Solar....how much wattage is enough

[MtB]

4 hours ago, Theo said:

The progress of this discussion is distressingly familiar.

 

Does any one remember the chap who threatened to take Daniel to court because his erroneous electircal opinions were hidden from general view ?

 

Makes me wonder if Horace is his reincarnation.

 

N

 

Yea I remember him. And I agree, Horace's determination not to understand and keep peddling his utter claptrap made up on the fly, rhymes perfectly. 

 

But what was his username??!!!

[Horace42]

4 hours ago, Richard10002 said:

Horace, I have 490W of solar panels, and a 40A Tracer BN MPPT controller and am at the point where I need new batteries. My power useage is about 100Ah per day, and I have the means to charge by engine or generator in the winter or if there is no sun.

 

What range of battery bank sizes would my panels be OK for?

First I don't know what a 40A Tracer BN MPPT is. But do I need to know? You have no doubt read all the post. You should have enough info from other experts, who say they know better than me, so on the their advice you can work it out yourself.

For my money if by new batteries you mean replacing the ones you already have - and if everything works OK - then get more of the same size.

But if it is something you genuinely would like an answer to (or just to test my knowledge) then basically you need 300Ah (this comes from WotEver 3 x daily demand formula)(although he did say minimum) so maybe a bit more. I don't know.

but a 490W panel at 12v gives 40A  (is that the 40 Tracer bit?) which for 10 hrs relates to 400Ah. So not far out.

These are simple engineering calculations to balance one thing against another to help reach the right answer.

It's your boat, it's your money and it's your decision. 

Good luck.

18 minutes ago, Mike the Boilerman said:

 

Could you explain what a 'balanced system' is in this context please?

 

I'm mystified. 

Yes, where everything is the right size and everything works as you want it.

[Horace42]

40 minutes ago, system 4-50 said:

can you fill in the presumably missing words to make it clearer what you are trying to say?

I think 'enough' is the word.

 

[MtB]

12 minutes ago, Horace42 said:

 

Yes, where everything is the right size and everything works as you want it.

 

This illustrates you haven't understood a word that's been written in this thread about solar. 

 

 

[reg]

5 minutes ago, Horace42 said:

I think 'enough' is the word.

 

Finally agree on something, would go further and say Enuf is Enuf 

Me finito with this. 

Edited May 28, 2018 by reg

[Dr Bob]

13 minutes ago, Horace42 said:

But if it is something you genuinely would like an answer to (or just to test my knowledge) then basically you need 300Ah (this comes from WotEver 3 x daily demand formula)(although he did say minimum) so maybe a bit more. I don't know.

but a 490W panel at 12v gives 40A  (is that the 40 Tracer bit?) which for 10 hrs relates to 400Ah. So not far out.

 

So the battery bank size has nothing to do with how much solar! Just what we have all been saying all along. I have 660Ahr 'cause I want to only go down to 85% Charge rather than WotEvers 3* . Absolutely nothing to do with the solar.

 

.....and a 490W panel will not give you 40A.

Finally got there. Well done!

[MtB]

46 minutes ago, Mike the Boilerman said:

But what was his username??!!!

 

I've remembered!

 

I think it was graham-m (or something similar). 

[Horace42]

1 hour ago, WotEver said:

You guess wrong

You guess wrong again

Wrong again!

 

You’re on a roll here. 

It is only your opinion and sorry to say I rate it as worthless - pity really because some of you contributions on other threads have been quite good.

 

Making fun of me - or belittling me to win the argument - simply suggests you have run out of plausible technical explanations. It might impress your mates but it will get you nowhere with me.

 

I will say it again, and keep on saying it for the benefit of other interested readers  - the demand, the batteries and the charging system must be balanced and matched to your pattern of usage.

 

Basic engineering!

 

 

[WotEver]

7 minutes ago, Horace42 said:

It is only your opinion...

Sadly it’s not. It’s fact. As has been explained to you by many other posters in this thread. 

 

As to whether or or not it impresses you why on earth do you suppose that I would care one way or the other?

Edited May 28, 2018 by WotEver

[MtB]

2 minutes ago, Horace42 said:

 

I will say it again, and keep on saying it for the benefit of other interested readers  - the demand, the batteries and the charging system must be balanced and matched to your pattern of usage.

 

Basic engineering!

 

 

 

Basic bollox, actually. 

 

The batteries and the charging system must be designed to match your demand and pattern of usage, to swap it around to read correctly.

 

And a charge source that delivers nothing for a quarter of the year obviously cannot form part of your 'balanced' system.

[WotEver]

Just now, Mike the Boilerman said:

 

Basic bollox, actually. 

 

The batteries and the charging system must be designed to match your demand and pattern of usage, to swap it around to read correctly.

 

And a charge source that delivers nothing for a quarter of the year obviously cannot form part of your 'balanced' system.

Spot on sir. However, writing it is, I fear, wasted electrons. 

[MtB]

Just now, WotEver said:

Spot on sir. However, writing it is, I fear, wasted electrons. 

 

No, don't overlook the fact that lots of people red this site to learn but never post. 

 

Countering twaddle helps people you and I will never hear of, or know about.

 

(Except on the odd occasion one surfaces here and says thank you - as happens from time to time!)

[WotEver]

Just now, Mike the Boilerman said:

 

No, don't overlook the fact that lots of people red this site to learn but never post. 

 

Countering twaddle helps people you and I will never hear of, or know about.

 

(Except on the odd occasion one surfaces here and says thank you - as happens from time to time!)

