters on my panels? I have no shading in my SSW facing roof.

Smk82
100 watts yesterday
0
100 watts 20th
100 watts 19th
0 on 18th
you caught me out exaggerating haha

BTW a immersion diverter will use any spare power, so if there is a surplus 100watts it will put that into the immersion heater whereas a smart switch could only turn on or off at the maximum the immersion takes (3kw).

positor1 Thanks - that's the bit of the puzzle I was missing/not understanding
Immersion switch pumps 3Kwh when on
diverter pumps in variable based on what's being exported to the grid
nice! 🙂

Tony B And would I need hybrid & AC if I don't have micro inverters on my panels?

Hybrid = solar panels + battery. AC-coupled = battery storage without panels.

The issue with multiple inverters seems to be that (Givenergy) multiple AC-coupled inverters configured as a single plant does not yet always work as expected.

If you want multiple Givenergy inverters, dual hybrids work just fine (or at least ours do) and there's no reason why a hybrid and a single AC-coupled wouldn't operate well together. That said, getting the numbers in the web portal to add up might take a little time but at least you will know that they are doing the job you require.

Tony B

Everything I have read here looks like decent advice.

In all honesty GivEnergy are no better or any worse than any other company that is available. They all have issues and if you are unlucky enough to experience them then you are unlucky.

Our GE has been, almost, problem free since it was installed. Gen 1 5kw Hybrid Inverter, 9.2 Gen 2 Battery (was an upgrade from 8.5 Gen 1) 14 x 405w Panels.

What is good is that they are UK Based for support etc unlike MOST other brands.

If I knew then what I know now (and money was no issue) I would change the following:

(1) Get the biggest inverter available that I can afford.

With our Gen 1 Hybrid 5kw we are limited to 2.4kw max output from battery, 5kw from Solar or a combination of the two.

With a 10kw Electric Shower we always draw from the grid to power at least 50% of this in the best circumstances.

Looking to the future if we were to add an Air Source Heat Pump to this then an average 8kw ASHP would exceed our current capacity of battery/solar (5.6kw at worst to 3kw at best).

So in an ideal world an 8-10kw inverter would be the "sweet spot".

GE don't offer this currently so if GE was a requirement then you would be looking at a Gen 2 Hybrid 5kw Inverter + 3kw AC Coupled. Although running multiple GE equipment currently appears to have some fairly large issues.

Otherwise personally I would probably have gone with a SunSynk Hybrid Inverter.

(2) GE batteries - it is both a positive and a negative that GE Inverters are only compatible with GE batteries, and vice versa). Whilst it potentially makes upgrading easy it ties you into the GE ecosystem so you can't use other, cheaper, oprtions.

(3) Battery size. For a home of 3 people in most of the day 9.2kw is just about enough. On bad days I wish we had another 50% for Load Shifting (using Octopus Go) on the battery.

If I had an ASHP installed I would probably wish I had another 2 or 3 x 9.2kw batteries.

Obviously the immediate alternative brand that comes to mind is MyEnergi with their Libbi products.

Obviously you pay a premium for that brand name but their new inverters and batteries are all built in China, the same as most other brands.

(4) Solar Generation as an Income Stream. Ideally you will want to use as close to 100% of your Solar PV as possible. Don't think of excess Solar PV as a source of income as at 4/6/7.5 or even 15p unit its not going to amount to enough to really matter.

My Ideal Setup
As many Solar Panels as can be installed on my roof.
1 x 8-10kw Hybrid Inverter
2 x 10kw Battery

Or the above with only 1 battery plus the addition of a Powerwall system (not necessarily Tesla) & battery
1 x Powerwall (gives approx 5-6kw throughput)
1 x 10kw Battery

A couple of other things to consider.
Are you expecting to be able to use your system during power cuts? Usually, the inverters will power down during power cuts, to avoid sending power to the grid when there could be engineers fixing it. You can get an EPS (external power source) that will enable you to use some low power circuits. If you have an AC 3.0 system you will be able to power the circuits from any power in your battery, but can't refill it from solar during the power outage. If you have a hybrid inverter you will still be able to utilise power from your solar panels as well as the battery. But, you need to have some special electrics for the EPS and an earth rod. If this is important to you, then it is something to discuss with your installer.
Also, consider anti-bird mesh. This fits around your panels to stop birds getting underneath the panels to nest and possibly damage your wiring.
SEG tariffs - try this
https://www.theecoexperts.co.uk/solar-panels/smart-export-guarantee#:~:text=The%20best%20SEG%20tariff%20for,who%20provides%20your%20grid%20electricity.

positor1 Is this data from your supplier billing or some other method? Can't see how it's possible to be honest.

judgepd
straight from the ge graphs.
Perhaps it seems odd because our situations are different.
I am the only resident, I do not use large appliances until the sun is up and producing something ( eco 7 over winter)
I don't cook , the microwave or induction hob do that. 😃
I can post the graphs if you are still sceptical?

