Thinking of making a start on Solar....

[Asbestos]

Ok, I have been looking at Solar, battery storage and inverters for a long time, Thinking of making a start in purchasing some items.... what would you all recommend ?

 

I will install this myself (I am competent - I already do alot of electrical). I dont think it is worth going for a grid tied inverter, the feed in/SEG payments are not worth it.

 

I want this to be completely independent from the main grid consumer unit. For e.g. I will have a seperate Consumer Unit which is fed from the solar inverter and will move certain circuits off the grid CU to the solar CU. The thing i liked about the Growatt SPF5000 is the bypass, ie when the solar and battery are depleted it will switch to grid and power the 2nd CU.

 

Anyway, still looking at options.... should I be looking at Micro Inverters, and suggestions as to Panels/Inverters .. Initial budget is approx £2000 and looking for something scaleable so can be added to in the future.

 

Welcome any suggestions/comments

Edited November 25, 2022 by Asbestos

[joth]

Do grid tied inverters cost that much more? For me, ignoring any export payment, the benefit of grid tie is not discontinuity when the battery runs out;  a transfer switch is never instantaneous.

Also it means (potentially) 100% of household can be powered from PV + solar in summer rather than having to segregate the house into 2 consumer units 1 of which can never get the benefit of PV.

Also, I'd imagine the battery inverter is not instant response so I bet the lights dim when you put on the kettle when on it, but that's a minor niggle compared to the other issues. 

 

[Asbestos]

Have a look at the SPF5000. There is a connection from the grid to the inverter, once the batteries and solar are depleted the grid takes over on the 2nd CU. In regards to transfer time I believe it is instant, shouldnt see any lights flicker. This is not a mechanical transfer switch that needs manually switching.

[Simon R]

1 hour ago, joth said:

For me, ignoring any export payment, the benefit of grid tie is not discontinuity when the battery runs out; 

I'll second that. We're grid tied and it has many benefits, for example we can set our battery to charge to a given percentage (enough for an average days consumption) using the cheap overnight 7.5 per kWh rate from Octopus. In winter this means we can get through days with little or no solar. It takes a bit of trial and error with setup parameters but you can get very close to never taking any electricity at the full rate.

Stay within the 3.6 kW for G98 unless you have a real need to bigger. It's surprising how few times you need more power if you simply avoid using the oven and kettle at the same time.....

[Dillsue]

1 minute ago, Simon R said:

 It's surprising how few times you need more power if you simply avoid using the oven and kettle at the same time.....

But only 50% of the population understand that principle

[Asbestos]

I am on octopus Go.... currently paying 5p per kwh at night and 14p per kwh during the day. My understanding is I will also be able to charge the battery at night and use that power to power the house during the day. 

 

That is with a hybrid inverter.

Edited November 25, 2022 by Asbestos

[JohnMo]

But how long will that rate last?  Then you will pay the same as the rest of us.

 

On Micro inverters, they will only work if grid tied.

 

If you have a battery system that is not grid tied, what do you plan to do with it winter, when you are only generating a couple of kWh per day?  

 

One advantage of off-grid is the system can be huge, with no input from DNO, if you want and any planning rules complied with.

[Asbestos]

My Octopus Go tariff ends in about a months time.... then it escalates upto crazy prices.....

[JohnMo]

8 hours ago, Asbestos said:

escalates upto crazy prices.....

You mean the now normal price, everyone else is paying 

[joth]

10 hours ago, Asbestos said:

My Octopus Go tariff ends in about a months time.... then it escalates upto crazy prices.....

Are you sure? Mine recently renewed and overnight just went from 5p to 7.5p. the daytime rate more than doubled, but that makes Go+battery more valuable, not less.

 

15 hours ago, JohnMo said:

One advantage of off-grid is the system can be huge,

There's no limit to the kWh of battery you can connect to a grid tie system. G99 is for peak power, not storage capacity 

[Dillsue]

On 26/11/2022 at 09:42, joth said:

There's no limit to the kWh of battery you can connect to a grid tie system.

So long as youve got an approved export limitation set up.......16amp for G98 OR whatever your DNO gives consent for under G99.

[Marvin]

On 25/11/2022 at 17:40, Dillsue said:

But only 50% of the population understand that principle

and some like us have a low wattage kettle....

[Marvin]

On 26/11/2022 at 09:42, joth said:

Are you sure? Mine recently renewed and overnight just went from 5p to 7.5p. the daytime rate more than doubled, but that makes Go+battery more valuable, not less.

 

There's no limit to the kWh of battery you can connect to a grid tie system. G99 is for peak power, not storage capacity 

When speaking to SSE (our DNO) they said it was about the maximum that could be exported and it has nothing to do with the panels or the battery storage capacity but the unlimited output of the inverter. ( So a 12kW inverter adjusted to 3kW would need permission). I also understood that the battery storage has to go through the inverter, making the inverter limit the maximum export. If however there is a direct link from the batteries to the mains, not going through the inverter, the storage has to be added to the inverter limit?

