Givenergy Full Set

Hi all,

Looking for a bit of advice as best way to set this up.

Currently have 18 x 410W panels, a Gen 1 5KW Inverter with two 9.5kw batteries and an Eddi for the hot water.

Looking to upgrade this a bit:

• 2 x 5kw Gen 2 inverters
• Givenergy EMS device - to better manage double inverters
• Giv-Gateway - to avoid power cuts
• Extra 9.5 kwh battery (to take me to 28kwh of storage)
• an extra 3kw of panels

Apart from the ongoing issues of Givenergy producing actual products that appear, are there any other things that I need to consider? Will the above work fine or are there any limits?

Is this financially going to pay you back?

I guess your issue now is on a cheap off-peak like Go you can't charge both batteries up fully, so you're eating some extra costs for daytime usage, but in the summer those panels should be able to fill both batteries up.

I'd run some maths by this based on your usage stats and see if it makes sense. I love solar and battery things but it has to be financially viable. In my case adding another battery won't make any sense until it's cheaper for example as Battery #1 will do most of the heavy lifting.

LordHippos I agree. A bigger system is only of any benefit if the energy (generated on site or stored overnight) is actually needed. A larger array results in summer overgeneration and larger batteries either cannot be fully used off-peak in winter or are not needed in the summer. Or worse, vanity projects come along to consume the extra "free" electricity.

With an ASHP and an EV, splitting my annual consumption into thirds (PV, off-peak and peak) seems about optimal.

Got to agree with the above. Our household is, I think, fairly high consumption. We have 8 people living in the house. I have a single 8.2 battery and I probably could use a second (daily consumption is around 30-35kWh) - but it would be borderline on payback.

Uhh why is the first question often will it pay you back? Its not all about saving on bills 😁

But things to consider in terms of solar sizing/adding to a system
1 how often do you run out of battery power?
2 how often do you max out solar generation, battery output combined?
3 What is the setup for your home? EV? ASHP? 100% electric appliances?
4 are you limited on export by your DNO?

If monies are a factor, a calculator online says my home should cost around £170 per month for my electric on the current price cap, I am 100% electric with ashp etc, this does not include my EV just my home. My actual DD is £30 per month. I have spent around £14000 on PV. I also got around £500 back via export last year (agile tarif). So "pay back" is 7 years? Less than 7. I could add fuel savings from solar going directly into my ev too.

When I added more panels last year I simply told my installer to max out my roof space. I went from 2.4kw East and 4.6kw West to 6.8kw East and 4.6kw West. I also added a 9.5kw battery to my 8.2. I am waiting for the EMS for a second AC3. Panels are cheap, I think genereally more panels the better as getting installers out later to add more carries extra costs. Batteries etc can be added later but I think maxing out panels is always good. Get on an export tariff and you can't lose really.

EDIT, question what is the giv-gateway? I know the all in one will have this but are they making a seperate box for customers with older kit? I am having a manual switch added to my system soon so isolate the grid in the event of a cut.

I totally agree Thall - I think if @LordHippos was sharper, he'd have spotted it might be about beating Ron-ski.... 😉

On a serious note, we're definitely a high use household - see attached for details: https://i.imgur.com/ss0SkSt.png

Ranging 35-80kwh per day (2 EVs and lots of other stuff!) - so I think it's safe to say having _30kwh of batteries is fairly safe to say we'll use.

In terms of payback, it seems therefore pretty aggressive - ie Octopus Go @ 7.5p vs 0.35p means an annual saving of ~ £953 which should give me a pretty short payback period of 3-4 years?

Totally agree re panels though - think I want to pick through all available options and see what we can max out - is there any complexities to consider if I have panels in different spots (eg shading of some panels, different directions?)

alphabeta77 wow (on that usage) but 2 evs makes sense. My highest this month is 48.5kw, will be worse when it goes back to sub zero though.

