Morning array - south facing?

[Tripplett]

I have two 4 panel EG4 Brightmount racks. I originally had them both in the best south facing spot in my yard - see picture. But this spot doesn’t get good sun until noon. 3 months ago I moved one rack of 4 bifacial panels to the other side of my yard, where they get good morning sun - 9am to 2pm. This helps get back off grid earlier if my 6000XP fails over to grid and also gives me good solar 9am to 5pm now.

Both arrays are facing south but recently I’ve wondered if I’d get better solar if I face the morning array (9am to 2pm) to where the sun is at 11:30, mid way through its 5 hr cycle. And the same for the other (12-5), face it to where the sun is at 2:30pm. Is south always better or is it better to point (and tilt?) toward the sun mid cycle on the given panels?
Thanks.

 

[Daddy Tanuki]

disclaimer: mind you not a pro, just a bum with a penchant for building stuff.

thats going to be really location dependent and there is a difference between magnetic south and solar south. I built my shop with the roof facing the road which looked to be roughly close to magnetic south, I got lucky after i built everything and found out it was facing solar south which is about 10 degrees different, this was to my benefit for my location.

 

[TomC4306]

Originally had mine pointed the same direction also.
Reoriented to half at 150⁰ and half at 210⁰.
3 panel strings, all to a 6 to 1 combiner box.
Works great.

 

[Tripplett]

disclaimer: mind you not a pro, just a bum with a penchant for building stuff.

thats going to be really location dependent and there is a difference between magnetic south and solar south. I built my shop with the roof facing the road which looked to be roughly close to magnetic south, I got lucky after i built everything and found out it was facing solar south which is about 10 degrees different, this was to my benefit for my location.

Yes, currently pointing solar south. I believe it’s offset from magnetic south about 7 degrees where I am. But I just used an app (SunQuest) to find solar south then a compass to set the panels.

 

[MichaelK]

One thing you didn't mention is what time is your noon? Most likely, it is NOT 12:00? Rather than rely on your compass, go out at night and focus on Polaris, the North Star. Easy to find in the Little Dipper. That will not be off because of magnetic anomalies. I laid a 20' section of PVC pipe out at night, pointing to Polaris, so I could come back to see North-South in daytime. Your noon will be when the sun is directly oriented towards due South.

One other very important observation. A neighbor had his panels on a skid-type frame like yours. He lost everything when a thunderstorm came through and flipped his arrays over. I'd strongly recommend that you get some kind of ground anchoring system in place to hold your array frames down.

 

[Tripplett]

One thing you didn't mention is what time is your noon? Most likely, it is NOT 12:00? Rather than rely on your compass, go out at night and focus on Polaris, the North Star. Easy to find in the Little Dipper. That will not be off because of magnetic anomalies. I laid a 20' section of PVC pipe out at night, pointing to Polaris, so I could come back to see North-South in daytime. Your noon will be when the sun is directly oriented towards due South.

One other very important observation. A neighbor had his panels on a skid-type frame like yours. He lost everything when a thunderstorm came through and flipped his arrays over. I'd strongly recommend that you get some kind of ground anchoring system in place to hold your array frames down.

Yes that would work. I used another method. My solar noon is 1:19pm and 179.2 degrees. I used a soup can on the panels to fix the tilt and direction exactly at that time.
This picture was taken the day we set them up. They are now anchored with mobile home hurricane tie downs screwed into the ground. Once we move to our new place and finalize placement they will be mounted with sono tubes.

 

[efficientPV]

It is a function of mind set, mostly just copying others bad ideas. South facing panels is an antiquated idea from back when panels were expensive and batteries were cheap. I have an east facing array. My batteries have charged, hot water is up to temperature, done laundry and dishes all before 11am. I'm using power when it is generated and I when need it most. People here spend money on batteries and that is just money down the toilet.

 

[Brucey]

If you need max winter generation and you live at higher or lower latitudes just an east facing array will prob not be optimal when the sun is low on the horizon. Once the days get longer then absolutely an east facing array can get you charging up nice and early.

 

[Tripplett]

If you need max winter generation and you live at higher or lower latitudes just an east facing array will prob not be optimal when the sun is low on the horizon. Once the days get longer then absolutely an east facing array can get you charging up nice and early.

Both arrays are south facing, but for array #2 the sun hits them earlier in the day and drops off earlier. I was primarily asking about those #2 array panels that get the morning sun - from 9am to 2pm… what direction to face them? At the sun at solar noon (1:19pm), or mid way through their sun cycle (11:30am).

 

[Noname142]

People here spend money on batteries and that is just money down the toilet.

Unless, Like many here: you want to be able to use your system when the power is out day or night.
Energy independence isn't "money down the toilet" IMO.
People have varying needs. I'm glad your system works the way you need, but I'm also glad mine works the way *I* need.

 

[BaylentheSky]

A newbie here, but in California with Time-Of-Use billing, it's better to face your panels West to reduce your usage during the most expensive period of the day (most likely 4pm - 9pm). I have 2 acres of land so plenty of room for my 24 ground mount solar panels, so I just face them all South. If you don't have room for that many panels, and have to pick and choose the best orientation for your system, I'd recommend to consider Time Of Use and face your panels accordingly.

 

[BaylentheSky]

It is a function of mind set, mostly just copying others bad ideas. South facing panels is an antiquated idea from back when panels were expensive and batteries were cheap. I have an east facing array. My batteries have charged, hot water is up to temperature, done laundry and dishes all before 11am. I'm using power when it is generated and I when need it most. People here spend money on batteries and that is just money down the toilet.

