Question for all you solar experts

CA Traveler wrote:
MPPT controllers take the input voltage and current and convert it to the output voltage and current. He can possibly get 17A output

I think I'm confused in that he's charging at 12v, not 24, so the 15a still holds.

2oldman wrote:

CA Traveler wrote:
MPPT controllers take the input voltage and current and convert it to the output voltage and current. He can possibly get 17A output

I think I'm confused in that he's charging at 12v, not 24, so the 15a still holds.

To say it in another manner;
The MPPT controller receives the 24 volt input from the panel and adjusts it to 12 volt without reducing the amps.
Thats the readers digest version. It would take several pages to cover everything involved.
Read Handy Bob Blog.

harold1946 wrote:
The MPPT controller receives the 24 volt input from the panel and adjusts it to 12 volt without reducing the amps.

It would have to increase the amps, right? If it doesn't, better get a better controller.

I use the Morningstar 15 MPPT with 300 watts of panels. This usage is permitted by Morningstar. Maximum output is just under 15 amps. Works great for me as am looking to optimize low light output and could care less about losing a few amps when the sun is high and bright. The controller is even more efficient at the higher (24) volt input. Should be a great system for you as long as you are happy with ~15 Amps.

Steve

I may just order two panels since the second panel has free shipping. Has anyone used the Morningstar Tri Star 45 watt MPPT controller? If one 250 watt 24 volt panel is good for about 17 amps then two should be good for 34 amps which means with two of these panels I should just go right to the 45 amp MPPT controller.

Lets hear from the folks that have the Morningstar Tri Star 45 amp MPPT controller.

With two of these panels working at optimum level, what size 110 volt inverter could it power through the batteries with minimal loss from the batteries during the optimum level?

Do you go up in altitude? My 230w panel sees a increase of over 50% at altitude, you may be loosing more than you think.

I've had good results using the Eco-worthy 20a MPPT controller with a single panel. I was hoping one of the really low cost ones would at least functions but no luck so I'll be getting a second Eco-worthy for the inverter bank.

69 Avion wrote:
With two of these panels working at optimum level, what size 110 volt inverter could it power through the batteries with minimal loss from the batteries during the optimum level?

34 x 13= 442w. It will power any size inverter, but it will not support more than 442w draw from that inverter.

So I guess you could say about a 500w inverter. The easier way is to simply think of it as having 2-250w panels for a total of 500w.

69 Avion wrote:
Lets hear from the folks that have the Morningstar Tri Star 45 amp MPPT controller.

I have the 60 amp driven by three 225w panels. In hindsight the 45a would have been fine even though Morningstar recommended the 60a. I really like the programmability of the 60a so all is good.

Strictly by the numbers (250 watts/ 14.4 volts = 17.36 amps) that controller is not large enough.
In the real world it will probably work fine since it limits the output to protect itself. The drawback is that during periods of intense sun and/or low battery you will be loosing power.
Morningstar makes some great charge controllers. I've got two of the their 45A models installed at 2 different off grid cabins. I've had no problems from either. Blue Sky is another brand you should investigate. I've got even more of their controllers installed, also with no problems.

JiminDenver wrote:
Do you go up in altitude? My 230w panel sees a increase of over 50% at altitude, you may be loosing more than you think.

I've had good results using the Eco-worthy 20a MPPT controller with a single panel. I was hoping one of the really low cost ones would at least functions but no luck so I'll be getting a second Eco-worthy for the inverter bank.

Jim, how has your Eco-Worth MPPT controller been working? It is the only one that I can find in the 20 amp range. It appears that it will work well with my 250 watt, 24 volt Sharp panel. The price is certainly better than the others as long as it actually is reliable and it works. Let me know what you think.
I may buy two panels since there is no extra shipping for the second panel and then just buy a second Eco-Worthy MPPT controller. I like the fact that it is reasonably sized. When you go to the Morningstar TriStar MPPT 45 amp controller, it is huge for RV usage.