Solar Array Production
northerner
Solar Expert Posts: 492 ✭✭✭✭✭✭
I'm curious what others are getting in energy production from their solar arrays??? For my system, I'm located in a northern area of Canada, at about 56 deg latitude, and recent air temps have often been below freezing.
I have an array of 6 Sharp solar panels rated at 1410 watts output (STC rating I assume?). In the past 6 weeks, I have been typically getting between 1300 and 1500 watts output, as shown on an MPPT controller. It's not unusual for the output to go to over 1600 watts, and I have seen it go well over 1800 on 1 occasion. In fact they also tripped a 63 amp breaker (24 volt system) at the output of the CC on another occasion.
As for energy production, I took in about 140 kwh in the last month, and of that, I utilized close to 100 kwh in an off grid system. On a good sunny day, I'm taking in over 8 kwh. Best day in the past month was 8.6 kwh on March 6th. My worst day in the past month was on Feb 24, with 1.7 kwh. I took in 8.3 kwh today, a sunny but somewhat hazy day.
I know that as summer approaches with warmer temps, I will not be getting these high outputs. Of course, overall energy production will increase due to the higher sun and longer days. I take it, that others living in warmer climates, are not getting these higher outputs from their arrays.
I have an array of 6 Sharp solar panels rated at 1410 watts output (STC rating I assume?). In the past 6 weeks, I have been typically getting between 1300 and 1500 watts output, as shown on an MPPT controller. It's not unusual for the output to go to over 1600 watts, and I have seen it go well over 1800 on 1 occasion. In fact they also tripped a 63 amp breaker (24 volt system) at the output of the CC on another occasion.
As for energy production, I took in about 140 kwh in the last month, and of that, I utilized close to 100 kwh in an off grid system. On a good sunny day, I'm taking in over 8 kwh. Best day in the past month was 8.6 kwh on March 6th. My worst day in the past month was on Feb 24, with 1.7 kwh. I took in 8.3 kwh today, a sunny but somewhat hazy day.
I know that as summer approaches with warmer temps, I will not be getting these high outputs. Of course, overall energy production will increase due to the higher sun and longer days. I take it, that others living in warmer climates, are not getting these higher outputs from their arrays.
Comments
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Re: Solar Array Production
I have nine 220w SPI Panels (1980w total) in 72-85 deg f, sunny weather. My CC has logged an array max of 2485watts.
8 kwh production a day sounds great for 1410watts of panel.
For me the issue will be cloudiness/rain later on in the year. Will be interesting to see what happens then.Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid. -
Re: Solar Array Production
So 2485 watts is about 1.25 times the rated output as a maximum.I have nine 220w SPI Panels (1980w total) in 72-85 deg f, sunny weather. My CC has logged an array max of 2485watts.
What are you getting for energy production, on a typical sunny day and monthly? Sounds like you are in a southern location. -
Re: Solar Array Production
I've never seen more that 7100W from my 6120W array (116%). Although, I have two XW MPPT-60 150 controllers which have max output specified at 3500W each (7000W total). I think they're limiting the output, so I wouldn't get more even if panels could do it. -
Re: Solar Array ProductionI've never seen more that 7100W from my 6120W array (116%). Although, I have two XW MPPT-60 150 controllers which have max output specified at 3500W each (7000W total). I think they're limiting the output, so I wouldn't get more even if panels could do it.
That's a pretty hefty array! What kind of energy production are you seeing, on an average sunny day and monthly?
When I make my upgrade this spring, I will have a 2115 watt array per Midnite Classic 150. So I'm thinking that on occasion, I will be very close to maxing out the CC. They are rated at about 94 amps max and 2700 watts for a 90 volt input. Of course, if I made the upgrade to 48 volts, they could handle plenty more power.
http://www.midnitesolar.com/images/classicFrontPage/graphs.php -
Re: Solar Array Production
I'm at latitude 42N and have seen 2.9kW from the 2.8kW array. Only been using about 8kWh/day and the battery is usually floating by about 3pm, but have seen 15kWh/day when they needed some recharging. Haven't used the generator since October.
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Re: Solar Array Production
Those graphs are interesting. I've started making use of diversion power, which helps make use of energy that would otherwise be wasted. That and colder temps helps make up for a more northerly location in winter, where the sun angle, and daylight exposure are less.I'm at latitude 42N and have seen 2.9kW from the 2.8kW array. Only been using about 8kWh/day and the battery is usually floating by about 3pm, but have seen 15kWh/day when they needed some recharging. Haven't used the generator since October. -
Re: Solar Array Productionnortherner wrote: »That's a pretty hefty array! What kind of energy production are you seeing, on an average sunny day and monthly?
