Struggling coming up with a cheap / efficient set up for a 250w 37.8voc panel, please help

[Joshbal12]

Hello from the UK!
Sorry I've done as much research as I can on this without seeking advice:

I've obtained an working scrap 250w panel with the below specs. I've got a 12v battery as bellow and I've been trying to thing of the most efficient and cheapest way of connecting the 2.
As far as I've read I think my kind of panel is unfortunately the type to be directly connected to a grid rather than dc 12v or 24v batteries?

In sunlight, straight across the panel I get about 32V with a multimeter.

I'm unsure whether to step down the panel voltage (with a cheap buck) and increase the amps, then feed into a cheap PWM charge controller which then goes to the battery.
I've also considered this to step it down before going into the PWM :

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Or if I should by the cheapest (real) suitable MPPT controller to sort the charging for me.
I'm really on a tight budget so reluctant to spend the £60 + for an MPPT unless it's necessary.

Can anyone recommend a real cheap MPPT for the UK?

Please let me know if I'm being completely ignorant with my set up ideas! I'm still very new to this!

 

[sunshine_eggo]

Hello from the UK!
Sorry I've done as much research as I can on this without seeking advice:

I've obtained an working scrap 250w panel with the below specs. I've got a 12v battery as bellow and I've been trying to thing of the most efficient and cheapest way of connecting the 2.

Pick one. Not both.

As far as I've read I think my kind of panel is unfortunately the type to be directly connected to a grid rather than dc 12v or 24v batteries?

Not necessarily, but it does require an non-inexpensive MPPT controller to effectively do so, but it could work with a 24V battery with a PWM controller.

In sunlight, straight across the panel I get about 32V with a multimeter.

"straight across" means perpendicular? If that's the case, you should have measured closer to 37.

I'm unsure whether to step down the panel voltage (with a cheap buck) and increase the amps, then feed into a cheap PWM charge controller which then goes to the battery.

If you get a PWM capable of 12 or 24V operation with a panel voltage rating greater than panel Voc, it will work, but it will underperform at 12V.

I've also considered this to step it down before going into the PWM :

28.32US $ 42% OFF|300/400W MPPT Step down Real time Tracking Solar Battery Recharging Controller LED Display 10~30V Output Voltage Adjustable|Solar Controllers| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

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Didn't look. Don't bother. Might as well just get a 20A MPPT.

Or if I should by the cheapest (real) suitable MPPT controller to sort the charging for me.

This.

I'm really on a tight budget so reluctant to spend the £60 + for an MPPT unless it's necessary.

Before you spend anything, you should really assess what you're trying to accomplish here. UK sun at this time of year is horrible, and this panel will produce almost no power.

 

[12VoltInstalls]

Can anyone recommend a real cheap MPPT for the UK?

I can’t recommend a cheap mppt anywhere, “real” cheap or imagined.

What wil you use the power for?

Anyways, a 10A Epever mppt is about US$55. That’s the least expensive dependable thing available in my knowledge base.

If the limited power is enabling you to live at a big monetary savings in other areas then tiny solar makes sense. The cost per watt at the tiny solar end of things won’t save you money cost by itself. My initial setup cost me like US$500 or so and I had some 8-year-old batteries. Ya, like $500 iirc but it enabled me to live and save about $1000/month while still having a daily shower, using lights, making coffee, charging phone, etc.
Every upgrade has basically been a one- or two-month payback period, so essentially no cost (cuz with a traditional apartment rental the money would be gone never to benefit me again, whereas my off-grid situation receives the benefit of my spending like an investment that provides a return every month thereafter.

Your single panel and a small battery may enable your situation but if money savings is focused on the powerco bill it won’t work for you.

 

[A.Justice]

With an MPPT controller you could charge at the full 250 watts the panel provides. The MPPT controller will step down the voltage while increasing the amperage, which would leave you with more power at a lower voltage. Basically, you could use the full 250 watts of your panel at the 14 or so volts it takes to charge your battery. This would be the most efficient choice.

A PWM controller will cut off the excess voltage while not increasing the amperage. The long and short is that it would cut off over half of your panels power production. PWM controllers are most efficient when the panel voltage is close to the battery charging voltage. Your panel is not that close. This would be the most cost-effective choice to get you up and running, but, I would highly suggest not wasting your money on a PWM controller with high(er) voltage panels. I can't stress enough that you will most likely be very disappointed with performance if you get a PWM controller.

The panels I use are something like 60v open. I charge my 12 volt system from 4 of them with an MPPT controller. I tried a PWM first and 1kw of panels never made over 200w. I switched to an MPPT, and I get full power now. The MPPT was double the cost, but it easily quadrupled my power output.