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diy solar

1000W, 24V, 7.1kWh DIY system w/diagram and costings. Looking for comments!

carboncontext

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Nov 14, 2020
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Hello everyone!

This is my first post on this wonderful forum after many months of reading and learning. I feel so lucky to have been able to benefit from all the knowledge on this website.

With all that I've learned so far I've designed a penny-pinching but powerful solar system that will fit onto a L3 (long wheel base) Ford Transit. If I've designed things right it should provide:
  • 1000kW solar array, with panels wired in a 2S2P config. for better partial shading performance. There will be spare space on the roof enough for a walkway which can be used to tilt or clean the panels easily.
  • 24V LiFePO4 battery storage with ~6kWh useable capacity (@85% depth of discharge). This should be enough to power everything I need (including heavy use of a video editting pc) for 2 days without charge!
  • Power delivery: up-to 2000W @ 240V AC or 840W @ 12V DC (2400W max total power output)
  • Option to charge from shore power
  • All at a low cost of around £3,050
I will be ordering all the components in the next few months and am aiming to complete the installation by October. I'm going to keep track of how things go and post updates here as and when.

The wiring diagram for the system is attached to this post and the budget is posted below. If anyone can see any issues with the design or ways I could do things better I would love to know! I will take note of any suggestions and once the system is done look forward to being able to post the final design to help out others looking to get into DIY solar.

Many Thanks,

David

ComponentPartCostNotes
4x 250W slim profile solar panelsPanasonic VBHN245SJ25 245 Watt Solar Panel Module £ 768.00 Wired in 2x2, provide 1000W @ ~105Voc, 15Asc. Profile allows 4x1 physical configuration.
45A MPPT, VocMax>110, >1100WVictron SmartSolar MPPT 150/45 £ 400.00 150V required due to high Voc of panels, the 45A model takes upto 1300W, giving some headroom
7168kWh 24V DIY battery8X 280Ah LiFePO4 cells from Basin (3.2V/280Ah)£ 650.00Includes shipped, but not import fees - ask supplies to switch from DAP to DAA for this
24V BMSOverkill Solar - BMS 100a 8s LifePo4 Battery Management System for 24v DIY Batteries, Programmable, Bluetooth Included.£ 110.00Recommended by Will Prowse. See here for cell configuration.
24V to 12V buck converterVictron Orion 24/12-70A DC-DC converter£ 140.00Could cheap out with a chinese model for £60
2000W 24V to 240V AC inverterGiandel 2000W Pure Sine Wave Power Inverter DC 24V to AC 240V with Dual AC Outlets with Remote Control 2.4A USB and LED Display£ 308.00Could cut the cost in half if I go for the 1000W version. Recommended by Will Prowse.
30A 230V AC to 24V DC mains chargerPortable Power Technology 30A 24V battery charger£ 275.00Expensive, but will charge the battery in 6h
Isolator/Changeover switchLotFancy Battery Isolator Switch 1-2-Both-Off Battery Disconnect Switch Waterproof for Marine Boat Car RV ATV UTV Vehicle, 6V 12V 24V 48V 60V Heavy Duty Cut off Battery Switch, 200/1250Amps£ 19.006-60V, 100A, 4 way action
2x isolator switchLotFancy Battery Disconnect Isolator Switch Waterproof for Marine Boat Car RV ATV UTV Vehicle, 6V 12V 24V 48V 60V Heavy Duty Battery Switch, 200/1250Amps (ON - OFF Position)£ 32.006-60V, 100A, 2 way action
Positive busbarBlue sea systems common busbar (100a, 4stud w/cover)£ 22.00
Negative busbarBlue sea systems common busbar (150a, 10screw w/cover)£ 30.00
12V fuse boxKohree Fuse Box, 12-Way Blade Fuse Block with LED Indicator, 12 Circuits Fuse Box Holder with W/Negative Bus for Automotive Car Boat Marine SUV RV Van£ 20.00Lots of alternatives. Is 12 channels enough? Comes with fuses up to 20A
4x 40/40/50/100A circuit breakerWaterproof Circuit Breaker, Keenso 12V-24V 50A 60A 80A 100A Circuit Breaker Reset Fuseholder Car Boat Circuit Fuse Holder for System Protection (80A)£ 44.00
Cable entry glandLink Solar Weatherproof ABS Solar Double Cable Entry Gland All Cable Types 2mm² to 6mm Solar Project on Rv, Campervan, Boat (Black)£ 12.00
2x 13ft 8 gauge UV resistant cablingSM SunniMix 8 Gauge Silicone Wire 13 Feet 8 AWG Super Flexible Silicone Wire Red£ 46.00Estimate 2m along roof and 2m drop down. Needs to be UV resistant.
2x MC4 branch connectorRenogy MC4 Male/Female Branch Connectors Solar MC4 Connectors T Connector Y Connector in Pair MMF+FFM IP67£ 16.00
Shunt and battery meterKETOTEK Digital Ammeter Voltmeter DC 6.5-100V 100A Shunt, Volt Amp Watt Meter DC Current Voltage Power Energy LCD Display Panel£ 18.00Not required as the Victron 150/45 covers these utilities (£18)
2m 4-ga. stranded, insulated wireNiceDD 4 gauge set£ 19.00
20m 10-ga. stranded, insulated wire10 gauge silicone wire£ 48.00
 

Attachments

  • bepop electrical 050421.pdf
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I'm going to keep track of how things go and post updates here as and when.
Welcome to the forums! Can't wait to hear how things go with your build.


Pansonic just announced back in January they're getting out of the panel game, too much competition from China. See Panasonic Quits Making Solar Panels - Price of Discontinued HIT Panels? So, if they're not at great discounts worth the bother than you might look for an alternative.
 
I would consider a proper breaker for the PV disconnect and not using a 48V rated disconnect switch. You will have voltages >70V on the PV lines. Those disconnects are built for low voltage but lots of current; you need something for higher voltages and lower current. Arcing can be a big issue as voltage goes up.

A 250VDC rated duplex breaker is the optimal to break both + and - at the same time; and under $30 on Amazon.

 
Hey, this looks great! Looks a lot like my design but with more solar panels. Have you started this build yet?
 
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