I'm not sure if I agree with your last sentence. Take for example the EG4 5KWh battery that can be had for $1300 at SS. With 8000 cycles at 80% DoD, we're talking about 32,000 KWh of capacity, which translates to about $0.04 per KWh. Depending on where you are, that's a fraction of what the utility company charges you. Here in San Diego, I'm paying 40 something cents per KWh during Off Peak, $0.60+ On Peak. That's a significant saving right there if you ask me. And that's not taking into account future rises in your power bill either.

 

[efficientPV]

That is if it lasts that long. Forums are loaded with peoples dashed dreams. I'm talking about adding extra battery storage to save energy at noon to use the next morning when the sun is shining.

 

[BaylentheSky]

That is if it lasts that long. Forums are loaded with peoples dashed dreams. I'm talking about adding extra battery storage to save energy at noon to use the next morning when the sun is shining.

There is a 10 year warranty on that battery if you're worried about it breaking before you're able to recoup the cost. And I don't know about people's application but from what I've seen, most people just want to have enough to cover their daily usage. The reason why we're on here is because we want to save money in the first place. Having excess battery capacity isn't exactly on everyone's agenda.

 

[zanydroid]

The cells should last 10 years. After than that, the question is about the BMS.

I'm not sure if I agree with your last sentence. Take for example the EG4 5KWh battery that can be had for $1300 at SS. With 8000 cycles at 80% DoD, we're talking about 32,000 KWh of capacity, which translates to about $0.04 per KWh. Depending on where you are, that's a fraction of what the utility company charges you. Here in San Diego, I'm paying 40 something cents per KWh during Off Peak, $0.60+ On Peak. That's a significant saving right there if you ask me. And that's not taking into account future rises in your power bill either.

I've done a lot of spreadsheets for California TOU prices. It's not as fast of an ROI as you think.

But to do honest cost accounting you have to include the 9540 inverter cost too. The 12kpv ought to be the cheapest one once all its certifications in place.

$3500 / 32000 = $0.11 / kWh (and the inverter has 10 year warranty)

So your LCOS is $0.15 if we charge full cost of the inverter to storage. Maybe we can divide by 2 if half of the cost of the inverter can be charged to solar. $0.075. This depends on individual installation situations. For instance, I already have a GT system, so the MPPTs on a hybrid give me nothing. But, there is also no battery-dedicated inverter, that costs less, that I can buy. So I have to inefficiently pay a $0.15/kWh LCOS

$0.15 LCOS to harvest a $0.20 spread between off peak and on-peak is not it.

The saving grace here is you're probably reporting numbers from a regular TOU and not a EV or Electric house plan. In PG&E territory E-ELEC is about $0.25/kWh IIRC, so the spread is more like $0.30-0.35

 

[45North]

Yes that would work. I used another method. My solar noon is 1:19pm

Makes sense since we're on Daylight Saving Time currently in North America until we "fall back" in the fall. I hope they don't make DST permanent, as some have proposed - there's just something intuitive and right about having the sun at its highest at high noon, not at 1:00.

 

[BaylentheSky]

The cells should last 10 years. After than that, the question is about the BMS.



I've done a lot of spreadsheets for California TOU prices. It's not as fast of an ROI as you think.

But to do honest cost accounting you have to include the 9540 inverter cost too. The 12kpv ought to be the cheapest one once all its certifications in place.

$3500 / 32000 = $0.11 / kWh (and the inverter has 10 year warranty)

So your LCOS is $0.15 if we charge full cost of the inverter to storage. Maybe we can divide by 2 if half of the cost of the inverter can be charged to solar. $0.075. This depends on individual installation situations. For instance, I already have a GT system, so the MPPTs on a hybrid give me nothing. But, there is also no battery-dedicated inverter, that costs less, that I can buy. So I have to inefficiently pay a $0.15/kWh LCOS

$0.15 LCOS to harvest a $0.20 spread between off peak and on-peak is not it.

The saving grace here is you're probably reporting numbers from a regular TOU and not a EV or Electric house plan. In PG&E territory E-ELEC is about $0.25/kWh IIRC, so the spread is more like $0.30-0.35

Absolutely. I always factor in total cost of my system when comparing to my utility rate for a comprehensive figure on my ROI. Just with my anecdotal experience, my total cost is $6000 (EG4 6000XP, 14.6KWh Battery, 24 245W used solar panels, everything DIY) that's completely off grid, not connected to my main panel at all. Right now the system produces about 33-35KWh/day. I have 2 mini splits running all day off of that, plus a heat pump water heater, and an EV, so pretty much no energy left unused for the day. At an expected annual daily average of 30 KWh produced, in 10 years that would make nearly 110,000 KWh, or about 5.5 cents per KWh. That was the figure that I based my purchase decision on.

I disagreed with efficientPV in my quote because he said battery itself is money down the toilet, which I supposed implied that everything else is money well spent but the battery. If you're off grid, battery is a must. If you're grid tie, battery is still a great investment if you're on NEM 3.0. The only time when a battery may not be necessary is if you're still on NEM 1.0, since you pretty much get full retail credit for every single KWh produced.

 

[Danke]

Never heard it called “Solar South.” (That does sound like a very inclusive term WRT our penal colony members) I know True directions, like True North and True South.

Just need to add or subtract the magnetic angular deviation (declination) for your location if you’re using a compass.

NCEI Geomagnetic Calculators

www.ngdc.noaa.gov