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Nex's build
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 it kept 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/freezer and all 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 could drop 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 1.5mm CSA, 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 each of the 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 emergency charging my Nissan Leaf would only need 3.3KWh.
R.Mitchell, Wattsup, charlie246 And 5 others like this post
Just done a "heart in mouth" moment. Started upgrading the firmware on my 4048HS to version 72.40. I got halfway through and realised I had the MS (MPPT version) firmware. I had to let it complete, or I would have bricked the unit anyway. 15 minutes of fingers crossed! It rebooted and works beautifully. It's lovely and quiet, has spent more time actually using the solar and batteries in the last 2 hours than it did in the last month. It now displays PV in watts, not vague amps. The Watchpower app now shows the solar PV input and current, whereas it didn't before. The battery capacity is showing a realistic amount as well, not just going from 100% to 60% as soon as it goes off grid, and then doing 10 seconds on battery before clicking back to grid power.
Stage 2 was completed today. 678 solder joints later and I have a fully operation 224 cell 14S16P board with 30A BMS. I just need to add the remaining 104 cells when the come in from GearBest in a week or so. Per board is now a nominal 2.5KWh. The 4048HS has been set up as follows; Low voltage shut down = 44.8V (3.2V per cell), max voltage 57.4V (4.1V per cell), On-battery voltage = 54V, On-grid voltage = 50V.    
Another update. A few more cells have arrived, but I am still waiting for another 56 to get into the UK. Some pics of where I am at now. 


Have you still got the PMG for the WT in the second image ?
(01-22-2017, 08:57 PM)Sean Wrote: Have you still got the PMG for the WT in the second image ?

I have a 48V 1KW PMG which is from a FuturEnergy turbine here (1st picture), but the second one (Hornet), I sold as a complete unit a couple of years ago. The Hornet had a better output, as it was based on a car alternator with neo magnets. The FE PMG still put out 1KW @ 32mph, so not too shabby.
(01-23-2017, 07:49 AM)nexsuperne101 Wrote:
(01-22-2017, 08:57 PM)Sean Wrote: Have you still got the PMG for the WT in the second image ?

I have a 48V 1KW PMG which is from a FuturEnergy turbine here (1st picture), but the second one (Hornet), I sold as a complete unit a couple of years ago. The Hornet had a better output, as it was based on a car alternator with neo magnets. The FE PMG still put out 1KW @ 32mph, so not too shabby.

I've sent you a PM  Rolleyes
Time for another update. It is finished with the initial 224 cells. Total storage is 2.5KWH. I have now ordered another 448 cells, but 112 LG MJ1 3500mAH and 336 Samsung 35E this time, spot welded with nickel strip to give a total of 153.6AH of storage, which at 4.2V across 14 clusters would give just over 9KWH. Pictures to follow.
Nice build

When you calculate the total energy you need to base it on the nominal voltage and not the top voltage. Because the top voltage will only last for seconds.
153.6*3.7*14 = 7.9kWh (Otherwise you will get very disappointed when you test it) Depending on load you may even use 3.6V as the factor but most cells work fine with 3.7.
nexsuperne101 likes this post
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more

Well, I added a few more cells. It now has 336 Samsung 35E, 224 Samsung 26F and 112 LG MJ1, which going on the 3.7V nominal gives me about 8KWh. All I know is that running the following items it is costing me about £5 a week in electric Smile

Fridge freezer
2 TV's
2 heating pumps (for solar space heating and hot water)
Washing machine (about 12 times a week)
Vacuum charger
Various laptop and phone chargers
CCTV system
Raspberry Pi3 (which the webserver that monitors power production is on)
Nissan Leaf (about 15KWh a night)
Electric Range cooker

If I wasn't doing quite so many miles for work, then that would be a bit lower, as I could charge the Leaf more on sunlight, as would be at home, and less on cheap rate overnight electric.

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