Hi, Joining for some advice.

[Ollie78]

I am a woodworker doing furniture and joinery stuff.

I have joined this forum as I am looking into having solar and a battery system installed in our house and it has been driving me slightly mental ! All quotes have been different in how they want to do it, what equipment to use etc. No two very similar at all.
I would have assumed ( naively ) that given our house is the same and the object of the brief is the same ( stay as self sufficient as possible and use a flux tariff ) that the resulting quotes would be similar. It is like comparing apples banans and oranges !


Ollie

This started in "introduce yourself" but has gone off topic, so I have moved it.

 

[Murdoch]

Welcome and yes this kit / solutions aren’t that easy to compare

 

[johnb2713]

I was in a similar situation 2 years ago and finally settled on a quote from a company which seemed to make most sense. The planning and installation was done with a prompt and efficient workforce and the system worked well. I did however find some shortcomings. The inverter (Growatt SPH6000) could only provide 3000w when being fed from batteries, switch the kettle on at night and we were annoyingly importing from the grid. Wintertime, the storage capacity wasn't enough to meet our needs. I embarked on a further expansion of our system with a bigger battery and an additional inverter (Victron Multiplus II), the two systems working together now give us 98% operation on off peak tariffs and during the better weather around 70% solar.
I would suggest the battery and inverter is priority in the funding with solar as a later add on. Make sure the inverter can handle your peak loads eg kettle and toaster for breakfast circa 5kW etc, a 6 to 8kW Inverter of known brand. Look at your typical daily consumption and that will tell you the size of battery needed eg if you consume 10kWh through the day, go for 12 to 14 kWh battery.
Tariffs, look closely at ones like Octopus GO, although an EV tariff, I know a lot of people on GO that dont have an EV, that will give you 4 hours off peak at 9.5p. If you venture into the world of EV's Intelligent gives you 6 hrs (and more) at 7.5p.

 

[Murdoch]

@johnb2713

Re your kettle, could you have bought one with a lower wattage element?

 

[johnb2713]

@johnb2713

Re your kettle, could you have bought one with a lower wattage element?

or use gas, but that's not the point as you know

We dont have a kettle as such, we have a hot tap anyway.

 

[Murdoch]

or use gas, but that's not the point as you know

We dont have a kettle as such, we have a hot tap anyway.

A new kettle would have been far cheaper

 

[Ollie78]

I was in a similar situation 2 years ago and finally settled on a quote from a company which seemed to make most sense. The planning and installation was done with a prompt and efficient workforce and the system worked well. I did however find some shortcomings. The inverter (Growatt SPH6000) could only provide 3000w when being fed from batteries, switch the kettle on at night and we were annoyingly importing from the grid. Wintertime, the storage capacity wasn't enough to meet our needs. I embarked on a further expansion of our system with a bigger battery and an additional inverter (Victron Multiplus II), the two systems working together now give us 98% operation on off peak tariffs and during the better weather around 70% solar.
I would suggest the battery and inverter is priority in the funding with solar as a later add on. Make sure the inverter can handle your peak loads eg kettle and toaster for breakfast circa 5kW etc, a 6 to 8kW Inverter of known brand. Look at your typical daily consumption and that will tell you the size of battery needed eg if you consume 10kWh through the day, go for 12 to 14 kWh battery.
Tariffs, look closely at ones like Octopus GO, although an EV tariff, I know a lot of people on GO that dont have an EV, that will give you 4 hours off peak at 9.5p. If you venture into the world of EV's Intelligent gives you 6 hrs (and more) at 7.5p.

This is quite similar to some of the quotes we have had.
To my mind the point is to use the grid as little as possible. A few of the systems we have had quoted were a 5kw hybrid inverter but this rating is the input from solar and the output from battery was 3kw which as you say is not enough to run the oven etc.
In our case we can only likely get a maximum of 12 panels on our roof, 4 on each side we are a semi detached with a hipped roof. We have south, east and west facing sides. So there will be little room for expansion, though we do have a lean to garage facing south it is at quite a low pitch and the roof is a bit ropey.

I quite like the look of the givenergy all in one and gateway which has 6kw output and is octopus intelligent compatible but it is probably out of our budget, at least according to one quote we had.

One company quoted an Alpha ess smile5 which has 11kwh storage and 5kw output but someone else said they cannot be force discharged making it less compatible with octopus tariffs. I have yet to get to the bottom of this.

Ollie

 

[johnb2713]

A new kettle would have been far cheaper

Not really

 

[Murdoch]

Not really

Kettle a few pounds .,,,

 

[johnb2713]

Kettle a few pounds .,,,

And the waiting time for it it boil every time more pounds.

