best solar regulator

[pcatterall]

I've seen odd snippits of info on this so appologies for raising it again but I havn't seen anything to pull it all together.
I am going solar ( one way or another!)
As a temp measure I think I will get 2 x 60 watt panels, mount one on the wheelhouse roof and have one 'floating'.
When I build my 'radar arch' I will mount both on that ( possibly tiltable) and possibly another.
I want to plan for up 200 watts being generated and need to consider regulation.
I understand that I can just connect all the panels to run into one regulator but will appreciate confirmation?
I guess that a 20amp regulator is called for?
I understand that maximum charging efficiency requires a PWM or a MPPT regulator rather than the basic ( voltage cut out type) ones on offer with panels. Can the experts confirm this and suggest which is best? and how much should I pay? and from where?
Is there really a cost saving versus simply buying another square foot of panel?
I am looking at some 60 watt panels 'German' at £1.20 a watt which seems a good price.
I am going for pairs partly to reduce shading loss risk.
Thanks again you loverly lot!!

 

[pcatterall]

Appologies for giving this another airing. My plans have no come into focus a little.
I am getting 2x 40 watt panels to start off with but may add more later. The first 2 are going on the pushpit rail as per my recent thread. Most of the stuff is on order but have not resolved the regulator issue yet.
Prices for these items seem very varied but at the moment the MPPT seem more expensive than the PWMs. Are they better?

 

[VicMallows]

An MPPT regulator should in theory be better, but it is very debatable whether the gain in a boating application will justify the considerably greater cost.

Most of the PWM controllers at around £12 on ebay are designed for solar powered street lights. Their problem I have found is that they cut the charge voltage back to float voltage (aprox 13.6v) far too quickly on a timed basis.

I override the controller (effectively the panels are connected directly to the battery) until I consider the batteries fully charged based on the battery AHr monitor. (With my particular controller this can be done by shorting the in/out NEGATIVE terminals).

Edit: The streetlight function on those controllers can actually be put to some use to control the anchor light!!

Vic

 

[RobBrown]

worth considering dual battery controller?

When I set my panel up, I eventually got a PWM off ebay- didn't feel the considerable extra cost of the MPPT was worth it in my set up, but I did get a dual battery controller, which lets my panel independently charge the start and house battery bank. I think it was around £20-£25.

I think this is the model I'm using:
http://www.ebay.co.uk/itm/Dual-batt...10805586375?pt=UK_Gadgets&hash=item19cc8711c7

But in the search I note MPPT controllers have come down a lot in price since I was looking 18m ago eg:
http://www.ebay.co.uk/itm/MPPT-15A-...30710846854?pt=UK_Gadgets&hash=item35b7702586

 

[mitiempo]

The panel voltage at max output in bright sun for a nominal 12 volt panel will be about 17 - 18 volts at a given amperage. PWM controllers chop this to the proper charging voltage - about 14.4 for bulk charge, and waste the excess as heat. MPPT controllers will convert the higher voltage to the proper voltage at a higher amperage, giving a gain of 15% to 30% in usable amps.

With a PWM controller the panels may only be connected in parallel, otherwise the voltage increase in series would be wasted. MPPT controllers allow series connection as long as the max voltage doesn't exceed the controller rating.

There is a good explanation here http://www.windsun.com/ChargeControls/ChargeCont.htm

 

[William_H]

MPPT regulator

As I read the details of http://www.ebay.co.uk/itm/MPPT-15A-S...item35b7702586 It regulates to 13.7 volts and does not do the 3 stage charging. That means that recharge of a battery will be much longer as the charge current will fall rapidly as voltage of the battery rises. ie just like an older car charging system.
Or put another way if you present 13.7 volts to the battery it will only take what it can regardless of the capabilities of the solar and MPPT controller. Of course for large battery banks this will not be so much of a problem. good luck olewill

 

[mitiempo]

You want about 14.4 volts for bulk charging. The 3rd stage of a 3 stage charger is float - about 13.2 - 13.4 volts, which will prevent boiling the battery. 13.7 is actually a bit worse than the old style regs on cars - they were usually 13.8.

