Help with first solar PV system shopping list using Victron kit

[Alexx]

Hello! I’m in the process of planning my first solar PV system and would appreciate your help. I have 6 solar PV arrays, each with different orientations and angles. I’m determined to maximise the number of panels, including on north-facing sides, by covering a garage door with vertical panels and possibly flat-mounting a couple over a dormer. It might seem excessive, but someone told me it can’t be done, so I’m set on proving them wrong the hard way!

Here’s my current list of major components—please let me know if I’m on the right track or missing anything:

• Victron MultiPlus-II 48/10000/140-100 230V (single phase) – For inverting and managing power.

• Victron SmartSolar MPPT RS 450/200-MC4 – For the 4 larger arrays.

• 2x Victron SmartSolar MPPT 150/35 – One for each of the smaller arrays.

• Victron Cerbo GX MK2 – For system monitoring and control.

• Victron Lynx Distributor – I’m unsure whether to go for the M8 version. As I understand it, this acts as a busbar to connect multiple batteries. I’m planning to start with two Gobel Power GP-SR1-PC200 16.5kWh batteries, with the option to expand to three or four later. They’re competitively priced, and I could profit from exporting at peak times or charging overnight.

• Victron Lynx Power In – Again, unsure about the M8 version. I’m still learning, but it seems to offer DC-side protection.

• Victron Energy Meter ET112 1 phase 100A max – For monitoring energy usage.

For solar panels, I’m torn between:

• JA Solar 595W N-Type Bifacial Double Glass Half-Cell-MBB

• Aiko Stellar 1N+ 645W N-Type ABC – Aiko’s marketing claims they’re “shade-proof,” which I’m sceptical about. I’m aiming for 18 panels in total.

For batteries:

• 2x Gobel Power GP-SR1-PC200 16.5kWh – These use EVE cells (same type/grade as those in EV battery modules) and offer great value.

Now, onto consumables—I’m still working out the details:

• Cables:

  • Between batteries and busbar—not sure if 50mm², 70mm², or 90mm² is best.

  • Between inverter and busbar—same uncertainty.

  • From solar PVs to MPPTs—thinking 6mm² due to long runs from the house to the MPPTs.

• MC4 connectors – For panel connections.

• Lugs – For cable terminations.

• DC isolators – One per MPPT, but should I have one per battery or just one for all? Better safe than sorry, so isolating everything might be wise.

• AC isolator – Between inverter and house. Does the inverter have a decent built-in one, or should I add an external one?

• Fuses – Should I include one per MPPT?

• Surge protection – Is this recommended? If so, one per MPPT?

• Bi-directional RCBO – For the AC side of the inverter.

Mounting rails for the sloped roof, flat roof, and vertical setup are a challenge I’ll tackle later. Right now, I’m focused on getting the Victron setup sorted, as learning and specifying the right kit is taking up most of my time.

Any advice would be greatly appreciated—cheers!

Edited Tuesday at 09:04 by Alexx

[SteamyTea]

I cannot be bothered to go though your shopping list in detail.

But a couple or three things.

What is your expected electrical usage?

Are there any panel optimisers in there?

Why not go for microinverters?

[Alexx]

  On 01/04/2025 at 09:06, SteamyTea said:

I cannot be bothered to go though your shopping list in detail.

But a couple or three things.

What is your expected electrical usage?

Are there any panel optimisers in there?

Why not go for microinverters?

Expand  

1. 20 to 30kwh a day
2. no optimisers, I will have one MPPT per array, so no need for any optimisers
3. I dislike the proprietary nature of microinverters. In my view, DC coupling batteries to solar PV makes more sense than convert DC to AC and then back to DC, then back to AC once load is generated. I even gave up on Sunsynk as it was my first option, but I want the system as open and modular as possible. I can just add a Victron EV charger later without needing any other 3rd party integrations for example.

[Dillsue]

You mention profit from export. Currently you generally need an MCS certified installer to get paid for export so you may want to get your installer involved in the design/spec to get their buy in.

[Alexx]

  On 01/04/2025 at 12:01, Dillsue said:

You mention profit from export. Currently you generally need an MCS certified installer to get paid for export so you may want to get your installer involved in the design/spec to get their buy in.

Expand  

 

Octopus and some others are not requiring MCS for export. I can install it myself and still be compliant with their requirements to export as long it is all done properly. 

[Dillsue]

Octopus do accept self installed systems but there's hoops to jump through and £ to pay! Have a search on here for discussion but I think consensus seems to be it's typically not worthwhile to bag an export tariff that can be withdrawn at any time.

[Alexx]

the £250 admin fee is nothing close to the amount of money a MCS rip off company is trying to get to install the system. Solar PV installers in the UK are just taking the mickey with their pricing. 

 

I found a few topics, but they are reasonably old Has anybody managed to get a feed in tariff from Octopus without an MCS Cert? - Photovoltaics (PV) - BuildHub.org.uk

[Dillsue]

Totally agree on the MCS pricing but just giving you the heads up on export constraints. I beleive Octopus also want to see building control sign off so there's another cost to add to the Octopus fee.

[Alexx]

  On 01/04/2025 at 17:07, Dillsue said:

Totally agree on the MCS pricing but just giving you the heads up on export constraints. I beleive Octopus also want to see building control sign off so there's another cost to add to the Octopus fee.

Expand  

do they require that as well for normal install or just for DIY?

Edited Tuesday at 20:22 by Alexx

[Mattg4321]

Octopus either want £250, Electrical Installation Certificate and Electrical Building Control Sign off (Part P notification) OR they want MCS 

 

 

[Alexx]

Thanks for the heads up guys. I now just need to figure out a way to get all the kit together and put the panels in place