How fast do you want to recharge them ? More panels = faster charging
Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
Hi, I am looking to charge 52V / 20-Amps lithium batteries with solar panels. How many solar panels will I need?
You have 1040 watt hour batteries. To charge them in 4 hours you will need ~260 watts. That's about 400-500 watts of panels after losses and realistic operating conditions. You will likely end up with two 72-cell panels, each about 250 watts. That will give you about 70 volts, which is what you'll need to run an MPPT charge controller.
Does not work that way with solar. You want a 4 hours charge rate. To do that you have to know the battery AH capacity. Example if it is 20 AH you need to charger that can supply 5 amps. Problem is even if that is a commercial AC charger takes 6 to 7 hours. There are not that many Sun Hours in a Day to do with solar.
I assume you have an E-Bike Right? I also assume you are using either LFP or LiPo battery. If that is correct you want to charge at C/1 or C/2 with solar and in practice will take 2 to 4 hours to charge. So if you have a 20 AH battery will take 20 or 10 amps respectively.
To do that on say a 52 volt battery the panel wattage required is easy to figure out. Charge Amps x Battery Voltage x 1.2 = watts using a MPPT Charger. So lets say 20 amps x 52 volts x 1.2 = 1248 watts with a 20 amp MPPT Controller. You are looking at a $2000 to $2500 battery charger. That wil getter done in 2 hours.
Or you can do 4 hours for 650 watts of panels and a 10 amp MPPT charger will cost about half that and do the job in 4 hours.
Hope you got lots of cash to go green. If it were me I would just buy a commercial charger for $50 and pay that mean ole POCO 1 cent to charge up in 2 hours.