Hello All.
I've been reading many threads on this forum for some time now and learnt so much already so a big thankyou to the community.
This is my first post so please be gentle with me as I may have made some obvious mistakes or incorrect assumptions.
Here's the background. I live in the UK and I have a grid tie 4kw solar system since 2012 that's been providing reliable energy and a steady income that's long since passed the break even point. We've been driving purely EV's for the last several years and been making use of cheap overnight electricity to run our cars for a couple of pence per mile (Octopus Go). Now with energy prices approaching 40-50p/kWh during the day and no rest bite for the foreseeable future over the summer I decided it was finally time to invest in some lifepo4 cells.
My goal's / approach is as follows;
1 - In the summer be able to utilize 100% of current solar production (no more exporting surplus) by storing the excess generation.
2 - In the event of a power cut ensure my solar keeps on producing
3 - In the event of a power cut have enough stored energy to keep the lights on (figure of speech - I expect to run more than lights!)
4 - In the winter when solar yields are low (and let's face it most of the year in the UK) be able to top up battery's using cheap overnight electricity
5 - Eliminate purchasing of expensive daytime electricity.
6 - Allow expansion for potential future additional solar via Victron MPPT's
7 - Have 2 separate batteries to allow single battery operation to permit maintenance/fault resolution etc on the other.
To this aim I am proceeding with the following;
1 - Victron Multiplus II 48v 5000 inverter/charger
2 - 2x 16S EVE 280Ah lifepo4 batteries. (from Amy@Luayan - the one's with the factory report)
3 - 2x Victron Lynx distributors (1 for battery side and 1 for inverter side)
4 - Victron Lynx shunt (sandwiched between distributors)
5 - 2x JK 200A BMS
6 - 70mm cable (which I think is 2/0AWG equivalent) - Cable runs are expected to be short
7 - 500A 80v CNN Fuse (Littelfuse) in the shunt
8 - 3x 200A 70v (Littelfuse) MEGA Fuse's in the Lynx distributors (batteryA, batteryB and Inverter)
9 - 2x Class T 250A Fuse (BlueSea) as close to battery positive as possible
10 - 3x Unknown Isolators/Switches between batteries and inverter and the Lynx side.
My initial questions are;
1 - What do you all think so far, is this a good sound start
2 - Regarding points 8 and 9 above. My intention is that the cheaper MEGA fuse in the Lynx would sacrifice itself in most situations with the more expensive Class T fuse only coming into play for a dead short on the battery and to protect against the larger currents in this scenario to prevent ARCing.
3 - What type of precharge resistor should I buy for the initial connection to the inverter - I went for 50W/30ohm in the end
4 - I was planning on adding a small fuse on the BMS cables to the cells, given that the BMS also does 2A balancing would a 3amp 5x20mm fuse be correct for these - I went for 5A in the end
Many thanks to all that take the time to read and contribute.
I've been reading many threads on this forum for some time now and learnt so much already so a big thankyou to the community.
This is my first post so please be gentle with me as I may have made some obvious mistakes or incorrect assumptions.
Here's the background. I live in the UK and I have a grid tie 4kw solar system since 2012 that's been providing reliable energy and a steady income that's long since passed the break even point. We've been driving purely EV's for the last several years and been making use of cheap overnight electricity to run our cars for a couple of pence per mile (Octopus Go). Now with energy prices approaching 40-50p/kWh during the day and no rest bite for the foreseeable future over the summer I decided it was finally time to invest in some lifepo4 cells.
My goal's / approach is as follows;
1 - In the summer be able to utilize 100% of current solar production (no more exporting surplus) by storing the excess generation.
2 - In the event of a power cut ensure my solar keeps on producing
3 - In the event of a power cut have enough stored energy to keep the lights on (figure of speech - I expect to run more than lights!)
4 - In the winter when solar yields are low (and let's face it most of the year in the UK) be able to top up battery's using cheap overnight electricity
5 - Eliminate purchasing of expensive daytime electricity.
6 - Allow expansion for potential future additional solar via Victron MPPT's
7 - Have 2 separate batteries to allow single battery operation to permit maintenance/fault resolution etc on the other.
To this aim I am proceeding with the following;
1 - Victron Multiplus II 48v 5000 inverter/charger
2 - 2x 16S EVE 280Ah lifepo4 batteries. (from Amy@Luayan - the one's with the factory report)
3 - 2x Victron Lynx distributors (1 for battery side and 1 for inverter side)
4 - Victron Lynx shunt (sandwiched between distributors)
5 - 2x JK 200A BMS
6 - 70mm cable (which I think is 2/0AWG equivalent) - Cable runs are expected to be short
7 - 500A 80v CNN Fuse (Littelfuse) in the shunt
8 - 3x 200A 70v (Littelfuse) MEGA Fuse's in the Lynx distributors (batteryA, batteryB and Inverter)
9 - 2x Class T 250A Fuse (BlueSea) as close to battery positive as possible
10 - 3x Unknown Isolators/Switches between batteries and inverter and the Lynx side.
My initial questions are;
1 - What do you all think so far, is this a good sound start
2 - Regarding points 8 and 9 above. My intention is that the cheaper MEGA fuse in the Lynx would sacrifice itself in most situations with the more expensive Class T fuse only coming into play for a dead short on the battery and to protect against the larger currents in this scenario to prevent ARCing.
3 - What type of precharge resistor should I buy for the initial connection to the inverter - I went for 50W/30ohm in the end
4 - I was planning on adding a small fuse on the BMS cables to the cells, given that the BMS also does 2A balancing would a 3amp 5x20mm fuse be correct for these - I went for 5A in the end
Many thanks to all that take the time to read and contribute.
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