nexsuperne101
New member
- Joined
- Dec 19, 2016
- Messages
- 21
I guess I should document this somewhere.
I started off many years ago with 4no 80 watt panels, which cost me 1000. Back in 2002, that was a really good price. Now I can get 250 watts for 110. How things have changed!
So from my 320 watt system, to the 3KW solar PV I now have,plus an 8KW wood burner and a 30 tube, 300 litre solar thermal water heater.
I did mess about with a small 3KW air source heat pump, but it was as near as useless in winter, as itkept freezing, so spent more time on defrost than making heat.
The lesson learnt here was that ASHP's are useless in high humidity sub zero temperatures, and woodburners work perfectly no matter what the weather is like.
I also had a 1KW wind turbine on the roof. The original black PAG blades used to create shadow flicker in my neighbours kitchen when it was sunny in winter at the right time of day, so I got hold of some clear blades. It stayed up and running for a few years, until we had a storm which clocked 103mph and broke the turbine mount (but not the turbine). I wrote it off as a bad idea after that, and just stuck with the solar and wood alternatives.
My original system consisted of 200AH of lead acid batteries, configured for 48V in 2 blocks of 4. Lead acid is fairly rubbish, so I only had a usable capacity of 100AH, or 4.8KWh to maximise the amount of discharge cycles. After about 3 years, the batteries needed replacing, so I have gone through a few sets in the last few years.
My current project has a pair of PIP-HS4048 inverters with parallel cards installed for 8KW continuous/16KW peak pure sinewave output. Total demand per day averages 4.8KWh, which comes from washing machine, CCTV, telecoms, TV,fridge/freezerandall the LED house lighting. Power generation in summer is fine, as the 3KW of solar puts out easily enough to recharge the batteries in 4 hours, including running the loads at the same time. Winter is a different story. Output on a cloudy day is terrible at 300 watts, so although the batteries do charge, it is barely enough. For this reason, we still have Economy 7 (off peak) electric here. That charges the batteries completely from midnight to 7am, then at 7am, the mains contactor disconnects the grid and we run on battery and reduced solar PV until midnight and it starts again. I will get more solar at a later date, as I want to get completely off grid.
The system I have gone for started as a 13S36P, split across 4 boards (13S9P), but it soon became apparent that 14S is the better choice with the 4048, as the threshold can be run from 42V (3V per cell) up to 57.4V (4.1V per cell). Whilst this isn't 100% of rated capacity, it is a better way to maximise the number of cycles. So my final system will be 14S64P, split across 4 boards (14S16P), to give 10KWh of storage using Samsung 26F 2600mAh cells. It isn't quite enough storage for the 3 days that it should be designed as, but its not a bad first attempt.
On this setup, I will have a temperature sensing 30A BMS on each of the 4 boards, as my concrete reinforced building coulddrop below zero C in the depths of winter. I have got a ventilation and heating system that monitors the environmental side of things, so that will maintain the temperature, but the BMS is just there for if the heater fails, the cells drop below zero and the charging will then cease.
The pack is mounted on a backboard 1600mm wide by 1600mm deep. Each board is 400mm, but they will be one above the other. I am not too restricted on space, which is why I went for the 4 module 18650 holders. The other reason is that if a cell fails, they are extremely easy to replace, just pop it out of the holder and chuck a new one in. No soldering required.
Each battery is joined to an interconnecting copper busbar, which is 1.5mmCSA, on the negative side. The main battery connections are 4mm CSA, as this is good for 37 amps, but will never exceed 30 amps. The positive side of eachofthe 224 cells per board will be connected to the negative busbar of the next cell by a 0.2mm (35SWG) tinned copper wire "fuse". This is designed to blow open if a fault develops between cells at 5 amps. The 26F is good for 2C (5.2A), so the fuse is the weak link (as it should be!).
With 16 cells in parallel per board, the 30A maximum will work out at 1.9A per cell, or well under 1C, so both charge and discharge currents are well inside manufacturers specifications.
Maximum output would be 6.9KW at 57.4V (120A), falling to 5KW at 42V (120A).
