EB150 + solar panel. A bit of help selecting the right panels please :)

vegas00

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Hi Everyone,

I hope I'm posting in the right section (sorry if not).

I work from home and am looking to build a home office here in the UK. Nothing big just a small shed style with good insulation. For power I would like to have something portable to bring into the house at night (crime is an issue here) and ideally solar powered.

I've checked my office watt usage using a simple Maxcio meter (cheap off ebay but seems to do the job) and other than my initial surge of just under 1000w the stable usage is 170-210w.

As such, I've looked at portable power stations and the PowerOak EB150 (also called BLUETTI in america I think) seems to suit the job with 1500watt power with a solar input option. I can see it has been mentioned on this forum a few times so I won't go into the specs here etc.

The problem I am having is trying to work out what solar panels I can use. I'm new to solar and trying to learn as fast as possible!

The EB150 says:
1.How to choose compatible Solar panel?

1)Open Circuit Voltage(OCV):16-60V/Max.10A, Max.500W (DC7907 to MC4 Charging cable is included)

2)MC4 Connector

make sure the total OCV(open circuit voltage) is no more than 60V if you connect several solar panel in series!!!!!

Further down the page it says:

3. Can I connect the solar panel in series or in parallel?
yes, you can. for example, connect 2*DC18V(rated power)/150W solar panel in series, if the OCV(open circuit voltage is 22V), so connect 2 pcs in series, it is finally total 44V/300W.

They do seem to sell their own mobile solar panel (foldable) but I would prefer to get some proper panels and fix them to the roof as I feel it would be much cheaper (plus their foldable panel isn't water proof from what I can see).

As such, I was looking at 2 X 100 watt panels from https://www.amazon.co.uk/gp/product/B08KW1DCJR (with the aim to buy more in the future and join them as and when money permits). I would then charge the EB150 overnight in my house then in the day take it to my office and use the solar to help slow down the discharge of the battery (with the end aim being to have enough panels that I no longer need to charge it in the home at night).

They panels above have the following specs:

ECO-WORTHY Solar Panel
100 Watt 12 Volt Monocrystalline Solar Panel
Maximum Power at STC: 100W
Open-Circuit Voltage (Voc): 21.6V
Short circuit current (Isc): 6.13A
Working current (Iop): 5.78A
Output Tolerance: ±3%
Temperature range: -40℃to +80℃

Now before I carry on, I'm more than happy to swap to any other solar panel brand etc if someone knows a good one that is well suited to my situation.

My understanding is that the EB150 can accept a max of 500 watts. The above panels connected in series (assuming everything I have read is right!) means that the if if bought 2 panels it would be 2X12V panels and would mean 24 Volts and still only 5.78 amps (5 X 12V panels would then be 60 Volts and still 5.78A). Is this correct?

So using what the EB150 stated online:

Open Circuit Voltage(OCV):16-60V/Max.10A, Max.500W (DC7907 to MC4 Charging cable is included)

If I bought 5 panels I would get 60 volts (which would be at the limit of what it can do) and I would have 500 watts of power but still 5.78A.

The part that's confusing me is the OCV/VOC. On the solar panels it says :

Open-Circuit Voltage (Voc): 21.6V

This is what I don't understand.

I think OCV/VOC are the same thing and it means the voltage if I tested a panel without anything connected (correct?). If so, would that be the volts and not the 12V stated in the product title? e.g. should I be doing 21.6V + 21.6V for two panels (43.2V)? If so, 5 panels would go well over the 60V limit the EB150 states.

Sorry for all the questions!

Thanks in advance for any help provided :)

Jon

p.s. I've just re-read my post and since the EB150 says:

make sure the total OCV(open circuit voltage) is no more than 60V if you connect several solar panel in series!!!!!

I think I'm correct in saying you would add the 21.6V together for series. If that is the case, I could only have two panels in series as three would be 64.8Voc. So does that mean I would need to do a Parallel connection so the Voc stay the same but the ams go up?

However, EB150 has a max of 10A. Does that mean two panels is 5.78A * 2 (11.56A) which would be over 10. As such, I'm clearly missing something here!
 
