Solar regulators

[Banshe]

Did you know you could be being robbed of up to 30% of the power your solar panels are generating because of your regulator? It seems the cheaper the regulator, the more they rob you. Even the new beaut expensive ones still rob you 5% or more.
I know all the books tell you it's essential that you install one, but for me, I have now been cruising for nearly four years without one, and still have my original batteries. I have an accurate battery monitor and an OFF switch. When it reaches 14.8 volts: Flick! I have 4X100ah wet acid house batteries, and 3X80 watt panels. On a good day they put out 12 amps continuous.
I have advised other cruisers to try bypassing the regulator for one day to see if they notice any difference. Nearly all have responded favorably, and many have installed a bypass switch so while on board they are getting the full amount from their panels, yet when ashore the regulator is turned on as not to cook their batteries.
Rule of thumb, batteries will withstand 1 or 2% of their amp hours continuous input. I.E. 100ah battery will accept 1 or 2 amps continuous without risk of damage.
I also know of a cruiser who almost lost his boat because the regulator overheated and caught fire. Fortunately it was mounted on fiberglass and it didn't generate enough heat to ignite the gel coat, but if it had been mounted on timber he would have probably lost his boat.
So: As a suggestion, why not try bypassing your regulator for a day to see if you notice any difference. I could be doing you a favor!

[noelex 77]

A lot of cheap solar regulators have poorly chosen and non adjustable voltage set points so I can understand how you have arrived at these conclusions. Rather than bypassing the regulator the solution is not to purchase this sort of equipment.

The better regulators will be superior your manual "off at 14.8v". To fully charge the batteries the absorption voltage has to held for around 1-2 hours and then the batteries are kept at a lower top off float voltage. This sort of algorithm will give a more complete charge. It is impossible to do manually especially if there is a load.

A good regulator is better for the batteries than the manual system you are proposing, but of course it is more expensive.

A good MPPT regulator will even extract a little more power out if the panels, but for a much higher cost.

[Maine Sail]

Originally Posted by noelex 77

A lot of cheap solar regulators have poorly chosen and non adjustable voltage set points so I can understand how you have arrived at these conclusions. Rather than bypassing the regulator the solution is not to purchase this sort of equipment.

The better regulators will be superior your manual "off at 14.8v". To fully charge the batteries the absorption voltage has to held for around 1-2 hours and then the batteries are kept at a lower top off float voltage. This sort of algorithm will give a more complete charge. It is impossible to do manually especially if there is a load.

There is no doubt that a good regulator is better for the batteries than the manual system you are proposing, but of course it is more expensive.

A good MPPT regulator will even extract a little more power out if the panels, but for a much higher cost.

Bingo..!!!!!!!

[CharlzO]

Not sure how well that would work for me if I draw the bank down during some cloudy and dark days, only to tie up at night and drive home. Can't very well leave the switch to on and cook 'em, so I'd much rather rely on a potentially inefficient controller to keep me decent after I've left the boat.

That's just me

[Maine Sail]

Originally Posted by CharlzO

Not sure how well that would work for me if I draw the bank down during some cloudy and dark days, only to tie up at night and drive home. Can't very well leave the switch to on and cook 'em, so I'd much rather rely on a potentially inefficient controller to keep me decent after I've left the boat.

That's just me

I would not stress about it. The only thing somewhat accurate about the original post is "don't buy cheap controllers"...

[belizesailor]

Originally Posted by Maine Sail

I would not stress about it. The only thing somewhat accurate about the original post is "don't buy cheap controllers"...

+1. Bad idea.

Buy a good controller and get appropriate charging of your batteries. Spring for MPPT and get a bit more than no controller.

Also you don't have to sit around and tend your battery charging. My boat now sits far away for the off season with the batteries tended by a good controller with the MAXV set point at 13.5...try that with a switch.

[onestepcsy37]

I also went four years without a controller. The trick is to have more draw than the panel can supply, so no chance to overcharge. And to be aboard 99% of the time. The downside is you are not really living on solar because your needs are greater than your supply.

So I eventually bought a Morningstar PWM in preparation for installing additional panels.

[barnakiel]

OK so every regulator robs us somewhat but what we get is our batteries do not get cooked. So, in my book, this apparent robbery is a trade indeed.