This is way beyond anything I would ever need, as even emergencycharging my Nissan Leaf wouldonly need 3.3KWh.
I started off many years ago with 4no 80 watt panels, which cost me 1000. Back in 2002, that was a really good price. Now I can get 250 watts for 110. How things have changed!
So from my 320 watt system, to the 3KW solar PV I now have,plus an 8KW wood burner and a 30 tube, 300 litre solar thermal water heater.
I did mess about with a small 3KW air source heat pump, but it was as near as useless in winter, as itkept freezing, so spent more time on defrost than making heat.
The lesson learnt here was that ASHP's are useless in high humidity sub zero temperatures, and woodburners work perfectly no matter what the weather is like.
I also had a 1KW wind turbine on the roof. The original black PAG blades used to create shadow flicker in my neighbours kitchen when it was sunny in winter at the right time of day, so I got hold of some clear blades. It stayed up and running for a few years, until we had a storm which clocked 103mph and broke the turbine mount (but not the turbine). I wrote it off as a bad idea after that, and just stuck with the solar and wood alternatives.
My original system consisted of 200AH of lead acid batteries, configured for 48V in 2 blocks of 4. Lead acid is fairly rubbish, so I only had a usable capacity of 100AH, or 4.8KWh to maximise the amount of discharge cycles. After about 3 years, the batteries needed replacing, so I have gone through a few sets in the last few years.
My current project has a pair of PIP-HS4048 inverters with parallel cards installed for 8KW continuous/16KW peak pure sinewave output. Total demand per day averages 4.8KWh, which comes from washing machine, CCTV, telecoms, TV,fridge/freezerandall the LED house lighting. Power generation in summer is fine, as the 3KW of solar puts out easily enough to recharge the batteries in 4 hours, including running the loads at the same time. Winter is a different story. Output on a cloudy day is terrible at 300 watts, so although the batteries do charge, it is barely enough. For this reason, we still have Economy 7 (off peak) electric here. That charges the batteries completely from midnight to 7am, then at 7am, the mains contactor disconnects the grid and we run on battery and reduced solar PV until midnight and it starts again. I will get more solar at a later date, as I want to get completely off grid.
The system I have gone for started as a 13S36P, split across 4 boards (13S9P), but it soon became apparent that 14S is the better choice with the 4048, as the threshold can be run from 42V (3V per cell) up to 57.4V (4.1V per cell). Whilst this isn't 100% of rated capacity, it is a better way to maximise the number of cycles. So my final system will be 14S64P, split across 4 boards (14S16P), to give 10KWh of storage using Samsung 26F 2600mAh cells. It isn't quite enough storage for the 3 days that it should be designed as, but its not a bad first attempt.
On this setup, I will have a temperature sensing 30A BMS on each of the 4 boards, as my concrete reinforced building coulddrop below zero C in the depths of winter. I have got a ventilation and heating system that monitors the environmental side of things, so that will maintain the temperature, but the BMS is just there for if the heater fails, the cells drop below zero and the charging will then cease.
The pack is mounted on a backboard 1600mm wide by 1600mm deep. Each board is 400mm, but they will be one above the other. I am not too restricted on space, which is why I went for the 4 module 18650 holders. The other reason is that if a cell fails, they are extremely easy to replace, just pop it out of the holder and chuck a new one in. No soldering required.
Each battery is joined to an interconnecting copper busbar, which is 1.5mmCSA, on the negative side. The main battery connections are 4mm CSA, as this is good for 37 amps, but will never exceed 30 amps. The positive side of eachofthe 224 cells per board will be connected to the negative busbar of the next cell by a 0.2mm (35SWG) tinned copper wire "fuse". This is designed to blow open if a fault develops between cells at 5 amps. The 26F is good for 2C (5.2A), so the fuse is the weak link (as it should be!).
With 16 cells in parallel per board, the 30A maximum will work out at 1.9A per cell, or well under 1C, so both charge and discharge currents are well inside manufacturers specifications.
Maximum output would be 6.9KW at 57.4V (120A), falling to 5KW at 42V (120A).
This is way beyond anything I would ever need, as even emergencycharging my Nissan Leaf wouldonly need 3.3KWh.
