Matching solar panels to batteries to consumption

[Adelie]

Originally Posted by newhaul

First off all sounds about right one item I would change is the oil anchor light change to an led anchor light. ( you will, still has p,entry of solar to make up for it) it will pay for itself in short order in saved oil.

Now to the controller for your install I would recommend something like the p20l pwm controller https://www.amazon.com/WindyNation-R.../dp/B015S39PTU the charge points are programmable to maxamise your system. Use the money saved over an mppt controller to pay for the led anchor light.

Purchase costs aside, PWM controllers are more efficient than MPPT controllers for small installations. The electrical self demand of the MPPT controller itself exceeds the extra power produced. In larger installations (400-500w) the MPPT is ahead.

[Sauntress]

Thanks,

So not an MPPT. That's good news because all this lot adds up.

[mitiempo]

Originally Posted by Adelie

Purchase costs aside, PWM controllers are more efficient than MPPT controllers for small installations. The electrical self demand of the MPPT controller itself exceeds the extra power produced. In larger installations (400-500w) the MPPT is ahead.

Disagree. MPPT wins even with smaller panels.

MPPT vs. PWM Controllers Photo Gallery by Compass Marine How To at pbase.com

About 20% gain with MPPT.

[newhaul]

Originally Posted by mitiempo

Disagree. MPPT wins even with smaller panels.

MPPT vs. PWM Controllers Photo Gallery by Compass Marine How To at pbase.com

About 20% gain with MPPT.

But with the cost diference on a small array you are ahead with a pwm controller and using the money saved to buy another panel.

[Pete7]

Originally Posted by mitiempo

Disagree. MPPT wins even with smaller panels.

MPPT vs. PWM Controllers Photo Gallery by Compass Marine How To at pbase.com

About 20% gain with MPPT.

Ageed. I have been looking at Morningstar MPPTs but the price has been to high to justify for a small solar system, as Newhaul says it would be better to buy more solar. There are lots of other makes but how do you know they are actually MPPT rather than just a cheap knock off on / off switch.

However, I have just seen the Victron 75/15 is now down to £80 which makes it an interesting option for smaller solar systems. If I upgrade our solar system this will probably be the controller we choose.

https://www.leadingedgepower.com/sho...FYM4Gwods3IBrA

[ramblinrod]

Originally Posted by newhaul

But with the cost diference on a small array you are ahead with a pwm controller and using the money saved to buy another panel.

Actually, one needs to review intended use, vessel real estate, and wiring scheme before choosing the controller.

In this case, I concur that their is likely sufficient real estate to install sufficient panel(s) with a PWM controller.

However, in most cases, it is best to get all of the solar one can. So after the non-shadowed installation space is used up, the MPPT controller gets the most out of those panels.

Doesn't necessarily have to be a large system.

If there is only space for a 100W panel and 200W of solar is desired/required, an MPPT controller will get one closer to their energy needs.

[mitiempo]

Originally Posted by Pete7

Ageed. I have been looking at Morningstar MPPTs but the price has been to high to justify for a small solar system, as Newhaul says it would be better to buy more solar. There are lots of other makes but how do you know they are actually MPPT rather than just a cheap knock off on / off switch.

However, I have just seen the Victron 75/15 is now down to £80 which makes it an interesting option for smaller solar systems. If I upgrade our solar system this will probably be the controller we choose.

Victron MPPT controllers are excellent and well priced, as well as allowing adjustment of all parameters.

As far as Pwm price vs MPPT, I think if you stick to a major brand - Victron, Bluesky, Outback, Morningstar, or Genasun for example - the price is not much more for the better output of an MPPT controller.

Genasun GV-4 for up to 50 watts is $65, the GV-5 for up to 65 watts is $75, and the GV-10 for up to 140 watts is $109.

[newhaul]

Originally Posted by mitiempo

Victron MPPT controllers are excellent and well priced, as well as allowing adjustment of all parameters.

As far as Pwm price vs MPPT, I think if you stick to a major brand - Victron, Bluesky, Outback, Morningstar, or Genasun for example - the price is not much more for the better output of an MPPT controller.

Genasun GV-4 for up to 50 watts is $65, the GV-5 for up to 65 watts is $75, and the GV-10 for up to 140 watts is $109.