 

[binky]

Given the smallish array, forget the hybrid and have separate inverters for the battery and solar. This will keep the solar array inverter efficient, but not compromise your desires for the battery

 

[Ollie78]

Given the smallish array, forget the hybrid and have separate inverters for the battery and solar. This will keep the solar array inverter efficient, but not compromise your desires for the battery

Thanks, I am considering going with Enphase because we have the 3 separate roofs.
It seems to be recommended that we have optimisers anyway so it can effectively be one string instead of 3 separate ones.
So if we have enphase it will optimise as well and we won't need a string inverter, only a battery one.



Ollie

 

[Ollie78]

As this has been moved to the appropriate solar section I will put the outline of the quotes we are considering to see if anyone has any opinion on the systems.
Our roof is 3 sections one south one east and one west. So we would probably get 4 panels on each, maybe only 3 on the end one.
Our consumption is low at 3100kwh per year which is an average of 8.5kwh per day.

System A

12 x Rea fusion 2 420 w panels
12 x Enphase IQ7 plus microinverters
1 x Alpha ess 5000w inverter
2 x Alpha ess SMILE5 5.7 kwh batteries
Including installation and bird protection.
Priced at £12,935

This one seems fairly good but my issue is that I was told the by a different company that " All Alpha ESS batteries do not have the functionality to export to the grid, their software simply does not have the capability yet, hence it is currently not compatible with the Octopus tarrifs."
Which is worrying and I will ask them specifically about this point as they seemed to be suggesting it was suitable, can anyone confirm or deny this.
And, that the micro inverters total output of 3,48 kw (290w x 12 ) is considerably less than the panels max of 5.04kw.
This company say that the way it is designed is less for maximum output but more generation in less than ideal circumstances, because the micro inverters require less power to start working etc. Hence better generation morning and evening and in winter. they claim that even if there is a small amount of clipping for a couple of days in june this system results in more generation over a year.

System B

11 x longi solar 410w panels
11 x Tigo TS4 A O optimisers
1 x Solax X1 4,2 kw inverter
1 x Alpha ess B£ 10.4kw inverter
Installed with bird protection.
Priced at £14,292

Alpha B3 battery has only 3kw maximum output and cannot be put outside. So not great.

Spoke to them and discussed this also mentioned micro inverters so they re did it as follows.

System C

11 x longi solar 425w panels
11 x Enphase IQ8 inverters
1 x Givenergy giv bat 9.5kwh
Installed with bird protection
Priced at £14,960

Interestingly these guys split the quote as follows Solar panel installation £8400.11 and battery installation £6590.50 which made me think a bit that i could add a battery later on. I can buy a givenergy all in one and gateway for £6.5 k at the moment.
Maybe I could get company A to do the panels only and later add the battery.
But there is something nice about getting it all installed and certified at once.

I quite like the Micro inverter method given our 3 side roof but the battery options are very varied indeed, don`t really want to spend more than £12k if at all possible but also do not want to waste money buying the wrong stuff.
We do want to use an octopus flux tariff and maybe intelligent octopus.

It does sometimes look like getting £9.5K worth of stuff for £15K, I understand there is other things like scaffolding and sending the paperwork etc but they say it can all be fitted in 1 or 2 days.

All advice welcome, thanks.

Ollie

 

[Campbell Dunn]

Thanks, I am considering going with Enphase because we have the 3 separate roofs.
It seems to be recommended that we have optimisers anyway so it can effectively be one string instead of 3 separate ones.
So if we have enphase it will optimise as well and we won't need a string inverter, only a battery one.



Ollie

If you install panels and batteries etc at one time it is VAT exempt. Installing the batteries later you pay VAT.

 

[binky]

At 290w those micro inverters will clip a lot more than a few days in June

 

[johnb2713]

At 290w those micro inverters will clip a lot more than a few days in June

380w on the HC version ?

This would put me off though:

"Enphase University certification is required to commission IQ8 Microinverters in systems with backup (Sunlight Backup, Home Essentials Backup, and Full Energy Independence)."

 

[Ollie78]

If you install panels and batteries etc at one time it is VAT exempt. Installing the batteries later you pay VAT.

This is good to know, thats a few quid to be saved, I would ideally like it all done at once anyway.

At 290w those micro inverters will clip a lot more than a few days in June

I was not sure about this, they were saying that the panel ratings are done in a controlled condition which is seldom replicated in real world situations in the Uk. I was thinking it was similar to when string inverters are indersized to the array.
Given the range of enphase microinverters it seems most will be undersized to the panel they are attached to.

380w on the HC version ?

This would put me off though:

"Enphase University certification is required to commission IQ8 Microinverters in systems with backup (Sunlight Backup, Home Essentials Backup, and Full Energy Independence)."

