New Installation, New to Solar

gulfyankee

Hello everyone, I've been lurking for several years, studying, plotting and planning. Through some recent good luck, and Craigslist finds, I've finally been able to take the plunge into the solar world. Here is what I've accumulated thus far:

Magnum MS4448PAE Inverter, with
ME-ARC remote
ME-BMK battery monitor kit
MidNite Solar Electrical Panel
Outback Flexmax 60 MPPT controller
(30) Schott Solar SAPC-175 panels; 5250 watts

To be purchased soon: 16 GC-2 6v batteries for a 48v, 464AH battery bank
Possibly another (10) Schott Solar SAPC-175 panels; total 7000 watts

I realize that the 30 panels would overload the Outback. I have no clear south-facing location on my property, but have 2 alternate locations in mind. One receives excellent sun from shortly after sunrise until about 1pm, and the other has excellent sun from about 2pm until sunset. My question is pretty much this; can I set up an array in each of these locations and operate them both with the same controller? I can put 15 panels in each array, and may purchase 10 more, for 20 panels per array. Independently, each array would be within the abilities of the controller as far as I can tell. Each location is shaded when the other is sunny. Would the array in shade put out enough energy to still overload the controller when combined with the array in sun? Is there a way to isolate the array not in use at the time? Or would it just be better to buy another controller?

icarus

Re: New Installation, New to Solar

You could isolate with a simple A/B switch of rated current, but to maximize harvest, I would suggest a second controller.

Tony

Ps Welcome to the forum

BB.

Re: New Installation, New to Solar

Personally, as long as you do not exceed the Voc-cold of the charge controller (too many panels in series for a Vmp-array>~100 vdc), then why not try it.

The best that will happen, is your controller will never, or hardly ever hit the 60 amp limit on your 48 volt battery bank (your "single" array in optimum conditions could be "cost effective" at upwards of 4,600 watts):

59 volts battery charging * 60 amp Charge Controller * 1/0.77 panel+controller losses = 4,597 Watt "max cost effective array"

If you hit the limits too much (both arrays have significant sun in the middle of the day)--You could always get a second charge controller later--Just run both array cables to the central power shed location and leave some slack/room if you mount a second MPPT charge controller later.

The "problem" with to arrays with unequal installation is that the array with full sun will run hot and give a slightly lower Vmp-array voltage vs the cooler one (that does not have as much "perfect sun" anyway).

Also, if your shading is "permanent" (way house is built, trees you don't want to cut down, etc.)--Then you will probably want to shift the "AM" array towards the south east and the "PM" array towards the south west.

You can play with PV watts and see that the "optimum" angles would be (PV Watts can output the wattage by the hour--so you could do your own "fragmented" day power summary to find the "optimum" angles.

Note that if you have, for example lots of summer thunder storms (and use a lot of A/C), the afternoon output of the "PM" array will be less than optimal--Similarly if you have AM valley fog impacting your "AM" array.

-Bill

NorthGuy

Re: New Installation, New to Solar

When dealing with the shade, there are two things to consider.

- The length and angle of the shade may be dramatically different in winter compared to summer
- The solar array usually is big and different corners of it will be shaded differently.

I think one controller should work fine. You're likely to loose all the production from shaded array, but that's very little.

vtmaps

Re: New Installation, New to Solar

Welcome to the forum.

There's several folks on this forum who have done what you propose with good results. As panels have become cheaper what you propose has become an alternative to using a tracker... it's cheaper and more reliable to have east and west facing panels than to have one set of panels on a tracker.

As BB. pointed out, you can always get a second controller at a later date if needed. I would suggest that you put a combiner box at each array, and then combine the two before the controller. In the event that you do buy a second controller you will be glad that you already have the two combiners.

by the way, do you have grid power?

--vtMaps

gulfyankee

Re: New Installation, New to Solar

Thank you all for your input. I believe I will try this initially with the single controller, then upgrade if necessary. And yes I am grid tired for now. I will be separating circuits one at a time to be run by the inverter. My initial goal is to run all of my 110v circuits by solar. The 3 loads I have on 220v will pose more of a challenge!

BB.

Re: New Installation, New to Solar

gulfyankee wrote: »

And yes I am grid tired for now.

Yes, many more people are getting "grid tired" now.

It is very difficult to save money with off grid power systems--Unless you have very high charges/minimum monthly fees.

Grid Tied solar power systems (array+GT inverters; no batteries) can save money for people--Especially as the price of power goes up. But, utilities are seeing loss of revenue with GT connected customers--So some of them are starting to charge high monthly fees (>$40 per month connection charges) and low $$$/kWH charges. Using GT Solar and conservation becomes less cost effective (in many locations, commercial customers already pay ~1/2 of their bill as fixed monthly charges for wiring/transformers/distribution costs).

Then you are left with the choice of going off grid--Ain't cheap. And you become your own power company--Responsible for designing, installing, and maintenance.

If you are looking at short term outages--A generator + 2 weeks of fuel is hard to beat.

If you are looking at long term outages (month or more--such as ice/wind storms in more remote areas)--Then off grid solar can be a better solution...

All a matter of personal choices.

-Bill

gulfyankee

Re: New Installation, New to Solar

Sorry, let me clarify. I am not "grid tied". my home is fully dependant on the utility company. I wish to remedy that situation. I am not looking for financial gain or a return on my investment. My bill ranges from $80 to $150 per month, depending on the season. However, my total investment thus far is under $4500, and will be well under $7000 when placed into service. I should be in the black within 7 years. and I already have a very reliable generator. This is to be a learning experience for my next home, which will be off grid from day one.

Photowhit

Re: New Installation, New to Solar

gulfyankee wrote: »

...I am not looking for financial gain or a return on my investment.

Cool!

gulfyankee wrote: »

...My bill ranges from $80 to $150 per month, depending on the season.

Looks like you've done a fair bit of conservation!

gulfyankee wrote: »

However, my total investment thus far is under $4500, and will be well under $7000 when placed into service.

You have done well! 5250 watt array, charge controller and a quality inverter, E-panel<$4500 but note if you had purchased new you might have gotten close to that value after the 30% tax credit!, While your new I would seriously look at a forklift battery as the best bang for the buck in storage over time, though we usually suggest cheaper 'starter set' for people new to solar.

gulfyankee wrote: »

...I should be in the black within 7 years...

That would be impressive, but I doubt you are considering all your costs including replacement costs. I'm expecting off grid solar at about 26 cents a Kw hour and few have shown me real numbers indicating much less than 50 cents a Kwh. I'll find a link to my thread showing how I figured my costs Mañana.