Slowboater33
Member
I'm a newbie to solar power, would like to fit an 80w panel to keep my 2 100ah batts topped over winter. What size controller do I need and should I get one sized enough to add another 100 panel in spring.
Thanks
Thanks
Newbie to solar
- Thread starter Slowboater33
- Start date
KeelsonGraham
Well-known member
I = P/V is your friend
I = 80/12
= 6.6 amps.
So, you’ll need an MPPT controller that handles at least that.
When you add your second (100W) panel:
I = 180/12
= 15 amps theoretical max. But, as I understand it, you’ll need a dedicated MPPT controlled for each panel - expensive.
Better to anticipate future needs right now and buy a 175 watt panel and run it through a Victron 75/15. This is what I do.
No doubt some electrical whizz will be along in a minute to correct me.
I = 80/12
= 6.6 amps.
So, you’ll need an MPPT controller that handles at least that.
When you add your second (100W) panel:
I = 180/12
= 15 amps theoretical max. But, as I understand it, you’ll need a dedicated MPPT controlled for each panel - expensive.
Better to anticipate future needs right now and buy a 175 watt panel and run it through a Victron 75/15. This is what I do.
No doubt some electrical whizz will be along in a minute to correct me.
Last edited:
JBPa
New member
A) Victron controllers limit the current they put out regardless of power available, e.g. you could get a 10A controller with a billion watt panel, and it would still only put out 10 amps. Victron controllers are rated by the current they will put out and the input voltage they can handle. I would guess other brands may work the same. You would probably never gain any advantage by using any over 10 amps with only 180W of power, maybe go 15 amps for a comfort factor since the price is nearly the same.
B) you don't want to mix an 80W panel with a 100W panel on the same controller.
C) If it were just keeping the batteries topped off, any inexpensive controller would work, even PWM instead of MPPT if you have lead batteries.
B) you don't want to mix an 80W panel with a 100W panel on the same controller.
C) If it were just keeping the batteries topped off, any inexpensive controller would work, even PWM instead of MPPT if you have lead batteries.
ghostlymoron2
Active member
I've only had 20w panels and controlled them through 10a ebay panels costing about £10. Not fancy but had no trouble in 8yrs.
Sandy
Well-known member
According to the Victron documentation the 75/15 is OK up to 200 watts.
You can tell I am currently working on a spreadsheet to calculate my daily consumption of amps!
B27
Well-known member
Beware of cheap controllers, some of them seem to want to overcharge the battery.
Even the best controllers may need careful setting up of course.
Even the best controllers may need careful setting up of course.
noelex
Well-known member
If your boat has a 12v house system, a Victron 75/15 would be a good choice for the controller. Go for the Smartsolar version with built in Bluetooth.
This will be fine for your eventual 180w, but the panels need to have similar Vmp (at least within 0.5v), if you are going to use them in parallel. The wiring needed for 180w will be thicker than for the the single 80w panel and this would be worth installing from the outset if you plan a future upgrade.
An alternative would be two Victron 75/10 controllers, one for each of the solar panels. This would result in a higher solar yield, valuable redundancy and the solar panels could have disparate Vmp specifications, but you will need seperate wiring between the panels and the controllers and it will be slightly more expensive.
This will be fine for your eventual 180w, but the panels need to have similar Vmp (at least within 0.5v), if you are going to use them in parallel. The wiring needed for 180w will be thicker than for the the single 80w panel and this would be worth installing from the outset if you plan a future upgrade.
An alternative would be two Victron 75/10 controllers, one for each of the solar panels. This would result in a higher solar yield, valuable redundancy and the solar panels could have disparate Vmp specifications, but you will need seperate wiring between the panels and the controllers and it will be slightly more expensive.
Neeves
Well-known member
I'm also lacking in the technical background.
I'm not sure why you want to add another panel in the spring. You will need the extra panel now, or soon, as the winter weather tends to be bereft of sun. You may want to consume power in the spring/summer but you are going harvest less solar in the winter. Plan big. One big panel (if you can fit it) might be better than 2 smaller ones. Why do you need to keep the batteries topped up with a big panel - do you use power over winter...?