I wonder if Enphase university is like FENSA where you just pay them to join as a company then send any random idiot to do the work ?

I am trying to work out if Enphase is better than tigos and a normal string inverter, given the 3 arrays. It seems like killing 2 birds with one stone in a way.

Given the multiple options of panel/ inverter/ battery ac/dc etc. How is it best to design a system ?
I have a fixed amount of roof so there is one place to start with, but even here there are different panels all promising to be wonderful.
Does maximum summer output matter more than winter performance, do I really need to be able to force discharge the battery etc. etc.

I thought solar edge or something similar might be a good way to go so that all the components from one place should work perfectly together but prices are pretty high on those systems.

I am trying to look at it with the same method I use for buying a new machine for my workshop or when I build a new PC, which is finding the sweet spot between price/performance/quality/ease of use and the job it must perform.

Its a tricky balance and comparing components individually is not enough because of the way it must work as a system together.

Ollie

 

[johnb2713]

I personally would turn it around the other way, look at your daily consumption figures and get enough battery storage to cover that plus a backup margin. Look at your peak consumption and use that to size the inverter. That creates a battery system that can run the house all day at off peak pricing. Now with the budget remaining get as much solar that the budget allows. There are times with companys like Octopus where they have 'saving sessions'. If you export to the grid during these times you get paid up to £4 per kWh (this years price), a considerable amount of money can be made if you have the capacity to store energy and discharge it into the grid at the appropriate time. On my system I bought energy at 7.5p kWh and sold between £2.25 and £4 giving me an income in December of £135. These grid balancing sessions are definitely on the increase and worth taking into consideration. During the good weather I export all what my solar generates with my house running on battery, again buying energy at 7.5p but selling my solar at 15p, not a lot but it does add up.

 

[bladerunnerpv]

Hi Ollie, suggest you take a look at the generation you'll get from the S.E.W. PV system.

You can get an idea of generation potential for your location with PVGIS or easy-PV and see how little you'll get p.a. or p.c.m. to help you see if it gives a worthwhile dent in your electricity consumption.

PVGIS will just tell you generation, pcm, and depending on the years selected in the 'monthly data' tab will give a +/- yearly spread

easyPV has an in-built usage profile too which varies with time of day and time of year so also gives an indication of how much self-consumption you'll get. It will do a shading factor calculation too. You'll need you annual usage as an input.

With only four panels per roof then an inverter with a low startup voltage would be preferable, e.g. Fox ? However not many have 3xMPPT trackers, i.e. one for each roof and it's not a good idea to mix directions on one string. So microinverters by Enphase or SolarEdge seems sensible.

Rough sums, retail, not trade, prices, for 12 panels
Enphase IQ8 about £150ea, envoy ~£380 = £2180
Solaredge S500 ~£60ea + 5kW Solaredge inverter ~£1050 = £1770 (5kw from 12*420W and the 6kW version is an extra £300)

I might be missing something but Solaredge looks similar price to Enphase solution ?

Edit: playing in easyPV with longi HiMo6 425W panels indicates an upper limit of 11 panels per 'branch' for Enphase, depends on the model, some are max 10 per branch. Assuming 4000kWh p.a. usage the yield is 30-35% of usage, without a battery. Solaredge should take 12 panels. Depends if you real limitation is roof space or Enphase.

 

[binky]

I was not sure about this, they were saying that the panel ratings are done in a controlled condition which is seldom replicated in real world situations in the Uk. I was thinking it was similar to when string inverters are indersized to the array.
Given the range of enphase microinverters it seems most will be undersized to the panel they are attached to.

all panels are rated by STC, standard test conditions, it's worth having a look at the Californian state tesing of panels or PTC, which is suppossed to be more 'real world' and usually knokcs 10-20 Watts off a panel , howver 290w on a 420 w panel, that's roughly 30% - drivel! Even my 12 year old panels still hit within a few watts of their peak output from installation on a regaular basis. They might be nearer the mark if you are based in the Shetland Isles....

I wonder if Enphase university is like FENSA where you just pay them to join as a company then send any random idiot to do the work ?

lots of manufacturers have 'training courses' which are free and mostly sales and marketing.

I am trying to work out if Enphase is better than tigos and a normal string inverter, given the 3 arrays. It seems like killing 2 birds with one stone in a way.

Tigos are enhanced bypass diodes, which all panels have, a completely different kettle of fish to solar edge and microinverters.

John is also correct, batteries offer greater financial savings than the solar panels do. Now I'm a bit biased in that I like solar for green credentials, but financially it's expensive to fit compared to batteries alone, plus risks potential roof issues if the fitters are 'not so clever'.