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mppt vs pwm


OldPeculier

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I will be fitting a new solar panel soon.  I only need 100w, to keep my batteries topped up. Just for the pumps and lights.  The advantages of a mppt controller are well established, but is it really necessary for a simple set up like this?  

I am thinking of the difference between a 10a Tracer at £63 from Bimble or their 10a PWM controller at £8.42

 

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An mppt controller will get slightly more power from your panels.  If you are struggling to get enough power, then the extra will be appreciated, but if the panel gives you more than you need then the extra power will not be used, so why pay for it???  If you did want more power, I would spend the extra money on more panels, when you have more than say 300W the advantage of an mppt controller may be worth i But again only if you will use it.

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23 minutes ago, stegra said:

Personally, I wouldn't consider anything other than MPPT. They effectively adjust according to light conditions to get the maximum from the panels so keep pulling usable power long after PWM have gone to bed.

Fully agree, but if the op has no use for the extra power, then it is money wasted.

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19 minutes ago, Chewbacka said:

Fully agree, but if the op has no use for the extra power, then it is money wasted.

I don't recall anyone ever mentioning that they were going to reduce their solar capacity but an awful lot looking to increase. I think power usage is like waist measurement; it only increases with time. There are plenty of budget MPPT controllers around that seem to perform well... There was one mentioned earlier in this thread that would probably suit the OP for only about £10 more than the PWM. I would consider it a false economy not to fritter away that tenner on such an extravagance.

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4 hours ago, WotEver said:

Or the one that Pete linked to a few days ago that gets a good review: http://m.ebay.co.uk/itm/181861868553?_mwBanner=1&varId=480900600645

But are we sure they are MPPT, rather than PWM with and MPPT label... lots of cons going on out there, and there's no such thing as a free lunch??

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10 hours ago, OldPeculier said:

I will be fitting a new solar panel soon.  I only need 100w, to keep my batteries topped up. Just for the pumps and lights.  The advantages of a mppt controller are well established, but is it really necessary for a simple set up like this?  

I am thinking of the difference between a 10a Tracer at £63 from Bimble or their 10a PWM controller at £8.42

 

I have just done exactly this. Got a 100w panel of Amazon for £99, it's rated at 5.4 amps max (I think). Got a 10 amp controller (PWM) about £10 with an LCD screen, it shows; temp, battery voltage, charge current and load current. 

Connected it up and had 3 very charged batteries ever since, I am not using all sorts of power hungry gadgets (just a TV and lighting) but on most days even the cloudy, rainy ones (which is most of them up to now) I have been getting 1.3 amps. 

The batteries get charged until they are at 15 volts, then it knocks off and they drop down to 14volts, then it starts charging again. After dark the voltage slowly drops with usage but by the time I get up in the morning the panel has got batts up around 13.5v.

Just wait to see how much it produces in summer (if we get one). 

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Ok, so I had no idea Mppt controllers had dropped in price.  When I started looking last year, they were still £50 - £60 .  That is of course if they are any good.  The situation is a bit like pure and modified sign wave inverters; just because its got a label on it, that doesn't make it so.

Like Canal321, my power requirements are very low.  I currently (haha) charge my batteries off the land line for 24 hours once a week with a little 4 amp charger and usually take the boat out for a run every month.  This keeps them at a decent voltage.  I use the landline for tv & laptop.  I put £20 on my meter in January 1016 and I've still got a bit left!

An interesting situation when the cables cost more than the components. 

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12 hours ago, Richard10002 said:

But are we sure they are MPPT, rather than PWM with and MPPT label... lots of cons going on out there, and there's no such thing as a free lunch??

Yes. 

Like I said, it got a good review.

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17 hours ago, WotEver said:

Or the one that Pete linked to a few days ago that gets a good review: http://m.ebay.co.uk/itm/181861868553?_mwBanner=1&varId=480900600645

Definitely MPPT, but not necessarily very efficient? Although a cheap MPPT solution for some situations.

He does an update video which allays his fears about the max voltage input, where he confirms that the 60V capacitors are in series, so can take 120V.

 

Edited by Richard10002
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Following on from this, none of the the cheap controllers do not have a digital display so can you fit one like this? http://www.ebay.co.uk/itm/DROK-Digital-Voltmeter-Ammeter-Voltage-Current-Meter-DC-4-5-30V-10A-12V-24V-/222425652581?hash=item33c99a1d65:g:~EMAAOSweWVXf5-x   Do you need to use one with a shunt?

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4 minutes ago, OldPeculier said:

Following on from this, none of the the cheap controllers do not have a digital display so can you fit one like this? http://www.ebay.co.uk/itm/DROK-Digital-Voltmeter-Ammeter-Voltage-Current-Meter-DC-4-5-30V-10A-12V-24V-/222425652581?hash=item33c99a1d65:g:~EMAAOSweWVXf5-x   Do you need to use one with a shunt?

The 10  AMP. ones don't require a shunt ,Have had a 200 AMP. version for 5 years,it uses a Shunt,only drawback is it needs a separate power supply

CT 

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