Thresher
Active member
Thank you Will. Searching further I found this:
Understanding Solar Controllers: MPPT vs. PWM for Your Solar System
Victron MPPT -Any good?
- Thread starter madabouttheboat
- Start date
Understanding Solar Controllers: MPPT vs. PWM for Your Solar System
Trident
Well-known member
It can do temp sense, and talk to any other Renogy products like their shunt but no, it cannot do a CSV file but why on earth would anyone need it to ? I have 4 Victron MPPT on my boat and what matters to me is that it charges my batteries - if the weather is poor etc and I get less charge than needed it doesn't really matter having a graph that shows how much less.
Trident
Well-known member
It all depends how much you have - I have 4 MPPT so all up for redundancy but on large arrays that many cats have now it can get silly - I fitted on last year that needed 5 60 amp controllers to work - that would have needed 6 Victron at £300 each for the 150/50 at £800 more than the Renogy which work just as well at doing what an MPPT needs to do
Ian_Edwards
Well-known member
I have a Victron MPPT control charging the LiFePO4 battery bank.
It does what it say on the tin, but it has quite a high quiescent current, which means you need to have a way of turning it off if your boat is stored out of the sun, or you put a winter cover over the panels. The standby severely depleted 5kWh of LiFePO4 batteries, when I forgot to disable it one winter. The boat is stored inside, West Coast Scotland.
It does what it say on the tin, but it has quite a high quiescent current, which means you need to have a way of turning it off if your boat is stored out of the sun, or you put a winter cover over the panels. The standby severely depleted 5kWh of LiFePO4 batteries, when I forgot to disable it one winter. The boat is stored inside, West Coast Scotland.
Sandy
Well-known member
Good to hear that the Renogy stuff does that.
I'm an engineer. I've spent my working life looking at data and what it tells me. But as they say we all do different things.
noelex
Well-known member
That is a significant price difference, although this must be a solar array over 3000W. With its associated large inverter(s), battery bank etc it is always going to be an expensive system.
With the move to large electrical systems it is a pity more boatbuilders don't switch to a higher voltage house system. At 24V the Victron 100/30 is equivalent to a 60A controller on a 12V system. The Victron 100/30 is available for about £75 and the higher voltage also means savings on all the associated wiring for the system.
madabouttheboat
Well-known member
Thanks all. Seems pretty unanimous. I’m sure I’ll have plenty of other questions as I go down the route of planning and buying.
noelex
Well-known member
When considering different solar controllers, one of the most important factors is how well the controller tracks the changing maximum power point, together with the overall voltage conversion efficiency and the self consumption.
There is a tendency to assume all MPPT controllers will be equally good at extracting energy from the solar panels, but in practice there are large differences between the cheap and the better designed products.
There is a tendency to assume all MPPT controllers will be equally good at extracting energy from the solar panels, but in practice there are large differences between the cheap and the better designed products.
William_H
Well-known member
Yes system voltage is a good point to ponder. Thinks back to old cars that had a 6v system. (Cheaper battery operhaps but soon became inadeqate especially for starter mortors. Then heavy vehicles are almost universally 24v systems. Again mainly for starter motor power. Like wise bigger boats with bigger diesel engines are 24v. A modern yacht with electric anchor winch thruster and large diesel engine would be far better off with 24v system. But many seem to be stuck in 12v land with it's associated difficulties. (like getting high current devices (inverters) fed with large enough wiring. ol'will
mil1194
Well-known member
I agree completely. I have a 1991 (ancient by most standards on here) Fairline 50m Fly but with immense battery capacities - luckily br the previous owner -but of course the saving grave is that everything is 28f. The engines need 24f to fire them over, the alternators rarely 14.4 each and I think they have they’re wired into VCR’s(?) to charge the house batteries when underway. I’ve never really needed to investigate as it just always work over the last 3years as the PO changed a lot of bits as he was a live board with an 8kw super silent weiderbecl(?) I’m not on board to check. We’ve come back from Monaco across the Med and around Spain etc with never an issue - we don’t have an invertor so to run 240v whilst under motion we have to use the genset - which really was only the washing machine as at night we were moored up so used shore power which charged batteries. Now we are on shore power most nights so we’’ve never needed to consider panels and extra kit. Looking at the chargers we’ve got and the enormous batteries it’s a pleasure - until they’re knackered of course. We did have to leave her in Salcombe on a floating pontoon for a month in March a few years ago and it was a constant worry about whether she’d start one let alone two engines but when we had the water taxi he’d been asked to wait for the thumbs up and it was perfect - a matter of turning the individual keys for a second. We’d (I) had worried for days before about this and having to get the taxi back to shore and buying boosters etc from 50miles away or getting her towed back to the mainland and leaving her for hours on shore power but thankfully it wasn’t needed) I always worry about these things. I suppose otherwise it’d be a matter of getting the geny started to run the chargers.
