Electrical SETECT ST-III and Battery Capacity

Rayden

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The manual states that this unit one or two batteries with max 100Ah caacity each can be charged. Can someone please advise what the impact is of using a 120Ah battery?
 

Boots in Action

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The manual states that this unit one or two batteries with max 100Ah caacity each can be charged. Can someone please advise what the impact is of using a 120Ah battery?
No impact at all @Rayden !!! Just a little longer to fully charge if down to 50%. I have a 120ah AGM connected to my Setec ST20 Series III for the last 6 years without ANY problems. Note that the Setec will only charge to 14.0 volts which is short of the optimum for AGMs which like 14.7 volts. If you you have a GEL type, they like around 14.3 volts which is closer to the Setec output of 14.0 volts. I only use the Setec when at powered sites and use my 15A 7 stage "smart" charger to get full charge when at home. When fully charged, I turn it off and charge again after 4 or 5 weeks. If you rely on the Setec, it definitely will NOT overcharge and will maintain battery in good condition whilst on FLOAT at approx 13.8 volts, but you will always be only 85% charged for your AGM. Look on the side of battery for manufacturers figures.
 

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mikerezny

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Hi @Rayden,
what the manual really means to say is that the ST series will correctly maintain a total battery capacity of between 100Ah and 200Ah.
So a single 120Ah battery is fine.

Hi @Boots in Action,
here are the voltages, from the manual, for the various charging stages of the STIII:

The power supply is a four stage battery charger with
Boost (VBoost = 14.05V),
Float (VFloat = 13.65V),
Store (VStore = 13.25V), and
Trickle charge modes to ensure long battery life.


take care
Mike
 
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Boots in Action

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The manual states that this unit one or two batteries with max 100Ah caacity each can be charged. Can someone please advise what the impact is of using a 120Ah battery?

Sorry @Rayden that I did not cover exactly what you meant by "impact". If you have a higher capacity battery (120ah instead of a 100ah battery), you have more storage capacity - last longer without recharging. It also means that the capacity used will take longer to be put back into the battery - charged to a full state. In theory, if you used 50% of 120ah battery ie 60 amp hours , it will take the Setec more than 6 hours to recharge to full again. Note that the Setec has a MAX charge rate of only 10 amps. This puts you ahead of a 100ah battery as regards capacity, amount that can be used and length of time to recharge to FULL capacity again. Anything in between in usage, say 20% discharged (approx 24ah used) is not a problem. So that will take more than 2 and a half hours charging at 10 amps. The greater the amp hour capacity of your battery, the better, but recharging time will be limited to the output of charging unit and the ability of battery to accept such a charge. Note the max initial charge rate recommended on side of battery, never going to be exceeded with the Series III Setec.
 

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Boots in Action

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Hi @Rayden,
what the manual really means to say is that the ST series will correctly maintain a total battery capacity of between 100Ah and 200Ah.
So a single 120Ah battery is fine.

Hi @Boots in Action,
here are the voltages, from the manual, for the various charging stages of the STIII:

The power supply is a four stage battery charger with
Boost (VBoost = 14.05V),
Float (VFloat = 13.65V),
Store (VStore = 13.25V), and
Trickle charge modes to ensure long battery life.


take care
Mike
Hi Mike @mikerezny, I knew you would be around on this one. I was aware of what the manual says as far as voltages was concerned too. However, with my 120ah AGM, the voltages when connected from the ST20 Series III Setec as shown on my equipment and multi-meters has been Boost (max) of 14.1 volts - still short of optimum for my AGM, 13.8 volts on FLOAT (close) and 13.3 volts on Store also close!!!. All at ambient of 25C. It is really only a 3 stage charger as trickle charge is at 13.8 when on Float and 13.3 volts when on Store. However, the Setec does the short boost charge on a daily basis before going back to STORE which is a good feature instead of Float charging at a higher voltage.
 