Then you have the $8 USD pwm controller that I have on . My 100 watt panel. Lcd and fully programable. 10A/20A/30A Solar Panels Battery Regulator Charge Controller 12/24V Auto USB New | eBay

[mitiempo]

Originally Posted by newhaul

Then you have the $8 USD pwm controller that I have on . My 100 watt panel. Lcd and fully programable. 10A/20A/30A Solar Panels Battery Regulator Charge Controller 12/24V Auto USB New | eBay

Hard to tell if it is programmable as it is unbranded and I see no link to the manual. Hard to tell many apart either, dozens look the same or similar. Yours may be good and you're knowledgeable enough to make sure - not everybody is. That is why I recommend a major brand only - better quality and someone you can call if there is an issue. It's a bit late when the batteries are destroyed by a $8 Chinese controller.

How adjustable? Below are the adjustments on any Victron MPPT controller:

[newhaul]

Well it is a pwm controller so it doesn't have all those adjustments but it does adjust for battery type from fla or agm, the other adjustments that are user adjustable are absorption voltage, float voltage, load disconnect, and reconnect voltages. What more do you really need and expect for a small solar array charge controller that costs less than twenty bucks. I actually paid $14 for mine ( the same unit I linked to except it was in California already) . The instruction sheet comes with it in the box you will just need a magnifying glass to read it.

[socaldmax]

I'm of the opinion if someone can't afford to spend $100 on an MPPT controller, they've got bigger problems than what size solar panels to install.

How do you check into other countries and pay the entry fees and all of the other misc. fees? The general consensus is that owning a boat is expensive; if $100 is too much to spend for quality equipment, what happens when you need new sails or new lines?

[newhaul]

Originally Posted by socaldmax

I'm of the opinion if someone can't afford to spend $100 on an MPPT controller, they've got bigger problems than what size solar panels to install.

How do you check into other countries and pay the entry fees and all of the other misc. fees? The general consensus is that owning a boat is expensive; if $100 is too much to spend for quality equipment, what happens when you need new sails or new lines?

Why do you assume that a person can't afford to spend a hundred bucks on an item just because they choose not to. I spent 14 because the controller does what I want it to and that saves me the extra 86 bucks. That will purchase a spare controller and a few extra prefilters for my water maker. Which means I won't have to try to source them in some far corner.

[socaldmax]

Originally Posted by newhaul

Why do you assume that a person can't afford to spend a hundred bucks on an item just because they choose not to. I spent 14 because the controller does what I want it to and that saves me the extra 86 bucks. That will purchase a spare controller and a few extra prefilters for my water maker. Which means I won't have to try to source them in some far corner.

Because even if PWM controllers were FREE, I'd never use one or endorse one. There is no sense whatsoever in installing any size solar panel and immediately throwing away 20% or more of it's potential output.

I'd buy the $100 MPPT controller. If I thought it was going to fail, I'd buy a spare, but since I haven't seen a single failure yet out of about 15 of them installed, it's not really a concern.

Again, if money isn't the concern, then there's no reason to be THAT cheap. Ever. I'm all for getting the best value for my money, but PWM controllers are never a good value. Yeah, I know you recommend using the extra money toward a 2nd panel, but since I can get 208w panels for a measly $65 ea and a great MPPT controller for $100, I wouldn't recommend anything less or cheaper.

[mitiempo]

Originally Posted by socaldmax

........but PWM controllers are never a good value. Yeah, I know you recommend using the extra money toward a 2nd panel, but since I can get 208w panels for a measly $65 ea and a great MPPT controller for $100, I wouldn't recommend anything less or cheaper.

If you have a home off grid extra panels make sense.

On a boat real estate is limited, no matter how large the boat. It makes sense to get the most you possibly can from the panels you are able to fit.

[newhaul]

Originally Posted by socaldmax

Because even if PWM controllers were FREE, I'd never use one or endorse one. There is no sense whatsoever in installing any size solar panel and immediately throwing away 20% or more of it's potential output.

I'd buy the $100 MPPT controller. If I thought it was going to fail, I'd buy a spare, but since I haven't seen a single failure yet out of about 15 of them installed, it's not really a concern.

Again, if money isn't the concern, then there's no reason to be THAT cheap. Ever. I'm all for getting the best value for my money, but PWM controllers are never a good value. Yeah, I know you recommend using the extra money toward a 2nd panel, but since I can get 208w panels for a measly $65 ea and a great MPPT controller for $100, I wouldn't recommend anything less or cheaper.

OK max here goes on most of my customers boats as well as my own much over a 100 watts is over kill. So it makes little sense to spend more on a controller than the cost of the panel.
Now your 208 watt panels are 24 volt units which need an mppt controller for the average 12volt system. On the down side they take up a lot of real estate on a small vessel (most of my customers are in the sub 30 range)
( the biggest array I had a customer want was 200 watts. ) and all I install are mono panels with an efficiency in the 20% range.