That is naturally limited by the amount that batteries can take. This would make more sense for grid-tie system.
The maximum I've got per day so far was 30.3kWh. The array produced 386kWh since the beginning of March. 332kWh in February. -
Re: Solar Array ProductionThat is naturally limited by the amount that batteries can take. This would make more sense for grid-tie system.
The maximum I've got per day so far was 30.3kWh. The array produced 386kWh since the beginning of March. 332kWh in February.
Have you looked into using diversion power for heating water or to run a space heater? If you could do that, it would help make use of the full potential of your array. -
Re: Solar Array Productionnortherner wrote: »Those graphs are interesting. I've started making use of diversion power, which helps make use of energy that would otherwise be wasted.
Aye, I need to do the same. At the moment I'm throwing away a lot of energy that could be used for water and even space heating.
EDIT: The house is about 200m from the array so I'll need to use basic on-off relays and some automation software. There will also be a number of optional loads I'd like to power so they won't all be PWM'able. Thanks to the automation software I can use some semi-intelligent rules to turn these optional loads on or off. E.g. if the hot water is already hot enough, then turn on the electric space heater. If there's still surplus power then turn on grow lights in the greenhouse, if there's still surplus power then pump more water from teh borehole, etc. -
Re: Solar Array Productionnortherner wrote: »Have you looked into using diversion power for heating water or to run a space heater? If you could do that, it would help make use of the full potential of your array.
So far, we're only trying to run all the machines when absorption is full force. I don't think it's much of an excess. It'll be a bigger problem if I install more panels.At the moment I'm throwing away a lot of energy that could be used for water and even space heating.
EDIT: The house is about 200m from the array so I'll need to use basic on-off relays and some automation software. There will also be a number of optional loads I'd like to power so they won't all be PWM'able. Thanks to the automation software I can use some semi-intelligent rules to turn these optional loads on or off. E.g. if the hot water is already hot enough, then turn on the electric space heater. If there's still surplus power then turn on grow lights in the greenhouse, if there's still surplus power then pump more water from teh borehole, etc.
I am placing a wireless system that can send information from the power room to the house (100 ft or so). It'll light a LED in the kitchen indicating that extra power is available. It can also switch loads on and off. The only trouble is that, aside of air conditioning, which we do not have yet, I cannot think of good loads to power during excess hours. -
Re: Solar Array ProductionI am placing a wireless system that can send information from the power room to the house (100 ft or so). It'll light a LED in the kitchen indicating that extra power is available. It can also switch loads on and off. The only trouble is that, aside of air conditioning, which we do not have yet, I cannot think of good loads to power during excess hours.
For the optional loads I think it's worthwhile taking the weather forecast into account when making decisions so that you're not limited to the exact moment there is spare power. It'll be more versatile if you can turn them on when you need them based on an estimation of spare power. My wife likes to do the washing in the morning (for reasons that are still mysterious), so the automation software will take the weather forecast + battery soc at 8am and then send her an email saying whether today will be a good day to do the washing
I want to take a similar approach for space and water heating, because we'd be using those more in the early morning and late evening, not so much in the afternoon when there is instantaneous spare power.
I'm using these wireless modules for the water pump at the moment: http://shop.ciseco.co.uk/rf-module-range/ and will also use them for the heating bits when I get around to it. Relatively cheap and great range. -
Re: Solar Array ProductionFor the optional loads I think it's worthwhile taking the weather forecast into account when making decisions so that you're not limited to the exact moment there is spare power.
I was thinking about that. However, either they do not renew the forecast frequently enough or we're too far from the big weather stations. So, they often miss. Promised huge snow yesterday, and I got the record production day. Promised sunny day today, but it's snowing heavily all morning.I want to take a similar approach for space and water heating, because we'd be using those more in the early morning and late evening, not so much in the afternoon when there is instantaneous spare power.
We only have in-floor heating in the bathrooms. I'm thinking on turning these on. It's only 800W, and they're on thermostat, so that's not even continuous.I'm using these wireless modules for the water pump at the moment: http://shop.ciseco.co.uk/rf-module-range/ and will also use them for the heating bits when I get around to it. Relatively cheap and great range.
I use these. Although, I believe they were $12 when I bought them. -
Re: Solar Array Production
For diversion power when it is cold out, I was thinking of building a circuit that will turn on multiple heating elements (ie could be multiple DC heaters) as the voltage climbs above a settable level. It would be desirable to also set the voltage difference between, when each circuit is turned on. This would allow one to use DC power directly, and you would not be pulsing a very high load. For example, at 28.8 volts, the 1st circuit would turn on. At 28.82, the 2nd, at 28.84, the third, etc... Each heating element would be a relatively small load, 400 watts for example.