 

Or am I just confused again.

[Dillsue]

1 hour ago, Marvin said:

 If however there is a direct link from the batteries to the mains, not going through the inverter, the storage has to be added to the inverter 

With batteries storing energy in a way that produces DC voltage, it's not possible to connect batteries directly to the AC grid. The energy from the battery has to go through an inverter to convert from DC to AC. It maybe that theres an inverter built into the battery pack or it maybe theres a discrete separate inverter, but there will be an inverter between batteries and the grid

[Marvin]

Hi @Dillsue

Sorry for the confusion. Perhaps this clarifies:

 

When speaking to SSE (our DNO) they said it was about the maximum that could be exported and it has nothing to do with the panels or the battery storage capacity but the unlimited total output of any inverters connected to the mains.

Edited November 27, 2022 by Marvin
Clarification

[joth]

4 hours ago, Marvin said:

Hi @Dillsue

Sorry for the confusion. Perhaps this clarifies:

 

When speaking to SSE (our DNO) they said it was about the maximum that could be exported and it has nothing to do with the panels or the battery storage capacity but the unlimited total output of any inverters connected to the mains.

Right , we're all saying the same thing slightly different ways.

It's the sum of the peak AC power output of ALL grid tied inverters that matter. If they total over 3.68kW you need G99 or export limitation.

It doesn't matter what is on the DC side of the inverters, i.e. size of panels, quantity of batteries or their peak DC output is irrelevant. so even if the panels and batteries can only output 1kW if they're on a 5kW inverter you'll need extra permission.

 

 

[Dillsue]

14 hours ago, joth said:

Right , we're all saying the same thing slightly different ways.

It's the sum of the peak AC power output of ALL grid tied inverters that matter. If they total over 3.68kW you need G99 or export limitation.

It doesn't matter what is on the DC side of the inverters, i.e. size of panels, quantity of batteries or their peak DC output is irrelevant. so even if the panels and batteries can only output 1kW if they're on a 5kW inverter you'll need extra permission.

 

 

That's sort of right but.......

 

AFAIK its not G99 OR export limitation, it's always G99 and if you want to add in an export limition system its G99 + G100

 

If your panels and batteries can only produce 1kw and are hooked up to a 5kw inverter then a smaller inverter would avoid the need for a G99 application

[Bramco]

On 27/11/2022 at 20:43, joth said:

It's the sum of the peak AC power output of ALL grid tied inverters that matter. If they total over 3.68kW you need G99 or export limitation.

 

Asking for a friend....  😉

 

How would they know?  Let's imagine that someone has 6kW PV installed and no limiting on export how would this be visible to the DNO?

[Dillsue]

10 hours ago, Bramco said:

 

Asking for a friend....  😉

 

How would they know?  Let's imagine that someone has 6kW PV installed and no limiting on export how would this be visible to the DNO?

A single 6kw install is probably undetectable but even if it was the DNO is probably not going to do anything about it. Fast forward 5-10 years when lots more people have done the same thing, some with permission and some without. Come a bright sunny summers day and the local voltage goes over the max limit due to all the PV exporting. When they look into why and find a load of unapproved installs they could send out formal disconnection notices and all those unapproved systems become useless.

 

G99 is a straight forward process and once youve got approval youve likely got it forever. What's more it seems to be free to apply in certain areas so arguably a no brainer

[Roger440]

On 25/11/2022 at 23:28, Asbestos said:

My Octopus Go tariff ends in about a months time.... then it escalates upto crazy prices.....

 

Slight thread diversion!

 

Octopus seem to be saying you can ony have this tarrif to charge an EV? Im assuming that some of you are not doing that. How does that work?

[Bramco]

19 hours ago, Roger440 said:

Im assuming that some of you are not doing that. How does that work?

 

We just applied.  Can't remember any questions about what EV.  Although my memory aint what it used to be.  Ours was a new connection.

Simon

[Bramco]

On 29/11/2022 at 08:48, Dillsue said:

G99 is a straight forward process and once youve got approval youve likely got it forever. What's more it seems to be free to apply in certain areas so arguably a no brainer

 

Straightforward, except it asks who your installer is....   (so my friend tells me)

 

Simon

[Dillsue]

55 minutes ago, Bramco said:

 

Straightforward, except it asks who your installer is....   (so my friend tells me)

 

Simon

The connection to the grid is electrical work so put down the name of your electrician. Failing that your local building control is obliged to test any work you do if you ask and pay their fee. On my application I just put down self installed with test and inspection by *councils* building control. All accepted and G99 approved.