My point is - I guess - we had a lot of 12/24v usage on board - lights, pumps tv’s/wifi etc but the I only big stuff was kettle/hob/fridge freezer which when we were working our way across from Monaco back to the uk we stopped every few days for supplies so they weren’t a big issue and on shore power even now I wouldn’t contemplate putting panels on which suits us
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Neeves
Well-known member
The question then is...
Which are the better designed products? Noelex is saying - there is an assumption all MPPT controllers are equally good but there are large (so measurable) differences between cheap and better designed (so presumably not cheap) products.
So what are they?
Which I think is, part, what Thresher was asking. Not MPPT vs PWM but MPPT vs other MPPT.
Jonathan
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mil1194
Well-known member
Some MUST be better than others… but it’s determining which is the issue
Maybe this isn’t quite relevant but we have enormous solar farms near us in BG and every six months or so they are changing the panels. This isn’t the odd one or two that may be faulty but systematically the entire farm. They must be getting better all the time. The answer would be to buy them when they’re coming off but it wouldn’t be worth ut for our house. We have a 4bed 4 bathroom with outdoor jacuzzi and well and ponds with small pumps etc and we keep it at 24deg all year round with dual flow aircon units. The elec bill is around 75lev a month - that’s about 34£. It’s nit worth spending money on panels and inverses etc. we do have a 20kv Hyundai auto start generator as we do get occasional power cuts but it used to be daily (10years ago) and now it’s an hour once a fortnight. That was bout two thousand pounds and we run that more than necessary just because they like being used.
noelex
Well-known member
Firstly, I would only purchase a known brand of MPPT controller. The cheap “no-name” MPPT controllers can be very poor. Some are PWM controllers sold with a MPPT sticker. Others select their input voltage simply by measuring the Voc at start up and subtracting a set value to select the Vmp. It can be argued that the voltage conversion makes these a MPPT controller, although there is no real tracking of the Vmp.
Buying a name brand such as Victron, Renogy, Outback, Midnite etc avoids these very poor controllers, but there are still differences between the speed and accuracy of the tracking. If you have a display of the input voltage and output current you can see the tracking in real time. Even the best controllers sometimes are too slow to react in rapidly changing conditions and occasionally become caught sweeping the wrong part of the voltage curve with multiple panels. This is particularly detrimental on a boat with constantly changing shadows.
It is also easy to measure the self consumption when the controller is sleeping. Some otherwise excellent controllers such as the Outback models have a high self consumption. This is not an issue for large domestic solar panel arrays (which is their main market), but becomes a problem for smaller systems, especially when using multiple controllers.
To help separate the smaller differences between the better MPPT controllers there are tests such as the one below. While these often do not control the variables as well as should be done, they do give a guide to the differences. For example, in the test below the Victron controller harvested around 3% more than the Renogy controller:
Finally I would always select a controller with user adjustable parameters for all the voltage set point and preferably the other charging parameters such as the absorption time. If these settings are not correct it will shorten the life of your batteries which often impacts the total cost more than the price difference between the controller models.
As a general recommendation for a medium or large boat system I would recommend one of the Victron controllers. If you have a very small solar array and want a very low cost controller I would select one of the cheap PWM controllers (providing you are using “12V” panels). The PWM controllers are very simple and cheap technology, so even the inexpensive controllers work well providing you are prepared to accept a lower yield.
