Solar panels

[ukracer]

They do last but only if you have to buy quality ones not the ebay cheap versions, I have fitted a fair few to boats. The main problem with the flexi ones are they are expensive for the amount of power that you get compared to the solid framed versions.

A charge controller is a must, it's worth getting a MPPT one and unless our customer wants some other brand we always fit a Victron Energy model as they're good kit and we've get no problems with them.

@ukracer since you're wanting it to keep your batteries charged up over winter you better fit a bigger system as they produce a lot less than the advertised power with the limited hours and strength of the winter sun, also you'd be better angling it to suit the low sun angle or the efficiency will suffer.

I missed this before. So i just checked and the problem is my panels are 31 volts and to get a victron one i need to get the 50 amp which is a fortune.

Why does nothing ever go smooth...

 

[wookie]

I missed this before. So i just checked and the problem is my panels are 31 volts and to get a victron one i need to get the 50 amp which is a fortune.

You could use the 100/30 model, which is good for 440w with a 12v battery, okay you loose the theoretical maximum that your 2 panels can make which is 570w but how often are you gonna get the maximum from the panels anyway ? That would save you about £90.

 

[ukracer]

You could use the 100/30 model, which is good for 440w with a 12v battery, okay you loose the theoretical maximum that your 2 panels can make which is 570w but how often are you gonna get the maximum from the panels anyway ? That would save you about £90.

Learning all the time. If you use too low a controller what happens if the sun comes up......does it only harvest 440 instead of 570 and not damage the controller.

When i see 12 / 24 /48 etc is that the size of battery?

I was told that PWM wont handle my panels which is one reason i need Mppt amongst others such as low light working better etc

 

[wookie]

Learning all the time. If you use too low a controller what happens if the sun comes up......does it only harvest 440 instead of 570 and not damage the controller.

Correct, once your panels produce the maximum that the solar regulator can handle it just limits the output even if the sun light then increases. Also don't forget panels degrade over time so after a few years you won't get the original output from the panel anyway.

When i see 12 / 24 /48 etc is that the size of battery?

That refers to the battery banks nominal voltage, if you look at the specs the solar regulator has a maximum voltage & maximum current and since power(watts) is voltage times current it can handle more power when used with higher voltage banks. That Blue solar 100/30 for example can handle 440w on a 12v system but 880w on a 24v system because the limiting factor is the current it can cope with.

As current increases you need fatter cables which cost more and weigh more, where as with higher voltage you just needs better insulation. But it's no good having a 48volt battery bank if everything you want to use is only 12volt, you're just making more headaches for yourself.

Another problem with higher voltage battery banks is you need a higher panel output voltage to start charging so with your two panels you'd connect them in series to make higher voltage so it starts charging sooner but then if one panel is shaded it will limit the other panel where as if you connect them in parallel you don't get the shading problem but you're back to needing thicker cables, it's always swings and roundabouts.

Whatever you do don't tempted to centre tap a battery bank to get a lower voltage i.e. you want 12v but have a 24v bank, it's a sure fire way to kill a battery bank in no time at all.

 

[ukracer]

Correct, once your panels produce the maximum that the solar regulator can handle it just limits the output even if the sun light then increases. Also don't forget panels degrade over time so after a few years you won't get the original output from the panel anyway.


That refers to the battery banks nominal voltage, if you look at the specs the solar regulator has a maximum voltage & maximum current and since power(watts) is voltage times current it can handle more power when used with higher voltage banks. That Blue solar 100/30 for example can handle 440w on a 12v system but 880w on a 24v system because the limiting factor is the current it can cope with.

As current increases you need fatter cables which cost more and weigh more, where as with higher voltage you just needs better insulation. But it's no good having a 48volt battery bank if everything you want to use is only 12volt, you're just making more headaches for yourself.

Another problem with higher voltage battery banks is you need a higher panel output voltage to start charging so with your two panels you'd connect them in series to make higher voltage so it starts charging sooner but then if one panel is shaded it will limit the other panel where as if you connect them in parallel you don't get the shading problem but you're back to needing thicker cables, it's always swings and roundabouts.

Whatever you do don't tempted to centre tap a battery bank to get a lower voltage i.e. you want 12v but have a 24v bank, it's a sure fire way to kill a battery bank in no time at all.

I will only have a 12 volt 110 amp leisure battery to start with my 230 amp pair are knackered and 500 quid to replace.

My current issue is spending 225 quid now when i had planned for 117 lol.

 

[ukracer]

Where do i get those solar panel brackets from. I can only see the corner ones and i need some straight onrs as well.

 

[ukracer]

Ok i took wookies advice and ordered a smart solar 100/30 as it was showing in stock on the website.....sadly they did not have one after i paid etc.

Anyway although its stiffed me over as they wont get one to me until wednesday and it means i cant go and fit it in decent weather it was 25 quid cheaper than anywhere else i could find (and none could guarantee me to have it by friday.) I am almost there.

I just need to know how to wife the panels. Would i wire in series or parallel?

 

[wookie]

I just need to know how to wife the panels. Would i wire in series or parallel?

If I've got the spec of your solar panels correct (31v and 285w) then you could wire them either way, your not gonna exceed either the max amps in parallel (30A) or the voltage in series (100V) so it depends on whether or not you're likely to have shading problems.

If you think you might get one of the panels partially shaded then parallel is the way to go, otherwise I'd go series and get away with thinner and therefore cheaper cables.

 

[ukracer]

If I've got the spec of your solar panels correct (31v and 285w) then you could wire them either way, your not gonna exceed either the max amps in parallel (30A) or the voltage in series (100V) so it depends on whether or not you're likely to have shading problems.

If you think you might get one of the panels partially shaded then parallel is the way to go, otherwise I'd go series and get away with thinner and therefore cheaper cables.

Cheers mate. I eventually managed to get some plugs and cable. It was a bit of a mission...... but got all the cable and plugs for 6 quid so alls well that ends well. SO FAR.

I forgot we have flu jabs booked or we would have had an early start to get it all done quickly tommorow. But at least i can get some kip and get cracking after our jabs in the morning now.