Solar setup help

[RubyOptics]

Lenny HB I need to pick your brains if I may!!

I'm planning our solar setup for the new van. I've read up on the difference between mono and poly panels, PWM and MPPT and want to run this by you before ordering parts if that would be ok?

plan would be for 2 of these 175W Victron mono rigid panels. These would be wired in parallel into this 100/20 Victron smart-solar controller.

I've used the Victron MPPT calculator for working out which controller I should be using, but would appreciate your expertise here as this is a bit new to me.

Want to stay with the victron controller at least, as I like the way their products seem to work well together and provide a good upgrade path for additional units to be linked in to a common infrastructure.

 

[steveh57]

The 100/30 hands down, otherwise you will be throwing away 70w from the two 175’s. It will work with the 100/20 but always limited to 280w despite you got more panel.
Your van is already limited in panel surface, so make the most of it. On a fixed installation, the over panel ig is not such a issue.

I currently have 2 x Yuasa L36 EFB 100Ah Yuasa suggest the maximum charge rate for these batteries is 7A. Am I correct in thinking the 100/20 will suffice unless I add additional Lead acid or switch (which is my hope) to Lithium

 

[Lenny HB]

I currently have 2 x Yuasa L36 EFB 100Ah Yuasa suggest the maximum charge rate for these batteries is 7A. Am I correct in thinking the 100/20 will suffice unless I add additional Lead acid or switch (which is my hope) to Lithium

It's the size of the solar panels that is relavant to the the controller, not the batteries.
7 amp max charge on a 100ah battery does not sound right. Normally it would be the C5 rate which would be 20 amps so with two batteries it would be 40amps.

To reduce the charge you would need to reduce the panel size.

 

[steveh57]

Cheers Lenny, You can limit the charge rate on the Victron MPPT from it's maximum of 20A, so currently I have it set at 15A. The datasheet suggests 7A which I'm guessing is required to achieve a full charge however is there any harm from going higher?

 

[Lenny HB]

It's says recommended charge rate not maximum still seems low.
Also they give a CCA rating so it's a dual purpose battery, if it was being used as a starter battery after starting an engine the alternator would be poking over 50 amps into it.

^{_{Subscribers  do not see these advertisements}}

 

[steveh57]

I'll turn it up then That's one thing about the Victron VRM Portal I can do that from anywhere. I'll be changing that controller next but I have to get out of my pit to do that.

 

[steveh57]

Going back to the OP and the suggestion for the Victron 100/30 controller. I believe those panels are 24V so if you wish to connect in series I'm not sure the Victron 100/30 will work at 48V. The next step up for a series connection @48V is the 150/35

 

[Lenny HB]

Going back to the OP and the suggestion for the Victron 100/30 controller. I believe those panels are 24V so if you wish to connect in series I'm not sure the Victron 100/30 will work at 48V. The next step up for a series connection @48V is the 150/35

The 100 is the max input voltage 100/30, 100v in, 30 amps out.
Not that you would want series on a Motorhome.

 

[autorouter]

I currently have 2 x Yuasa L36 EFB 100Ah Yuasa suggest the maximum charge rate for these batteries is 7A.

It's says recommended charge rate not maximum still seems low.

I also think that 7A charge rate is very low. I think it's a 'suggested charge rate' for a dumb fixed-rate charger, that won't cause too much damage if left on accidentally a bit too long. I think an intelligent 3-stage charger can put in a much higher current, because it is monitoring the battery response, and will reduce the current as the battery becomes fully charged.

I think if you are being really careful with lead-acid batteries you limit the max amps to C/10, ie 10A for a 100Ah battery. However many people charge at C/5 (ie 20A for a 100Ah battery) and still get long life from their batteries.

I'd install as much panel area as you can. When it comes to winter there'll be days when there's hardly enough to charge your phone.

 

[Raul]

As autorouter says, the C/10 charge rate is the Goldilocks, with C/8-C12 being the margins where you need temperature compensated charge. You got that on the controller, set it to 4mv per cell as 24mv per battery. This is important when you up the rate from C/8 and above. The C/12 limit is to prevent stratification on flooded open and flooded sealed batteries. Does not apply to gel or agm. I would let that controller to it’s full 20a potential.