I'd also consider a decent battery monitor which will define what is the state of charge of the 2 batteries. I think you can get Blue Tooth enabled equipment that will allow you to monitor independently - but that's more money
If my suggestion curries favour with the experts then NASA, in their Clipper range, do a, shunt, battery monitor for both lead or lithium, 2 different controllers, both cost around stg100 (you don't define if your batteries are lead or lithium.
Looking at the kit - Victron is the industry standard and have been around for decades. Highly reputable. Their prices are high accordingly (in fact I have not seen higher). A Victron battery mon costs about 2 times that of the NASA unit. The Victron units may have more bells and whistles - but I don't know if you actually need them, nice though they may be. A member here has been using the NASA unit for lead batteries without problem. I guess NASA will also offer MPPT controllers.
You can also buy shunt battery monitors through aliexpress or Temu at less than half the price of the Clipper units - but I have seen no independent feed back.
We had a Xantrex battery mon, before Victron sold their kit, it lasted 25 years (the Xantrex type unit has been much copied). We also had a Victron charger/invertor - they were early in the piece for a marine version. This latter was good value (but it needs 1 amp (?) to power it).
We are looking at a Lithium, 200 amp/hr, single battery, based version of what you might be doing currently - and the Chinese (lithium) shunt battery mons look attractive (some are water proof) - it is their unknown performance/quality that is the stumbling block ..... decision, decisions - but we don't need to commit yet. Victron is Dutch, NASA say made in the UK - as said, lots of Chinese suppliers.
Jonathan
I'm not sure why you want to add another panel in the spring. You will need the extra panel now, or soon, as the winter weather tends to be bereft of sun. You may want to consume power in the spring/summer but you are going harvest less solar in the winter. Plan big. One big panel (if you can fit it) might be better than 2 smaller ones. Why do you need to keep the batteries topped up with a big panel - do you use power over winter...?
I'd also consider a decent battery monitor which will define what is the state of charge of the 2 batteries. I think you can get Blue Tooth enabled equipment that will allow you to monitor independently - but that's more money
If my suggestion curries favour with the experts then NASA, in their Clipper range, do a, shunt, battery monitor for both lead or lithium, 2 different controllers, both cost around stg100 (you don't define if your batteries are lead or lithium.
Looking at the kit - Victron is the industry standard and have been around for decades. Highly reputable. Their prices are high accordingly (in fact I have not seen higher). A Victron battery mon costs about 2 times that of the NASA unit. The Victron units may have more bells and whistles - but I don't know if you actually need them, nice though they may be. A member here has been using the NASA unit for lead batteries without problem. I guess NASA will also offer MPPT controllers.
You can also buy shunt battery monitors through aliexpress or Temu at less than half the price of the Clipper units - but I have seen no independent feed back.
We had a Xantrex battery mon, before Victron sold their kit, it lasted 25 years (the Xantrex type unit has been much copied). We also had a Victron charger/invertor - they were early in the piece for a marine version. This latter was good value (but it needs 1 amp (?) to power it).
We are looking at a Lithium, 200 amp/hr, single battery, based version of what you might be doing currently - and the Chinese (lithium) shunt battery mons look attractive (some are water proof) - it is their unknown performance/quality that is the stumbling block ..... decision, decisions - but we don't need to commit yet. Victron is Dutch, NASA say made in the UK - as said, lots of Chinese suppliers.
Jonathan
wonkywinch
Well-known member
If you are considering high load items, eg hob or oven, the NASA Clipper battery monitors only cover a max of 100A for lithium/lead acid (BM1) or 200A (lead acid only). 100A only allows for a 1200 watt inverter assuming 100% efficiency. 2.4kw for the 200A model but restricted (at the moment) to lead acid.
noelex
Well-known member
They haven't so far. The Victron MPPT units are hard to beat.
