Hello from Chester !

[markcarline]

Hi all !

Just joined the forum and currently have nothing (yet!).

I am looking at hybrid inverter & battery, solar etc and i'm 99% certain it'll be a Fox Hybrid inverter with cube battery system. I already have an EV (VW iD3) which is being charged via a granny cable via intelligent octopus go (which works perfectly since day 1).

Our house is a bit of a nightmare to add Solar to, we have around 7-8 roofs which could each take Solar panels (anything from 1-6 panels each) with a total of around 22 panels. I think about 3-4 roofs would be 3+ panels so perfect for an MPPT string.

I'm technically "between jobs" (as they say lol) and doing freelance Photography so I can't do all the installation in one go so looking to approach my installation in a Agile project management way. My rough plan is:

Phase 1) 7kw Hybrid Inverter (no solar connected) & 2x 4.66 kWh Battery modules (total battery capacity 9.32kWh) & get DNO pre-approval for inverter & export size (G99A application)
Phase 2) Add additional 2x 4.66 kWh Battery modules (total battery capacity 18.64kWh)
Phase 3) Add 10x Solar panels
Phase 4) Add additional 2x 4.66 kWh Battery modules (total battery capacity 27.976kWh)
Phase 5) Add 10x Solar panels
Phase 6) Add electrical heating to our home (Heat pump, IR panels etc)

My intention is to try and ensure that I added all the extra batteries (phases 1-5) within the 1st two years based on fox recommendation I saw somewhere.

I think the fox gear will be a K series 7kW single phase hybrid with the Cube battery system. It should allow me to have 3x MPPTs and then maybe have other smaller roofs (any which are less then 3x panels) connected via a (ideally!) fox micro inverter(s) all connected together somewhere and monitored via the CT2/Meter2 point on the K series inverter.

The inverter / batteries will be in a separate part of the house (a small garage) which is about 18m away from my main consumer unit which is already connected via a 3x core 16mm ev-ultra cable (with unused Cat5e) to it's own new 17 way consumer unit which today only has a surge protector / rcbo for the dedicated external 13A 3 pin socket for the EV charging.

Any comments / suggestions please let me know.

I will update this post with my progress over time.

Thanks in advance.

Mark

[Dave Foster]

Hi Mark, interesting project - that should give you hours of fun.

Just a few quick points from me - if you go for the KH9 rather than the KH7 you will get 4 MPPT's which might come in useful in the future - if your DNO doesn't allow you to have a 9kW export capability, it is possible to set a hard export limit to reduce it to the DNO proposed limit.

The Foxess micro inverters are delayed and not yet available, but I would say it is better not to mix a DC system with an AC system if it can be avoided, much better if everything goes through the same inverter.

Ideally fit no less than 4 panels on one string, below that the startup power is often not sufficient to wake the MPPT up - if you have several smaller roofs pointing in different directions you can link the arrays together to form a larger array and fit Tigo TS4-A-O optimisers to each panel which will effectively optimise them out of the system if one roof is in full sun when the other is in the shade.

I think that's it for now, but i'll update if I think of anything else that might help.

[markcarline]

Thanks for your comments Dave, a few follow up comments:

a) KH9 vs KH7
Yes - I was originally looking at the H5/H6 but jumped up to the K series to get an extra MPPT. I think the key question will be how many mppt do I really need on my roof (so my end state panel design).

b) delayed Foxess micro inverters / better not to mix a DC system with an AC system
Yes i have been waiting for these, but dead keen to see the integration with a mixed AD/DC system and how export limitation might work (if at all). Solar won't be until Q2 next year anyway now.

c) no less than 4 panels on one string / several smaller roofs pointing in different directions.....fit Tigo TS4-A-O optimisers
Yes but Tigo said to me:

1) try to put in series group of panels with same azimuth only (preferably with max +-30° delta only)
2) optimizers must be applied on all PV modules
3) make sure Vmin is reached on all strings of the inverter
4) it's better to have long strings than short ones