A good point well made

[MtB]

1 minute ago, WotEver said:

A good point well made

 

Thank you.

 

And for the record, despite your somewhat abrasive posting style sometimes, I have learned shedloads from your posts for which I'm very grateful (even if I may not seem it at at times). Now seems an apposite time to say 'thank you'. Thank you!

 

 

[Horace42]

31 minutes ago, Mike the Boilerman said:

 

This illustrates you haven't understood a word that's been written in this thread about solar. 

 

 

I understand enough for my own satisfaction - and likewise I could say the same about you.

 

36 minutes ago, Dr Bob said:

So the battery bank size has nothing to do with how much solar! Just what we have all been saying all along. I have 660Ahr 'cause I want to only go down to 85% Charge rather than WotEvers 3* . Absolutely nothing to do with the solar.

 

.....and a 490W panel will not give you 40A.

Finally got there. Well done!

You might have got there - The battery size is to do with the demand - and solar panel is to do with charging it. They compliment each other.

but not 40A - do you mean I should have said 40.83333.....  or?

So what current will a 490W panel give

[WotEver]

1 minute ago, Mike the Boilerman said:

Thank you.

 

And for the record, despite your somewhat abrasive posting style sometimes, I have learned shedloads from your posts for which I'm very grateful (even if I may not seem it at at times). Now seems an apposite time to say 'thank you'. Thank you!

Aww shucks. You’ve helped me many times too - that’s what forums (fora?) like this are for. So thanks back. 

[WotEver]

1 minute ago, Horace42 said:

So what current will a 490W panel give

An absolute maximum of 34A at charging voltage. Far more likely to be mid-20’s here in the UK on most days. 

 

The actual charging current will of course entirely depend on the state of charge of the batteries. 

[MtB]

3 minutes ago, Horace42 said:

 

So what current will a 490W panel give

 

Depends on the weather. 

 

And the state of charge of the battery being charged. 

 

And the type of controller.

 

But you're not interested really. I can see that. Nothing sinks in. 

 

You ARE graham-m and I claim my five pounds!

[Horace42]

13 hours ago, WotEver said:

Geez... it can’t!  Let me explain very slowly again... The. Bank. Size. Is. Irrelevant. To. The. Amount. Of. Solar. 

Sorry, isn't stage 2 the demand/load, not battery size.

[Dr Bob]

26 minutes ago, Horace42 said:

 

but not 40A - do you mean I should have said 40.83333.....  or?

So what current will a 490W panel give

A tad over 30A in full sun which is what wotever said. Note in full sun. In yesterday's thunder storm it was zero. For 3 moths of the year it is almost zero. That of course is only when the batteries will accept that charge. 

 

You are are living in cloud cuckoo land if you think you can have a balanced charging/battery system on a boat that depends on solar. It ain't goin to happen. Just like Mike has said.

[Horace42]

10 minutes ago, Mike the Boilerman said:

 

Depends on the weather. 

 

And the state of charge of the battery being charged. 

 

And the type of controller.

 

But you're not interested really. I can see that. Nothing sinks in. 

 

You ARE graham-m and I claim my five pounds!

Everything sinks in, except the Graham-m bit is a bit -  over my head. I just pick the technical bits that are relevant - the rating given was 490W - that at 12V should be able to deliver 40A - in the rated design mode. I appreciate there could be quirks in operation - so what does the 490W refer to.

[MtB]

6 minutes ago, Horace42 said:

so what does the 490W refer to.

 

CBA.

 

Not responding to your trolling any more. GFY.

 

 

Edited May 28, 2018 by Mike the Boilerman

[Horace42]

3 minutes ago, Dr Bob said:

A tad over 30A in full sun which is what wotever said. Note in full sun. In yesterday's thunder storm it was zero. For 3 moths of the year it is almost zero. That of course is only when the batteries will accept that charge. 

 

You are are living in cloud cuckoo land if you think you can have a balanced charging/battery system on a boat that depends on solar. It ain't goin to happen. Just like Mike has said.

You will see my reply to Mike - what does the 490W rating mean if it will only deliver 30A at the best of times - assuming a 12V system.

 

[Horace42]

Regret I must retire for the night - to cloud cuckoo land. I am having trouble fielding the replies and can't concentrate any more - there are too many - but I think I have responded to all those to date.

On balance we have to agree to differ. It has been interesting though.

Tomorrow onwards I've got to stop writing letters and concentrate on getting my boat ready to take to the dry-dock for blacking and valuation.

Do you think Solar panels add value?

If so, it seems as though I might need to come back for some helpful tips.

Goodnight!

 

[reg]

56 minutes ago, Horace42 said:

You will see my reply to Mike - what does the 490W rating mean if it will only deliver 30A at the best of times - assuming a 12V system.

 

A fair question. As far a I understand it it goes as follows 

490w rating is given as the STC rating, which is an industry wide rating which allows one manufacturers panel to be fairly measured against anothers and is arrived at by measuring under a controlled set of conditions and parameters. 

In practice though you would do your calculations based on normal operating conditions, as a rule of thumb you would multiple your 40a by 0.75 to give a real world figure, which in your example would arrive at 30A.

Basically the published figures are a device for panel output comparison between manufacturers. To calculate for normal operating conditions use the 0.75 multiplier to give a more accurate output figure when trying to establish an array Size.

 

Google Solar Panel STC and NOTC for more info(which is what I did) 

 

I'm happy to be corrected on the above if I am wrong. 

Edited May 28, 2018 by reg