^{_{Subscribers  do not see these advertisements}}

 

[Raul]

Going back to the OP and the suggestion for the Victron 100/30 controller. I believe those panels are 24V so if you wish to connect in series I'm not sure the Victron 100/30 will work at 48V. The next step up for a series connection @48V is the 150/35

The panels are fine, as Lenny says, it refers to the input voltage. The 175w panels are 36cell. You can series connect them, and still within limit of 100voc, no issue. The 48v you mention is the output. Usually a 36cell panel is known as 12v because it’s the minimum needed to charge a 12v battery. The panel voltage needs to be at least battery voltage being charged, plus 5v above to start charging,hence 18v output on 12v panels that are 36cell. The 24v panel it has more cells, usually 72 cells to cope with the high absorb voltage on 24v -28,8v and more. Also 60 cell panel can charge a 24v. The 150/35 can take two 72cell or tree 60cell for 48v output. That’s what I use strings of tree 60 cell panels for the house on 150/85, and strings of six 60 cell panels on 250/85. You can make up the voltage by series multiple panels, but keep below controller voc limit.

 

[steveh57]

Thanks everyone very informative, sorry OP for butting in. Looks like a discussion for me on Monday with the supplier regarding the controller they supplied with the panels.

 

[RubyOptics]

Going back to the OP and the suggestion for the Victron 100/30 controller. I believe those panels are 24V so if you wish to connect in series I'm not sure the Victron 100/30 will work at 48V. The next step up for a series connection @48V is the 150/35

I will be having the panels wired in parallel. I don't mind losing a bit of peak charging if it means I don't lose 50% of my charging if a gnat creats a micron of shade on a panel somewhere.

 

[RubyOptics]

I'd install as much panel area as you can. When it comes to winter there'll be days when there's hardly enough to charge your phone.

Couldn't agree more. We fully intend on using this van year round much like the old one. For winter though we are going to need grey tank heaters (eugh) which suck down power at a rate of knots, as does diesel heating (at least on start up, the tick-over is more acceptable but still higher than gas). Hence why solar is one of the systems we'll put in place to deal with our increased power load. Lithium, increased capacity and B2B being the others.
If anyone has suggestions for anything else, I'm all ears!

 

[Raul]

What space have you got on the roof? There is better than victron out there in terms of solar, for more money.

^{_{Subscribers  do not see these advertisements}}

 

[RubyOptics]

What space have you got on the roof? There is better than victron out there in terms of solar, for more money.

The roof space is being measured hopefully Monday. I think that for us, Victron strikes a good balance of performance/price, so unless the alternatives perform substantially better, I think Victron (for the common infrastructure, reliability and brand reputation for good customer service) is a price point we feel comfortable with.

 

[Raul]

I was referring to the panels only, the rest of the gear is very good. They subcontract their panels, I have some victron 115w panels and compared to others, victron panels are well behind.

 

[steveh57]

There is slightly more detail given on this Excel spreadsheet from Victron regarding solar panel vs controller set up. Where as the 100 /20 comes up as the only option in their online calculator, you can select your 2 x 175 panels and choose your controller. The 100 20 comes up as limited at high and low temps, the 100 30 limiting at low temps only . Whether it's relevant or helpful with my knowledge?

https://www.victronenergy.com/upload/software/VE-MPPT-Calc-4_0.xlsm

 

[Raul]

There is slightly more detail given on this Excel spreadsheet from Victron regarding solar panel vs controller set up. Where as the 100 /20 comes up as the only option in their online calculator, you can select your 2 x 175 panels and choose your controller. The 100 20 comes up as limited at high and low temps, the 100 30 limiting at low temps only . Whether it's relevant or helpful with my knowledge?

https://www.victronenergy.com/upload/software/VE-MPPT-Calc-4_0.xlsm

Doesn’t make sense what you say. I think you confuse voc voltage open circuit with amps? I see on that link 5 305w in series.

 

[steveh57]

I sure am confused but capable of learning hopefully.

I've entered the 2 panels i.e 2x175 Victrons into the spreadsheet, parallel connected with the 100/20 and the 100/30 see below.

^{_{Subscribers  do not see these advertisements}}

 

[autorouter]

It's telling you the maximum output current from the controller when the panels are in full sun, and the temperature varies.

At the maximum temperature (you it at set 70 C) the max current is 23.6A. The 30A controller will not limit this, it will let 23.6A pass through. However the 20A controller will limit the current to 20A.

I don't know what the max current is at the minimum temperature. It is over 30A, so let's imagine it's 33A. Both the 20A and 30A controllers will limit the output current, to 20A and 30A respectively.