So I just checked and it's going to be difficult getting a decent string & confirming to tigo rules:

My roofs are:

Office:
- 3x at Azimuth (NE) -120.2 degrees / Inclination: 35 degrees
- 1x at Azimuth (SW) 60 degrees / Inclination: 35 degrees

Main loft office side:
- 3x at Azimuth (NE) -120.2 degrees / Inclination: 40 degrees

Kitchen:
- 6x at Azimuth (SE) -30 degrees / Inclination: 14 degrees

Main loft rear:
- 4x at Azimuth (SE) -30 degrees / Inclination: 40 degrees

Main loft side:
- 3x at Azimuth (SW) -57.7 degrees / Inclination: 40 degrees

Main loft side front:
- 2x at Azimuth (SW) -57.7 degrees / Inclination: 40 degrees

Vestibule:
- 1x at Azimuth (SW) -57.7 degrees / Inclination: 28.6 degrees

Can i really use tigo's pointing NE (3x panels) and SW (1x panel) in a single string? I thought those would make a good candidate for these Fox micro inverters:

https://www.fox-ess.com/micro-inverter/

[Dave Foster]

Thanks for your comments Dave, a few follow up comments:

So I just checked and it's going to be difficult getting a decent string & confirming to tigo rules:

My roofs are:

Office:
- 3x at Azimuth (NE) -120.2 degrees / Inclination: 35 degrees
- 1x at Azimuth (SW) 60 degrees / Inclination: 35 degrees

Main loft office side:
- 3x at Azimuth (NE) -120.2 degrees / Inclination: 40 degrees

Kitchen:
- 6x at Azimuth (SE) -30 degrees / Inclination: 14 degrees

Main loft rear:
- 4x at Azimuth (SE) -30 degrees / Inclination: 40 degrees

Main loft side:
- 3x at Azimuth (SW) -57.7 degrees / Inclination: 40 degrees

Main loft side front:
- 2x at Azimuth (SW) -57.7 degrees / Inclination: 40 degrees

Vestibule:
- 1x at Azimuth (SW) -57.7 degrees / Inclination: 28.6 degrees

Can i really use tigo's pointing NE (3x panels) and SW (1x panel) in a single string? I thought those would make a good candidate for these Fox micro inverters:

https://www.fox-ess.com/micro-inverter/

Hmmm yes you do have some very interesting roof shapes there! - yes you're right Tigo's work best on larger arrays where each array is capable of supplying sufficient voltage to keep the MPPT happy.

With your radically differing roof azimuths and elevations if all were in one string you would be ok as long as you had 4 or more in each plane, but with small arrays (3 + 3 or 3 +1 ), there wouldn't be enough power to keep the string running if one roof was shaded (which is likely with large azimuth or elevation deltas), so quite agree micro inverters would make much more sense for the NE (3 Panels) and SW (1 panel).

I understand why Tigo say all panels should be fitted with optimisers, but where you have a larger array where a shadow is cast by a chimney or gable on just a couple of the panels at some point during the day, it is perfectly acceptable to optimise only the ones that are affected as long as you understand the suns path and possible shadows that might be cast throughout the year.

I have an 8 panel array on the front of my house (not optimised) and it works fine for 10 months of the year but in winter when the suns angle is low 2 of the panels have a shadow cast on them which blocks the array from starting up for approx an hour - in hindsight it's frustrating (for a geek like me that watches the PV power meter waiting for the array to start up) but it's not worth putting scaffold up to rectify it - hence the if you are in doubt and unsure of moving shadows throughout the year then the fit to all panels rule is simplest and makes sense.

[markcarline]

Yep Cheers Dave. I'll circle back on here when i have more info. I think it's an interesting mixture of different Solar technologies which will be deployed over a longer than normal timeframe.

btw - I wonder if Tigo would be an option on the 3 panel ones with a Fox ESS micro inverter for optimisation & monitoring.

Thanks