 

[Beyondhelp]

MPPT chargers are worth their weight in gold imo. Solar panels are expensive, I'm surprised that MPPT controllers are not everywhere, other than the fact the inflated prices of them.

www.ebay.co.uk/itm/140594542286

Don't know if that is any good, but its price is good. Anyone want to buy one and send one to me and I'll do some efficiency load/stress tests

I had a 80w solar panel running my house lighting a few years ago. - Not a big house but did run all the lighting needs for 3 months of the summer with no help from JUST the 80w panel. However I never got more than about 60w from it due to the fact that I didnt have a MPPT charger at the time.

 

[noelex]

The gain from MPPT is small on a boat, somewhere around 5-10% improvement would be typical. It is cheaper to install more wattage on the panels, if you have room. Even better money spent on power saving products is usually cheaper. If you have installed the maximum sized panels and power saving electrics MPPT can be worthwhile, but don't expect miracles.

It is worth installing a PWM regulator instead of a simple on off switching design, and get a regulator with at least bulk and float voltages, preferably adjustable. Make sure if will cope with the maximum wattage you may install in the future.
When you combine these features especially in the higher currents many regulators are MPPT anyway.

 

[noelex]

The gain from MPPT is small on a boat, somewhere around 5-10% improvement would be typical for the better models. Cheap MPPT regulators can be poor and I would stay away for the eBay specials. It is cheaper to install more wattage on the panels, if you have room. Even better money spent on power saving products is usually cheaper. If you have installed the maximum sized panels and power saving electrics MPPT can be worthwhile, but don't expect miracles.

It is worth installing a PWM regulator instead of a simple on off switching design, and get a regulator with at least bulk and float voltages, preferably adjustable. Make sure if will cope with the maximum wattage you may install in the future.
When you combine these features especially in the higher currents many regulators are MPPT anyway.

 

[Beyondhelp]

"PWM regulator instead of a simple on off switching design"

What's the difference?

That's not clear at all!

 

[noelex]

"PWM regulator instead of a simple on off switching design"

What's the difference?

That's not clear at all!

When regulating A PWM will switch the solar panel very rapidly on and off so the voltage remains at the desired level. A simple switching regulator Will turn off completely and not reconnect the panels utill the voltage has dropped by a volt or more. It can take a long time for the surface charge to drop on a marine battery bank so there is often no solar output for output for many minutes.
Another way of understanding the process is that PWM can regulated the output of the panels smoothly from 100% to 0%. A switching regulator can only do the two extremes 100% or 0% there is nothing in between.

 

[vyv_cox]

When regulating A PWM will switch the solar panel very rapidly on and off so the voltage remains at the desired level. A simple switching regulator Will turn off completely and not reconnect the panels utill the voltage has dropped by a volt or more. It can take a long time for the surface charge to drop on a marine battery bank so there is often no solar output for output for many minutes.
Another way of understanding the process is that PWM can regulated the output of the panels smoothly from 100% to 0%. A switching regulator can only do the two extremes 100% or 0% there is nothing in between.

I can watch this happening with my Sunworks controller. I have the 10 amp, dual battery bank version shown here. When the domestic bank is fully charged the voltage switches between it and the starter battery at a rate of, I guess, one or two times per second. It's visible on the display. When both are fully charged the switching goes between battery voltage and zero.

Originally I had a Fox i90 from Sunware. This was many years ago and the unit used mechanical relays that could be heard clicking. This failed after five or six years when the points on the breakers became sticky. I replaced it with the Sunworks around five years ago, since when it has performed faultlessly. I have 125 watts of solar panel, 3 x 110 Ah domestic bank, 1 x small AGM (Red Flash 900) starter.

 

[Beyondhelp]

When regulating A PWM will switch the solar panel very rapidly on and off so the voltage remains at the desired level. A simple switching regulator Will turn off completely and not reconnect the panels utill the voltage has dropped by a volt or more. It can take a long time for the surface charge to drop on a marine battery bank so there is often no solar output for output for many minutes.
Another way of understanding the process is that PWM can regulated the output of the panels smoothly from 100% to 0%. A switching regulator can only do the two extremes 100% or 0% there is nothing in between.

I didn't realise 'switching' regulators were so basic, or existed. Sounds like a horrific design.

I'd just put a rail clamp across the solar panel @ 14.4 volts if I was going to do something that basic. Granted it would have to dissipate some heat, but failing that I'd just use a MPPT rather than a something like a voltage controlled relay (be it solid state or not) with a large switching hysteresis.

Some strange products seem to make it to the market that's for sure.