Energy Matters Forums

[phil]

[Moderator: moved from Solar Analyser Support to a more appropriate section]

Hi I've contacted you before about my power losses problem because I am at 12volts, rather than buy massive cables I want to fit an MPPT controller. I have 800watts of panels and as there are 10 panels I could wire them to 48volts but they are of mixed ratings and ages and I have been warned that the controller might not work as well as it could,but it must work better than at present right ? I am using a tristar at the moment. Would a 60ampere MPPT do the job ? A guy called Franks suggested that there are good tiwaneese regulators on the market does anyone have a tested name I could use as budget is as tight as it always was and I cant really afford a big name like outback .Any other suggestions appreciated. Thanks

[Gordon-Loomberah]

If you can arrange your panels so that you have parallel strings with the same Vmpp in total, and the panels in those strings produce the same current (but each individual one doesn't need to be the same Vmpp), then the MPPT regulator should work perfectly well. A 60A MPPT regulator would cover you most of the time, you may lose a little due to clipping during cloud edge effect peaks, but that would be an insignificant amount of lost potential power production, given the range of panels you have.

I cant comment on the cheap MPPT regulators, other than to say that you generally get what you pay for with sophisticated electronic equipment.

[franks]

Indeed you get what you pay for, I was suggesting a basic MPPT charge controller..example 60amps, 150Voc, used with 3x190w panels and 2x200amp hour 12 volt batteries, at a mates shack.
cost with postage after offer $320
http://www.ebay.com.au/itm/max-60a-1500 ... 20bc8f4e6f

[Tracker]

I have 800watts of panels and as there are 10 panels I could wire them to 48volts but they are of mixed ratings and ages and I have been warned that the controller might not work as well as it could

That does actually prompt the $64,000 question.. "WHAT are they?"

If you could list what you think you have, there might be a suggestion for optimisation..!
We understand that they are all the same voltage (to be confirmed), but the POWER is presumably Different..
..
.

[phil]

Hi
To be exact I have the following panels
6 x 80watt bp panels about 2 years old
2 x 110w siemens about 11 years old
1x 80w solarex about 12 years old
2x siemen 50w age unknown

Yes they are all 12 volt panels I cannot give you any more details as they are all mounted on the roof and I cannot read the backs of them. I dont understand Vmpp ?
Thanks guys

[Gordon-Loomberah]

It's the Vmpp and Impp that is important. That is, the voltage and current at which the panel delivers its highest power. Voc (open circuit) is also important, to stay within the rating of the charge controller.

[franks]

Assuming your still keeping the 12 volt battery bank.
I would put the 6 same type 80watt panels in series with bypass diodes fitted into the new 150 Voc MPPT charge reg, keep the odd panels in parellel with 10amp blocking diodes into your current PWM charge reg.
you will get aprox 20% better charge yeild with the MPPT charge reg.
Also keep in mind the Voc of the 6 panels in series is aprox 22x6= 132volts..work with caution (technically its not legal for a non sparky to work above 120v dc)

[phil]

Thanks for that and I understand why the mixed panels should be kept seperate but this would mean fitting another cable. If I could expect an increase of around twenty percent could I as a trial wire the other panels up aswell(are the panels just wired in series up to the max 150Voc so I would have two strings ?) and put them through the MPPT and just see what readings I get ?