Not another one!

Just want a system that works well and ideally has full off grid back up during short powercuts.

Average annual consumption from the grid is 8500kWh.

ASHP 3000kWh.

Solar PV 3500kWh.

Our Current Setup :

• Solar PV: 3.74kWp array installed back in 2011, that has averaged 3,500kWh of generation annually. Works a treat.

• Diverter & DHW: We have a V1 Myenergi Eddi (Model 16A1P01) sitting in the plant room, diverting our daytime solar surplus straight into our hot water cylinder immersion.

• House Spec: We are an all-electric household (no gas or oil). Heating and DHW from Mitsubishi Ecodan, monitored by an Elster meter.

• Outbuildings & Sub-Main: A sub-main supply loops out 8 metres from the plant room to a garage consumer unit. This zone houses a separate full-time live-in space with its own appliance baseline.

• Data Link: We have a pre-installed, active Cat6 data cable running the 8-metre span between the house router/plant room and a network switch in the garage.

I am looking at the Myenergi Libbi 5kW 230V IP65 Hybrid Inverter & 15kWh Battery Kit (LIBBI-KIT-5.0K/15KWH).

The plan is to install the inverter and three 5.12kWh battery blocks out in the garage outbuilding, running back to the garage consumer unit. To hook up the grid-boundary sensor, we want to split our existing Cat6 cable, to hardwire a direct RS485 Modbus data loop from the house plant room straight to the garage inverter.

We will configure the system via the Myenergi ecosystem so that the Libbi Battery acts as Priority 1 and the legacy V1 Eddi acts as Priority 2 (with "Avoid Drain" enabled).

I have found the 5kW / 15kWh Libbi kit online for £5,628 including 20% VAT (approx. £4,690 trade/wholesale at 0% VAT).

Two options.

1. Supply Only + Electrician Friend: Buy the kit myself and have a close friend who is an industrial electrician (he installs large-scale commercial solar and container-sized utility battery networks) fit it for me.

2. Supply & Fit Quotes: Contact local independent installers to quote for the package.

Your thoughts much appreciated. Thank you.

If I understand you correctly, you are not changing the solar system but adding a battery system?

There might be part P issues with option 1. Your friend might not have the ability to do the part P compliance stuff. (You need Part P compliance for any work in a house, work outside of one, maybe not, but if the garage contains a live in unit then it likely counts)

Assume you aren't bothered about MCS certification? Good reasons not to be (markup by MCS folks) but MCS questions are common when selling a property so something to consider.

Do you have FIT with your current system? (Maybe your existing install predates that??) If so you want to make sure that nothing you do affects that.

1 hour ago, -rick- said:

If I understand you correctly, you are not changing the solar system but adding a battery system?

There might be part P issues with option 1. Your friend might not have the ability to do the part P compliance stuff. (You need Part P compliance for any work in a house, work outside of one, maybe not, but if the garage contains a live in unit then it likely counts)

Assume you aren't bothered about MCS certification? Good reasons not to be (markup by MCS folks) but MCS questions are common when selling a property so something to consider.

Do you have FIT with your current system? (Maybe your existing install predates that??) If so you want to make sure that nothing you do affects that.

Yes , keeping existing PV system with FIT with no alterations. It is upstream of the house on another outbuilding sort of on its own loop.

I will get some quotes from MCS certified installers but not really bothered.

My friend who has been very busy recently with these large solar + battery farms is a residential electrician but will check with him.

I assume the grid export limit on the Libbi will be set to 0.0kW so cannot back feed to grid and compromise the FIT.

Think will need a formal pre installation G99 grid notification certificate.

Thanks Rick.

Only going from what I've read here do check the FIT regs. You should be able to do what you want but you might have to follow some registration process or ensure things are done a certain way. Can't say more than that as not an area I know that much about.