This would allow you to make use of extra power automatically, without affecting the battery charging, use DC power directly, and without pulsing a heavy DC load. -
Re: Solar Array Production
My highest 1-day production was 39.8 KW-h so far. About 5.8KW is the max array output I've seen. I'm running around 38KW-h on sunny days now. Was at 32-33KW-h when commissioned in February. Cold fronts spike my production by 2 KW-h. Typical high array output is 4.8-5.2 KW (March)
27 Canadian Solar CS6P 240-watt. 12 are at 20.5 tilt (Patio 15" tilt legs), 9 are at 26.5 tilt (Roof 7" tilt legs), 6 are at 0.5 tilt (face east/west, reverse tilt 15" tilt legs).
Phoenix, AZ. My Lattiude is about 33.5 degrees North. High temps are running upper 80s to low 90s currently. Summers get 110+ degree days.
I have a bi-modal system (grid-tie with partial house off-grid ability), so my diversion load is selling to the grid (if off-grid, charge controllers go into fixed current mode when batteries are full). -
Re: Solar Array ProductionYehoshuaAgapao wrote: »(if off-grid, charge controllers go into fixed current mode when batteries are full).
Most CCs will implement Float as a constant voltage which is lower than the Absorb voltage, although there may also be a maximum current limit. A high current drain from a load will then increase the amps at Float and either drive the CC out of float or bring the voltage down to where the CC starts a new charge cycle.
A few CCs will measure the actual battery current via an external shunt.SMA SB 3000, old BP panels. -
Re: Solar Array Production
Ah ok. I would think it would be constant current on the PV side and constant voltage on the battery side. I sometimes see the charge controllers go into constant voltage and do a sweep for a few seconds between several times per minute and once every 5-10 minutes. Not sure if that is PV side or battery side but I would think it is PV side.
So in absorption and float, the battery side would be on constant current, but if PV supply exceeded demand, the PV would have to be current-limited -
Re: Solar Array ProductionYehoshuaAgapao wrote: »So in absorption and float, the battery side would be on constant current,
No.
The battery side is constant current (all the PV can produce, up to the rating or setting of the CC) during Bulk and the MPPT CC will sweep to find the maximum power is can get from the PV. The PV is inherently current limited based on the amount of light, so more power will come from letting the voltage rise to ~80% of Voc.
In Absorb and Float the MPPT CC is trying to hold a constant voltage on the batteries, and will draw less than maximum current from the PV to maintain that as the battery current decreases. In the process of doing that the CC will let the PV voltage rise closer to Voc, so the PV current will be lower.SMA SB 3000, old BP panels. -
Re: Solar Array Production
I have a 5.5 Kw array consisting of a mix of Evergreen and Sharp panels. In good conditions (cool, full sun) it will hold a steady 4.6 Kw output for several hours if I have enough opportunity loads connected. I have seen output of about 105% of STC with the Evergreens, but it doesn't last long at my warm location before the panels heat up (latitude 30 N).
With all opportunity loads on (water heating plus electric heat or AC) I can pretty consistently get 23-24 Kwh on a sunny or mostly-sunny day. Last week I had my best-ever production week of 132 Kwh. My battery bank is relatively small (17.5 Kwh capacity), so the lion's share of that goes to opportunity loads. -
Re: Solar Array Production
Oh ok. The charge controller manipulates the voltage to set a specified current level. The voltage would be the throttle then. Why do charge controllers have constant current mode then? is that for when PV outputs more than what the controller can handle?
Constant voltage - fix the voltage and let the current be whatever. Thinking this is when the PV voltage is too low for the batteries or too high for the controller. Constant current - fix the current, adjust PV voltage to keep that fixed current. Thinking this is when PV output needs to be regulated because it exceeds the controllers capacity or there would be no place for it to go. -
Re: Solar Array ProductionYehoshuaAgapao wrote: »Oh ok. The charge controller manipulates the voltage to set a specified current level. The voltage would be the throttle then. Why do charge controllers have constant current mode then? is that for when PV outputs more than what the controller can handle?
Constant voltage - fix the voltage and let the current be whatever. Thinking this is when the PV voltage is too low for the batteries or too high for the controller. Constant current - fix the current, adjust PV voltage to keep that fixed current. Thinking this is when PV output needs to be regulated because it exceeds the controllers capacity or there would be no place for it to go.
Try to keep separate what happens on the PV side of the CC and what happens on the battery side of the CC.
Bulk is constant current on the battery side, Absorb and Float are constant voltage on the battery side. This assumes that enough power is available from the PV to make that happen.