Now do you (@OP) know that when you keep your solars flat (or poorly angled) this "robs" you of way more potential than that regulator does?

1. angle your panels, if you can,
2. get best regulator that makes economical sense with you solar area,
3. that's about that.

Remember a good pwn will be more efficient than a poor mppt. Read tests, buy quality.

Cheers,
b.

[barnakiel]

PS Off course you can eliminate the regulator in some cases but these are pretty specific cases.

And (IMHO) zero regulator setup will not beat proper mppt installation (say 24V panels to 12V battery). In very rough terms this happens because you cannot have a zero regulator setup with 24>12 config while 24>12 mppt has some very clear advantages.

b.

[sanibel sailor]

This maybe too broad of a question, but what should I expect to pay for a decent MPPT controller for a small (~100 watt) system?

[DeepFrz]

Okay, if I screw up here I'm sure I'll be set right.
sanibel sailor, for a 100 watt system use a good PWM controller. Its not worth a MPPT controller unless you are planning on upgrading your system to about 350 watts or more. Even then it depends on the voltage of your panels.

Here is a good place to start.
Matching solar modules to MPPT charge controllers | Victron Energy

Edit: There are cheap "MPPT" controllers. Some of them really are MPPT but a lot of them are not. They are low current devices but again, what is the voltage of your solar panel?

[newhaul]

[ a suggestion, why not try bypassing your regulator for a day to see if you notice any difference. I could be doing you a favor![/QUOTE]

Hate to tell you but wrong again wood is harder to start burning that gel coat
Here is a list

Flame Spread Indices Of Common Building Materials:

White Oak 100
Douglas Fir 83 - 100
Eastern White Pine 85
Southern Yellow Pine 130 - 195
Western Spruce 100
1/2” Exterior Douglas Fir Plywood 130- 150
3/4” Birch Plywood (veneer core) 114
1/2” Particleboard 156
1/4” Lauan Plywood 150
3/8” FRP (polyester & glass fiber) 200+
1” K-FAC 19 Mineral Fiber Board 25

And the lower the number the safer it is.

[socaldmax]

Originally Posted by sanibel sailor

This maybe too broad of a question, but what should I expect to pay for a decent MPPT controller for a small (~100 watt) system?

There is a 20 amp MPPT controller from Eco-worthy that works great for $100 delivered, it has a very nice display and is very adjustable. There's another one called Trace that's available in a 20 amp model on Ebay for about $100. It has no display, but you can buy a display for $50, or buy a cable for cheap and connect it to a laptop, which allows the adjustment of a lot of settings and monitoring of output.

[colemj]

Originally Posted by onestepcsy37

I also went four years without a controller. The trick is to have more draw than the panel can supply, so no chance to overcharge. And to be aboard 99% of the time. The downside is you are not really living on solar because your needs are greater than your supply.

So I eventually bought a Morningstar PWM in preparation for installing additional panels.

Yes, using more power than can be supplied is the only way to safely go without a controller if one cannot always be present to switch off the panels.

However, to the OP's assertions, a direct connection can only be made if one is using 12V nominal panels. These are becoming increasingly rare on boats, as most are going higher voltage and using MPPT controllers.

I was recently looking to purchase a couple of 85W 12V nominal panels because of the footprint size. These are not even made anymore. In fact, I found very few 12V nominal panels still being manufactured. The ones I found start at >100W (with the corresponding footprint) and the majority of them are no longer the typical rectangle sizes of the old panels. The main market in lower watt 12V nominal panels seems to be the flexible panels or small very low watt panels.

Also, a direct connection pulls the panels down to battery voltage - which is always lower than the maximum power point that the panels are optimal for. Forgoing an MPPT controller will rob you of daily output, even taking into account the power overhead of the controller.

Mark

[barnakiel]

Originally Posted by sanibel sailor

This maybe too broad of a question, but what should I expect to pay for a decent MPPT controller for a small (~100 watt) system?

Victron 75/15 (15A) @ EUR 100 or thereabouts, in the EU.

User programmable, resin encapsulated board, etc.

Here, it is roughly an equivalent of extra 50W (3A) of solar area, so make your calculations before you decide which way to go.

I think it about equals PWM on a 150W system. I would stay with PWM @ below 150W but I would get a MPPT on any new system above or 150W and also on any system where you run out of solar space and are still behind your energy budget.

b.