mikerezny

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Hi Mike @mikerezny, I knew you would be around on this one. I was aware of what the manual says as far as voltages was concerned too. However, with my 120ah AGM, the voltages when connected from the ST20 Series III Setec as shown on my equipment and multi-meters has been Boost (max) of 14.1 volts - still short of optimum for my AGM, 13.8 volts on FLOAT (close) and 13.3 volts on Store also close!!!. All at ambient of 25C. It is really only a 3 stage charger as trickle charge is at 13.8 when on Float and 13.3 volts when on Store. However, the Setec does the short boost charge on a daily basis before going back to STORE which is a good feature instead of Float charging at a higher voltage.
Hi @Boots in Action,
from what I can surmise, the tolerance for the 12V voltage settings on the Setec appear to be +/- 0.1V or +/- 0.2V, although the manual does not specifically state the tolerance for all the voltages.

But, I agree, they are on the low side for either AGM or GEL batteries. Especially when used off-road frequently. More suitable for situations where the Setec is maintaining the battery for long periods in between off-road trips.

In my case, I am rarely connected to 240V, and rely on my Solar setup to maintain the batteries with 14.4V bulk charge and 13.7V Float. My Falcon, which does not have a smart alternator, will sit at 14.4V which provides about 13.8V to the van battery taking into account the 0.7V drop across the isolation diode in the Setec when charging via the AUX input terminal.

take care
Mike
 

Boots in Action

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Hi @Boots in Action,
from what I can surmise, the tolerance for the 12V voltage settings on the Setec appear to be +/- 0.1V or +/- 0.2V, although the manual does not specifically state the tolerance for all the voltages.

But, I agree, they are on the low side for either AGM or GEL batteries. Especially when used off-road frequently. More suitable for situations where the Setec is maintaining the battery for long periods in between off-road trips.

In my case, I am rarely connected to 240V, and rely on my Solar setup to maintain the batteries with 14.4V bulk charge and 13.7V Float. My Falcon, which does not have a smart alternator, will sit at 14.4V which provides about 13.8V to the van battery taking into account the 0.7V drop across the isolation diode in the Setec when charging via the AUX input terminal.

take care
Mike

I agree with your idea about tolerances, but perhaps it is MY equipment that needs calibrating. But then, really very close in all cases. And yes, your solar controller will do a better job of maximizing charge into your battery if Setec charger is unable to get closer to the optimum for your battery. Even with your car alternator, and taking in the voltage drop in wiring and power diode, you are at least up near the FLOAT voltage for your van battery. However, I do like the fact that the Setec lowers the charging voltage whilst in STORE mode and this helps reduce the corrosion on Positive plates if maintained at Float voltage for long periods. That's why I do not continuously charge my van battery with the "smart" charger as it does not go below 13.8 volts whilst on Float charge continuously. Cheers
 

Drover

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If you use parks and 240 then it isn't much of a worry so long as you keep it trickle charging at home or leave it to the solar to do the job of keeping things juiced up, if you are mostly off grid camping then the Setek isn't used but if you are regularly bringing your battery down to 50% then you need more storage... It should be noted that most of the claims for capacity of batteries and panels is overstated so if relying on the maths for how long and how much a unit will provide always drop it back a bit, just like the fuel economy sticker on cars they have a touch of fantasy.
 
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Fallen

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To follow on from this interesting topic, I know many people add a new solar controller to the standard Setec setup, which adds extra current when on 240 plus most new solar controllers go up to AGM voltages of say 14.7V. What are the thoughts on connecting an additional Cetek 5V battery charger while the Setec is still on? Would it be a similar outcome to those who add a solar controller, in that it will provide additional current (quicker recharge) plus get to the voltage required to properly maintain AGM batteries?
 

Drover

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If your just in a park most of the time the Setek will do a good enough job, since your not really using your battery as the Setek provides the 12v supply really and is only trickling the battery most of the time, if doing 90% off grid then chuck the Setek and go for a complete upgrade of Solar and batteries......
If you run your Calcium/AGM/GEL batteries down all the time then you need a decent system to bring back to charge but it really means you don't have enough storage to start with so that would be your first issue, more capacity then you would look at possibly a better charging system but may find the basic unit does the job... Many look at the problem from the wrong angle.
 