B27
Well-known member
Some of the no-name items are complete junk, mate of mine has just found his charging the battery at 16V, which is surprising seeing the sun has barely shown itself this week. Maybe he blew it up by connecting the panel before the battery, but it's dead! It looks the same as many others on ebay, but came in a deal with a cheap panel so didn't really cost anything. The panel is excellent.
It's important to understand what your controller is doing, you don't want another hour of 14.4V every time the sun comes out from the clouds, if you're not using your boat. When the boat's idle, a slow charge now and then is enough to maintain the batteries.
My newer battery seems to have barely any self-discharge at all, running the engine for an hour every fortnight seems more than enough charging. The older, engine battery seems to want a few mA. I've changed down to a small panel, but even so, efficiency doesn't matter, control does.
Victron stuff is good, but people have killed batteries with it by using it wrong.
It's important to understand what your controller is doing, you don't want another hour of 14.4V every time the sun comes out from the clouds, if you're not using your boat. When the boat's idle, a slow charge now and then is enough to maintain the batteries.
My newer battery seems to have barely any self-discharge at all, running the engine for an hour every fortnight seems more than enough charging. The older, engine battery seems to want a few mA. I've changed down to a small panel, but even so, efficiency doesn't matter, control does.
Victron stuff is good, but people have killed batteries with it by using it wrong.
Neeves
Well-known member
Given the costs of solar panels I wonder if owners are that concerned over a harvest improvement of 3% - just buy another, or a bigger panel.
Some owners want simplicity.
There have been an increased frequency of threads on reasonably large Lithium house banks. The realisation is there that you can have an electric, rather than gas, galley. If you have a large display, supporting a large, say 400amps, house bank, or a display that has variable shadow areas are you going to have one controller? Recent posts suggest multiple controllers are common place.
PWM controllers have been damned - interesting, but sensible, that you recommend against the flow.
Jonathan
noelex
Well-known member
This is a reasonable point, but the surface area for solar panels, especially the relatively unshaded surface area, is usually limited on a yacht. In addition, suitable areas for mounting solar panels is often expensive to install.
Mounting options such as solar arches are costly. It pays to extract the maximum power from the available area. The efficiency of the solar panels plays a big role, but the performance of the solar controllers, as well as wiring options can also have an impact.
There is generally no extra complexity in selecting more efficient solar controllers or solar panels. The solar yield is simply greater.
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noelex
Well-known member
Electric cooking is great. If you have the available energy it is a wonderful option. We always use this in areas of reasonable solar insolation.
Yes, multiple MPPT solar controllers are generally the best option for large solar arrays.
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noelex
Well-known member
For a small solar panel a PWM controller is better than a cheap no name MPPT controller providing you are using "12V" panels.
A quality MPPT controller is a better option, but try to avoid the cheaper "no name" MPPT contollers.
As B27 points out inexpensive units can be poor:
No name PWM can also have faults, but as the technology is simple and inexpensive this is less likely than with a MPPT controller.
If you want to buy a quality controller the MPPT option is better, but if trying to reduce cost as much as possible a cheap "no name" PWM is a better choice than a cheap "no name" MPPT controller.
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B27
Well-known member
A cheap, no name 'MPPT controller' is quite likely just a poor controller with a more inventive label.
There's a variety of stuff in the industry.
Real MPPT actively tracks the maximum power point to get the most out of a panel.
There's chips available which use a preset panel voltage say 18v or so, where max power is expected to be, then convert that to whatever battery volts.
A lot of the cheap controllers just seem to switch the panel on and off quite slowly and don't do any meaningful DC/DC conversion. No trading excess volts for more current.
But unless your panel is on the small side, efficient conversion only matters on dull days.
What matters is treating the battery correctly.
The question is, is your battery getting what it needs and no more.?
A lot of these products, including Victron are mostly sold for applications where there's a daily discharge, like lighting, roadsigns, cctv, lots of these things absorb many more units than a few boat owners who need to maintain their batteries over winter.
Luckily, the good old Lead Acid battery will take some abuse.
