Solar Power regulator: Any Recommendations?

[Norman_E]

I am going to install a total of 100 watts worth of solar panels (actually 5 times 20 watt panels) and need a 10amp regulator. There is a bewildering choice from very cheap ones like this http://www.ebay.co.uk/itm/300906468537?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
though ones like this, which appears a bit more sophisticated http://www.ebay.co.uk/itm/110805574281?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT through to MPPT controllers like this http://www.ebay.co.uk/itm/390929010022?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
Does anyone know whether its worth paying the extra for an MPPT controller, or should I go for the cheaper PWM type? Is there a reliable brand to look for? There are some cheap MPPT controllers on e-bay, has anyone bought one, if so is it any good?

 

[ghostlymoron]

The consensus seems to be that mppt are only justified for larger installations. A pmw would be suited to your size. Whether you go for a branded one is up to you. I've had Chinese cheapies and found them satisfactory.

 

[SimbaDog]

I recommend one of these, will do two separate banks as well, also has a nice optional display unit
http://www.sunstore.co.uk/EP-Solar-Duo-Battery-Solar-Charge-Controller-12-24v-10A.html

 

[Ravi]

I recommend one of these, will do two separate banks as well, also has a nice optional display unit
http://www.sunstore.co.uk/EP-Solar-Duo-Battery-Solar-Charge-Controller-12-24v-10A.html

Perfect timing. Your recommended device is EXACTLY what I was asking about on a different thread - i.e. an integrated battery monitor display and solar device for dual batteries.It looks like I will be buying one of these. Thanks.

 

[Trundlebug]

I am going to install a total of 100 watts worth of solar panels (actually 5 times 20 watt panels) and need a 10amp regulator. There is a bewildering choice from very cheap ones like this http://www.ebay.co.uk/itm/300906468537?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
though ones like this, which appears a bit more sophisticated http://www.ebay.co.uk/itm/110805574281?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT through to MPPT controllers like this http://www.ebay.co.uk/itm/390929010022?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
Does anyone know whether its worth paying the extra for an MPPT controller, or should I go for the cheaper PWM type? Is there a reliable brand to look for? There are some cheap MPPT controllers on e-bay, has anyone bought one, if so is it any good?

I've recently purchased at 150w solar panel and also found it quite difficult deciding what controller to buy.

Eventually I decided to go for one of these http://www.victronenergy.com/solar-charge-controllers/mppt7515/
I picked one up on offer at the boat show for around £70 I think.
I thought it was worth getting a proper MPPT controller.
Fitting an MPPT controller is equivalent to having a larger solar panel - you get quite a bit more out of the panel you have compared to a standard PWM controller.

Out of the three you linked to, my choice would be the last one.
Mainly because, to get the best out of the panel you have you need to optimise the output, and have the best controller you can afford.
It does seem from my research that you get what you pay for with solar controllers. Forget the cheap ones unless you only have a small panel.

Rule of thumb IMO is that the bigger the panel, the more important output is, (and more has been spent on the panel) so get the best out of what you have. With larger panels, Relative to the cost of the panel the controller cost is more justifiable.

Ultimately the choice is yours.

 

[Ravi]

......
Fitting an MPPT controller is equivalent to having a larger solar panel - you get quite a bit more out of the panel you have compared to a standard PWM controller.

......

There is a lot of contradictory information on the forum about the actual benefits of MPPT vs. PWM which has left me scratching my head.

There are many posts citing owners' tests where they have seen little or no benefit from MPPT. The general impression that I get from reading the many threads is that the benefits of MPPT are limited, if any, on a small array (<150W - 200W), especially with cheaper MPPT controllers.

 

[Norman_E]

Very interesting. I just read the manual for the Victron controller. It is clear that if an MPPT controller like that is used the panels need to be in multiples of two, in series. The reason is that the panel voltage has to be 5 volts higher than battery voltage for charging to start. The reason is that my panels have a maximum power voltage of 17.2 and an open circuit voltage of 20.64 therefore it may be the case that if battery voltage was say 12.5 I might get no charge unless the panels were in series. It appears that MPPT controllers are generally designed to take higher input voltages than other types and derive their greater efficiency at least in part from the ability to produce a charging current when lower light levels have dropped panel voltages below the point where a single 12 volt panel would be useless, but two in series are still providing enough volts.

 

[charles_reed]

Having had PV panels for about 14 years on and off I'm surprised at the certainty expressed by so many.

A good MPPT controller is worth a lot of effective power, it is, despite the claims made by the sellers, not like adding to your solar array. What it does is ensure the incoming charge is above the system volts which means that your solar panel is more likely to put a charge into your batteries.
Most allow you to put in a feed at a higher voltage than the nominal 12v of your system and ensure the voltage differential is maintained.
As none of the e-bay descriptions say a peep about the specifications of the controllers, I'm not in a position to pass a valid opinion on any, except to say that 5 years ago, when I bought my BZ 500 from the States it was $196 and with 330 watts of PVpanel it allows me to sit at anchor for 5 days, in Greek waters, with computer, fridge etc all working and without having system volts go below 12.2 under load.
So I'd tend to go for an MPPT controller, but probably not an E-Bay one lest I was buying a pig-in-a-poke.
As already said - fit as much as you can get on - starting now I'd buy big domestic panels with an output of 48v or 72 volts - in terms of output m2, there is no comparison with an array of 12v nom panels in series.

PS Don't "economise" on the panel quality - amorphous are cheap, low output and short lived. Kyocera have some of the best conversion rates (18.3%) on their latest PV panels, Solarex have absorbed BP who used to be the marine panels of choice. Siemens used to have a good reputation. There has been a glut of PV panels, due to enormous Chinese capacity - much of which is now being mothballed. Some panels produced there are very high quality, many aren't. Kyocera produce in Guangdong. Far more critical than controller is panel quality..