Kelpie
Well-known member
If you don't need to wring out every last bit of power, then a cheap and cheerful PWM controller will be fine for topping up batteries over winter. Try the likes of Bimble or 12voltplanet. 10A is ample for a 80w panel.
E.g. 10A PWM Charge Controller 12v 24v
E.g. 10A PWM Charge Controller 12v 24v
Kelpie
Well-known member
We have an Aili battery monitor, £50 from Amazon, rated up to 500A. Full time liveaboard with 1200w of solar, lithium, and electric galley. Seems to work just fine.
Our charge controllers are Epever, 40A MPPT units. About a third the price of Victron. They don't have Bluetooth so no app etc, but they do the job.
William_H
Well-known member
Graham your calculations on solar PV panel current are flawed. They are usually rated in watts as max current multiplied by max volts. So you should be dividing power by 20v (sometimes 18v) to get max current which in fact will be quoted usually on the panel. So OP 80w panel gives I expect 4 amps max. That means that almost any controller will happily control it. (avoid over charge of batteries). I have the Victron 10A at home and am very pleased with it. However only suitable for one battery. (not dual) so OP needs to decide if he wants the 2 x 100AH batteries in parallel for charging. ie when leaving boat. OP will discover that biggest problem with solar PV panels is in finding a place for them on a small boat. ol'willI = P/V is your friend
I = 80/12
= 6.6 amps.
So, you’ll need an MPPT controller that handles at least that.
When you add your second (100W) panel:
I = 180/12
= 15 amps theoretical max. But, as I understand it, you’ll need a dedicated MPPT controlled for each panel - expensive.
Better to anticipate future needs right now and buy a 175 watt panel and run it through a Victron 75/15. This is what I do.
No doubt some electrical whizz will be along in a minute to correct me.
Neeves
Well-known member
I was thinking similarly.
If the intent is only to keep the batteries healthy then a small solar panel, possibly not needing a controller ? - would do the job.
If the desire is to provide power to replenish a battery, in this case 200amp/hrs, during better weather through the winter months used to 50% capacity and extend for 'off grid' summer usage next year - then plan and invest for next year. The advice will be different for each scenario.
There are lots of, shunt, Lithium (and Lead) battery monitors, so many you will never find them all. I've not checked all the specs - simply looked at the cross section of prices. (I need a spreadsheet
). NASA is middle of the road but the cheapest (made in China) is around stg25 (excluding UK tax/duty) - just google 'Shunt battery monitors'. Quoting top of the range is not much use to many forum members and Kelpie's hands on experience is invaluable.They are hard on the wallet as well.
100A and 1200 watt inverter seems fine to me, this is the NASA Battery Mon Lithium (below), - about half the price of the Victron unit (which might do much more, but more than we need).
I agree if you need extra you cannot save lots of money - its too easy to pay for unnecessary bells and whistles.
Jonathan
Stemar
Well-known member
I would suggest fitting as much solar power as space and the budget allow - you'll appreciate it at anchor. If you're putting the panels somewhere like the hatch garage, where they're likely to get shaded, fit two smaller ones rather than one big one, as even a small shadow on a panel will reduce the output of the whole panel.
Do you have a separate starter battery? If so, you'll want a controller that can handle two battery banks.
Do you have a separate starter battery? If so, you'll want a controller that can handle two battery banks.
noelex
Well-known member
If you are considering an MPPT controller, the output current will be the limiting factor.
Therefore you should divide the output wattage of the solar panel by the battery voltage, not the (18-20v) solar panel voltage to determine if the controller has an adequate current rating.
When charging the battery, voltage is not likely to be as low as 12.0v (although this is possible). 13-14v is typically used and this is fine providing the controller can limit the current to prevent damage (nearly all modern controllers incorporate this self protect mechanism).
So 80/13.5 = 5.9 A
Alicatt
Well-known member
Was thinking about using solar to supplement/replace the shore power for the winter months and was looking at the local Victron supplier for ideas.
