Matching solar panels with charge controllers and batteries.

[CamperJack]

I've spent a long time trying to get my head around all of this. I think I've got it?

While doing my research I found this video to be very helpful.




I'd love to hear any comments you guys have. Please let me know if I've got anything wrong or overlooked anything! Thanks for your continued help and advice. It's proved vital in previous threads.


Solar charge Controler and Solar Panel Matching

I plan on getting the EPEVER 40A MPPT Solar Charge Controller, pairing it with two Perlight 250W Mono Solar Panels.

I think they go together safely?

The data sheet for the controller says max panel array wattage is 520W. The two 250W panels add up to 500W.

Also to be considered it the Voc (open current voltage). The controller data sheet max is 92V. The panel Voc is 38V. For two that's 76V.

Additionally there is Isc (Short circuit current). The controler is 40A and the panel data sheet says it is 8.78A. For two that's 17.58A.


Batteries

I will buy two 110Ah Hankook sealed leisure batteries for now and may buy more should I feel I need it and when funds allow.


Links

Controller:
eBay: <Broken link removed>

Solar Panels:
PVDirect: http://www.buypvdirect.co.uk/Perlight_250W_PV_Panel

Batteries:
eBay: https://tinyurl.com/Hankook110ah

 

[Jev88]

Hi.
I have read up and learnt quite a lot about solar here in the forum.

Epever and Victron seem to be held in high regard for MPPT controllers.
Consider if you want Bluetooth remote control type aspect to monitor and control your controller.

There are long debates about whether connect in serial, parallel or have separate controllers for each panel.

Hankook batteries have a good reputation and are keenly priced for wet leisure batteries but lithium is what us geeks lust after (high price though).

 

[Lenny HB]

Sounds like you are planning to connect your panels in series. Although series connected is slightly more efficient parallel connected is far better for Motorhome use.
If connected in series any shading on one panel you will lose all your output. In parallel if one panel is in shade you will still get the full output from the other panel.

I would be inclined to go for a better controller you get what you pay for with solar regulators a Votronic or Victron regulator although more expensive they are well worth the extra.

 

[CamperJack]

Sounds like you are planning to connect your panels in series. Although series connected is slightly more efficient parallel connected is far better for Motorhome use.
If connected in series any shading on one panel you will lose all your output. In parallel if one panel is in shade you will still get the full output from the other panel.

I would be inclined to go for a better controller you get what you pay for with solar regulators a Votronic or Victron regulator although more expensive they are well worth the extra.

I see, you think I'm going to wire in series because I've added the voltage together. In reality I've not really thought too hard about it and just instinctively added them. Whereas wiring in parallel the vaults would remain the same. Have I got that right?

I didn't know that wiring in series means had that impact with the shade on one panel stopping the other working too! I'll be sure to wire them in parallel. Thanks a lot for that observation! I assume that's okay to wire these panels in parallel?

Part of the appeal of this particular solar controller is the value for money and I've seen them in other people's builds. They seem to get good reviews. In what way are Victron ones better?

Thanks again!!

 

[CamperJack]

Hi.
I have read up and learnt quite a lot about solar here in the forum.

Epever and Victron seem to be held in high regard for MPPT controllers.
Consider if you want Bluetooth remote control type aspect to monitor and control your controller.

There are long debates about whether connect in serial, parallel or have separate controllers for each panel.

Hankook batteries have a good reputation and are keenly priced for wet leisure batteries but lithium is what us geeks lust after (high price though).

This comes with a MT-50 so I can fit that screen in the living space to see what's going on. Having it on my phone would be a nice thing to have, but it's not a game changer. I think you can get a Wi-Fi thingy bob that plugs into the Epever controller for that?

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

 

[Lenny HB]

art of the appeal of this particular solar controller is the value for money and I've seen them in other people's builds. They seem to get good reviews. In what way are Victron ones better?

I don't know anything about the controller you have mentioned but from experience with various controllers I know that you get what you pay for. The price of that one for a 40 amp controller I just can't see it performing that well.
My previous controller was a well recomened one that cost £80 for a 20 amp one it worked well. Then I replaced it with a Votronic costing twice the price the increase in performance was noticeable.

 

[CamperJack]

Hi all.

I have one further question which I'd be grateful for you advice on.

Once the panels are joined in parallel a cable will go through the roof, via a gland, to the solar charge controller. What cable is this?

I assume it has an MC4 connector on one and and is simply stripped cable at the other end for inserting into the solar charge controller ports.

Do you buy these ready made? Or do I get some 16mm2 cable and crimp an MC4 connector to one end?

Cheers.

 

[Lenny HB]

Buy an MC4 extension lead (male to female) twice the length you need and cut in half.

 

[CamperJack]

You're a genius.

