Need advice/Help on a simple setup...2x235w 24v, 2x12v, Xantrex C60, Aims 5000W

Re: Need advice/Help on a simple setup...2x235w 24v, 2x12v, Xantrex C60, Aims 5000W

Welcome to the forum, Daniel.

Now stop before you spend another dime. You're going about it the wrong way 'round.

What you've got: two 235 Watt panels for a total of 470 Watts. These Sharp 235 have a Vmp of 30 Volts if I recall correctly. That will not charge a 24 Volt system unless you put them both in series and use an MPPT style charge controller, which the C60 is not.

The AIMS inverters are in my opinion badly designed and not worth spending any money on.

The marine/RV batteries aren't really suited to RE applications and will soon disappoint you.

You can not use the "dump mode" function of a C60 to power a grid tie inverter. This is designed to be used with wind turbines to 'bleed off' power they produce to an 'opportunity load' once the batteries are full. GT installs have to be done with the co-operation of the utility and local authorities. The systems are quite different to off grid in respect to their wiring and function.

Back to what you've got; the two panels.
With an MPPT controller (necessary with those panels) you could expect enough charge current to support about 300 Amp hours @ 12 Volts or 150 @ 24. You could expect them to yield just under 1kW hour on the AC out of an inverter per day. That will also depend on how much power the inverter itself consumes.

Given the nature of the panels and their output potential, what you need is a Rogue MPPT 3024 - which has unfortunately been temporarily discontinued. Otherwise your up against spending a lot of money for a "full size" controller: one side or the other of $500. With it you could charge a 12 or 24 Volt bank comprised of golf cart batteries. Were it me I'd go with 12 Volt and have some extra current to spare.

It is unlikely you will need 0 AWG between the batteries and the controller as your peak current will only be around 30 (for 12 Volt) or 15 (for 24). Most controllers accept up to 6 AWG and that should be fine (keep lower Voltage DC runs short). It should be fused according to the current potential of the controller used.

You can do quite a lot with 1kW hour per day. And there are several good small 12 Volt inverters which could power your lighting easily. The plasma 50" not so much so.

Re: Need advice/Help on a simple setup...2x235w 24v, 2x12v, Xantrex C60, Aims 5000W

If you want to charge a 24 Volt battery you need more than the 30 Volts these panels put out at maximum power. You need about 35. So you put them in series and use the MPPT type controller to "down-convert" the now 60 Volt panel string to proper charging Voltage. It will turn the higher Voltage into current, so there's no large power loss.

If you want to charge a 12 Volt battery you have the opposite problem: the 30 Vmp is too high to be used with a 12 Volt system and PWM type controller. As a result, you lose some of the power potential of the panel. Instead of Imp * Vmp you get Imp * battery Voltage: 7.8 Amps * 30.1 Volts = 235 Watts, but 7.8 Amps * 14.4 (charging) Volts = 112 Watts! Magically 123 Watts vanishes because panels are a current source and will allow their Voltage to go down without a fight.

Your installer was thinking along the lines of Voltage drop over distance, reasoning that two runs would suffer less power loss. Technically that is correct, but you can get the same effect with either using larger wire for paralleling the panels or putting them in series to increase the Voltage. Parallel the panels would be 30.1 Volts @ 15.6 Amps. Series they would be 60.2 Volts @ 7.8 Amps. Same Watts arranged to different ways. The higher Voltage/lower current way leads to less Voltage loss with any given wire size/distance.

Since you have to use an MPPT type controller to maximize the power from these panels with either Voltage system you might as well wire them in series and reduce the Voltage drop in the down lead.

The ground, btw, should not be run into the house. It should go down the outside to a ground rod to keep stray Voltage from lightning activity from 'lighting up' the panels and anything they're attached to. There is a lot of discussion about grounding practices, and a lot of disagreement.

Re: Need advice/Help on a simple setup...2x235w 24v, 2x12v, Xantrex C60, Aims 5000W

Rogue made (and will again soon) a very good quality 30 Amp 12/24 Volt MPPT controller for a reasonable price.
Xantrex is more money, a 60 Amp unit (for the MPPT one), and buggy.
I'm not familiar with Steca controllers and haven't seen a listing for an MPPT unit from them.
Blue Sky makes some in about the right range, but frankly their specifications are confusing.

We are talking about $300 range controllers here. Go up to $500 and you can get a MidNite Classic 150 lite which will handle a lot more current and is frankly one of the best on the market (the 'full' version being the best) today. This is one reason why you need to consider possible future expansion now. One of the smartest things I ever did was shell out $900 for an Outback MX60 back in 2008. It was the best controller available then. I used three panels on a 12 Volt system originally, and now have four wired for 48 Volts nominal (70 Vmp) on a 24 Volt system. What's more I know I can add panels to it or change over to an even bigger array or even up the system Voltage again without having to replace the controller.

10 AWG would handle 60 Volts @ 8 Amps up to a distance of about 100 feet before the Voltage drop (at full power) started to climb above acceptable limits.