 

[JumbleDuck]

I recommend one of these, will do two separate banks as well, also has a nice optional display unit
http://www.sunstore.co.uk/EP-Solar-Duo-Battery-Solar-Charge-Controller-12-24v-10A.html

I have one of those, with the display, and it works very well indeed. Recommended. If buying the two separately, not that there are two displays, for the single- and dual-battery controllers. The dual-battery one has a much longer lead, which is a useful cross-check.

 

[Ravi]

I have one of those, with the display, and it works very well indeed. Recommended. If buying the two separately, not that there are two displays, for the single- and dual-battery controllers. The dual-battery one has a much longer lead, which is a useful cross-check.[/QUO
Thanks for the timely warning as I am about to order one. Curiously, the supplier in the link above does not list Greece as a delivery country but allDOES list Gabon, Gambia, Guadeloupe and Guam. Weird! =-O

 

[Trundlebug]

There is a lot of contradictory information on the forum about the actual benefits of MPPT vs. PWM which has left me scratching my head.

There are many posts citing owners' tests where they have seen little or no benefit from MPPT. The general impression that I get from reading the many threads is that the benefits of MPPT are limited, if any, on a small array (<150W - 200W), especially with cheaper MPPT controllers.

The reason many people don't see a benefit from an MPPT controller is that many controllers that claim to be, (cheapos from eBay) aren't actually MPPT at all.
As I said, you get what you pay for. I came to the conclusion that to get a genuine MPPT controller you need to be paying about £70+ at current prices.

When you search round you can see that there is a price jump from about £5-30 range, to £70-150.
The higher bracket ones are the genuine MPPT's, so the challenge is to get one of those from a reputable manufacturer at the lowest price.

 

[JumbleDuck]

The reason many people don't see a benefit from an MPPT controller is that many controllers that claim to be, (cheapos from eBay) aren't actually MPPT at all.

Yup. People regularly ask here about a £30-ish MPPT controller on eBay ... if you check the manufacturer's website (in China, natch) you find that it's a PWM one.

 

[Norman_E]

Yup. People regularly ask here about a £30-ish MPPT controller on eBay ... if you check the manufacturer's website (in China, natch) you find that it's a PWM one.

It appears that the one I linked in my first post is a genuine MPPT controller at less than £50. I have not decided yet but if I get a 6th 20 watt panel I could wire them as two banks of three in series (or three banks of two) to give the controller the high voltage input that it clearly wants. This is the manufacturers specification http://www.epsolarpv.com/en/index.php/Product/pro_content/id/156/am_id/136

There is at least one good report on it on YouTube, and some bad ones on cheaper alleged MPPT controllers.

 

[GHA]

For anyone interested in what goes on under the hood there's a good YouTube playlist of a home built one here....

https://m.youtube.com/playlist?list=PLjzGSu1yGFjWv4KeN-7TSYeQIcicM9Ghl

 

[Ravi]

The reason many people don't see a benefit from an MPPT controller is that many controllers that claim to be, (cheapos from eBay) aren't actually MPPT at all.
As I said, you get what you pay for. I came to the conclusion that to get a genuine MPPT controller you need to be paying about £70+ at current prices.

When you search round you can see that there is a price jump from about £5-30 range, to £70-150.
The higher bracket ones are the genuine MPPT's, so the challenge is to get one of those from a reputable manufacturer at the lowest price.

Certainly, if you pay more money, you are likely to get a better quality product. If I had unlimited funds, I would go for a top of the range MPPT controller - but then I probably wouldn't want solar panels spoiling the lines of my custom built 60' wooden yacht. ;-)

The electrical solar bod that I have been speaking to has convinced me that an MPPT controller would be a waste of money for the single 60-80W panel that I propose to fit to operate in Greek temperatures. Of course, if I add additional panels, I may regret my decision, but that is unlikely because of space constraints on my little 30' boat.

 

[Trundlebug]

Certainly, if you pay more money, you are likely to get a better quality product. If I had unlimited funds, I would go for a top of the range MPPT controller - but then I probably wouldn't want solar panels spoiling the lines of my custom built 60' wooden yacht. ;-)

The electrical solar bod that I have been speaking to has convinced me that an MPPT controller would be a waste of money for the single 60-80W panel that I propose to fit to operate in Greek temperatures. Of course, if I add additional panels, I may regret my decision, but that is unlikely because of space constraints on my little 30' boat.

Ref my post #5 above.
IMO there is a general rule of thumb that MPPT controllers are probably not economically worth it below about 100w. Above 100w, more so.
If you have 100w, then it's a more difficult decision, based on personal choice and pocket depth!

 

[JumbleDuck]

IMO there is a general rule of thumb that MPPT controllers are probably not economically worth it below about 100w. Above 100w, more so.
If you have 100w, then it's a more difficult decision, based on personal choice and pocket depth!

I agree. There is another boat like mine in the yard, and I chat to the owner regularly. Last year he fitted 2x40W rigid to his boat and I fitted 2 x 50w flexible to mine. He has a very posh MPPT controller and I have the thirty quid dual-battery PWM one. On a nice day I get 4A and he gets 3.5A, so the controllers really don't seem to make much difference at that sort of power level.

 

[pappaecho]

Bought a 10 amp two battery bank from Maplin 4 years ago Cuts off at 14.2 volts and charges until second bank reaches 14.2 volts and it then goes open circuit. I think I paid about £12 . Excellent