# Solar calculations

Posts: 205Solar Expert ✭✭
Have they done it right ?

http://propakistani.pk/2014/07/07/everything-need-know-setup-solar-energy-pakistan/

To make clear I'm not associated with that blog.

• Posts: 17,615Banned ✭✭
Re: Solar calculations

Let's see ...

1). Vague generalizations about power consumption. That's bound to cause mistakes.

2). Left out charge controller from basic equipment list.

3). Implying that panels actually produce rated Watts and that is how much energy you will get/have.

4). No mention of the really important Watt hours quantity.

I'd have to give them a failing grade. This sort of "planning" is what I so often clean up after.
• Posts: 205Solar Expert ✭✭
Re: Solar calculations

In preparing this post, they got help from someone who actually install / Sell solar panel. :pThis make it more funny.
• Posts: 205Solar Expert ✭✭
Re: Solar calculations

As for CC, they are talking about chinese inverters with built in MPPT charge controller

spec sheet http://www.voltronicpower.com/oCart2/files/brochure/Axpert_KS_DS.pdf

Manual http://www.voltronicpower.com/oCart2/files/manual/Axpert%20KS-1-5KVA_manual.pdf

any issue with inverter ? I mean anything wrong in there.
• Posts: 2,334Solar Expert ✭✭✭✭
Re: Solar calculations

On page 6 I don't get this line
NOTE:
• Posts: 17,615Banned ✭✭
Re: Solar calculations

I do not like "all-in-one" units because of their limited abilities. Check out the specs on that and you see what I mean:

Maximum solar input Voltage 30 for the 12 Volt model, 60 for the 24 Volt, 90 for the 48. That limits your array configuration.
Charging current 50 Amps. That limits your battery bank size.
The "solar charger" is optional, btw.

I do not like the fact it has a "transfer time" of 10 or 20 ms; good inverters are instantaneous.

Not saying it wouldn't work, just that it's not up to snuff compared to what we're used to here in North America (and in many other places around the world). Never seen one of these so I can't judge the quality of it. The real pity is that they could build something like this with a full-range charger controller built in and make it simple (integrate circuit protection and SPD as well). But we're still in the realm of mix and match for the most part, as the number of existing systems dictate upgrades in pieces as-needed rather than in whole units.

Off grid systems are still highly individualized and grid tie systems are still mainly straight GTI which restricts the market somewhat for all-in-one solutions. Perhaps in the future they will be more prevalent.

I'd like to see utility meter boxes with built-in line side taps for GTI installs too. That would make that simpler.
• Posts: 205Solar Expert ✭✭
Re: Solar calculations
solar_dave wrote: »
On page 6 I don't get this line
probably it isn't designed for FLAs batteries.
• Posts: 762Solar Expert ✭✭✭
Re: Solar calculations

Egads - they are applying a gel voltage of 14.1v to both gel and agm.

That is ok for gel, but will undercharge and eventually sulfate an agm. P.29 Too bad. If the user is using agm, then perhaps they may want to purposely set this unit to flooded to 14.6v, IF their agm is rated to handle that.

This is unusual in that most cheap units make this mistake backwards, and fry gels instead.
• Posts: 1,218Solar Expert ✭✭✭✭
Re: Solar calculations

PN, AGM setpoints do seem to vary quite a bit from battery to battery. My large 2v cells absorb at 2.35V pc.

PNjunction wrote: »
Egads - they are applying a gel voltage of 14.1v to both gel and agm.

That is ok for gel, but will undercharge and eventually sulfate an agm. P.29 Too bad. If the user is using agm, then perhaps they may want to purposely set this unit to flooded to 14.6v, IF their agm is rated to handle that.

This is unusual in that most cheap units make this mistake backwards, and fry gels instead.
1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar

• Posts: 762Solar Expert ✭✭✭
Re: Solar calculations
zoneblue wrote: »
.. My large 2v cells absorb at 2.35V pc.

Yes, definitely go by the manufacturer's instructions.

However, I think there is a compensation factor for running them lower in voltage than most conventional agm's in cyclic duty ...

The specs for those Toyo's show that the plates are made of lead-calcium, which ordinarily means a maximum inrush of 0.25 - 0.3C. Yet they state there is no limit for initial current, much like a pure-lead type. Huh? Maybe they figure you'll never be able to provide a 100A charge current, unless you were very industrial..

What I'm thinking is that due to their tall height, where stratification can become an issue with agm's, they are lowering the voltage a bit to be conservative and not burn the tops off... Either that, or their materials just can't handle it like an East Penn / Deka could. Perhaps they are stiffening the tall plates with more calcium than normal and hence the need to lower voltage.

Still, just an overall guess - I'd have to get past a marketing agent, and talk to one of their engineers to get to the truth.
• Posts: 1,218Solar Expert ✭✭✭✭
Re: Solar calculations

I did email them, but their english wasnt that flash. So, hard to know for sure. And i will put them on their sides when i get a moment. Will also get a true fully charged rest voltage, by turning everything off one afternoon. That should give something to go on.

PNjunction wrote: »
Yes, definitely go by the manufacturer's instructions.

However, I think there is a compensation factor for running them lower in voltage than most conventional agm's in cyclic duty ...

The specs for those Toyo's show that the plates are made of lead-calcium, which ordinarily means a maximum inrush of 0.25 - 0.3C. Yet they state there is no limit for initial current, much like a pure-lead type. Huh? Maybe they figure you'll never be able to provide a 100A charge current, unless you were very industrial..

What I'm thinking is that due to their tall height, where stratification can become an issue with agm's, they are lowering the voltage a bit to be conservative and not burn the tops off... Either that, or their materials just can't handle it like an East Penn / Deka could. Perhaps they are stiffening the tall plates with more calcium than normal and hence the need to lower voltage.

Still, just an overall guess - I'd have to get past a marketing agent, and talk to one of their engineers to get to the truth.
1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar