BUILD LOG - LOTS OF PHOTOS - 64KWH Smart Home Energy Trading System, with solar and heat pump

[wrightjd95 (James)]

Hello all!

I’ve been building Victron systems for many years in automotive and marine applications. This is my first fixed installation, and it is for my home. I’m an engineer by trade, and I work as dealer support for a manufacturer of CT scanners.

Here is the system plan:

Here is the system plan:

• MultiPlus-II 15000/48

• 2x Seplos Mason 560 32kWh: These are ready-to-go batteries with a great active BMS, 157A rated continuous charge/discharge, 200A max, and a built-in fire suppression system. Total of 64kWh. [Link here]

• MPPT 250/60 DC-side solar charger

• Lynx 1000 M10 Power In and Lynx Distributor

• SolarEdge AC grid-tie inverter: This was an existing system that I had to keep, since it’s getting a government feed-in payment grandfathered at a very high rate—60p per kWh, I believe.

• Cerbo GX: This will also control the room ventilation via the relays.

The system is a work in progress. I will show you the build photos!

First, the battery room:

I wanted to create an environment that will keep the batteries and the Victron equipment at peak performance and longevity. Keeping lithium batteries around 21 degrees is good for them, and they definitely shouldn’t drop below zero.

I didn’t have space in the house; I hate attic installations and hard-to-reach, awkward setups. I dislike how such important infrastructure is often installed as an afterthought. Also, having a large battery system inside the house can void your insurance, as there is a possibility of fire.

With that in mind, I wanted to build an insulated, fire-resistant room inside my outbuilding garage.

I used metal stud walls for fire resistance, followed by pinkboard fire-resistant drywall. This will also help maintain humidity levels in the room and reduce condensation.

The room is insulated with 70mm Rockwool and will be completely airtight. I will duct in controlled, filtered ventilation to prevent dust build-up. The room should self-heat due to the waste heat produced by the system (though will have a backup space heater). The ventilation will run only to reduce the room temperature.

A galvanized steel back wall is installed on top of the drywall, as drywall can’t take a screw easily. I wanted to be able to install the hardware easily anywhere with self-tapping screws. It also makes for a clean look and provides additional fire protection.

The concrete floor is sealed with a 2K industrial epoxy.

More in the next post!

[wrightjd95 (James)]

The batteries were shipped from China and arrived on heavy-duty pallets. They are extremely heavy, making them impossible to lift even with two people.

Quality is great, very substantial chassis, they seem very industrial.

I built a wooden ramp using the shipping box and rolled them off the pallet!

Victron bits!

Ready to install!

[wrightjd95 (James)]

I mounted a hook and used a pulley system to hoist the MultiPlus, as it seemed dangerous to try to lift it by myself.

Started mounting the equipment!

Making the cuts in the trunking is no joke! It took ages! I’m making sure to follow all regulations and protect the wires from sharp edges.

With the holes cut, I’m now starting on the wiring.

Progress so far!

I decided to go with these big rotary isolators for the AC input and output on the MultiPlus. I think they’re going to look great!

On the left is the SolarEdge. Above it, I will install a changeover switch to select between connecting the house to the ESS or directly to the grid (in case the system fails, it’s a good backup). I’ll also install a submain distribution board, which will send power out to the house, the EV charger, and various outbuildings via heavy shielded cable.

[wrightjd95 (James)]

Here is a mockup of how the room will look. It’s a tight fit, but I’m not worried since there will be significant forced ventilation.

Digging the trench to the house! Horrible job!

I’m also going to install a hot water supply so has to be quite big.

Started work on the house supply, lots of stuff to be stripped out. Will reuse the changover switch.

[Rene71 (René Vermeulen)]

It looks impressive, and it’s going to be quite a substantial system! I don’t have room for a separate outbuilding. For safety reasons, I want to install my system in a steel Rittal cabinet, as these are designed for industrial electrical installations. It’s expensive, but I’m not comfortable leaving inverters and batteries loose in my garage.

Good luck!

[wrightjd95 (James)]

Hello,

Thank you! Yes is it is the biggest system I have worked with. I am usually installing very small systems in campers and helping friends install their systems.

I didn’t build a new building for it, the system is inside the garage, I merely built a room for it. The garage itself happens to be an outbuilding.

Have you considered the heating of the battery if you place it in a cabinet? The bms will shut the battery off and you’ll get an error if the internal temporature drops below freezing.

I’ve been doing the tedious task of making up the cables so not much progress.

