January 19, 20233 yr I am putting a small system together. Intend using a 12v Lifepo battery 200AH How do I size the panels? And what regulator do I use - I intend using a Victron PWM regulator but how does one size it?
January 19, 20233 yr 4 minutes ago, Clivevan said: How do I size the panels? if all you want to do is charge the battery, look at the supported charge current and size th panel according to this, unless you're happy to have the battery be charged over a few hours, then you can go smaller... the question really is, what are you trying to achieve? if you are trying to run part of your house off solar + battery, you'd need to look at what your consumption is, a single 12V 200Ah battery won't go very far... but if all you;re powering is an internet connection + a PC, then this should run for a while... again your need to look at what the consumption is on your end in order to come up with realistic answer...
January 19, 20233 yr Author No I know all that - but is there a formula for sizing an inverter and a panel? IOW if I want to charge that battery in 5 hours I need to feed it approx 400 watts per hour. So does that mean 1x 400 watt panel? And 1 x regulator of what size?
January 19, 20233 yr Author Assuming the panel provides 400 watts per hour - does that mean it will automatically be configured by the regulator into 12v at approx 35 amp and thus delivered to the battery? I am trying to understand how to size the panels and the regulator as a general proposition. For now I assume a 200Ah lifepo and that I will drain it about 80% over a 24 hr period. If you can further consider and assist?
February 4, 20233 yr On 2023/01/19 at 2:45 PM, Clivevan said: So does that mean 1x 400 watt panel? And 1 x regulator of what size? if you want to feed 400W, you'd probably want to look at, lets make it a 500W panel... usually you can budget 10-15% down on the Wp value and also the regulator will also self consume some, albeit probably not vary much... if your battery can consume 400W/14V approximate charge voltage = lets call it a 30A charge current... this would ideally require a 300+Ah lead acid setup, or, I suppose a 100Ah LiFePO4 battery should be happy with this current, check the manufacturer specs of the battery... On 2023/01/19 at 2:51 PM, Clivevan said: does that mean it will automatically be configured by the regulator into 12v at approx 35 amp the regulator should have bulk and float voltage settings at least, so, no automatic setting and you should make sure those setting fall in line with the battery... the MPPT or PWM regulator should have 35A or so charge capability you could go for, let's say 100A capability and thus be slightly future proof if you intend to add more battery capacity and solar panels down the road... On 2023/01/19 at 2:51 PM, Clivevan said: For now I assume a 200Ah lifepo and that I will drain it about 80% over a 24 hr period. if there's a constant load, that would amount to (200A * 13V ± * 0.8 = 2080W / 24 hours) 86Wh, sounds a bit skraal, specially if you're running via an inverter... most inverters have a self consumption rate close to or approaching 80Wh
February 4, 20233 yr 2 hours ago, Kalahari Meerkat said: if you want to feed 400W, you'd probably want to look at, lets make it a 500W panel... usually you can budget 10-15% down on the Wp value and also the regulator will also self consume some, albeit probably not vary much... if your battery can consume 400W/14V approximate charge voltage = lets call it a 30A charge current... this would ideally require a 300+Ah lead acid setup, or, I suppose a 100Ah LiFePO4 battery should be happy with this current, check the manufacturer specs of the battery... the regulator should have bulk and float voltage settings at least, so, no automatic setting and you should make sure those setting fall in line with the battery... the MPPT or PWM regulator should have 35A or so charge capability you could go for, let's say 100A capability and thus be slightly future proof if you intend to add more battery capacity and solar panels down the road... if there's a constant load, that would amount to (200A * 13V ± * 0.8 = 2080W / 24 hours) 86Wh, sounds a bit skraal, specially if you're running via an inverter... most inverters have a self consumption rate close to or approaching 80Wh About all the current range of controllers do auto adjust to 12/24V specially the cheaper China type that's why the battery must be connected 1st. There are however some that have a fixed configuration and need to be set. Mostly MPPT.
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