Question for all you solar experts

[69_Avion]

I have ordered a 250 watt Sharp 24 volt Solar panel. Now for my question. I would like to use a Morningstar Sun Saver 15 MPPT controller. The problem is that the sales person said that the 15 amp MPPT Sun Saver controller isn't large enough for my panel. Does anyone have experience with this? I don't want to have to go to a 45 amp controller unless I absolutely have to.

[69_Avion]

That is a great link. Thanks,

It is clear that the Sun Saver will work with the 250 watt, 24 volt panel, it just won't use the panel's maximum output but it should easily outperform a 200 watt panel in less than ideal conditions.
I'm going to order two panels since I can get free shipping on the second one. Then I need to decide which controller to try.

Thanks to everyone for your input.

[JiminDenver]

At least there are a few more functioning smaller MPPT controllers now. The Eco-worthy didn't come out for a year after I found my panels and everything else that was affordable was fake junk. After paying $50 a panel it was hard to swallow hundreds to stay charged up for a week or two at a time.

Even though 230w has been more than enough for us, I would get the second panel in a heartbeat. You will want a matched set if you ever mount both and combine them. I'm stuck with separate systems if I use both panels.

As far as bumping the limit, unless you are really draining a big bank or doing big power draws at noon, you may not have to worry about it. Even with our panel flat we were in float pretty early and never saw full power at noon unless I was trying to use power.

the two things I'd change on the Eco-worthy are to have the ability to turn off the MPPT when it's cloudy and be able to set a time duration on the absorb stage. It doesn't last long with shallow discharges and while I can hold the float up to 14.5v if I want, it's not automatic. Other than that I can't find any bad reviews after a year .

[full_mosey]

http://www.morningstarcorp.com/en/support/library/MPPT-Primer2.pdf

Morningstar page 3 wrote:

Q2. Can I exceed the nominal wattage ratings of MPPT controllers? Will it void the warranty?

You can size Morningstar’s MPPT controllers well above the Maximum Nominal Solar PV Input rating without damaging the controller and without the charging current exceeding the maximum output current rating. The controller can limit output current and will run at 100% of rated current output and not higher. The controller was designed with this power-shaving capability and when oversized it does not void the warranty

A 240W panel can outperform a 200W panel!

Page 5 wrote:
In this case almost twice as much energy is gained (green area) than lost (red area) with 12.5% more energy available to charge the batteries than the 200W module.

HTH;
John

[ktmrfs]

brulaz wrote:
The Rogue manual suggests a little formula for determining the "maximum usable PV array power when taking into consideration system losses"

PV(watts) = (A x Vb) / 0.90

A is the amperage rating of the MPPT controller, Vb is battery voltage, which he takes to be 14.4V for the 3048 with 12V batteries, and 0.90 is the assumed efficiency.

So the new Rogue 20A MPPT controller should handle a 320W array.

By the way, the downloadable manual is a very useful source of info.

Based on the above numbers the sunsaver 15A MPPT controller would be good to about 200W. Based on what I see from mine with a 160W panel, that's formula works out pretty well. With my 160W panel into a bank at 50%SOC I've seen 11+amps into the battery bank with "perfect" sun conditions. Extrapolating to 200W would yield just at 15A, right at the sunsaver current limit.

And I agree, what is needed is a 20-25A MPPT controller. It's big jump in price from the 15Aish to 45A units.

[69_Avion]

JiminDenver wrote:
Since we had already discussed what a system can actually run, I had a pretty good idea that you were talking cost. I'm sure the Rogue 20a wont be Eco-worthy cheap but there is a need for a affordable basic controller.

There is no doubt that there is a need for a quality, basic controller for one 250 watt, 24v PV panel. I never thought that finding a decent, small MPPT controller would be so difficult. If I can't find anything else soon, I will try the Eco-Worthy. I can always change it out if I don't like it. What I do like is the size. I don't need anything extremely large for an RV.

[JiminDenver]

Since we had already discussed what a system can actually run, I had a pretty good idea that you were talking cost. I'm sure the Rogue 20a wont be Eco-worthy cheap but there is a need for a affordable basic controller.

[69_Avion]

smkettner wrote:

69 Avion wrote:
Any idea what it will run?

Generally a controller does not run anything. Controller charges the battery.

20a 12v will run anything up to 240w. But you can run anything you want from an inverter connected to the charged battery.

Or do you mean what solar panel?

The term "run" was actually a question of how much does it cost? I should have been more specific. I use too much slang.

[time2roll]

69 Avion wrote:
Any idea what it will run?

Generally a controller does not run anything. Controller charges the battery.

20a 12v will run anything up to 240w. But you can run anything you want from an inverter connected to the charged battery.

Or do you mean what solar panel?

[2oldman]

69 Avion wrote:
Any idea what it will run?

Did you miss my last post?

I don't know why this thread is still in TT.

[69_Avion]

westend wrote:

lorelec wrote:
Rogue will be coming out with a 20A MPPT around the end of the month. 100v max on the PV input, 12v or 24v battery. There's a pic of it and little more information about it on the Rogue Facebook page.

There you go, Avion. A perfect fit for your situation.

Rogue Power Technologies on Facebook

Any idea what it will run?

[brulaz]

The Rogue manual suggests a little formula for determining the "maximum usable PV array power when taking into consideration system losses"

PV(watts) = (A x Vb) / 0.90

A is the amperage rating of the MPPT controller, Vb is battery voltage, which he takes to be 14.4V for the 3048 with 12V batteries, and 0.90 is the assumed efficiency.

So the new Rogue 20A MPPT controller should handle a 320W array.

By the way, the downloadable manual is a very useful source of info.

[westend]

lorelec wrote:
Rogue will be coming out with a 20A MPPT around the end of the month. 100v max on the PV input, 12v or 24v battery. There's a pic of it and little more information about it on the Rogue Facebook page.

There you go, Avion. A perfect fit for your situation.

Rogue Power Technologies on Facebook

[lorelec]

Rogue will be coming out with a 20A MPPT around the end of the month. 100v max on the PV input, 12v or 24v battery. There's a pic of it and little more information about it on the Rogue Facebook page.

[JiminDenver]

69 Avion wrote:

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.

I've had the Eco-worthy for around a year and am happy with it for the money. It is simple, easy to set up and you can set the float and absorb voltages. I'm glad it has a display so I don't have to fire up the laptop to see what's going on.

[69_Avion]

ktmrfs wrote:

69 Avion wrote:
I have ordered a 250 watt Sharp 24 volt Solar panel. Now for my question. I would like to use a Morningstar Sun Saver 15 MPPT controller. The problem is that the sales person said that the 15 amp MPPT Sun Saver controller isn't large enough for my panel. Does anyone have experience with this? I don't want to have to go to a 45 amp controller unless I absolutely have to.

He's correct. 250/13=20A that's what the controller will try too dump as a maxx into the batteries. I have the sunsaver 15 controller,wonderful controller but not for a 250W panel.

Thanks for the input. That is what I was trying to confirm. I may just try the Eco-Worthy. There are a few folks on the internet that say they actually work. I wish the Sun Saver was 20 amps, but it isn't.