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Rednecktek

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I think I'm correct in saying you would add the 21.6V together for series. If that is the case, I could only have two panels in series as three would be 64.8Voc. So does that mean I would need to do a Parallel connection so the Voc stay the same but the ams go up?

However, EB150 has a max of 10A. Does that mean two panels is 5.78A * 2 (11.56A) which would be over 10. As such, I'm clearly missing something here!

Nope, you've got it pretty much right on the money. The VoC and the OCV are the same thing, different terms so your math is correct that 2 panels is OK but 3 is not.

If the unit says max 10 amps of PV input then again you are correct that your panels would cook it if you set up a 2s/2p config.

The problem stems from the fact that neither panel makers OR unit makers can agree on how they want to do the math. The EB150 says it can take 500w of power, which would be 50v@10a, but there's no such thing as a 50v@10a setup that any PANEL manufacturer makes. The best thing you could possibly do is to find that unicorn panel that's rated at 30VoC @ 4.99a or 150w panels and max the unit out with 2s/2p at 60v/9.98a. And hope it never gets really cold.
 

vegas00

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Hello @Rednecktek , Thank you for your help with this :)

On the amazon listing for the poweroak it says:
Charge time: About 6Hrs with 2PCS PowerOak SP200
On their own website it says:
  • A built-in MPPT solar charge controller in the PowerOak Bluetti PS8 EB150 ensures up to 40% fast charging time with solar modules.
  • Recommended solar module: PowerOak Bluetti S120 S160 S200 S220 and S330 solar module. We are not responsible for the use of third-party modules.
  • 2 x S330 connect parallel
  • 2 x S220 connect in series
  • 3 x S200 connect in series or parallel (please ask for instructions)
Now the problem is those panels are (from what I can see) not really waterproof / can be left out all year. The most powerful being the s330 which on their site is:

Max Power 330W
DC Max Power Voltage 40V
DC Max Power Current 8.25A
DC Open Circuit Voltage 48V
DC Short Circuit Current 8.95A
Maximum System Voltage 600V
Cell Efficiency 23%
Max Power tolerance +(0~32)

Since it says you can have two s330 in parallel I get this as 40V (since volts dont go up with parallel), but the Watts as 660W (since the watts would be added together still).

660W! 160 over what the EB150 states it can safely receive. This is where it just gets confusing!

1 quick question though, is the below statements correct (just trying to get it all clear in my head)

  • Series = Add the watts together from each panel. Add the VOC/OCV together. Add the amps stay the same e.g. if panel says "Working current (Iop): 5.78A" then 2 panesl in series would be 5.78A still(?)
  • Parallel = Add the watts together from each panel. The VOC/OCV stays the same. Add the amps together(?)
Its the amps bit thats got me re-confused!

p.s.
And hope it never gets really cold.
This I've missed somehow whilst researching. So a quick google shows that a gold bright day gives more power than a warm bright day. Just adding this to the end of this message so I don't forget it!

Also side note, does anyone know why the panel at https://www.amazon.co.uk/gp/product/B08KZDFPG8 has two VOC ratings:
  • VOC: 20.3V / VOC: 16.6V
 
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vegas00

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I think i've worked most of this out.
  • Series = Add the watts together from each panel. Add the VOC/OCV together. Amps stay the same
  • Parallel = Add the watts together from each panel. The VOC/OCV stays the same. Amps add together
Again, please correct me if I'm wrong.

As such, I'm not likely to get 500w of input power without a lot of messing about and expensive ' unicorn' panels :LOL:. As such, the next best thing I can see is either the 150W panel or the 120W panel below. Both say they are 12 volts:

150: https://www.amazon.co.uk/ECO-WORTHY-100Watts-Monocrystalline-Applicable-Motorhome/dp/B08KXMQ83P/

Rated power: 150W
VOC: 20.3V / VOC: 16.6V

Short circuit current (Isc): 9.61A / working current (IOP): 9.04A
Output tolerance: 3%
Temperature range: -40℃to +80℃
Frame: heavy duty aluminium / SLA battery voltage: 12V
Dimensions (L x W x H)mm: 1315*665*35mm(51.77*26.18*1.38 in) / weight: 25.56Lbs(11.596kg)

So from what I can see, the best way for the 150w would be in series of 2. So 2 panels which assuming I'm getting this all right, would mean 40.6VOC (which is less than the 60V limit stated by the EB150), 9.61Amps (since it's in series and stays the same for two panels) and 300 watts.

