The EB70 takes 12-28V on its solar input, 200W max (which it will regulate). This means you have to use 12V panels. One or two panels in parallel. You CANNOT put them in series because the open-circuit voltage of a 12V panel is typically 22V+. So if you were to put two 12V panels in series, you would wind up with 44V or more open-circuit which will blow up the EB70. They are called '12V' panels because the working voltage once the MPPT finds the best power point is typically south of 18V. But their open-circuit voltage is in the 20's.
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Now, unfortunately, even if you put two 12V panels in parallel you are not likely to get 200W out of it. It is almost always better to put panels in series... except doing so will blow up the EB70 (and EB55, and most power stations which spec for 12V panels).
But there is a workaround. If you do want to put two 12V panels in series you can run the resulting voltage (44V+ open circuit) through a 48V->24V DC-to-DC converter and then run the output of the converter into the Bluetti. I do this on my camping EB55. With two 100W Renology panels in parallel I only peak at around 85W. But when I put them in series and throw in a DC-to-DC converter to get the voltage down to 24V, my EB55 will suck in around 140W at peak.
The DC-to-DC converter I happen to be using is this one (and for which I am certain to receive a bot followup for pasting an Amazon URL). But no, I'm trying to sell these things. Its just the one I happen to be using that I got off of Amazon. YMMV. It says that its DC input can go up to 60V, max 20A output, 480W (I don't actually believe the 480W bit but it stays plenty cool enough at 140W), and it produces 24V.
https://smile.amazon.com/dp/B09KGCDDW5?psc=1&ref=ppx\_yo2ov\_dt\_b\_product\_details
Requires a bit of messing around with cable adapters and wires. I get the appropriate cable adapters, tin the ends of the wires, and usually just use WAGOs to paste everything together. And neaten-up the result with a bit of masking tape or electrical tape.
But if you aren't comfortable messing around with stuff like that, just use one 12V panel, or put two in parallel with the appropriate adapter cable and be done with it.
I had similar problems with my two Renology 100W panels in parallel. One panel would give me around 60W or so. Two panels would only give me 80W or so. Lots of people seem to have similar issues. Bluetti's MPPT algorithms have issues across their product stack.
There is a solution, but it requires a bit of electronics experience, soldering, using a multi-meter. The solution is basically to put the panels in series and then run the panel output into a 48V-to-24V DC-to-DC converter. The output of the converter can then go into the EB55. Normally running panels in series would blow up the bluetti (22V open-circuit x 2 = 44V+, the EB55 can only take 28V max). But the DC-to-DC converter solves that. Not only does it solve it, but it tries to maintain 24VDC output so the bluetti's MPPT only needs to do current control. I get around 140W now (instead of 80W).
https://smile.amazon.com/dp/B09KGCDDW5?ref=ppx_yo2ov_dt_b_product_details&th=1
This is just the one I found with the right specs, which I am using right now. I am not trying to advertise these and I wouldn't trust it with more than 200W anyway. But it can handle 60V on its input and outputs 24V. So it can handle two panels in series (but not three).
The only issue with this solution is that you need to have some knowledge of electronics. You'd need the appropriate cable adapters (or perform surgery on your existing cables), wire cutters and strippers, some WAGOs (or whatever) to connect everything together, electrical tape to neaten up the cables and reduce physical stresses, and a multi-meter to double-check and verify polarity and voltage and that everything is working properly before you plug it into the bluetti. Otherwise you will likely blow something up.
If you do decide to do something like this, wire the stuff up with the panels in off-light (not in full sun) so they don't try to push 200W into any mistakes you make until you can properly use the multi-meter to check that polarity and voltages are correct. Use the multi-meter to verify which MC4 is which to make sure the proper polarity goes into the DC-to-DC converter's inputs. The output of the DC-to-DC convert would be run to an XT60 connector. The XT60 connector that goes into the EB55 is 'positive' on the flat-end and 'negative' on the pointy-end. If wired properly, you should see 24V across it, with the proper polarity. Triple-check that the polarity and voltage is correct. The converter should be able to produce 24V even with the panels in off-light / shade outside (it just won't produce very many watts).
Once in full operation, make sure any cable ends / adapters don't get too hot. Its easy to accidentally buy cable adapters that have the wrong-gauge wire and heat up too much. In the case of the XT60's, they often come with very thick wires that actually have to be trimmed down a bit to fit into crimp connectors or WAGOs. In anycase, YMMV.
Its easy for anyone used to tinkering with cables. But not so easy for anyone who has not.