Unsure about Solar options

Luke80

Hi everyone, looking for some advice re. a PV installation; based in Cheshire in a new-build house with gas combi-boiler & heating.

I went out to about 10 providers to cast the net wide. About half responded, of those had 5 quotes back. 3 of the quotes were comparably less competitive.

Each seemed to have a different spin on things (see below) despite providing the same basic information and usage stats. That's where things get a little complicated.

Mar 21 - Mar 22 had us at 3400kWh electrical usage.

Mar 22 - Mar 23 has us at 5000kWh. I believe the significant increase this represents is twofold:

1. Charging a 10.8kW (usable) hybrid car twice a week since early Dec 2022
2. We have been the custodians of some small 'pets' that live in a converted shed heated 24/7 Nov-Mar since Sept 2022.

Without going into details, we expect this living situation to remain consistent for another 2 winters, after that the significant heating bill would no longer be a factor, but from Spring '25 my company car will either be another hybrid or possibly full EV. So predicted usage:

• 2023: 6000kWh
• 2024: 6000kWh
• 2025-2029: 4500+ kWh (dependent on EV or hybrid)

The house has a 10m x 7m 4-sided roof, with 2 elevations approx. 45deg from South. If the diagram one of the companies (2a & 2b below) showed is to be believed, the more westerly elevation can only house about 4nr panels, with the longer elevation being able to house another 12nr.

Since at least one of us is home most of the day, we were unsure about the extra outlay of a battery, so each company quoted with and without:

QUOTE 1a: £7600

Panels: 14 X Sharp (NU-JC410B)

Inverter: 3.6kW single phase (Fox ESS F3600)

MCS Reg, Scaffolding included

QUOTE 1b: £10700

Panels: 14 X Sharp (NU-JC410B)

Inverter: 3.7kW Hybrid (Fox H1)

Battery: 5kWh (2 x Fox ESS MIRA 2500)

MCS Reg, Scaffolding included

Est. system output: 4695 kWh

QUOTE 2a: £8700

Panels: 16 X Canadian Solar (CS6R-395MS)

Inverter: 3.6kW single phase (Fox ESS F3600)

MCS Reg, Scaffolding included

QUOTE 2b: £11600

Panels: 16 X Canadian Solar (CS6R-395MS)

Inverter: SUNSYNK-3.6K-SG02LP1

Battery: 5.12kWh (SUNSYNK)

MCS Reg, Scaffolding included

Est. system output: 5080 kWh

QUOTES 3, 4, 5

2.8kWh system for £6.4k (7 x JW Solar panels, Solis mini inverter, no battery)

4kWh system for £7.7k (10 x Longi panels, Solis inverter, no battery)

4.6kWh system for £10.2k system (11 x Jinko panels, Growatt inverter) or £12k with 4.8kW Pyrontech battery

Firstly thank you if you managed to read this far! I've read a few posts on here which suggest the quotes are on the upper end of the going rate. I've used the online calculator referenced in numerous threads which suggests the larger system providing a slightly quicker ROI if selling back at 15p or more, but frankly my mind is in a pretzel!

Any thoughts on (for our situation):

1. Battery vs no battery
2. Quality of components
3. Charging car during generating hours or going onto a tariff with a reduced off-peak rate
4. Any other advice

Thanks!

Screwdriva

A few thoughts:

1) Your consumption highlights the need for a battery.
 
2) Your quotes are a mixed bag. Some have spec'd Sharp Panels which are excellent but Fox is a budget Chinese brand I would avoid. I recommend a Libbi inverter/ battery combination for the following reasons: A) Excellent integration with the Zappi EV charger B ) Superb Customer service and reputation C) Expandable modular design and capable specification D) No need to purchase a separate inverter as it is built in.

3) The Libbi/ Zappi combination will work very well to charge during off peak hours.

4) You should expect to pay < £11K for 16 quality panels (Sharp/ Hyundai/ REC/ Panasonic/ Solarwatt) + a 5kW Libbi inverter battery.

Some may suggest that the brand's reputation doesn't matter. In my experience, this is true only till one experiences an issue, after which it becomes the only thing that matters. Best of luck! 

Luke80

Thanks, that's useful to know. Looks like I'll need to do some haggling and I've asked them if the bird protection is included too (assuming unlikely).

Couple of follow-up questions if I may:

5. Does a 3.6kW Inverter seem reasonable for the array size? I guess I might be lose out on peak output in summer but it's sized to balance for its efficiency curve during less optimum conditions throughout the year? Or is there something else going on here?

6. We have a Project EV EVA-07S-SE (which was pre-installed when we moved in 2 years ago).I'm sure it mentions in the manual about being compatible with off-peak. Any experience of whether that would more compatible with certain batteries?

ABrass

It's a small inverter as there's a lot more paperwork to go over 3.68kW. Undersized inverters are common (see signature) but thats a pretty big difference. The efficiency curve is overstated in my opinion, but it didn't hit me just how often panels will be producing at far below full power until I got mine. It will be less of an impact than you'd expect.

You're a low power user with an EV. The battery will help smooth out PV for use in the daytime and get sucked flat in a heartbeat by the EV.

Is the car out during the day or mostly at home? 

Screwdriva

Luke80 said:

Looks like I'll need to do some haggling 

It's a normal process to haggle/ tweak upfront. Best to get it right before you pay. 

5. Does a 3.6kW Inverter seem reasonable for the array size? I guess I might be lose out on peak output in summer but it's sized to balance for its efficiency curve during less optimum conditions throughout the year? Or is there something else going on here?

For a 16 panel, 6.4kW setup, you'll likely need a larger 5kW inverter to achieve the optimum balance. Still undersized but far more lucrative. The Libbi is available with both options out of the box

Some installers try to spec to avoid G99 paperwork but its the right way to go for your system size. 

2nd_time_buyer

Pylontech batteries are a good (cheaper) alternative. They have been around a while and there doesn't seem to be too many reported issues. They are modular, so can be added to later, and individuals modules can be replaced down the line if things go wrong, and being lighter they are easier to handle (e.g. getting up into a loft). Having said that the newer/bigger one are still quite hefty.

Alnat1

I'm another user happy with Pylontech batteries. We have a 4.8kw US5000 for now as we're fairly average users, 3200kWh last year. We would feel confident buying another battery online and adding it ourselves which was something we took into consideration when buying the system.

Haven't read that many reports of panel problems, so wouldn't consider buying "premium price" ones. Most of the problems seem to be with inverters so read up reviews on those.

Luke80

ABrass said:
Is the car out during the day or mostly at home? 

It's mostly at home - at least enough to find the 2 hours twice a week to re-charge it. Clearly if we switched to a full EV charging time would change but it would still often be home during the hours of generation.