Multi orientation array, single MPPT CC

westbranch

My question is: How will a single MPPT CC 'handle ' the output of, eg. a 1200 w array made up of 3 x 400w sets of panels oriented in SE, S, and W directions.

Since the Vmp will be different for each set, what will the amount of loss be compared to all panels oriented in the same direction. Will the production from the non optimal orientation ( for time of day) even be used by the MPPT CC? Is there an MPPT CC that can work in this case?

The reason for asking is that I get a ~ 1 hr. 'shot' of morning sun ( 8 - 9 am) and then shading for about an hour, then full sun 11 AM - 7 PM in the summer and very low production after 3 pm due to incidence angle. Panels on building not pointed due S. Considering manually adjusted pole mount vs fixed mounts, as high buffeting winds are frequent.

TIA
Eric

Peter_V

Re: Multi orientation array, single MPPT CC

westbranch wrote: »

My question is: How will a single MPPT CC 'handle ' the output of, eg. a 1200 w array made up of 3 x 400w sets of panels oriented in SE, S, and W directions.

Since the Vmp will be different for each set, what will the amount of loss be compared to all panels oriented in the same direction. Will the production from the non optimal orientation ( for time of day) even be used by the MPPT CC? Is there an MPPT CC that can work in this case?

The reason for asking is that I get a ~ 1 hr. 'shot' of morning sun ( 8 - 9 am) and then shading for about an hour, then full sun 11 AM - 7 PM in the summer and very low production after 3 pm due to incidence angle. Panels on building not pointed due S. Considering manually adjusted pole mount vs fixed mounts, as high buffeting winds are frequent.

TIA
Eric

Not very well, in fact I'm not sure any charge controller will work well in that scenario. If you HAVE to have panels pointing in three different directions, use three charge controllers. You'd be better off with 3 cheap controllers than one expensive one in this case.

Also you're wasting panels setting ones up to only work in the morning, that one hour worth of light isn't worth wasting a panel on.
With a fixed array the bulk of your charging occurs over a 6 hour period. typically from 9am to 3 pm. If, as you say, you don't get anything from 9-11am, then orient your array to catch the sun from 11am to 5 pm. I.e. point it so it directly faces the sun at 2pm instead of noon.
Then you can use a single charge controller.

Another option is to use a tracker like mine. More expensive than a roof or pole mount, but cheaper than panels that aren't producing most of the day and it will boost you panels' production by about 25%.
Then you can catch the sun all day long.
The Zomeworks are designed to handle strong winds and if you get REALLY high winds (70+ mph) they make a high wind kit for additional stability in strong winds.
Note: even without the high wind kit, they come stock with a lockout bar that fixes the array in the noon orientation. Takes about 3-5 minutes to install so as long as you get a little advanced warning you can install the lockout.

The shading in the morning might be a concern. Since they are passive (work using the heat from the sun) it takes them about an hour to flip over in the morning, which means you'd still lose that hour of morning sun, but they would be pointed in almost the right direction to start tracking at 11 am, so you'd get full harvest from 11 to about 6pm

westbranch

Re: Multi orientation array, single MPPT CC

thanks for confirming my suspicions Peter.

The Heaviest winds we get start with the sound of an approaching 747(in the distance) or a train, and are the result of onshore winds (approaching Low Pressure) that wind their way > 60 miles from the west coast of BC, then just before they reach us they make 2 - 90 degree changes in direction, then rise over the 2000 foot ridge across the lake from us and drop, tumbling over 1000 ft till they change direction again. Sometimes they never get to lake level, just blast on over us, but when they do it has caused a harmonic ripple in the steel roofing, scary when you are inside. It has happened 3 times while we have been inside... another thing they make are water spouts > 200 feet in the air over the lake... so far they have stayed to the other side of the lake( fingers crossed) though we have seen evidence that they have been there as stuff is strewn around in a circular pattern...

My use of the word buffeting is at best an understatement...

mike95490

Re: Multi orientation array, single MPPT CC

How much wind blown debris do you get ? Would it break PV panels?

westbranch

Re: Multi orientation array, single MPPT CC

Hi Mike, not much flying debris big enough to break a PV panel. What has blown around are empty oil drums, some styro insulation that was well under the sundeck and solar garden lights, cyclonic events appear strong but short lived.

We work at burning that sort of stuff every year and there are no dead trees close enough to damage any of the panels if they fall. I turn them into firewood asap.:D
The old 1960 shack is coming down as soon as we can access it and a newer building, similar to my avatar, just bigggger, will go up on the same location. New place will not have many wall mounted panels (max of 4) so need to build an array...

tallgirl

Re: Multi orientation array, single MPPT CC

If you have so much wind, why not consider adding a wind turbine?

And total agreement on not bothering trying to get one hour of morning light from a panel or three. Find out where your visible window of sky is and point the array right out the middle of that.

westbranch

Re: Multi orientation array, single MPPT CC

Hi TG, thanks. Amended my statements about winds to 'heaviest winds' in previous post.

It is sort of a feast or famine but I have thought, since we bought the place, that wind would be a good fit with the solar array, as when the sun is not out we get winds.

I have a small AirX turbine to install after the house construction is done. I just hope it can survive the turbulence of erratic swirling tumbling winds.

I am thinking that Peter may have hit it on the nose when he said to use a separate controller for that afternoon/evening sun aligned array. I have played with aligning one panel manually with my existing set up and have been happy with the +- 3 hrs of added production.:D

Eric

Cariboocoot

Re: Multi orientation array, single MPPT CC

As a general rule, turbines like consistent wind. They especially do not like gusts, turbulence, or squalls. That's what tends to rip them apart and send pieces hurtling all over the place.