Tony B The reasin why I have an AC coupled inverter is because my 4kW PV was installed in 2011 and I get FIT of over 50p per kWh GENERATED - if it went through my battery system first, the FIT registered power would be much less.
GivEnergy have quoted me 15% loss on conversion is normal but the battery system (13.6 kWh) still works out much cheaper than direct grid usage - I charge from the grid to 80% (winter), now 60% and 40% in Summer, from Octopus GO at 7.5p per kWh and it is usually topped up to 100% by PV.
The only complaint that I have is that when the battery system is over 70% charged, more PV energy is exported to the grid than is applied to charging the batteries. Does anyone know if this is normal or could it be an inverter fault ?

positor1 I can post the graphs if you are still sceptical?

I'm sure your Givenergy portal data does give those values. However, you might want to check your energy supply meter (ie smart meter). Our portal regularly says we're importing 0.1-0.3kWh but the energy supply meter has it more like 0.7-0.9kWh and since that's what our energy bill is based on, that'll be what we pay.

Tim
from octopus
20TH MAR - 24TH MAR
0.7kWh of electricity
so yes you are correct it isn't zero
adding up each day from the custom report on octopus site gives me 1.056kwh 17th march onward

positor1 I was pretty sure that would be the case. GE always under reports grid usage.

Big battery to charge from grid in winter at cheap night rate. On cloudy days you will struggle to charge a big battery but if the timed charge works, they have problems with it at the moment, and you get on a good supplier ( sea creature with eight legs not mentioning any names) then you can still save by charging when power is cheap and using when it's not.

positor1 1.056kwh 17th march onward

From the Octopus site, your consumption as measured by Octopus on your smart meter between 17/3 and today is 1.056kWh? That's pretty amazing! You say you're the only resident? I can't place the credit for our 0.7-0.9kWh/day on any individual but ironing, hair drying, kettle and oven are all contributors. The only time none of these impact on grid import is when we are exporting; export just dips until the inverters ramp up to meet DNO limit of 3.68kW.

"Re big battery to charge". It depends what tariff you are on. In the winter I go for ECO7 - that gives me 7hrs to fully charge the battery, so unless you run it down to 4% it is possible to keep it fully charged each night. If you are on a tariff with a shorter window then - yes- it will be difficult to fill in 3-4 hours. I have now swapped to Octopus Flux, because I know that I will have enough solar during the day to recharge the battery during the the day, but in the autumn (probably around mid Oct) I will move back to ECO7 for the winter

Tim Thanks Tim - I had not made that connection re hybrid & AC for solar & non solar. Like I say I'm a newbie and every day's a school day atm! 🙂

dragon2905 Thanks Dragon
I'm limited to what I can put on my roof so I want to go as highly rated as possible (I'm being quoted on 415kW panel, but I know there are efficient 450kW ones out there with 30 year warranties).

I is possible to add another inverter after the event if I need more throughput?

Amny thanks for your help! Tony

Karen Thanks Karen
Currentyl I have no need for EPS functionality (is this known as 'island' in other speak?)

Great link on SEG, answers lots of my questions! 🙂

Tony B As a new pv customer i feel island mode is a winner. And method 3 or 4 as shown in the linked GE kb article is the way to maximise the use of your EPS (backup supply when the mains power fails). With these options you will be able to keep the house running within the kw output of the eps output. Even if you don't want full island mode then best to get youe EPS socket somwhere you can use it in a power cut eg for your freezer/fridge or to keep your broadband router, tv etc runing in a power cut. Choice is yours.
https://kb.givenergy.cloud/assets/EPS%20Configuration%20v2.pdf

I have island mode 3. It’s there as a catchall just in case. I’ve probably had 4 power cuts in 20 years.

But knowing I can run off battery and solar (I have a hybrid inverter) is very useful.

I’m not obsessed with keeping my battery topped up just in case, as I’m more interested in using the ‘free’ energy I’ve spent thousands on. 🤔