Jump to content
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
Blue Knight

Advice On Solar Panel Technology Please

Featured Posts

A big thank you to all you guys for your in-depth responses tonight. I don't claim to understand it all at the moment but I'll sit down in the morning with fresh eyes, a coffee and a jotter and then engage brain.

 

We have now gone into lockdown mode in Durham so it's safe to say that I have a bit of time on my hands to think about this subject.

 

Thanks again chaps 😉

 

All the best,

 

Andrew

 

 

Share this post


Link to post
Share on other sites
1 hour ago, David Mack said:

 

But you can customise the Bimble kits. So it can be quite an easy way to work out all the bits and pieces you need by starting with a kit and then adding or substituting items as you wish (or even deleting the odd item if you can get something better/cheaper elsewhere). 

Which is exactly what I suggested,  and dont take their advice ....ask elsewhere. 

Share this post


Link to post
Share on other sites
10 hours ago, dmr said:

OK, first it amp-hours rather than amps, and this forum can be a bit harsh if you get this wrong. We have Trojan T105/T125s which are wet lead acid. I am keeping a close eye on Lithiums but at present the Trojans make better economic sense. The 50% thing is a bit of a myth, though so deeply rooted its not worth arguing about. Proper lead acids go down to 20% though 40% to 50% is a good target as a safety margin is nice.

I try to keep the batteries above 50% but really don't stress if they go down to 40 or even 35.

 

Any more than about 800 amp-hour then 2v tractions are a better bet, and in the next few years it will swing in favour of Lithium, AGM is not a good option unless your boat design or personality makes topping up difficult.

 

..............Dave

 

The % SoC you can safely discharge down to depends on the lead acid battery type.

 

Most "leisure" batteries are rebadged starter batteries with thin plates, so 50% depth of discharge and limited cycles for longer life of 2-4 years.

 

Trojans are semi traction batteries with thicker plates, so can go down to 25%   SoC and can deliver more cycles. Typical life is 10 years

 

Finally you can get traction batteries. Very thick plates and deliver many cycles.The ones I used to work with had a capacity test to 0% every 2 years and used lsst 25 years plus.

 

With AGMs you tend to get what you pay for. My boat was fitted with Lifeline AGMs when I bought it, which have an excellent reputation in the salty marine and critical power industry. They are now in their 13th year, and still have over the 50% of original capacity left. However they are not cheap.

 

When they fail they will be replaced by Trojans, or LifePO4 if off the shelf drop in systems are available at reasonable prices by then.

  • Greenie 1

Share this post


Link to post
Share on other sites
10 hours ago, dmr said:

OK, first it amp-hours rather than amps, and this forum can be a bit harsh if you get this wrong.

He said Amps per day, not Amp Hours per day, so I let it slide. If he had said Amps per Hour, then no mercy! 😁

Jen

  • Haha 1

Share this post


Link to post
Share on other sites
11 hours ago, matty40s said:

Bimble have offered very dubious advice on occasions, I have had to get customers to send stuff back and exchange it for a better fit which wont blow up the controller before now.

 

Bimble offer the best prices for what they stock. But dont buy the kits, buy what is best for you.

This, Bimble are good price wise soloing as you know what you need beforehand. 

Share this post


Link to post
Share on other sites
51 minutes ago, Jen-in-Wellies said:

He said Amps per day, not Amp Hours per day, so I let it slide. If he had said Amps per Hour, then no mercy! 😁

Jen

Hmmm... how is amps per day any better than amps per hour, or amps per leap-year? Amphours per day would have been perfectly acceptable. 

Share this post


Link to post
Share on other sites

Bang for Buck for panels is

cheapest per watt are domestic 36 volt (OC) panels in the 240 to 350 watt range

middle per watt are '12 vol't 100 to 150 watt, 18 volt (OC) panels

more costly are flexible of any type and many of them have a shortened life due to steel rooves getting very hot reducing panel efficiency and cracking bits due to differential expansion, and although walkon in winter in workboots covered in towpath grit is not the best mix.

use a MPPT controller even for the '12volt' panels as the extra 20% is worth having, you have to be careful with small MPPT controllers which are often PWM with the wrong label.  Put panels in parallel or at most 2 in series and pairs in parallel if more than 4, this reduces the effects of shading from trees, ropes, buildings etc as the current is limited by the shaded panel if wired in series.

Do not expect the rated output in the UK, in summer you may approach 80% on a good day for an hour or so, but can have 10 hours above 50%. In winter you are very lucky to get more than 25% for a few minutes on an ideal day, normally recon on 10% of rating for 2-3 hours.

Edited by Detling
more
  • Greenie 1

Share this post


Link to post
Share on other sites
15 minutes ago, WotEver said:

Hmmm... how is amps per day any better than amps per hour, or amps per leap-year? Amphours per day would have been perfectly acceptable. 

We each have different pedant engagement thresholds. Amps per Hour will have me spraying coffee over the screen though. 😁

Share this post


Link to post
Share on other sites
16 minutes ago, Jen-in-Wellies said:

We each have different pedant engagement thresholds. Amps per Hour will have me spraying coffee over the screen though. 😁

One of my favourites is “I have a 100 Amp battery”. My response to myself is always “Gee, it must be pretty small. I wonder what its capacity is...”