Panels. So yes there are somethings to consider and ways round it. First one shading, fix is optimisers. Effectivly makes each panel its own string. So 1 panel will turn off when shaded not the whole string. Second strings, panels need to be same voltage as each other so you can't mix any panels you like. Ideally they all need to be facing the same direction on the string too. You can move the old panels to 1 string and add the new panels on another. Which is what I did last year. 8x300w panels went onto string 1 and 11x400w panels went onto the second string.

Your installer should cover all these issues though. My larger 8kw inverter allows for 3 strings as well, the difference in cost between the 6kw and 8kw inverter was sub £150.

THALL

Indeed - with the EVs alone it adds up to 100kwh of batteries to charge, so plenty of usage! (but obviously saving a huge amount on petrol!)

Yes interesting re strings - think I'll need to dig into this. What's your 8kw inverter? Assume not Givenergy - don't know if they can work together or are they effectively two separate systems?

BTW Giv Gateway - effectively a UPS for the house: https://www.givenergy.co.uk/products#giv-gateway

alphabeta77 Solis single phase, both my PV inverters are Solis. A 8kw for my East facing 6.6kw array and a 5kw for my 4.6kw Wast facing array. My givenergy inverter is the AC3. You should only need optimisers on the array which will get shading.

Ignore what I said about optimisers, there aren't any for the givenergy hybrid inverters.

Edit I think that gateway is only for their all in one device. Same as the tesla powerwall.

THALL

Ah ok, so you've got Solis for your PV and then is your AC3 for just charging batteries or something?

Ah - good spot re the gateway, didn't spot only for AIO!

alphabeta77 Exactly that. 2 solar arrays both with their own solis inverter. My AC3 is able to monitor both arrays and charge my batteries. There was a 2.4kw array on my home when I moved in so to keep cost down and waste I went AC3 instead of Hybrid.

Depending on your installer they may want to hold fire on adding a second inverter until this EMS arrives. My installer for example is not happy to install a second AC3 for me at the moment.

THALL Uhh why is the first question often will it pay you back? Its not all about saving on bills 😁

Because it's the most important one, this will differ from person to person, best to maths it out and see. If it makes sense, fire away.

You're not able to get over 11KW of panels and two batteries like you have installed for £14K today, most people getting installs now are like half that size and almost that cost (if not more!).

alphabeta77 I totally agree Thall - I think if @LordHippos was sharper, he'd have spotted it might be about beating Ron-ski.... 😉

Impossible! 😆

LordHippos To be honest I am not sure on current prices. But my extra 4.4kw, 8kw inverter and 9.5kw battery added was £7250 back in October. My AC3, 8.2 batt and 4.62kw panels were installed by EON back in July 2021 for £68** . But I do feel the pay back question should be way down the list. I love making my own power rather than sucking juice from a coal power station. I like being green, as green as I can afford to be. Panels on their own should last 20 years and providing the installer is not ripping you off they will be pay themselves and then some.

Green for the win 😄

THALL Couldn't agree more. It seems to be the only purchase that everyone jumps to the payback question on. There are plenty of other valid reasons for wanting to do it other than payback.

THALL

Reckon your install would be around £20K today, give or take, at least based on the kind of quotes I'm seeing people get.

Then it really does start to bring the financial side of it into the equation.

Also pointless sizing so big and then not using it, there is more to solar than "just do it". For some people they'd use so little they'd never see ROI even after 25 years.

I like sub-10 years as a benchmark, feels like you can balance that with being green but also saving money. Got to size these things right to take advantage of them efficiently.

judgepd if the motivator is saving the planet, rather than pure financials, the same rationale should apply... don't buy a bigger system than you actually need as mining the materials has an environmental impact. That's why I consider annual throughput per installed kWh for batteries.

stevelewis But the output does not go to waste with a grid tied system. It can all be used by someone else. Plus benefits like greater generation in low light conditions, more in winter months when we really need it. More months hitting the wanted generation target to minimise grid draw. I wouldn't add 100kw of batteries but I would still maximise solar panels on the roof 😄

THALL Agree that oversizing the PV array to an extent makes sense for the reasons you list and the marginal cost is low for extra panels. Unlike batteries, the number of panels tends to be self-limiting due to roof area which correlates with floor area and consumption.