Solar upgrade

[Foggy66]

I’m looking to expand the solar array on our boat. It currently consists of 3x100w panels wired in series via a 30amp/100v Victon MPPT controller.

I want to add a further 3x100w panels thus creating a 600w array. 
My initial thought is to add a 2nd set of 3 through a 2nd controller but I’m not sure if this would be the most cost effective  and/or efficient method.

Thoughts please

[DaveP]

How long have you had the panels /how big are they?

What roof estate do you have, are you single-handed?

Are you a liveaboard, what's your average consumption, what other electricity generating equipment do you use?

What controller have you got and what are you thinking of for the 2nd?

 

If you've got the room, then I'd recycle the current panels, and get a pair of 300w domestic panels (either the 295w or 325w ones from Bimble), and (if you want a second controller) a 20A Epever one, or a 40A one.  These can't cope (but won't be harmed) with the full rated output of the panels (assuming you're outputting 12v), but it would be extremely unusual for the panels to overload the controller up here in the UK even in the height of summer.

 

295w - https://www.bimblesolar.com/solar/large-panels/295w-perlite-54cell-small

325w - https://www.bimblesolar.com/solar/large-panels/ja-325w-halfcell

 

20A - https://www.bimblesolar.com/offgrid/mppt/XTRA2206N-XDB1-BUDGET-20a-mppt-solar-controller

40A - https://www.bimblesolar.com/offgrid/mppt/XTRA4210N-XDB1-BUDGET-40a-mppt-solar-controller

 

MT50 Meter for the controllers - https://www.bimblesolar.com/offgrid/mppt/MT50-meter

 

 

 

[Jen-in-Wellies]

41 minutes ago, DaveP said:

but it would be extremely unusual for the panels to overload the controller up here in the UK even in the height of summer.

Don't go boating in the Sahara desert though. Oh wait, right. ?

[Alan de Enfield]

6 minutes ago, Jen-in-Wellies said:

Don't go boating in the Sahara desert though. Oh wait, right. ?

 

 

You've not seen the film "Sahara" then ?

 

(A US Civil war 'Ironclad' found in the Sahara desert)

[Sea Dog]

4 minutes ago, Alan de Enfield said:

 

 

You've not seen the film "Sahara" then ?

 

(A US Civil war 'Ironclad' found in the Sahara desert)

Is it based on a true story...?

 

[Jen-in-Wellies]

7 minutes ago, Alan de Enfield said:

 

 

You've not seen the film "Sahara" then ?

 

(A US Civil war 'Ironclad' found in the Sahara desert)

Did it have solar panels?

[Alan de Enfield]

2 minutes ago, Sea Dog said:

Is it based on a true story...?

 

 

It was based on a Clive Cussler novel

[robtheplod]

If you need to go for narrower panels so you can walk up one side, these fit nicely on one side:

 

190w Solar Panel (148x68cm) — Craig Solar

[Detling]

You would probably do better with the panels in parallel to cope with partial shading. I have 6 x 100 watt panels but I have a 40 amp controller. Panels are wired in my case as 3 serial pairs in parallel. I have a monitor on the solar and the maximum current I have had in the last 3 years is 33.6 amps on one day in 2019, usually daily max is under 30 amps. A MPPT controller will just lose any extra watts it can't pass on to the batteries and limit you to 30 amps maximum you would need to check the manual for maximum permitted overload but in the UK I doubt if your 600 watts of panels would ever produce more than 500 watts. 

[LadyG]

I sold my 3x100 watt panels and chinese controller because they were getting on, then put in 2 x275 new panels and 40 amp Epever from Bimble.

No problems, touch wood.

We used the frame which had held the original panels, saving a lot of time and money. I do tie them down when we get a storm, but I've never seen them move, I rarely go on the roof, just bring the stern alongside the lock ladders instead.

Solar kicked in last week, after the usual winter sulk, and I think I might have to fire up the engine for a few hours  this week unless the sun re-appears.

I expect the fridge will be switched on in about a month, at the moment fresh food is kept in the beer cellar under the steps.

Edited March 18, 2021 by LadyG

[Sea Dog]

10 hours ago, Detling said:

A MPPT controller will just lose any extra watts it can't pass on to the batteries and limit you to 30 amps maximum you would need to check the manual for maximum permitted overload but in the UK I doubt if your 600 watts of panels would ever produce more than 500 watts. 

I've done this very thing with my Victron mppt, which handles any over current without fuss. As you say, the OP would need to check the specs for his 30a 100v Victron to see what max current it can tolerate, and wire the panels in a configuration so as to stay below max volts, but a bit of parallel in the mix won't hurt. With this in mind, depending on his needs, 30 amps of charge on a regular basis might do the job.

 

My Victron 75v mppt does it for me at 15 amp max from 300 watts of panels, but I do cruise most days so it's topping up after the alternator has done an hour or more as a rule. That said, in the summer my batteries have been full again about lunchtime without starting the motor. You don't get a tank of hot water then though but, if I have no neighbours, an hour of engine in the morning will give me that and let the panels finish the charge, which was my aim. YMMV.

 

[MarkH2159]

On 17/03/2021 at 16:14, robtheplod said:

If you need to go for narrower panels so you can walk up one side, these fit nicely on one side:

 

190w Solar Panel (148x68cm) — Craig Solar

Agreed, thumbs up for the slimmer panels from Craig Solar.

Ordered my 3 x 180w panels online and was able to go and pick them up directly from Craig.

Apart from very reasonable pricing and good quality panels, Craig has been very helpful with design of installation and I can highly recommend dealing with him.

 

Currently in the process of installing the 3 panels set off to one side so I can walk past them without any issues.

[cheesegas]

Worth changing the existing panels if they're getting on a bit. How old are they?

 

I have 2 x 325w half-cell panels with a moderate load - 12v fridge running during the day, laptop most days and a router. Cruised yesterday (so full batteries) until 6pm, fridge off at 9pm, back on at 10am and my 4 x 110ah batteries were on float shortly after.

 

Highly recommend newer panels, these are far, far better in overcast conditions than my old 300w.

 

I don't know much about Victron stuff, but I can recommend the AN series Epever controller, buy from the Epever store on Aliexpress, cheaper than Bimble if you can wait a couple of weeks. These can be slightly optimistic about their cooling ability so I'd recommend picking one significantly above the capacity you need. They can also be paralleled via their RS485 ports with a little box from Epever, but you can't then use the remote monitor.