I swear I read it on this forum last night but must have forgotten to book mark it. Someone was talking about a MPPT charge controller which sent power from the panels to the load BEFORE going to the batteries and how much more efficient this would be. Was I just dreaming or is anyone aware of that controller?
Solar charge controller which powers load from solar before batteries
- Thread starter mlrtime99
- Start date
calicamper
Expedition Leader
Silly no... The battery acts as a power calming ie stability device. But regardless of that, power in - power out it doesnt matter.
Think of it like a water system, if you only water directly from your rain gutter its either flood or drought. Add a water tank and you can control flow. Same concept with a battery and any power gen source, solar, wind, hydro, altenator etc.
You want your battery to be the source.
Think of it like a water system, if you only water directly from your rain gutter its either flood or drought. Add a water tank and you can control flow. Same concept with a battery and any power gen source, solar, wind, hydro, altenator etc.
You want your battery to be the source.
dwh
Tail-End Charlie
No such beast that I've heard of.
There are plenty with a little 10a load circuit with a low-voltage disconnect on the load circuit, but the load still runs from the battery.
Midnite Classic is designed for either solar or wind, so it has a dump load relay that can be used to switch on certain loads if the solar is still producing *after* the battery is full.
But solar often isn't a steady source of power, so running loads directly from the solar without a battery to make the power smooth and steady usually isn't practical.
There are plenty with a little 10a load circuit with a low-voltage disconnect on the load circuit, but the load still runs from the battery.
Midnite Classic is designed for either solar or wind, so it has a dump load relay that can be used to switch on certain loads if the solar is still producing *after* the battery is full.
But solar often isn't a steady source of power, so running loads directly from the solar without a battery to make the power smooth and steady usually isn't practical.
verdesardog
Explorer
op must have seen controller that had output for loads...power still comes from the battery of course just the controller will shut down the load on battery under voltage.
calicamper
Expedition Leader
Off grid lighting controllers designed to be in a box with the battery double as the power source for the light. I run one in my power box. I power my set up using the controller to take advantage of its cut off logic, to prevent battery damage. Power comes from the battery.
Coachgeo
Explorer
with the improvements in Capacitors IMHO it may well start to become that it solar panels will seemingly send power direct to item pulling load. course in reality the Capacitor will be the water tank as described above instead of battery.
thinking of that..... a good topic for another thread/conversation.... which might be in here already, would be about when we should start considering using a non-typical storage bank such as 1/2 bank of battery, 1/2 bank of capacitors. "Batteries only" providing the juice in conditions of light loads and that planned for night time. Capacitors in strong light and planned heavy loads.
thinking of that..... a good topic for another thread/conversation.... which might be in here already, would be about when we should start considering using a non-typical storage bank such as 1/2 bank of battery, 1/2 bank of capacitors. "Batteries only" providing the juice in conditions of light loads and that planned for night time. Capacitors in strong light and planned heavy loads.
DaveInDenver
Middle Income Semi-Redneck
My Morningstar controller has a connection for the load as well as the panels and battery, so it may appear to do what you're suggesting. But the battery is definitely powering the load. The reason for this configuration is that the controller has a low voltage disconnect/reconnect that prevents the battery from being discharged excessively. On the flip side it won't reconnect the battery until the panel is providing enough power to actually charge it.
If you power the loads straight from the battery you would need to make sure you take care of avoiding this. There may be perfectly valid reasons you would not want an auto cut-off, such as life support or safety equipment that must remain powered even at the expense of ruining a battery. But most of the time you want to preserve your battery lifespan so an LVD is handy.
If you power the loads straight from the battery you would need to make sure you take care of avoiding this. There may be perfectly valid reasons you would not want an auto cut-off, such as life support or safety equipment that must remain powered even at the expense of ruining a battery. But most of the time you want to preserve your battery lifespan so an LVD is handy.
DaveInDenver
Middle Income Semi-Redneck
That may be dwh, there are portable panels that let you plug in a USB device without a battery connected. I have a Goal Zero Nomad 4-panel (I think 21 watt or something) like that, it has a little 5V regulator built in. Never bothered to remove it since it's actually kind of handy to have even though it's primary use is to feed a controller (in this case a Buddipole controller) to charge a 60W-hr pack I use for portable radios.
Here we go, it was actually the Flexopower review on the forum - http://expeditionportal.com/field-tested-flexopower-atacama-79-watt-panel/
"Instead of following the traditional system in which the panel is run to the battery before the fridge pulls from it, they ran the panel and the fridge to the controller first and then to the battery. This allows the fridge to receive power directly without the loss associated with conversion in the battery."
Is there an assumption that some internal circuity is directly feeding the load from the solar input and thereby saves on any losses of the solar input being smoothed out to 14.4 before going to the battery? Are there losses by sending the power to the battery or was this just the first time he saw a charge controller with a load connection on it? Sorry my electrical engineering isn't up to snuff. Just trying to figure out if he mispoke since this is the first that I've heard/read this kind of statement.
