Solar Charger + AC Inverter/Charger

[Willuz]

I'm planning on running both a solar charge controller (Morningstar TS-45) and an inverter/charger (Triplite APS1250) at the same time. The Triplite would be turned on only when I need the AC inverter or I'm plugged into shore power and want the extra charging for my batteries. My concern is that when shore power is plugged in the charge current from the inverter/charger will conflict with the solar charge controller. My feeble understanding of this leads me to believe that both would be seeing each others voltage instead of the actual battery voltage so they would cycle on/off repeatedly.

Do I need to install a relay to disconnect the solar charger when my shore powered inverter/charger is on?

[absolutsnwbrdr]

I'm pretty sure that that the solar charge controller recognizes that there is an incoming charge from another source and prevents the situation you are concerned about. I have 140W panel with a Morninstar SS-10, and also a 25A charger/converter, so its a similar setup. I haven't had them both "on" at the same time yet. In fact I haven't plugged my trailer in since I installed my solar panel.

Don't take my word for it though. There's much more knowledgeable people around here when it comes to solar.

If I'm wrong, somebody scold me and I'll go sit in the corner.

[eamarquardt]

If you have AC power why would you need to have your solar panels connected to your batteries? I'd just install a double throw switch to switch between "shore power" and solar panel power. Nah, it's not "automagic" but it will get the job done.

Cheers,

Gus

[Shadow Catcher]

I have a Progressive Dynamics converter and a Morningstar MPPT controller and they play well together, but I talked with engineers at both Morningstar and PD before doing it. I have a Mornigstar Sursine inverter and I used a 30A DPDT switch to feed AC to the AC circuits with out feeding the converter.

[Willuz]

If you have AC power why would you need to have your solar panels connected to your batteries? I'd just install a double throw switch to switch between "shore power" and solar panel power.

I won't always have AC power because I will frequently be off the grid but not always. The complication/solution comes from the combination of the inverter with the charger. The inverter/charger can be easier because it includes the 120v pass through so when I plug in external power it goes to the 120v outlets without any switching or relays required. Plugging in external power causes the Triplite to become both a 120v pass through and a 12v battery charger so it has the potential to make the switch from solar to shore power seamless.

I just don't want to fry the TS-45 so it looks like I'll be on the phone with Morningstar to make sure.

[eamarquardt]

If you have AC power why would you need to have your solar panels connected to your batteries? I'd just install a double throw switch to switch between "shore power" and solar panel power.

I won't always have AC power because I will frequently be off the grid but not always. The complication/solution comes from the combination of the inverter with the charger. The inverter/charger can be easier because it includes the 120v pass through so when I plug in external power it goes to the 120v outlets without any switching or relays required. Plugging in external power causes the Triplite to become both a 120v pass through and a 12v battery charger so it has the potential to make the switch from solar to shore power seamless.

I just don't want to fry the TS-45 so it looks like I'll be on the phone with Morningstar to make sure.

I'm not sure what your planning on running on inverter power, when yer gonna run it, or for how long yer gonna run it. The 45 amp solar controller and 1250 watt inverter are pretty hefty units. You'll need about 1500 watts of solar power or/and a pretty big battery bank to make full use of the power of those two units. W/O solar panels and batteries that are "matched" to your other components you may have a bit of "stranded" capacity/expense.

In addition, a PWM controller will "dump" any power above your nominal system/battery voltage so it's important to keep your solar panel output close to your system voltage. Depending on your plan you might consider a MPPT controller.

Hope this helps.

Cheers,

Gus

[bdosborn]

Do I need to install a relay to disconnect the solar charger when my shore powered inverter/charger is on?

Nope, you're good. You won't have any problems with plugging in to shore power while out in full sun, I do it all the time. The solar controller will see the increased voltage due to the charger and adjust it's output accordingly. Same for the charger.

This is a standard configuration for just about every offgrid PV installation out there; both the battery charger and the PV controller are connected directly to the battery.

Bruce

[Willuz]

Thanks for all of the information. It looks like I accidentally cornered myself into a Tristar MPPT 45. I ordered the Grape Solar 250W panel from Home Depot before realizing it was a high voltage panel. Unfortunately, it exceeds the maximum wattage of the Sunsaver MPPT so I have to go with the Tristar and might order another panel so the controller doesn't seem like a waste. Can't say I'm particularly sad about this as I've always believed you can make anything better by controlling it with a computer.

[Shadow Catcher]

The SunSaver MPPT controller will handle the over curent from the panel according to a white paper I read this morning. If you mount the panel to the roof you well seldom get full watts anyway.
Ours works very well.

[bdosborn]

Yeah, the Susnsaver MPPT controller will limit its output to 15A. You could potentially waste 50 watts but I doubt you'd get the full output with the panel very often, especially if it stays flat. I've pegged my Sunsaver MPPT once or twice but it took 300 watts of panels (220 on the roof + an 80 watt portable) to do it.

Bruce

P.S. I have the Morningstar remote meter hooked up to my controller, that's how I know I don't reach the controller maximum very often and never with the 220 watts laying flat.

[bdosborn]

Just to muddy the water, the Tristar PWM controler has a Voc of 125V so it would handle the 37.7 Voc of your panel. However, you'd only get a around 8.15A*14.4V=117 Watts out of the panel. So yeah, you're better off with an MPPT controller.

Bruce