So if you want to never limit the output current, ie always use every last bit of solar energy, the you'd need the next size of controller - the 100/50 I think.

If you are happy with a bit of limiting in rare circumstances (full sun with panels at -10 C) then the 100/30 is fine.

If all you ever want is 20A, but want the bigger panels so that you still get 20A when the light is not so strong, then the 100/20 is OK.

 

[steveh57]

Thanks I think I'm getting there finally , yes 70 C did seem rather high but there are suggestions for the ranges at the bottom of the spreadsheet .

 

[Raul]

I sure am confused but capable of learning hopefully.

I've entered the 2 panels i.e 2x175 Victrons into the spreadsheet, parallel connected with the 100/20 and the 100/30 see below.

View attachment 508389

View attachment 508390

That’s more like it. You got the gist. As Autorouter says, the 20a controller is limiting to its output on cold but also on hot. To small. On the other hand, the 30a is limiting only on cold. Very acceptable, because those situations will account for very limited hrs per year. When a panel can do more but it’s limited by the controller, it’s called clipping, often caused by intentional overpaneling.The amount of clipping depends on energy vs cost of hardware. Most of the time a good design allows clipping up 10% of energy per year and up to 30% peak power. You will very often see a 3,6kw grid inverter with 4kwp panels, intentionally to account for grim days. That will give some clipping in ideal harvest condition. You can’t have both.

 

[RubyOptics]

Just wanted to thank you all again for your help and advice with all this. We've just ordered 2 of the Victron 175w mono panels and the 100/30 Smart solar controller to go with it. Feeling pretty confident we have a good, solid foundation for our 12v system that we can add onto as and when we need to. Much love and appreciation for you all!

 

[RubyOptics]

Raul Lenny HB autorouter sorry for pinging you all guys, but I need a bit of semi-urgent help. We ordered the 100/30 controller as per this thread, however the supplier has completely screwed us over and the order has been cancelled at the last minute. We need to get the controller to our dealer for fitting by tomorrow and now find ourselves all dressed up with no place to go. I can't find the 100/30 anywhere locally at all. Would the 100/50 be a suitable replacement? As I understand it I would be going slightly overkill on the controller for the setup I will be installing now, but it would give me a bit of overhead if I want to install another panel in the future. Would you guys go for the 100/50 in this situation?

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

Yes I would go for the 100/50.

 

[tonyidle]

Raul Lenny HB autorouter sorry for pinging you all guys, but I need a bit of semi-urgent help. We ordered the 100/30 controller as per this thread, however the supplier has completely screwed us over and the order has been cancelled at the last minute. We need to get the controller to our dealer for fitting by tomorrow and now find ourselves all dressed up with no place to go. I can't find the 100/30 anywhere locally at all. Would the 100/50 be a suitable replacement? As I understand it I would be going slightly overkill on the controller for the setup I will be installing now, but it would give me a bit of overhead if I want to install another panel in the future. Would you guys go for the 100/50 in this situation?

Exactly as you say. The only disadvantage of overkill is the extra you pay for it.

 

[RubyOptics]

Exactly as you say. The only disadvantage of overkill is the extra you pay for it.

Indeed! The difference isn't huge, more annoying than anything else. After all the planning that's gone into this, is incredibly frustrating to be scrambling around last minute due to a dodgy supplier.

 

[Richard n Ann]

Indeed! The difference isn't huge, more annoying than anything else. After all the planning that's gone into this, is incredibly frustrating to be scrambling around last minute due to a dodgy supplier.

Amazon will deliver tomorrow. No idea if this is a good price but they've got one..

Amazon product ASIN B073ZJ3L13

 

[steveh57]

That's a bugger, I don't think there's an issue with 100/30 supply in the UK at present, but I think your outside. I did look at the 100/50( it ticked all the boxes) when I realised my 100/20 was probably insufficient but decided to save a few pennies with the 100/30.

Probably ought to stick the 100/20 in classifieds unless it's worth keeping as a spare.

^{_{Subscribers  do not see these advertisements}}

 

[Raul]

This may work in your advantage with future use changes. Yes absolutely no problem going one bigger, just the cost.
If you have space for a portable 175w, you could have one stored at the back, with two tails ready from the same controller, and deploy plug in as needed. I have two portable 115w x2 with door hinges on to store them shut at the back doors. The solar connects to the panels via MC4’s with the tabs clipped so I can pull them out when I pack up.