Fallen

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Good point. For my case, we are 75% grid, 25% off grid. Our 2 x 135Ah batteries are doing ok with the Setec and 2 x solar controllers (the stock TPS 1230 with stock roof solar, plus a AGM-specific controller with portable panels) but I'm concerned I'm not leaving home for off-grid camping with as much battery capacity as I could be since the batteries have just been maintained on Setec and TPS 1230 power for 4-6 weeks prior to leaving. Rather than having the portable panels out for a few days prior, I was thinking of just having a small Cetek 5A AGM charger connected. Probably a good thing to keep it connected for the 4-6 weeks to keep the batteries in their sweet spot for longer.
 

mikerezny

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Hi,
here is an excerpt from the Setec manual. (The rest of the manual is well worth reading as well)

Power supply unit should only be powered from either 240VAC mains or Auxiliary Power (Auxiliary Power also includes solar power) but not both. Failure to do so may result in damage to power supply.

Protection: the power supply provides automatic protection for overload including short circuit, over-voltage, over-temperature and reverse connected battery. In such instances the Fault indicator will illuminate and the power supply will shut down. It will attempt to automatically restart every 5 seconds until such case that the fault is removed.


If the power to the Setec is switched off, it will happily function as a 12V distribution system and provide a low voltage disconnect to avoid deeply discharging your battery and thus extending its life. Then it is quite ok to add other chargers directly to the battery be it another 240V charger or a solar controller. Do not connect these devices to the aux input to the Setec. There is a protection diode in series with this connection which drops about 0.7V. This will upset multistage chargers as they attempt to maintain the battery correctly and in this case will see a low battery voltage and attempt to keep bulk charging the battery to get the voltage up and possibly overcharging and ruining an otherwise perfectly good battery.

In your circumstances, you need to understand how to measure the State of Charge (SOC) of your batteries. Briefly, this is best done by measuring the terminal voltage after the batteries have not been charged or discharged for an hour or more.
This gets more complicated as the batteries age and the battery capacity deteriorates. If one suspects that the batteries are not providing the stated capacity, one must determine whether that is because the battery has aged and has now not got the stated capacity OR has the battery not been fully charge, OR possibly a bit of both. This can only be determined by accurately measuring the battery SOC (you need a digital multimeter capable of measuring to 0.01V accuracy and once the battery has reached 100% SOC and then doing a load test.

The three step process to setting up a 12V system for off-grid use is roughly:
1: Determine your average daily 12V requirements in Ah.
2: Determine the maximum number of days you want to have power assuming no sun for solar power. This is a tough question with many side issues. One consideration is the power source for the fridge. If it is gas, the food in the fridge will not go off if the 12V system fails. If one has a generator AND a high capacity 30-40A charger, it can be used to maintain the batteries until the sun comes back.
From this you can estimate the battery capacity needed bearing in mind that the most economical use of batteries is achieved by avoiding regularly discharging them below about 50%. Deep cycle batteries don't suddenly die if deeply discharge, but their life is determined by the number of discahrge cycles AND how deeply they are discharged. My Ritar RA12-100DG GEL battery is rated to provide roughly 450 100% discharge cycles down to 9.6V. At which time the battery capacity will be down to 60Ah (60%). In comparison, if discharged to only 50%, the battery is rated to provide about 1,100 discharge cycles. Bear in mind that the expected life of these batteries when used in caravans is about 6 years, 300 weeks. So if the batteries are 100% discharged once every weekend they would die from old age before they die from being discharged 400 times. There are numerous charts around showing the relationship between battery voltage and SOC for various types of batteries.
3: Once the first two items are determined, then the solar system is designed to ensure the batteries are recovered each day with some spare to catchup when the batteries were not fully recovered on previous days. Rough rule of thumb, assume a maximum of 5 hours of sunlight per day, add some more to allow for camping spots that do not get direct sun every day, then allow some more if considering roof mounted solar since the panels are NEVER optimally aligned or regularly cleaned.
4: (Yeah, I said three, but I lied.) Ensure you understand every aspect of your usage, battery capacity, and solar system and have the necessary tools to measure voltage and current.