120: https://www.amazon.co.uk/ECO-WORTHY-100Watts-Monocrystalline-Applicable-Motorhome/dp/B08KXMQ83P/

Related power: 120W
Open circuit voltage (Voc): 21.6 V
Maximum / maximum voltage (Vmp): 18 V
Short circuit current (Isc): 7.72A
Maximum / maximum current (Imp): 6.67A
Output tolerance: ± 3%
Temperate isc coefficient: (010 +/- 0.01)% / ℃
Tempered Voc coefficient: - (0.38 +/- 0.01)% / ℃
Tempered power coefficient Voc: -0.47% / ℃
Size: 996 * 665 * 35mm (99.6 x 66.5 x 3.6cm)
For the 120 watt panel, in series of 2 would mean 43.2VOC, 7.72Amps and 240 watts.

I'd appreciate it if someone could confirm this (and also if they know why the 150 panel has two VOC ratings)
 

vegas00

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Brill thank you @Rednecktek.

Do you know if there is any safety fuse adapter or something you can connect between the solar panels and the eb150? e.g. to make sure there's no way the amps can go over 10?
 

Rednecktek

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Yeah, I just remembered those a second ago. AFAIK they're a pretty standard size fuse so if you don't like the one that's in there, just swap it out. I think the US or UK is just where they bought it and what electrical codes that one was stamped with. No difference.
 

Pete7

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Rather than mess about with small solar panels, why not fit a single 300w+ panel which will have 34v @ 9.3A. I have the 300w what on the yacht and it works brilliantly running all our loads for 3 weeks continuous sailing apart from twice when rain and fog on the way to Brixham we needed a couple of hours charging with the engine. The point is, once you step above about 250w solar panels are much cheaper as they are made for house installations, so hundreds about. Bimble also do some interesting seconds at astonishingly cheap prices.


Really cheap. I keep thinking about one of the LG bi facial panels for the yacht :)

 
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vegas00

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Hi @Pete7, I looked at larger ones but I found it a bit confusing since the EB150 (I think) needs a minimum of 16v to charge. The only panels I managed to find were under 16v. I found it confusing though as the panels e.g. say 12v in their title but have a VOC of 20+ so want sure if it was still under the 16v (I assume it is). What's the model number of yours?
 

Pete7

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Mine isn't made anymore, but Perlight 60 cell 300w. Connects to a 120Ah Sterling Power LifePO4 battery and a lead-acid in parallel. Picture in the avatar. Charging is controlled by Victron 100/20 for now but Santa Claus will bring me a 100/50 hopefully. That allows us to replace the panel with one of those LG panels. On a yacht we can make use of the bi-facial because the panel is 2.5m above the water. Sea water isn't great for reflecting light, but the stern of the yacht is white GRP so that helps. I would go for 2 x 300w but worried about the weight at 36 kgs times the height. 1 x LG 440w is 22kgs so much more manageable.

So what does 300w do for us? Well laptops, lights, 12v yacht fridge, 12v small freezer and the inverter to run the 1kw Argos 230v kettle. Being English we drink tea, lots of tea. Then there is the toaster and we have just added an induction hob, so a few more wiggly amps required when its cloudy, as you know not an unknown occurrence on a little island of the NW corner of Europe at 50'N.
 

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Pete7

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Sorry just saw your links. Shame they don't deliver the reconditioned ones
Been wondering now I get one on the roof of a Peugeot 207 😂

You could always ask them for a quote, not a good time of year to sell solar in the UK, so might be wilco to the idea to gain a sale.

The panel voltage btw is "nominal" so 12v etc. The actual output is higher, so you need to read the specs. Most MPPTs and that battery pack will have one must have more volts than the battery to charge. Victrons MPPTs need 18 from solar to start charging. Thankfully even a 36 cell solar panel can achieve this, though be aware there are some really odd nasty cheap panels on FB with weird voltages, like 9v all the way up to 60v.
 