 

[Top Hat]

500w of panels serving 2 110a/h battery's will probably be ok for winter months but in the summer you will be wasting solar, the rule of thumb is 100w solar to serve 1 100a/h battery.

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

 

[CamperJack]

What size wire mc4 extension should I be buying to conect my 500w solar and 40A controller?

500w of panels serving 2 110a/h battery's will probably be ok for winter months but in the summer you will be wasting solar, the rule of thumb is 100w solar to serve 1 100a/h battery.

The idea with the large solar is to get as much as I can coming in while to sun is actually out. That way I’m more likely to get the batteries full.

That said I know 220 ah is small for 500w of solar. But it is only 220ah for now. I plan on adding another 110 ah battery at a later date if I think I need it. I’m trying to spread the cost out a little.

I’ll probably only order the one 250w panel for now too and add another one down the line. Again to spread the cost.

 

[Suvvi]

I have just installed the epever 20a with 180 solar panel and the mt50 read out for in the hab area. It also serves as a clock with date when you don't need to see what's going on. It seems to be pretty efficient from what I've seen so far.
My only gripe with the mt50 is i have taped over the led as it is the brightest single green led i have ever seen and actually kept me awake!

I'm also running a single hancook battery for the meantime as I had limited space however I have incorporated extra space in the build that I could add a second so I'll see how i get on.

I'd see your set up should be fine with a lot of bang for your buck! The epever stuff seems to be an anomaly on the price quality ratio. Incidentally i ordered mine from Aliexpress along with the mt50 and saved about another 30%+ on sourcing it in the UK.

Good luck with the install whichever way you go.

 

[Raul]

CamperJack
You are wasting resources there.
For the size of that 250w perlight, you could get a trina 300-340w or JA solar for better money value. Many don’t have the room for the 1X1,65m panels, if you do, take advantage of the most watts you can. Panels fitted flat, output about half of they nameplate on average. So don’t even think you got to much. Cables, cut the mc4, run them thru four glands to a connection box in your high cupboard. In there fit two fuse holders with two 10A gPV 10x38 fuses. Fuse the plus+ and connect the negatives on a buss bar. From the box, you can run a 6-10mm cable to your controller ( voltage here is about 30v). From controller to batts, run a 16mm with a 50A mega or midi fuse in a holder.

Controller, go straight for the victron 100/50 and you will never have to change it ever, or need a upgrade.

Batteries; never mix old with new, and never parallel if capacity can be done to avoid that. Do yourself a favour and go for Trojan or Rolls 6v agm blocks. If you can vent them, then flooded for double the life. That if, you can’t afford at least 100ah LiFePo4. There are 100ah’s Li out there for under 500 quid now.
Give a call to cclcomponents and speak to a person or “wind and sun”.
I dealt with these over 10 years and had great service.

 

[CamperJack]

CamperJack
You are wasting resources there.
For the size of that 250w perlight, you could get a trina 300-340w or JA solar for better money value. Many don’t have the room for the 1X1,65m panels, if you do, take advantage of the most watts you can. Panels fitted flat, output about half of they nameplate on average. So don’t even think you got to much. Cables, cut the mc4, run them thru four glands to a connection box in your high cupboard. In there fit two fuse holders with two 10A gPV 10x38 fuses. Fuse the plus+ and connect the negatives on a buss bar. From the box, you can run a 6-10mm cable to your controller ( voltage here is about 30v). From controller to batts, run a 16mm with a 50A mega or midi fuse in a holder.

Controller, go straight for the victron 100/50 and you will never have to change it ever, or need a upgrade.

Batteries; never mix old with new, and never parallel if capacity can be done to avoid that. Do yourself a favour and go for Trojan or Rolls 6v agm blocks. If you can vent them, then flooded for double the life. That if, you can’t afford at least 100ah LiFePo4. There are 100ah’s Li out there for under 500 quid now.
Give a call to cclcomponents and speak to a person or “wind and sun”.
I dealt with these over 10 years and had great service.

Lots of good advice there, so thank you. You mention a few good products, like the massive Victron controller and LiFePo4 batteries. Sadly they're not in my budget.

I have seen bigger watt rated solar panels of the same size as the 250w perlight ones. However the solar charge controller can only handle 520w. So 500w of solar is all I can have. I could get a bigger controller but, again, it starts to get too expensive for my budget. I could have had one big panel for comparatively cheaper per watt but I went for two panels because if one is shaded the other will still produce power.

I'm no expert but what I have should, hopefully, meet my needs if I got my sums right. And you can always adapt your living style and power usage with the weather. Combining that with going for a blast up the motorway with the battery to battery charger I will install you have options.

I ordered one of the panels yesterday, so I'm stuck with it now anyway. So fingers crossed it all turns out okay. ?