If this sounds daunting, just start at the beginning and work slowly through it. Time spent at home reading manuals, getting familiar with the equipment and documenting in the comfort of your home will greatly enhance your ability to have camping trips that are not frustrating or result in cutting a trip short because the 12V system goes pear-shaped. There are spreadsheets around in previous posts to help with the calculations.

Just as an example:
Step 1: My average daily requirements are 4Ah. I have measured and recorded the current draw of every 12V device we use when out camping.
Step 2: Battery capacity is 95Ah.
Step 3: Portable solar panel is 40W, maximum output current is 2.2A.
Step4: I have copies of all the manuals: Setec, Solar controller, Solar panel, deep cycle battery. A digital clampmeter that can measure DC current, A power analyser that can measure charge voltage, charge current, and accumulated Ah charge into the battery.

From that, I can survive for a maximum of 24 days (100% discharge), but preferably no more than 12 days (50% discharge). I need 2 hours of direct good sunlight to recover 4Ah each day and I have the capacity to provide about 10Ah per day with 5 hours of direct sunlight. Armed with that information, I can exist indefinitely as long as I get two good days out of 5 days.

I hope this has been of some help. It is a very short summary of what I have learnt from the input of people on this site over the past 5 years. In that time, I have never had a 12V problem and never had to cut a treip short or cmpromise a camping experience in any way due to 12V problems. In that time we have spent well over 300 nights off-grid.

take care
Mike
 

Boots in Action

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If your just in a park most of the time the Setek will do a good enough job, since your not really using your battery as the Setek provides the 12v supply really and is only trickling the battery most of the time, if doing 90% off grid then chuck the Setek and go for a complete upgrade of Solar and batteries......
If you run your Calcium/AGM/GEL batteries down all the time then you need a decent system to bring back to charge but it really means you don't have enough storage to start with so that would be your first issue, more capacity then you would look at possibly a better charging system but may find the basic unit does the job... Many look at the problem from the wrong angle.
But @Drover , it is a known fact that while the Setec may be capable of trickle charging the batteries whilst at a van park and connected to 240 volt power, if the batteries need charging to their full capacity, they need to be charged at the correct voltage first (14.7 volts for AGMs) before dropping back to the FLOAT voltage of 13.8 volts) and the Setec will never get close to that at 14.05 volts as per the manual. At only 14.0 volts, approx 15% of battery capacity (AGM) will never be achieved and constant undercharging means permanent loss of storage capacity. Also see attached.
 

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Drover

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In that case @Fallen , you certainly have the storage sorted, a roughy figure for those batteries would be at least 400w of panels to keep them happy. I would leave the Setek as is, it will run happy just for the parks and replace the TPS unit with a good solar regulator of MPPT variety and wire things up so you can plug your portables in as additional to the roof panels, making sure to disable the portable panels reg first....... That should cover you for off grid, I don;t even use my 240 charger relying just on solar but then each case is different, equipment, wiring etc. I did find by replacing my PWM controller which was a goodie the MPPT unit does get things up to speed quicker in the low light has even allowed me to get about 3-4 days in rainy/foggy overcast weather before the power station is needed........... I rarely camp where 240v is available hence why I don't rely on it, solar does it all even at home.
Relying on solar at home I find if I power up the 240 charger it only goes to float anyway.
 