Started looking at batteries, first was a 180Ah Victron LiPo, next was a 2.4MWh in a 40ft container https://www.cclcomponents.com/energy-storage/batteries Was not until I got to the bottom of the page that the battery packs were getting to manageable sizes. Prices, well that is not so manageable!
Started looking at batteries, first was a 180Ah Victron LiPo, next was a 2.4MWh in a 40ft container
https://www.cclcomponents.com/energy-storage/batteries Was not until I got to the bottom of the page that the battery packs were getting to manageable sizes. Prices, well that is not so manageable!Neeves
Well-known member
The market has developed.
I understand that solar panels - the component you need to harvest the sun - are as cheap as chips in the UK. Victron, and others, identifying the needs have developed increasingly sophisticated components to manage, control and document the harvesting at costs, for each component, factorially greater than the solar cells.
Someone wanting to harvest the sun finds that the costs have grown exponentially when all they wanted to do was have a bit of free electricity - free as long as you steer clear of Victron.
As Kelpie points out there are cheaper options - but these are ignored by the majority who want to exclusively suggest management systems costing totally out of proportion to the desires of the OP(s). Do take note of Wonkywinch's cautionary post, also above - and make sure your and the suppliers specs coincide
No-one who wants to simply have a bit of solar for the a weekend or 2 is going to invest in the Victron options. In fact many who fancy a bit more solar, a bit more off grid, are going to look at Kelpie's suggestions - and ignore the Victron suggestions.
What is lacking are more suggestions along the lines of Kelpie's installation.
I have not looked at MPPT controllers yet but if you google: 'Shunt battery monitors' and add, as individual searches the brands 'Xeron' ; 'YKSEI Autoparts' ; ' 'ECO-Worthy'; 'Aili'; 'TR16 Coulomb meter' maybe also add 'Temu' or 'Aliexpress' you will find battery mons ranging in prices from about 20stg - 40stg (and more). If you don't like the idea of a Chinese source then look at NASA. To cut back on the responses also add 'lead' or 'Lithium'.
I suspect you can make the same search replacing 'shunt battery monitor' with 'MPPT controller'.
Some of the suppliers have customers comments, many do not. Sometimes the 'English' can be a bit quaint. But if you buy through Aliexpress and especially Temu you can send the item back if it does not perform (I think Temu is UK based, its Chinese but based in the US, Australia etc etc - its a recent development of the supply route - but apparently very successful and popular).
I have no personal experience of any of these items - you are on your own. But read Kelpie's posts, above. The risks are low - if you are happy with the returns policies - and the prices are factorially lower than Victron.
We have bought a cross section of 'stuff' from China (direct) and from Aliexpress and Temu. My 2t load cell, a crane scale, a chain winch, my coating thickness meter for galvanised coating thickness. Our snubbers, plus all the chains (+ shackles etc etc) I have processed for those who want to downsize their rode We have not had any disasters. I will be buying my battery monitor through either Aliexpress or Temu (Temu is convenient if they hold stock locally). NASA who are 'sort of' middle of the road in terms of price would be another option (for our battery mon for Lithium).
I don't recommend buying direct, unless you speak Chinese fluently - go through Aliexpress or Temu. We gained confidence as we ran a business selling into China and maintain some useful contacts.
But for a solar harvesting display for a few weekends a year - Victron will simply discourage the investment. Think outside the box.
Alicatt - lithium battery prices have dropped, or they have here in Australia. There is a developing market for Lithium for caravans, motor homes etc. Look for different suppliers, different to Victron.) If you read back through the threads on those who have hanged to Lithium there is a huge volume of member experience (like Kelpie and Geem)
Jonathan
I understand that solar panels - the component you need to harvest the sun - are as cheap as chips in the UK. Victron, and others, identifying the needs have developed increasingly sophisticated components to manage, control and document the harvesting at costs, for each component, factorially greater than the solar cells.
Someone wanting to harvest the sun finds that the costs have grown exponentially when all they wanted to do was have a bit of free electricity - free as long as you steer clear of Victron.
