Solar panel regulator - lots of choice, much confusion

[CLB]

This is not for my boat but thought you guys would have the answer as it is basically the same setup that I guess you would have on a boat. I have a 60w solar panel that will be linked to a single 200Ah gel battery. The battery will run an 300W invertor which runs a few low powered charging units for phones, tablets, laptops etc and I will also run some 12V LED lights direct from the battery. I reckon max draw at any one time will be 100w @ 240v (circa 3A) through the invertor and about 12w at 12v (circa 1 amp) direct from the battery. So a total of around 4A over a period of around 9 hours. I guess that means I am using 36Ah out of my 200Ah battery. Anyway the question is, what regulator should I use? There seems to be some very cheap ones on ebay for around £5 and some on Maplins for over £100. I don't mind spending the money, just don't want to if the cheaper ones will do the job just as well.

Soooooooooo, can anyone recommend me a decent value for money, not necessarily cheap, regulator for the above setup?
Cheers

 

[VicS]

100 watts at 240 volt from your inverter is going to pull a good deal more than 3 amps from a 12 volt battery. Over 8 amps if the inverter is 100% efficient which it isn't.

Cheapest regulators are those that simply disconnect the panel from the battery when the volts rise to the determined figure and dont reconnect until fallen again to a much lower figure. Least effective except perhaps to prevent over charging of a lightly used system.

Much better; "Pulse width Modulation" (PWM) which actually controls the charging rate as the battery becomes charged.

Best, esp if needing to get the max out of the panel, is "Max power point tracking" (MPPT) which will control the panel at its maximum power production, converting the excess volts into more amps for charging. Some are apparently not as good as others. If you need to squeeze the maximum from the solar panel investing in a good MPPT regulator may be your best option


I think you will need a larger panel than 60 watts maybe an alternative ( wind turbine ??) as well

 

[Rigger Mortice]

I'm trying to work out your 3 amp figure for the inverter. 100 watts will be a lot more than 3 amps from the battery.
Is there an error in your calculations?

 

[CLB]

oops, yes more than one mistake I think. Firstly I was using 240v, then I got the numbers the wrong way around. So my incorrect figures should actually have been 0.5A, allowing for some losses. So using 12V instead of 240, the power drawn will actually be more like 9-10 amps plus another amp for the LEDs. So I am looking at a draw of 10-11 amps, but the solar panel will only put in 5 amps at best. Might need to rethink the system a bit.

 

[Rigger Mortice]

Do away with the inverter and get 12 volt chargers for your electonic gizmo's. The figures should end up being a lot better.

 

[CLB]

Do away with the inverter and get 12 volt chargers for your electonic gizmo's. The figures should end up being a lot better.

That would make sense, and would work with things like phones and tablets but I'm not sure I can charge the laptop from 12v and it accounts for about 50 of the 100 watts.

 

[Rigger Mortice]

I don't know what laptop you have but I assume that you're concerned about it needing more than 12 volts?
There are 12 volt adapters that can do the job. A quick look at the specification will give you an idea of the efficiency; it should be better than using an inverter.

 

[xeitosaphil]

This is not for my boat but thought you guys would have the answer as it is basically the same setup that I guess you would have on a boat. I have a 60w solar panel that will be linked to a single 200Ah gel battery. The battery will run an 300W invertor which runs a few low powered charging units for phones, tablets, laptops etc and I will also run some 12V LED lights direct from the battery. I reckon max draw at any one time will be 100w @ 240v (circa 3A) through the invertor and about 12w at 12v (circa 1 amp) direct from the battery. So a total of around 4A over a period of around 9 hours. I guess that means I am using 36Ah out of my 200Ah battery. Anyway the question is, what regulator should I use? There seems to be some very cheap ones on ebay for around £5 and some on Maplins for over £100. I don't mind spending the money, just don't want to if the cheaper ones will do the job just as well.

Soooooooooo, can anyone recommend me a decent value for money, not necessarily cheap, regulator for the above setup?
Cheers

I am in the same confused state as you are !
I did consider an MPPT controller as VicS suggested but when I looked into it, the amount of extra gain was possibly only going to be about 0.5 amp using a 100w solar panel. It would appear that MPPT controllers only come into their own when your PV array is over 200w or more when the benefits really do make a difference. The more I read the more I have come to think that a PWM controller would suit better for 100w or less, that is if you don’t want to screw the last once out of your panels.

The two I have short listed a the moment is the EP solar PWM at £38

http://www.ebay.co.uk/itm/EP-Solar-...=UK_Gadgets&hash=item1e728254b1#ht_883wt_1018

And also the Morningstar Prostar 15M

http://www.ebay.co.uk/itm/MORNINGST...ltDomain_0&hash=item1c27a466ea#ht_2748wt_1018

Which is a lot more expensive but is made in the USA and I wonder if it is more reliable? Even if it is a bit lacking in monitor options and usability.
Cheapest I can find is my local agent Beco solar at Totnes £130

http://www.becouk.com/solar-pv/ They supply a lot of Navigation Bouyage and Cardinal mark Solar Systems etc.

Others have said they use the Sun Works at £79 which works for them.

http://www.sunworks.co.uk/MotorhomesandBoats.html

I too am in a quandary as to which one to purchase as there are so many available, and I only ever want to have to buy one!

Good luck and let me know which one you go for in the end.

 

[sam_uk]

Agree with getting rid of the inverter.

Some laptops/netbooks are better than others on power. My Sony N220 draws about 10watts.

My understanding is that MPPT converters are more effective, particularly in winter.

I got one of these and it seems to work: http://www.ebay.co.uk/itm/10A-15A-2...595516?pt=UK_Gadgets&var=&hash=item27d4018b3c

If I was buying one now i'd be tempted by this cheap IP68 rated one: http://www.ebay.co.uk/itm/15A-MPPT-...21094975996?pt=UK_Gadgets&hash=item1c31d2b1fc

 

[charles_reed]

I use 12v chargers for my laptops for about 95% of their working life. They're used on a boat for 6/7 months a year and then sit at home whilst I use a desktop instead. Look up Amazon.co.uk for suitable chargers for your laptop.

If in the UK you'll find your specified PV panel totally inadequate. Even if the panel is tracked to maximise insolation it will only put in about 10ah/day in summer and half that in winter.

To avoid confusion about watts - let's work in amp-hours , that is watts/volts/time. No device will be entirely loss-free in its conversion and a DC/AC inverter will be the most loss-ridden.

In Greece, with 330 watts of PV panel, I cater for all my needs in summer in winter I have to run the engine every 5th day to recharge.

Unless you have an MPPT controller the PV panels will only maintain battery charge at an ever-decreasing level.

So I'd suggest you work out your power requirements for every 24 hours and convert to amp-hours. Specify a battery on at least x4 that capacity and PV panels to supply x2 that amp-hour requirement - specify an MPPT controller rather than an PWM controller and ignore the simple on-off ones.