Share this post


Link to post
Share on other sites
25 minutes ago, Jen-in-Wellies said:

We each have different pedant engagement thresholds. Amps per Hour will have me spraying coffee over the screen though. 😁

Amps per hour is a possibility. 1 Amp per hour would mean for example, that you are using 1 Amp of current in the first hour, then you switch on some more lights, and use 2 for the next hour, then switch on some more (and your coffee maker) and use 3 during the next hour etc etc. A log scale would be better, so you could (say) double your current consumption every hour. The boat would get rather hot by the end of the day..... 

Share this post


Link to post
Share on other sites
1 hour ago, WotEver said:

One of my favourites is “I have a 100 Amp battery”. My response to myself is always “Gee, it must be pretty small. I wonder what its capacity is...”

Surprisingly the 90Ah battery on my car, made by Yuasa, is labelled all over in big letters "850 Amps". This seemingly relates to the current that is supposed to register on their drop-tester when it is placed across the terminals. The drop-tester instructions, relating to this particular battery, even state that the battery "should be replaced when its capacity has fallen below 550 Amps"

Share this post


Link to post
Share on other sites
11 minutes ago, Keeping Up said:

Surprisingly the 90Ah battery on my car, made by Yuasa, is labelled all over in big letters "850 Amps". This seemingly relates to the current that is supposed to register on their drop-tester when it is placed across the terminals. The drop-tester instructions, relating to this particular battery, even state that the battery "should be replaced when its capacity has fallen below 550 Amps"

Yup, that’s my point. Your 850 Amp battery only has a capacity of 90Ah. Imagine how small a 100A battery would be. 

Share this post


Link to post
Share on other sites

G'Day All,

 

I've made a few short notes so that I can help configure a plan. I'll first need to see how my batteries are performing when I see the boat for its survey on the 14th Oct but other than that I reckon that Im now getting the gist of what you fine folk are advising.

 

Here goes:

 

1.  @DaveP  Consider 'redundency' for those dark drizzly days, 2. Panels are c.30% more efficient when angled, 3.  Don't buy expensive batteries for your first set (get to know your usage rates first),  4. Check the effiency of the panels which I intend to buy, including the voltage and current specs and match the solar regulator accordingly,  5.  Consider shorepower as  a supplementary support method, wherever possible, and use the fridge sparingly during dark months.

 

@WotEver  6.  Battery bank capacity should be at least 3 times daily usage,  7.  Try and generate 120% of daily usage.

 

@nbfiresprite  8.  Use fixed panel technology only, avoid flexi and stick-downs.

 

@dmr  9.  A good battery choice is the Trojan T105/T125,  10. The 50% DoD on lead acids is a myth if the correct battery specs are used,  11.  Don't stress If the battery bank (with appropriate wet acid battery types fitted) reaches 35-40% DoD.

 

@Dr Bob  12.  Gives a good example of the performance of a 30A MPPT with 500W of solar,  13.  Select a suitable 5-6 battery sized bank as long as your charge regime can support it,  14.  Try not to reduce to 60%-70% SoC if possible.

 

@cuthound  15.  Most standard leisure batteries are just rebadged starter batteries,  16.  Trojans are semi-traction type and can drop to 25% SoC.

 

@Detling  I'll reply separately to your post if I may.

 

With these guidelines in place I reckon my plan will come together soon enough.

 

Regards to all,

 

Andrew

Share this post


Link to post
Share on other sites
4 minutes ago, Blue Knight said:

With these guidelines in place I reckon my plan will come together soon enough.

Note that a 5-battery bank becomes a 10-battery bank if you go for Trojan T105s as they’re 6V batteries. It’s easy to overlook that when you’re budgeting for space and cost. 

  • Greenie 1

Share this post


Link to post
Share on other sites
3 hours ago, Detling said:

Bang for Buck for panels is

cheapest per watt are domestic 36 volt (OC) panels in the 240 to 350 watt range

middle per watt are '12 vol't 100 to 150 watt, 18 volt (OC) panels

more costly are flexible of any type and many of them have a shortened life due to steel rooves getting very hot reducing panel efficiency and cracking bits due to differential expansion, and although walkon in winter in workboots covered in towpath grit is not the best mix.

use a MPPT controller even for the '12volt' panels as the extra 20% is worth having, you have to be careful with small MPPT controllers which are often PWM with the wrong label.  Put panels in parallel or at most 2 in series and pairs in parallel if more than 4, this reduces the effects of shading from trees, ropes, buildings etc as the current is limited by the shaded panel if wired in series.

Do not expect the rated output in the UK, in summer you may approach 80% on a good day for an hour or so, but can have 10 hours above 50%. In winter you are very lucky to get more than 25% for a few minutes on an ideal day, normally recon on 10% of rating for 2-3 hours.

A very good post, I appreciate it, thanks;-)

 

Can I pick your brains on your reference to the '12v 100-150W 18v(OC) panels' for a second.