 

[CamperJack]

What size wire should I be using to join the two batteries?

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

 

[Raul]

Fair play, but the 520w you will only see if angled and pointed to the sun. Flat on the roof is going to be much less, maybe half in fair weather. Hence my recommendation for over panelling. Also, a good mppt controller CAN limit the power in, and you don’t have to limit by design. It simply shifts the power point to the requirement given at that time.
Anyways, look forward for updates of your build. It’s nice to see someone else’s ideas put into practice.
?

 

[Raul]

What size wire should I be using to join the two batteries?

It depends on the current draw. A 25mm would probably be more than enough.

 

[CamperJack]

It depends on the current draw. A 25mm would probably be more than enough.

Say if I was to install a 2000w inverter. I mean I'd likely go smaller, but if we calculate for that sort of overkill, it doesn't really matter with the price of short wires to connect batteries.

The sum I did was:

2000W / 12V = 166.67A. I feel that 25mm² rated at 170 amps is too close for this and so I am thinking about using 35mm² rated at 240A wire.

I'd be interested in people opinions about if this is simple and I'm doing the right kind of calculation before I install anything.

Thanks to everyone for their continued help! It's great to have people to ask and is making this a lot easier.

 

[tonyidle]

500w of panels serving 2 110a/h battery's will probably be ok for winter months but in the summer you will be wasting solar, the rule of thumb is 100w solar to serve 1 100a/h battery.

You can't waste solar. More=better. I know the output won't be needed on a sunny day but solar output becomes really important early and late in the year. What the OP describes might be enough in Winter but I've not spoken to anyone who has too much solar.

 

[CamperJack]

You can't waste solar. More=better. I know the output won't be needed on a sunny day but solar output becomes really important early and late in the year. What the OP describes might be enough in Winter but I've not spoken to anyone who has too much solar.

The key thing putting me off is that fact that it says in the solar charge controller data sheet that the maximum allowed is 520W. I don't want to blow the thing up if, for example, I go to the south of Spain in the middle of summer. And it's not a cheap thing for me to replace. £170 is a lot of money to me. I'm so far from an expert and I certainly don't know better than the manufacturers. If the thing does break I'm sure the warranty would be worthless if I've ignore manufacturers instructions.

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

 

[tonyidle]

The key thing putting me off is that fact that it says in the solar charge controller data sheet that the maximum allowed is 520W. I don't want to blow the thing up if, for example, I go to the south of Spain in the middle of summer. And it's not a cheap thing for me to replace. £170 is a lot of money to me. I'm so far from an expert and I certainly don't know better than the manufacturers. If the thing does break I'm sure the warranty would be worthless if I've ignore manufacturers instructions.

Your panels are 250W each? If the controller says 520W you're safe. The panels are likely to match their rated output on a sunny mid-summers day at the Equator so UK / Europe you're very safe.

 

[CamperJack]

There being no screams of "you're getting all this wrong" I'm going to order 35mm² 240A battery wire to connect the batteries together and the solar charge controller to the battery terminals.

Thanks to all for your help!

 

[Wagoneer]

I'm going to order 35mm² 240A battery wire to connect the batteries together and the solar charge controller to the battery terminals.

Think you'll find the terminals on the solar controller can only accommodate up to 10 mm sq cable.

 

[CamperJack]

Well spotted. Thanks a lot!

 

[jollyrodger]

Up on the roof I have 2 x 100w monocrystaline panels £60 each.
A 20A duo charge controller set up.
Feeding two banks of batteries
2x110Ah Varta & 2x90Ah .
For the last couple of years UK , Spain, Scandinavia,and UK till now .
Batteries in fine fettle ,running all the usual gumph Smart TV and microwave via inverter when needed.
Didn't go overboard on initial set up would rather spend it on travels .
Just saying

http://rover.ebay.com/rover/1/710-5...0001&campid=5338547443&icep_item=282178038190

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

 

[CamperJack]

Up on the roof I have 2 x 100w monocrystaline panels £60 each.
A 20A duo charge controller set up.
Feeding two banks of batteries
2x110Ah Varta & 2x90Ah .
For the last couple of years UK , Spain, Scandinavia,and UK till now .
Batteries in fine fettle ,running all the usual gumph Smart TV and microwave via inverter when needed.
Didn't go overboard on initial set up would rather spend it on travels .
Just saying

http://rover.ebay.com/rover/1/710-5...0001&campid=5338547443&icep_item=282178038190

Jolly Rodger. I understand what your saying and I had that debate with myself. However I decided to get something pretty good now, so I'll be happy with it for the foreseeable. Rather than buying cheap and then buying again later when I upgrade. That way I'll save money buy not buying twice. And lets face it, I don't think I'll be traveling to far flung destinations for quite some time.