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Boots in Action

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In that case @Fallen , you certainly have the storage sorted, a roughy figure for those batteries would be at least 400w of panels to keep them happy. I would leave the Setek as is, it will run happy just for the parks and replace the TPS unit with a good solar regulator of MPPT variety and wire things up so you can plug your portables in as additional to the roof panels, making sure to disable the portable panels reg first....... That should cover you for off grid, I don;t even use my 240 charger relying just on solar but then each case is different, equipment, wiring etc. I did find by replacing my PWM controller which was a goodie the MPPT unit does get things up to speed quicker in the low light has even allowed me to get about 3-4 days in rainy/foggy overcast weather before the power station is needed........... I rarely camp where 240v is available hence why I don't rely on it, solar does it all even at home.
Relying on solar at home I find if I power up the 240 charger it only goes to float anyway.
Hi @Fallen , @Drover is pretty well on the ball with your situation. You can get away with just using the Setec when in parks for a while, but for FULL charging of batteries, at home, use a "smart" charger with multiple stages. I use the Setec when at parks, but use my 15A "smart" charger as soon as possible when I get home to ensure batteries are brought up to maximum storage capacity. I think you should be looking at at least a 10A (preferably 15A) charger as you have 2 X 135ah batteries to bring up to full in as short a time as possible. The rule of thumb for battery charging is charge at one tenth of amp hour capacity max. which for you is 135 X 2 equals 270ah divided by 10 comes to 27 amps which is approx 13 Amps per battery. This was really applicable to the old wet cell lead acid type , but AGMs can accept a lot higher charge without getting hot and bothered - see side of battery probably - around 30 to 40 AMPS. So a 5A would be too low IMO. And there are a lot of good chargers around without resorting to the big name brands with the BIG prices too.

As far as the TPS1230 solar controller is concerned, it is a PWM type of 30A capacity. The big problem with it though is that it only shows battery voltage and amps IN. Unless you have the LOADS connected through the solar controller, you don't have any way of knowing what your current usage is. It also has a max charging voltage of 14.4 volts? and IMHO, a far too low Low voltage disconnect of 10.8 volts.

If you have a MPPT controller there is a lot more info available to you to monitor what's happening if you want.
My unit (link below) does not have any blue tooth arrangement as all readings are available on the screen. Besides continuously changing real time readings for Battery voltage, PV voltage, Charging Current, Load Current and Battery temperature, I also have access to the following automatic logging details:

Number of working days (since last reset), number of days of Over current cut outs, number of times full charge achieved, number of times low voltage cutout occurred, current PV power (in watts), accumulated amp hours generated, accumulated discharge amp hours. There are also user variable settings for Float voltage, Boost voltage (max charge voltage) Load disconnect voltage, Load reconnect voltage, and also controller temperature if you don't use the remote temperature sensor ( I have mine taped to top of battery for more accurate battery charging). So there is a lot you can monitor at any time. So every morning when off grid, one of the first things I do is reset the day before data to zero ready for a fresh day, whatever it may bring!! The three portable panels (total of 580 watts rated but never achieved!) has on more than several occasions produced up to 25A when single battery was down to 60% but usually charges at 15A to 16A for a short time in the morning and fully charged by midday, even when I have used up to 50ahs the day before. There is a lot of sophisticated gear out there with Blue tooth etc, which I did not need or want to pay extra for. But individuals are limited by only their interest/needs in their electrical
system/demands and the amount of cash they wish to spend.

 

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Johnanbev

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Hi @Boots in Action, have just ordered an MPPT controller to replace the TPS 1230 in the van.
I have chosen the same one as you have as it seems to be value for the price and I don't see that blue tooth or other new fangled stuff is a
necessary requirement.
Will let you know how I get on.
 
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Fallen

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Am I reading it right that the MPPT controller you linked to only has a boost voltage of 14.4V? Or does it let you select AGM to get to 14.7V?
 