This appears to be the controller in question - http://www.phocos.co.in/products/ca-series-6-14a
"Instead of following the traditional system in which the panel is run to the battery before the fridge pulls from it, they ran the panel and the fridge to the controller first and then to the battery. This allows the fridge to receive power directly without the loss associated with conversion in the battery."
Is there an assumption that some internal circuity is directly feeding the load from the solar input and thereby saves on any losses of the solar input being smoothed out to 14.4 before going to the battery? Are there losses by sending the power to the battery or was this just the first time he saw a charge controller with a load connection on it? Sorry my electrical engineering isn't up to snuff. Just trying to figure out if he mispoke since this is the first that I've heard/read this kind of statement.
This appears to be the controller in question - http://www.phocos.co.in/products/ca-series-6-14a
dwh
Tail-End Charlie
Nah.
That controller is what I already described - has a load circuit with low-voltage disconnect. (Which isn't needed anyway since those fridges all have internal LVD.)
Electricity follows the path of least resistance, so it's easy to imagine that putting the fridge closer to the solar has some benefit...but that's just vague thinking.
Say the solar puts out five amps, and the fridge draws two amps. That leaves three amps going into the battery. Doesn't matter if you connect the fridge at the charge controller or the battery...the math doesn't change.
That controller is what I already described - has a load circuit with low-voltage disconnect. (Which isn't needed anyway since those fridges all have internal LVD.)
Electricity follows the path of least resistance, so it's easy to imagine that putting the fridge closer to the solar has some benefit...but that's just vague thinking.
Say the solar puts out five amps, and the fridge draws two amps. That leaves three amps going into the battery. Doesn't matter if you connect the fridge at the charge controller or the battery...the math doesn't change.
dwh
Tail-End Charlie
And, if you disconnect the battery from that charge controller, the CC is gonna shut down and the fridge won't have power, so it's not like the fridge is running off the solar anyway.
Imagine it like an air compressor. The battery is the tank. The solar is the pump. Doesn't matter where you tap that thing, you still draw air from the tank. Maybe the pump puts out enough to supply the load and keep the tank topped off. Or if the load is more than the pump can supply, the tank drains.
Now say you connect an air line for an air tool. Does it help to connect the air line closer to the pump instead of just hooking it directly to the air tank?
No. Makes no difference either way.
Imagine it like an air compressor. The battery is the tank. The solar is the pump. Doesn't matter where you tap that thing, you still draw air from the tank. Maybe the pump puts out enough to supply the load and keep the tank topped off. Or if the load is more than the pump can supply, the tank drains.
Now say you connect an air line for an air tool. Does it help to connect the air line closer to the pump instead of just hooking it directly to the air tank?
No. Makes no difference either way.
DaveInDenver
Middle Income Semi-Redneck
Sending power to the battery first or not is inconsequential, the majority of the losses are in the DC-DC conversion from the panel.
A solar controller only converts power to power, on one side (the PV) is varying and generally at a higher voltage than is not useful to nominally 12V loads (even potentially damaging). So the ideal converter just transfers the maximum energy across at any instant in time. But what the characteristics of that conversion are depends on what you want to do. Most of the time you want to keep a battery fully topped and so the power transfer is optimized for that. A battery charger has a fairly consistent and well understood profile it's relatively easy to build a controller to optimize for it. This is especially true of MPPT algorithms but even PWM control loops are not difficult to make highly efficient when the load is consistent and only the PV side is varying.
The problem is loads that are not uniform or consistent, such as a radio or fridge that have wide swings in consumption. In the case of fridge it goes from zero consumption to it's maximum consumption frequently and somewhat randomly. This sort of load drives most controllers bonkers and over time your efficiency is terrible since the controller is trying to close the loop on two systems of variables that are not stable. The battery serves to smooth that peak and valley demand and they are extremely good at that.
The only reason to put the load ahead of a battery charging circuit would be to minimize system losses if the current is sizable. But you have that problem regardless where it lands. So usually the best option is to keep higher current components close with the shortest lengths of cable.
A solar controller only converts power to power, on one side (the PV) is varying and generally at a higher voltage than is not useful to nominally 12V loads (even potentially damaging). So the ideal converter just transfers the maximum energy across at any instant in time. But what the characteristics of that conversion are depends on what you want to do. Most of the time you want to keep a battery fully topped and so the power transfer is optimized for that. A battery charger has a fairly consistent and well understood profile it's relatively easy to build a controller to optimize for it. This is especially true of MPPT algorithms but even PWM control loops are not difficult to make highly efficient when the load is consistent and only the PV side is varying.
The problem is loads that are not uniform or consistent, such as a radio or fridge that have wide swings in consumption. In the case of fridge it goes from zero consumption to it's maximum consumption frequently and somewhat randomly. This sort of load drives most controllers bonkers and over time your efficiency is terrible since the controller is trying to close the loop on two systems of variables that are not stable. The battery serves to smooth that peak and valley demand and they are extremely good at that.
The only reason to put the load ahead of a battery charging circuit would be to minimize system losses if the current is sizable. But you have that problem regardless where it lands. So usually the best option is to keep higher current components close with the shortest lengths of cable.