 

I've not yet checked the technical specs of the various panels for sale on the web pages but are you recommending that any solar set-up is configured just from 100-150W panels, and not from the 240/270/300/320/340W panels that you see available on some of the web sites.

 

Is that the optimum size for efficiency?

 

Regards,

 

Andrew

 

 

Share this post


Link to post
Share on other sites
19 minutes ago, WotEver said:

Note that a 5-battery bank becomes a 10-battery bank if you go for Trojan T105s as they’re 6V batteries. It’s easy to overlook that when you’re budgeting for space and cost. 

Thanks @WotEver that's a really good point you make.  My battery bank space is probably limited to 5 × standard sized units which in theory should be OK for most things (famous last words).

Edited by Blue Knight

Share this post


Link to post
Share on other sites
14 minutes ago, Blue Knight said:

Select a suitable 5-6 battery sized bank as long as your charge regime can support it, 

I didnt say anything about needing to  consider charge regimes supporting a larger bank.

If you have 4*110Ahrs and have a routine of using and charging then increasing the bank to 5 or 6*110Ahr will have zero effect on the charge regimes. You are still going to be putting the 80Ahrs or wotever back in each day and charging with a charge source that is not that different in ratios. You will be spending less time in bulk but charging with more Amps during the reducing tail current period. There are 'rules' about the size of charge sources versus battery capacity but a lot depends on what you do. An example is on our last boat, we had 6*110Ahr 'cheapos' with a 100A victon combi charger. I wanted to go to separates so bought a 30A vicron charger and used the combi as an inverter only. Was 30A big enough as a charger for my 660Ahr bank? Yes of course it was, as I only ever charge when in the marina (dont use a genny) and as we are out and about over 50%  of the time it doesnt get used much. It is turned on when we get back to the marina (when we are there) but by the time we get in, the alternator has mainly charged the batteries so I didnt need big amps going in - and we were usually there for more than 24 hrs so 30A would charge anything. Yes, if we had a genny then maybe a bigger charger would have been more efficient....but we didnt.

Ignore your charge regimes if considering adding a couple of extra batteries.

  • Greenie 1

Share this post


Link to post
Share on other sites
3 minutes ago, Dr Bob said:

I didnt say anything about needing to  consider charge regimes supporting a larger bank.

If you have 4*110Ahrs and have a routine of using and charging then increasing the bank to 5 or 6*110Ahr will have zero effect on the charge regimes. You are still going to be putting the 80Ahrs or wotever back in each day and charging with a charge source that is not that different in ratios. You will be spending less time in bulk but charging with more Amps during the reducing tail current period. There are 'rules' about the size of charge sources versus battery capacity but a lot depends on what you do. An example is on our last boat, we had 6*110Ahr 'cheapos' with a 100A victon combi charger. I wanted to go to separates so bought a 30A vicron charger and used the combi as an inverter only. Was 30A big enough as a charger for my 660Ahr bank? Yes of course it was, as I only ever charge when in the marina (dont use a genny) and as we are out and about over 50%  of the time it doesnt get used much. It is turned on when we get back to the marina (when we are there) but by the time we get in, the alternator has mainly charged the batteries so I didnt need big amps going in - and we were usually there for more than 24 hrs so 30A would charge anything. Yes, if we had a genny then maybe a bigger charger would have been more efficient....but we didnt.

Ignore your charge regimes if considering adding a couple of extra batteries.

That makes perfect sense plus the various examples you made above are thoughtfully written in a way that us newbie fickies can understand. 

 

Very helpful indeed @Dr Bob

 

Very best,

 

Andrew

 

P.S. Now we're cooking on gas 🙂

 

  • Greenie 1

Share this post


Link to post
Share on other sites
45 minutes ago, Blue Knight said:

Now we're cooking on gas 🙂

Thank the Lord you didn’t suggest cooking with electric...

  • Greenie 1

Share this post


Link to post
Share on other sites
6 hours ago, WotEver said:

how is amps per day any better than amps per hour

 

You get 24 times as many amps, obviously!

  • Happy 1
  • Haha 1

Share this post


Link to post
Share on other sites
3 hours ago, Blue Knight said:

G'Day All,

 

I've made a few short notes so that I can help configure a plan. I'll first need to see how my batteries are performing when I see the boat for its survey on the 14th Oct but other than that I reckon that Im now getting the gist of what you fine folk are advising.

 

Here goes:

 

1.  @DaveP  Consider 'redundency' for those dark drizzly days, 2. Panels are c.30% more efficient when angled, 3.  Don't buy expensive batteries for your first set (get to know your usage rates first),  4. Check the effiency of the panels which I intend to buy, including the voltage and current specs and match the solar regulator accordingly,  5.  Consider shorepower as  a supplementary support method, wherever possible, and use the fridge sparingly during dark months.

 

Just a point on the last item. _Don't_ use the fridge.  Each time you use it, a huge amount of power will be taken to get it down to operational temperature (disregard in the case of using a shoreline to do this).  

 

 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.