As Kelpie points out there are cheaper options - but these are ignored by the majority who want to exclusively suggest management systems costing totally out of proportion to the desires of the OP(s). Do take note of Wonkywinch's cautionary post, also above - and make sure your and the suppliers specs coincide
No-one who wants to simply have a bit of solar for the a weekend or 2 is going to invest in the Victron options. In fact many who fancy a bit more solar, a bit more off grid, are going to look at Kelpie's suggestions - and ignore the Victron suggestions.
What is lacking are more suggestions along the lines of Kelpie's installation.
I have not looked at MPPT controllers yet but if you google: 'Shunt battery monitors' and add, as individual searches the brands 'Xeron' ; 'YKSEI Autoparts' ; ' 'ECO-Worthy'; 'Aili'; 'TR16 Coulomb meter' maybe also add 'Temu' or 'Aliexpress' you will find battery mons ranging in prices from about 20stg - 40stg (and more). If you don't like the idea of a Chinese source then look at NASA. To cut back on the responses also add 'lead' or 'Lithium'.
I suspect you can make the same search replacing 'shunt battery monitor' with 'MPPT controller'.
Some of the suppliers have customers comments, many do not. Sometimes the 'English' can be a bit quaint. But if you buy through Aliexpress and especially Temu you can send the item back if it does not perform (I think Temu is UK based, its Chinese but based in the US, Australia etc etc - its a recent development of the supply route - but apparently very successful and popular).
I have no personal experience of any of these items - you are on your own. But read Kelpie's posts, above. The risks are low - if you are happy with the returns policies - and the prices are factorially lower than Victron.
We have bought a cross section of 'stuff' from China (direct) and from Aliexpress and Temu. My 2t load cell, a crane scale, a chain winch, my coating thickness meter for galvanised coating thickness. Our snubbers, plus all the chains (+ shackles etc etc) I have processed for those who want to downsize their rode We have not had any disasters. I will be buying my battery monitor through either Aliexpress or Temu (Temu is convenient if they hold stock locally). NASA who are 'sort of' middle of the road in terms of price would be another option (for our battery mon for Lithium).
I don't recommend buying direct, unless you speak Chinese fluently - go through Aliexpress or Temu. We gained confidence as we ran a business selling into China and maintain some useful contacts.
But for a solar harvesting display for a few weekends a year - Victron will simply discourage the investment. Think outside the box.
Alicatt - lithium battery prices have dropped, or they have here in Australia. There is a developing market for Lithium for caravans, motor homes etc. Look for different suppliers, different to Victron.) If you read back through the threads on those who have hanged to Lithium there is a huge volume of member experience (like Kelpie and Geem)
Jonathan
Last edited:
Kelpie
Well-known member
Victron batteries are a crazy price.Was thinking about using solar to supplement/replace the shore power for the winter months and was looking at the local Victron supplier for ideas.
Started looking at batteries, first was a 180Ah Victron LiPo, next was a 2.4MWh in a 40ft container
Best bang for buck with lithium is to buy cells and BMS and assemble it yourself.
I spent £407 on my first battery, 271Ah and it's been in daily use for over two years, running the galley.
My second one arrives on Monday on the slow boat from China- 280Ah for $548 plus whatever Grenada customs charges me for import duty.
If you don't want to assemble a pack, you can get 'drop in' lithium for around twice the price. Still a lot cheaper than Victron.
simonfraser
Well-known member
'No-one who wants to simply have a bit of solar for the a weekend or 2 is going to invest in the Victron options. In fact many who fancy a bit more solar, a bit more off grid, are going to look at Kelpie's suggestions - and ignore the Victron suggestions'
those solar weekend warriors may want their kit to work 100%
i'm happy to pay for Victron monitors / shunts etc
no buttons to go wrong all bluetooth - excellent kit imo
those solar weekend warriors may want their kit to work 100%
i'm happy to pay for Victron monitors / shunts etc
no buttons to go wrong all bluetooth - excellent kit imo
