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Solar charger reccomandation
#1
Hello
Im just getting into solar, wonder if someone can tell me who makes good mppt chargers? Seen many but unsure on what is actually good
Not really looking for a basic unit something that is maby a bit more advanced maby? With a good data logger ect..
Thanks
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#2
You can spend anything between £10 and £1000 on a solar charger, there's a wide range - you'll get more defined responses if you clarify what you'll be using it for (in terms of system voltage, expected current etc etc)
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#3
For *off-grid*, I can highly recommend Midnite Solar Classic (150, 200, 250). I run 2 x Midnite Classic 150s. These are $600-$700 range (expensive side) but they have
1) top efficiency - each one capable of around 4.5kwh PV array input and wide battery voltage range
2) internet monitor
3) auxiliary relay controls
4) a ton of options/features and can expand to many of them running in sync'ed settings
5) are ETL certified.
6) Good youtube support

Been running mine for over a year steady with no trouble
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#4
Id like to save money if i can id like a top end one, that i can grow into really, ie not buy cheep ones that are not any good.
my battery im aiming for is a 13a 48v, one to tie into an inverter. but unsure what capacity i need yet
output is 230v and up to 8kv Which is average household usahe in the uk
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 300, untesteded.
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
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#5
(07-20-2019, 12:45 PM)jonisingt35r@gmail.com Wrote: Id like to save money if i can id like a top end one, that i can grow into really, ie not buy cheep ones that are not any good.
my battery im aiming for is a 13a 48v, one to tie into an inverter. but unsure what capacity i need yet
output is 230v and up to 8kv Which is average household usahe in the uk

13a @ 48v is aprox 650wh(s).   Assuming 70% DOD that's 500watts (~ .5kv) for an hour or 230v @ 2amps for an hour.  At this level, a smaller system / controller would be OK.  Depending on your panels, perhaps something like an MPT7210 ($46) would be a good starting place.
completelycharged likes this post
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#6
(07-20-2019, 12:45 PM)jonisingt35r@gmail.com Wrote: Id like to save money if i can id like a top end one, that i can grow into really, ie not buy cheep ones that are not any good.
my battery im aiming for is a 13a 48v, one to tie into an inverter. but unsure what capacity i need yet
output is 230v and up to 8kv Which is average household usahe in the uk

There's a bit of unit confusion creeping here.

I'm assuming you mean 8kWh a day usage - that's quite low, the actual will likely be nearer to 12kWh - if you record the numbers on your electricity meter every day (around the same time) for a week you'll get a good average of your actual.

You'll then need to figure out if you've got enough physical space to install enough PV, wind, hydro to charge a battery large enough to provide for the above consumption - assuming you are grid tied you'll probably want a grid parallel system (rather than have all loads go via the inverter)

There are plenty of options, and opinions - just dont assume that embarking on a project like this will ever save you money (it might eventually)
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#7
Guys please dont mix Wh and kWh with W and kW. Its quite different.

Offgridinthecity you have mentioned kWh for useage but should be kW and then suddenly kv? kV is kilo-volt Wink
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
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#8
The real question is how to actually value what a controller is worth (PWM or MPPT).... then match this to the supply options....

If you have 2 solar panels with an MP voltage of 30V each (60V series wired) and you have a battery with a charge voltage range of say 46V to 58V then how much is an MPPT controller going to make for you as a return on investment ?

Say the solar panels are 250W and cost say $120 each and will give out 9% on average over the year (8760 x 9% x 250W) = 197kWh per year per panel

If you value the panels over say 5 years (short for solar) then you are looking at 197kWh x 5 = 985kWh per solar panel

Split this over the cost of $120 for the solar panel ($120 / 985kWh) = 12.18ct/kWh

This is how much the energy is worth from the solar panel output (note this excludes wiring, etc. at this point)

Next..... if you have to buy a charge controller for $500 then you need to consider how much benefit it is really giving you compared to the MP voltage if you were to use a simple and cheap PWM controller.

With a PWM controller and 2 panels in series (you may have multiple sets of 2 panels in series....) the loss of energy due to pulling the solar voltage down to your lower battery voltage is worke out by (roughly - there are other slight variations due to temperature, etc. but it's ok for a ballpark finger in the air does it make sense) :
Solar Vmp = 30V x 2 = 60V.
Say your average battery voltage is 54V, in which case your average voltage difference is 60V - 54V = 6V, or 10% difference / loss.

If your loosing 10% energy by not using an MPPT controller (this is ignoring efficiency losses and differences between PWM and MPPT at this stage) then that 10%, using the 985kWh value figure from earlier, workes out to be say 99kWh. This is the difference per panel.

If your solar setup is only using 2 panels then your energy difference would be 198kWh between an MPPT controller and a PWM controller.

Now that you know how much of an energy diference an MPPT controller makes, then consider how much you need to spend to gain that extra 99kWh per panel, which then work out like :
$500 MPPT contoller / (2 x solar panels x 99kWh energy difference) = $2.52/kWh, yes the cost of that additional power is 20x the solar output in this example..

If you have 4 solar panels (2 in series x 2 in parallel) then the cost of the incremental energy is halved and when you have a lot of solar panels it can make a real difference, however for small scale systems MPPT controllers have to be cheap to make sense..

The other consideration is if you have solar panels where the Vmp is higher or lower and the losses would be greater OR your stringing together more panels for a higher series voltage (maybe due to cable cost or distance or limiting the amps) in which case MPPT is the only route to drop the voltage efficiently..

If you know your budget, then you can shortlist the MPPT supplier options down or even consider PWM....

Yes, I know there are a lot of parts missing, like over/under voltage control, losses, temperature, wiring, fixings, etc. missing,. but I am just trying to show that MPPT is not always the best choice for smaller systems, not leasst if reliability (disaster option) is a consideration.... with the PWM direct approach, worst case option is a direct connection (supervised to prevent over voltage) in the scenario you can't fix the problem and miles away from anywhere. Horses for courses...
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#9
Thanks leared a lot from theat
Battery is li iron using 18650s, 14s, 0p, and growing cell so far 300, untesteded.
Bms is a diy open source by stuartpittaway.
No solar yet, 
Building wind turbine, 48v im after a 48v motor if anybody has one for sale.
Cells 2000 to 2500ma.
Cells 1500 to 2000ma.
Cells 1000 to 1500ma.
Reply


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