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Bvillebob

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To get back to the basics, you might want to look at a daily/weekly power budget. It's not clear how many hours a day your use the space and are drawing the 200w of power or so, but remember you have to account for winter. Here in Oregon my 10KW of panels might only make 1000 watts on a lot of winter days between the low sun and thick clouds, so figure 5-10 percent of your claimed output for some days on end in the winter, or rather fall/winter/spring. Several days of that can drain your batteries pretty quick. The basic rule is you always need more than you think you need, but it begins with "how many watts x how many hours x how many days of reserve storage" balanced against "how fast can I recharge them""
 

Pete7

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but remember you have to account for winter.
A good point. If the budget will allow and its always easy t spend someone else's money, then a pair of 330w panels mounted with individual switches could be used in parallel during the autumn or spring and as a single panel during a good summers day. 330w will give you 25A at 12v at mid day, oodles. Inn winter on a damp heavily cloudy day we can see just 30w, so use the house mains to charge the battery.
 

vegas00

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Hi @Pete7 @Bvillebob, thanks for your help and information on your setups etc.
Been wondering now I get one on the roof of a Peugeot 207
two words.... do it!

I've been looking all night and I thought I had found the perfect panel... not the "unicorn" panel but pretty dam mythologically close! Plus a bonus that it's not from amazon.


The specs are:

Max Current (Imp) 10.6A
Max Voltage (Vmp) 24.5V
Short Circuit Current (Isc) 11.3A
Open Circuit Voltage (Voc) 29.6V
Weight 15KG
Dimension 134x100x3.5cm
Cell Technology Monocrystalline
Certified CE & TUV
Warranty 25 years

Now this is where I could use one final advice push over the finish line! The Max Current (Imp) and Short Circuit Current (Isc) are both over the EB150 powerbanks max of 10A.

I opened a chat with PowerOak.co.uk and they said:

Hi, is the below panel ok for the EB150?
260w
Max Current (Imp) 10.6A
Max Voltage (Vmp) 24.5V
Short Circuit Current (Isc) 11.3A
Open Circuit Voltage (Voc) 29.6V
Will that be ok or will the 10.6A be too high for the unit?

Yes they are suitable

so the 10.6 would not be too high?
(it just says 10 on the eb150 documentation)

It does not matter. Mppt regulates the Voltage

I didn't know that. So If I put higher than 10 amps (so above 10 "PV Max Input Current") it will just lower it down?
It won't damage the machine?

Correct
Voltage should never exceed 60v

Now that's something I was not aware of and also something that I'm a little worried to go over. Is this something you guys have seen in the past with other powerbanks/controllers?

I've just received a response from another panel manufacturer where they said "The 300W panel has an open circuit voltage of 39.80V. The poweroak would need to be able to accept a voltage at least 10% higher than this".

Now the poweroak can accept a voltage up to 60V so that's not an issue BUT it got me thinking, is that the case for all panels that you should factor in a 10% safe margin? e.g. so instead of trying to get a solar setup as close to 60V I should be looking at 54V max with a 6V buffer?
 
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Pete7

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I would definitely keep below the maximum voltage of the MPPT. However, slightly different with current (A). You will rarely get 100% in the UK due to the weather and also your panels aren't going to be pointing exactly at the sun. We loose about 4Ah if its really sunny but its not a problem. The limit is our Victron MPPT which won't feed more than 20A into the batteries but the panel could generate 24 if perfect conditions.

Pete
 

vegas00

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Hi @Pete7 thanks again for your help.

I bit the bullet yesterday and bought two https://www.ebay.com/itm/2029953514...=1&mkrid=711-53200-19255-0&ufes_redirect=true

It should give me 320w in perfect conditions. I have a flat roof where I can position the panels virtually uninterrupted from the sun so should get some decent watts. I have a few old small stepper motors and a few raspberry pi's knocking about so I might try and build a mount so the panels turn to track the sun in summer.

I'm going to do some more reading on adding an extra panel of lower power in parrell but don't know enough yet on how that would affect the others in the array.

What do your panels get out of interest in cloud or rain compared to a perfect UK day?
 
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