On the PV side, the MPPT controller will do whatever it takes to get as close as possible to the power level that the battery charging algorithm is calling for.
If that is not possible (end of day and light is fading, for example), then exactly what happens will vary from one CC model to another.SMA SB 3000, old BP panels. -
Re: Solar Array ProductionBulk is constant current on the battery side ...
Constant current is a historical term and is a liitle bit confising. When applied to solar chargers in bulk mode it usually means "put into batteries as much as possible". -
Re: Solar Array Production
Eric L
I am going for a system that will closly match yours. pv and battery bank. Intending the water heating. What type of air conditioner are you running?
Thanks
gww -
Re: Solar Array Production
Right, but with some sort of maximum limit which the PV may or may not be able to meet.Constant current is a historical term and is a liitle bit confising. When applied to solar chargers in bulk mode it usually means "put into batteries as much as possible".
The key point is that the voltage will vary both with SOC of the battery and to some lesser extent with the current (internal resistance of the battery).SMA SB 3000, old BP panels. -
Re: Solar Array ProductionWhat type of air conditioner are you running?
Just two window shakers -- Frigidaires. One 6.5K BTU and one 8K, about 10.5 EER. Longer-term I'd like to replace these with a pair of mini-splits, however together they do a surprisingly good job of keeping a 2000 sq. foot house cool during the day. Our house is well shaded, which helps a lot.
I have them set up as follows: I have some CAT 5 wire running from the AUX 1 output of a charge controller to each AC unit, with an SSR at the AC end. Using the "Vent Fan High" setting, they are programmed to shut off when the battery voltage falls below a certain set point so they cannot drain the batteries. If I'm not going to be home, then using the timer on the AC units, I set them to turn on in the late morning when the forecast is for some sun, since by this point the batteries are into absorb and there is enough power to finish the cycle. Eventually, I think automation software like Stephendv is experimenting with above will remove the need for this daily programming step. :cool: -
Re: Solar Array Production
Eric L
Thank you for the detailed answer. I guess when you have the aux 1 set to fan it doesn't pulse the ssr like it would if set to divertion load. It is either on or off?
Thanks
gww -
Re: Solar Array Production
Yes, it's a non-PWM mode so it's either on or off. You could also use a mechanical relay for this function, but the SSR works fine. -
Re: Solar Array Production
Eric L
Thanks
gww -
Re: Solar Array Production
I just had a record day of production today from my 1.4 kw pv array, producing 9.8 kwh. We had a relatively clear sunny day, with cool temps, between -21 and -14C.
The space heater I was using for diversion failed (fan stopped working), so I just set another heater on low nearly the entire afternoon. It's not recommended to pulse the fan, as it doesn't appear to survive long, doing so. I will have to rig up the fan to a regular 120 vac outlet. -
Re: Solar Array ProductionYehoshuaAgapao wrote: »My highest 1-day production was 39.8 KW-h so far. About 5.8KW is the max array output I've seen. I'm running around 38KW-h on sunny days now. Was at 32-33KW-h when commissioned in February. Cold fronts spike my production by 2 KW-h. Typical high array output is 4.8-5.2 KW (March)
27 Canadian Solar CS6P 240-watt. 12 are at 20.5 tilt (Patio 15" tilt legs), 9 are at 26.5 tilt (Roof 7" tilt legs), 6 are at 0.5 tilt (face east/west, reverse tilt 15" tilt legs).
Phoenix, AZ. My Lattiude is about 33.5 degrees North. High temps are running upper 80s to low 90s currently. Summers get 110+ degree days.
I have a bi-modal system (grid-tie with partial house off-grid ability), so my diversion load is selling to the grid (if off-grid, charge controllers go into fixed current mode when batteries are full).
More evidence that solar arrays in warmer locations often produce much less than their rated outputs. At least you would have a more seasonally consistent array output in a location that's closer to the equator. Plus you don't need to provide much heat, as do those living in the extreme north (or south) need, when the sun is at it's lowest, and days are short. Air conditioning is another matter though.
I'm really surprised at the outputs I'm getting from an array in very cold conditions. It's often producing more than the rated output. Temperature has a very significant effect on solar panel output! -
Re: Solar Array Productionnortherner wrote: »I'm really surprised at the outputs I'm getting from an array in very cold conditions. It's often producing more than the rated output. Temperature has a very significant effect on solar panel output!
This is well known, you can find the NOCT (Normal Operating Cell Temperature) values for many panels. They tend to be 75-80% of panel rating.
Then there are PTC Ratings used for some california rebates/credits these I think use yet another set of values.Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites, Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
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