Hi All,
So first some info. I am in the UK, midlands / South West. The peak output from my PV in the summer is about 500 kw/h/month and drops to about 175 kw/h/month in the winter) The solar array is just under 5 kw peak, which feeds a hybrid grid-tied inverter (Solus RHI 5Kw 5G) which supports separate AC-in and AC-backup, 2 strings of PV max 8 kw @600V max, and various standard 48v battery banks (like LG and Pylon) and also programmable but dumb lead-acids. From the manual it can charge and discharge at 100A.
More info: my background consumption is about 1 kw/h constant day/night (several computers, networking, security system, fridge etc for which I will put in a new circuit to feed from the backup AC). My smart meter during sunshine usually indicates between 3-3.5kw being wasted (going to the grid for about 2p kw/h compensation ). My consumption usually goes up for a few hours in the evening as we like to watch TV/movies on a projector and that's quite hungry (another 4 or 500 W).
My main goal is to reuse the excess energy my array generates during the day to offset pulling from the grid at night. My secondary goal is to provide power to fridge/freezer, security, and networking infrastructure in the event of a blackout (which is quite rare in the UK these days - thankfully, and when it does it's usually resolved in a few hours at most).
So I need help with sizing a LifePO4 pack. As I see it, if capacity is too small you never get the full benefit from your solar array, and if too large you just waste money on batteries because you can never fully charge them... that's my simplistic impression anyway. The easiest thing for me to do is to order 16x 280ah or similar from China to make a 48v, ~13.5 kw/h pack and be done, or do I need to buy 32 cells (+ a couple of spares) for ~27 kw/h? Or something else?
I am wondering about buying Winston's (from EU) which are mega-expensive for comparable capacities but probably a good deal if quality/longevity is considered.
Oh I also need a (or maybe two) BMS, with CANbus. Currently the Seplos is at the top of my list followed by JK/Heltec. Would consider any advice here too.
Thanks a lot and sorry for the long post!
So first some info. I am in the UK, midlands / South West. The peak output from my PV in the summer is about 500 kw/h/month and drops to about 175 kw/h/month in the winter) The solar array is just under 5 kw peak, which feeds a hybrid grid-tied inverter (Solus RHI 5Kw 5G) which supports separate AC-in and AC-backup, 2 strings of PV max 8 kw @600V max, and various standard 48v battery banks (like LG and Pylon) and also programmable but dumb lead-acids. From the manual it can charge and discharge at 100A.
More info: my background consumption is about 1 kw/h constant day/night (several computers, networking, security system, fridge etc for which I will put in a new circuit to feed from the backup AC). My smart meter during sunshine usually indicates between 3-3.5kw being wasted (going to the grid for about 2p kw/h compensation ). My consumption usually goes up for a few hours in the evening as we like to watch TV/movies on a projector and that's quite hungry (another 4 or 500 W).
My main goal is to reuse the excess energy my array generates during the day to offset pulling from the grid at night. My secondary goal is to provide power to fridge/freezer, security, and networking infrastructure in the event of a blackout (which is quite rare in the UK these days - thankfully, and when it does it's usually resolved in a few hours at most).
So I need help with sizing a LifePO4 pack. As I see it, if capacity is too small you never get the full benefit from your solar array, and if too large you just waste money on batteries because you can never fully charge them... that's my simplistic impression anyway. The easiest thing for me to do is to order 16x 280ah or similar from China to make a 48v, ~13.5 kw/h pack and be done, or do I need to buy 32 cells (+ a couple of spares) for ~27 kw/h? Or something else?
I am wondering about buying Winston's (from EU) which are mega-expensive for comparable capacities but probably a good deal if quality/longevity is considered.
Oh I also need a (or maybe two) BMS, with CANbus. Currently the Seplos is at the top of my list followed by JK/Heltec. Would consider any advice here too.
Thanks a lot and sorry for the long post!