Crusty181

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Hi @Fallen , @Drover is pretty well on the ball with your situation. You can get away with just using the Setec when in parks for a while, but for FULL charging of batteries, at home, use a "smart" charger with multiple stages. I use the Setec when at parks, but use my 15A "smart" charger as soon as possible when I get home to ensure batteries are brought up to maximum storage capacity. I think you should be looking at at least a 10A (preferably 15A) charger as you have 2 X 135ah batteries to bring up to full in as short a time as possible. The rule of thumb for battery charging is charge at one tenth of amp hour capacity max. which for you is 135 X 2 equals 270ah divided by 10 comes to 27 amps which is approx 13 Amps per battery. This was really applicable to the old wet cell lead acid type , but AGMs can accept a lot higher charge without getting hot and bothered - see side of battery probably - around 30 to 40 AMPS. So a 5A would be too low IMO. And there are a lot of good chargers around without resorting to the big name brands with the BIG prices too.

As far as the TPS1230 solar controller is concerned, it is a PWM type of 30A capacity. The big problem with it though is that it only shows battery voltage and amps IN. Unless you have the LOADS connected through the solar controller, you don't have any way of knowing what your current usage is. It also has a max charging voltage of 14.4 volts? and IMHO, a far too low Low voltage disconnect of 10.8 volts.

If you have a MPPT controller there is a lot more info available to you to monitor what's happening if you want.
My unit (link below) does not have any blue tooth arrangement as all readings are available on the screen. Besides continuously changing real time readings for Battery voltage, PV voltage, Charging Current, Load Current and Battery temperature, I also have access to the following automatic logging details:

Number of working days (since last reset), number of days of Over current cut outs, number of times full charge achieved, number of times low voltage cutout occurred, current PV power (in watts), accumulated amp hours generated, accumulated discharge amp hours. There are also user variable settings for Float voltage, Boost voltage (max charge voltage) Load disconnect voltage, Load reconnect voltage, and also controller temperature if you don't use the remote temperature sensor ( I have mine taped to top of battery for more accurate battery charging). So there is a lot you can monitor at any time. So every morning when off grid, one of the first things I do is reset the day before data to zero ready for a fresh day, whatever it may bring!! The three portable panels (total of 580 watts rated but never achieved!) has on more than several occasions produced up to 25A when single battery was down to 60% but usually charges at 15A to 16A for a short time in the morning and fully charged by midday, even when I have used up to 50ahs the day before. There is a lot of sophisticated gear out there with Blue tooth etc, which I did not need or want to pay extra for. But individuals are limited by only their interest/needs in their electrical
system/demands and the amount of cash they wish to spend.

Hey Boots. The 30A reg you mentioned has a max panel output of 400w at 12v, how would you achieve the rated 30A with 400w of panels ???
 

Boots in Action

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Hey Boots. The 30A reg you mentioned has a max panel output of 400w at 12v, how would you achieve the rated 30A with 400w of panels ???
Hi @Crusty181 , yes, the rated INPUT of panel wattage to controller is listed as 400 watts, but as @Drover has said on a lot of occasions, the advertised output figures from panels is rarely possible. If , under perfect conditions of light, direction, heat and no losses in line, you might achieve 70% of rated output from your panels. Whilst I have 580 watts of panels in SERIES, if I harvested approx 140W on average from each panel (70%), still puts me just over the 400 watt mark. In any case, if a miracle of production occurred, the unit would limit the input as it is designed. Also remember that I removed all the silicon diodes in the panels and replaced them all with Schottky diodes which have a lot lower voltage loss. This means that I have a higher VOLTAGE coming from panels (around 56 volts at times under light loads) and this helps the MPPT controller produce more charging current and attain 25A at times. Never got to 30A as yet.
Yes, Mike @mikerezny , it is possible to achieve higher wattage from a solar panel, but for a fleeting minute or two only, As you are aware, wattage advertised is calculated at max charging voltage (Vpp) multiplied by max amperage (Imp) so a "rated 200 watt" panel under standard test conditions (STC) would look like this : 18.3volts X 10.92 amps amounts to approx 200. But when a reasonable load is placed on the solar output, voltage drops to a much lower value. And all that is still based on rarely obtainable outputs. Yes correct technically should better than STC conditions occur.
 
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