Best,

James

[Rene71 (René Vermeulen)]

Hi,

This Rittal cabinet will be installed in my heated garage. In principle, the temperature shouldn’t drop below 10°C. I’m taking into account that I’ll need to install an anti-condensation heater, also known as a cabinet heater, at the bottom of the cabinet.

Are those AC main switches that you’ve installed below the inverter?

[wrightjd95 (James)]

Yes, they’re 3 pole 100A rotary isolators. On an inverter both poles, neural and live should be isolated. Ground should never be switched.

In the UK, isolators must be installed right next to the equipment.

There is also the distribution MCB board which will also act as an isolator, but regulations require lockable isolation. Technically since its a lockable room this is enough, however, I like big obvious rotary isolators so any layman knows how to turn off generation, this is standard practice in the UK.

I have installed the inverter DC cables and now working on the AC.

I shall use a label gun to clearly and nearly label the isolators.

I have been impressed by this 25mm HO7RN-F cable. You can order it here H07RN-F Rubber Cable - 3 Core 25mm2 / HO7RN-F-3C-25 - CSE Industrial Electrical Distributors Ltd

[wrightjd95 (James)]

Hello all!

I’ve been working on the the building control application and the permission from the energy grid to commission the system.

I’ve built these diagrams, this is the property diagram that shows you where everything is:

I’ve also updated my line diagram to include more infomation:

[wrightjd95 (James)]

Building the trunking for the battery connections:

DC Solar input installed:

[wrightjd95 (James)]

Installing the grandfathered AC tie meter:

More trunking going in:

Now time for the submain distribution, big hole at the top cut to connect to trunking:

Change over switch fitted:

[wrightjd95 (James)]

Progress so far, got the trunking covering on as submitting current progress to building control:

[wrightjd95 (James)]

I’ve been thinking quite a lot about grounding and protection, as it isn’t something that seems to get discussed all that much here.

My current grid connection uses PME earthing, where the neutral is also used as the earth connection when it comes into the building.

A Victron system like this benefits from having a proper earth rather than operating as a floating system. It gives the RCDs a reference to work against, and I’m also not particularly comfortable with having long runs of SWA underground. With those cable runs, there will inevitably be some induced currents, and I want to keep any potential touch voltages as low as possible.

There is also the fact that I have stables with horses on the property. Horses are particularly sensitive to relatively small differences in voltage because they are standing on four legs, so I’m much more conscious of stray voltages and potential differences than I probably would be in a normal domestic installation.

I’ve also never been particularly happy with relying entirely on the grid earth where I live in the UK. I’m quite rural and the supply relies on overhead cables, which have been damaged during storms before. As the grid infrastructure gets older and storms become more severe, I don’t think it’s unreasonable to consider the possibility of a fault developing on the PME system.

With PME, if the neutral conductor is damaged or lost upstream, the neutral to earth connection can cause the potential of the properties earthed metalwork to rise. In the worst case, things like the metal casing of the fridge, metal switches, pipework and even the water coming out of a shower can become dangerous to touch.

I’ve actually experienced a fault like this first hand before, so it’s something I take seriously.

For that reason, I want to move away from relying on the PME earth and install a proper local earthing system at the property, using multiple ground electrodes and bonding everything back to that.

The other important issue is fault current.

A local earth electrode system isn’t capable of carrying anything like the amount of current that the grid neutral can, so I can’t rely on a conventional circuit breaker to disconnect every earth fault. I’ve also realised that when the Victron MultiPlus is operating in off grid mode, it won’t necessarily be capable of supplying enough fault current to trip the larger circuit breakers.

That means the installation needs to rely heavily on RCD protection, with several layers of protection and discrimination between them.

My thinking at the moment is:

1. RCBOs on each individual circuit in each building.

2. A time delayed 100 mA RCD protecting the submain feeding each building. The time delay is important so that a fault on an individual circuit doesn’t immediately trip the entire submain and take the whole building offline.

3. A time delayed 300 mA RCD protecting the main grid feed into the property and the cable run from there. This would have a longer delay than the 100 mA devices, so that a fault on a downstream submain should be cleared locally without unnecessarily tripping the main incoming protection.

The idea is to have several layers of protection, with the protection closest to the fault operating first, while still having backup protection further upstream if something fails to disconnect the fault.

[sahmdahn (Sean Traynor)]

Very impressive system James. I am in the US, but I have a similar background. Installing Victron/Lithium system on RVs/Vehicles for 3 years. I am now in the Commercial Solar industry, but hope to build out a system like this at my own property in the next 2-3 years.

I can’t speak too much on the grounding situation you discussed last, but it seems you have put some good thought into it. I am excited to see the rest of the build! Good luck and have fun! I’m very jealous haha