solar questions, plans for expansion

[maple flats]

I have no problems with my equipment combination. I went MPPT because of the distance from panels to the sugarhouse (240'). I am running 96V nominal but when the winter temps and in the sun it makes over 120V quite often. If I connected a 5th panel in series the charge controller would shut off at cold temps in good sun and waste the energy when I might need it the most. A MPPT controller actually gives far higher efficiency than a PWM (pulse width modulated) controller. My controller is in the upper 90's percentile for efficiency, I'd need to read it again but my inverter and controller were each at 95% or higher, one was 96% and the other at 97%. This gives me the highest possible. Now, at best battery conversion is much lower. When I use the power as it is being generated I get very good efficiencies but by the characteristics of batteries, I get less use from my stored energy. When I need more power I start the generator. Then the inverter syncrinizes the wave form. the gen power is priority, and surplus charges the batteries. If I draw a load too high for the generator it is supplemented from the batteries.
This is still a learning experience.
One thing really surprised me back in March sometime, we had a "super moon" and I noticed the moon was charging the batteries.

[OlJarhead]

I have no problems with my equipment combination. I went MPPT because of the distance from panels to the sugarhouse (240'). I am running 96V nominal but when the winter temps and in the sun it makes over 120V quite often. If I connected a 5th panel in series the charge controller would shut off at cold temps in good sun and waste the energy when I might need it the most. A MPPT controller actually gives far higher efficiency than a PWM (pulse width modulated) controller. My controller is in the upper 90's percentile for efficiency, I'd need to read it again but my inverter and controller were each at 95% or higher, one was 96% and the other at 97%. This gives me the highest possible. Now, at best battery conversion is much lower. When I use the power as it is being generated I get very good efficiencies but by the characteristics of batteries, I get less use from my stored energy. When I need more power I start the generator. Then the inverter syncrinizes the wave form. the gen power is priority, and surplus charges the batteries. If I draw a load too high for the generator it is supplemented from the batteries.
This is still a learning experience.
One thing really surprised me back in March sometime, we had a "super moon" and I noticed the moon was charging the batteries.

Funny you mentioned that -- I get a lot of charging out of my setup when the sun is hiding behind trees or clouds and even a decent trickle when it isn't even fully up above the horizon.  Seems any light in the sky gives me something.

On the other hand I've not seen the panels give me the power they are rated at.  So far the most I've seen is 299 watts but that may not mean anything as I've yet to see them perform in full sun directly on the panels with a need to produce...we will soon see that though ;)

I'm always amazed at how the MPPT controller adjusts the voltage and amps to meet the needs of the system too...amazing.

[OlJarhead]

I should add that I have a Xantrex C40 but swapped it out for the Morningstar MPPT because I was was running 54vdc from the panels (actually as high as 67vdc) and the C40 isn't designed for that kind of use so I was wasting a lot of charging power.

However, I fail to see how it would impact an inverter??  The charge controller charges the batteries, the inverter draws power from the batteries....shouldn't matter what controller is being used and for that matter NO controller is required to run an inverter (you could just plug it into the batteries and use an iota charger and a generator to keep them topped up if you didn't have solar).

[logman]

I think the main reason the company said a C series controller wouldn't work is that it wouldn't communicate with the inverter. 

[maple flats]

My FX80 does not communicate with the controller. It works fine. It might tweak the efficiency if it did however.

[maple flats]

Update. I have now ordered my next 4 panels. When connected they will now total 1520 watts.
The main reason to use higher voltage inverters and array strings is max power potential. For example my FX80 controller will handle 80 amps and 80 x 48V is far more energy than 80A x 12V. The controller will run anything from a 12v, 24v, 36v, 48v or 60v battery bank and can accept power in up to 150V. There was not good choice for a 60V inverter so I chose the XW 6048 which is grid capable if I go that way. It is 6000 watt max continuous at 48v nominal voltage in. When I get bigger, I can interconnect up to 3 such inverters. At present my weak link is my battery bank. I am still using my old battery bank from my first solar endeavor of 300 watts. Since batteries of differing ages should not be mixed I will just wait until the first bank needs replacing. The old ones are only 3 yrs old When I do replace the batteries I will decide which to use but it will still be a 48v bank. Just the AH will be far larger. I also want it to be 1 string so the batteries will be huge. I have looked at some over half a ton and one over a ton. No decision yet. I can set batteries up to about 2500# and lift them into place using my excavator, but I would stay a safe margin under that so nothing goes wrong when placing them. Using such an undersized battery bank I will never get the typical 7 yrs life expectancy for Trojan 6V,  240 AH FLA batteries. In fact I started with a 24v inverter of low quality and moved up to the XW6048 less than a year later and added 4 more batteries, so I have 2 different ages now. This alone will shorten the battery bank's life.