Where is the weak link?

[zuluphil]

O.K. Update:- I have since added a 30amp MPPT controller(much better),put individual switches on the 50w floodlights, added a switch between grid supply/Solar supply and put a timer switch on the load circuit (6p.m. to Midnight) So now to monitor for the next few nights Queries:- Is it normal for the inverter to be making quiet sqeaking noises when the load is not on? I have put heavy duty cable between batteries and inverter ( one metre) is that necessary? and I think that my batteries are already damaged as although the reading under charge reaches 100% full ,it gradually drops to 65% at night even though no load has been used. I have connected my batteries as per dia. Is this O.K. as I have read that feed and load should be on the same terminals, why is this? Comments much appreciated.\

[Sunking]

OK let's reverse engineer things starting with the batteries. You have 24 volts @ 200 AH. That is a total capacity of 4800 watt hours. Of that 4800 wh based on 20% daily discharge is about 1000 wh/day or 1 Kwh. So you need to limit your daily discharge to 1 Kwh/day.

You have 600 (3 x 200 watt panels) watts of solar panels with a 30 amp MPPT charge controller. I assume all 3 panels are wired in series. The had better be wired in series. OK 600 watts / 24 volt battery = 25 amps maximum charge current which produces a C/8 charge current, or the maximum your batteries can handle so you have a good match up between panel wattage and battery Amp Hour.

So what is out of balance is you are trying to use more power than the system can deliver. Limit your daily discharge to 1 Kwh. To figure that out total up how many watts you will have turned on, then find the amount of hours you can run the load. For example let's say the total conected load is 200 watts in lights, and you can use 1000 watt hours. Just factor out watts to leave you with hours. 1000 watt hours / 200 watts = 5 hours.

[zuluphil]

O.K. I understand that perfectly and as I have turned off 2 x 50 watt lights leaving me with 2 x 50 + 3 x 8 = 124 w/h x 6 = 744 watts, So I will be O.K. but I will monitor as I,m afraid that the batteries are already damaged and a live run now will confirm. Now then , as I stated in my opening statement my panels are in parallel, they are GE-M-200 12 v mono panels, installed this way by the installer, to quote "Panels cannot be in Prime(my insert: odd )numbers as it only leaves you one option all in parallel. Either loose a panel or gain a panel." The Imp/A is 5.47 x 3 = 16.41a and the Sticker says Vmp 26.5 and Voc 32.4 so I guess the installer was going for more amps. (I feel an impending thunderstorm is imminent)
Before the lamblasting re; panels in series, how about the mouse noises from the inverter and the HD cable from batteries to Inverter?

P.s. Is the battery diagram O.K.?

[daz]

Now then , as I stated in my opening statement my panels are in parallel, they are GE-M-200 12 v mono panels, installed this way by the installer, to quote "Panels cannot be in Prime(my insert: odd )numbers as it only leaves you one option all in parallel. Either loose a panel or gain a panel." The Imp/A is 5.47 x 3 = 16.41a and the Sticker says Vmp 26.5 and Voc 32.4 so I guess the installer was going for more amps.

You have a slight problem here....
Your panels are wired in parallel, so they only provide a Vmp of 26.5V, but........a 24V battery bank needs aprox 28-30V to fully recharge. So you are a bit short!

It is not a problem though, as you have an MPPT controller. You just need to rewire the panels in series. The only thing you have to be careful of is the Voc of the controller. Do you know what the maximum input voltage of the controller is (ie 50V, 150V, etc)?

[daz]

I have connected my batteries as per dia. Is this O.K. as I have read that feed and load should be on the same terminals, why is this? Comments much appreciated.\

It is done that way to help keep the battery bank balanced. Always connect your load to the same place as the charging points.

[Sunking]

as I stated in my opening statement my panels are in parallel, they are GE-M-200 12 v mono panels, installed this way by the installer, to quote "Panels cannot be in Prime(my insert: odd )numbers as it only leaves you one option all in parallel. Either loose a panel or gain a panel." The Imp/A is 5.47 x 3 = 16.41a and the Sticker says Vmp 26.5 and Voc 32.4 so I guess the installer was going for more amps. (I feel an impending thunderstorm is imminent)

Your installer is an idiot. With a 24 volt system the minimum Vmp is 35 volts.

If you have a true MPPT controller check th especs and look at maximum Voc input. If equal or greater than greater than 120 Voc wire all 3 panels in series. This will input to the controller 80 volts (Vmp) @ 5.5 amps or 440 watts. Wait I thought you said these were 200 watt panels? No way 26.5 Vmp @ 5.5 amps is 200 watts, it is 145 watts, not 200. At any rate you cannot use 3 12 volt panels in parallel with a 24 volt battery. Impossible, they have to be a minimum of 2 in series. You need to get the numbers straight before we can help. Because if those are 140 watt panels, you are going to have to downgrade power again.

[zuluphil]

TNX Daz for the battery advice will re-do a.s.a.p. The controller is 150V DC Max and the specs I gave are from the internet spec sheet although the sticker says Imp of 8.22, and the panel is 200 watt on both sticker and spec sheet. As I currently get a max reading on my display of 30v and 15 amps input in parallel at different stages, will the increased voltage more than make up for the loss of amperage by going in series ?

[SunEagle]

TNX Daz for the battery advice will re-do a.s.a.p. The controller is 150V DC Max and the specs I gave are from the internet spec sheet although the sticker says Imp of 8.22, and the panel is 200 watt on both sticker and spec sheet. As I currently get a max reading on my display of 30v and 15 amps input in parallel at different stages, will the increased voltage more than make up for the loss of amperage by going in series ?

A panel's wattage is calculated by multiplying the Imp x the Vmp.

You indicated your panel's Vmp = 26.5 volts and the Imp = 5.47 amps. That calculates out to (26.5 x 5.47) = 145 watts.

Now you state you panel has a rating of Imp = 8.22. If it also has a Vmp = 26.5 then the calculated results in ~ 217 watts.

The best way to build your system is to keep the amps down and the voltage up. The end results is still the same amount of watts but with the lower amps the wire size can also be reduced.

Option 1: 3 panels in parallel. That calculates to; 26.5 x (8.22 + 8.22 + 8.22) = 653 watts. Amp total = 24.7. Volts = 26.5

Option 2: 3 panels in series. That calculates to; (26.5 + 26.5 + 26.5) x 8.22 = 653 watts. Amp total = 8.22. Volts total = 79.5.

Does that help you understand?

[zuluphil]

O.K. Update on weak system,
Batteries re-wired and panels now in series giving 90 Volts! Battery is charging up fully each day (but loses some charge quickly after dark-suspect damage) and system running 125w for 6 hrs a night presently, I will monitor for a week and hopefully move onto next project! Thanks to everyone for helping out.