Solar question

[jenevers]

My solar array is 4 x 100w panels. At the moment my 6 Trojans are at 13.9v. The weather is sunny but the inlet voltage is only 15v and 1A. I’ve seen it at 88v in the past. Is this inlet voltage so low because the batteries are full?

[Robbo]

8 minutes ago, jenevers said:

My solar array is 4 x 100w panels. At the moment my 6 Trojans are at 13.9v. The weather is sunny but the inlet voltage is only 15v and 1A. I’ve seen it at 88v in the past. Is this inlet voltage so low because the batteries are full?

When did you see 88v?   Summer?   The inlet voltage goes on the amount of sunlight.  It's winter and we don't get any decent sunlight, sunny or not.

Edited January 17, 2018 by Robbo

[WotEver]

6 minutes ago, jenevers said:

Is this inlet voltage so low because the batteries are full?

Nope. It’s just because it’s winter. 

[jenevers]

5 minutes ago, Robbo said:

When did you see 88v?   Summer?   

Yep,

 

4 minutes ago, WotEver said:

Nope. It’s just because it’s winter. 

Oh good. Thanks.

[Alan de Enfield]

2 minutes ago, jenevers said:

 

Oh good. Thanks.

There have been a huge number of threads on the 'value' of solar in the Winter, personally I work on the principle that between October and March I will get nothing from the Solar, if I get a little it is just a bonus.

You will get 'some' charge but it is totally an unknown quantity - a few days of overcast and it'll be almost nothing, a few bright days and you get a reasonable amount.

Just make alternative arrangements for battery charging in the Winter.

[Phil.]

56 minutes ago, jenevers said:

My solar array is 4 x 100w panels. At the moment my 6 Trojans are at 13.9v. The weather is sunny but the inlet voltage is only 15v and 1A. I’ve seen it at 88v in the past. Is this inlet voltage so low because the batteries are full?

You won't get anywhere near the summer value, but 400 watts of solar should produce more than 1 A in bright sun, even in winter. Just check that you don't have any shading effecting the panels as this can seriously reduce the amount you get. Just by way of example my 235 watt panel is producing 3.2 amps now in the sun.

[Quaysider]

as already said, my batts are currently on 12.7... the solar is showing 14.4 v...  when I look again at lunchtime, it'll be up to circa 80v (assuming the sun is out).

I've resigned myself to running the engine for and hour and a half in the morning (less if the webasto hasnt been on) to get the batts back up to 80% on smartgauge... leave the solar to do what it can until tea time and then have another half our or so to top up the hot water for showering.  This way, the batts usually end up about 95% by the time i sit down to watch tv.  

 

By morning, they tend to be at 80% ish - or somewhere between 65 and 70 if the webasto has been set to come on for a couple of hours.

[Detling]

I think you have a tracer mppt controller and your panels are connected in serial.

It is a known fault_problem that their tracking is poor when they have low current. When the controller is switched on, or the panels connected the controller reduces/loads the panel voltage down in steps right down to 15 volts, if it does not achieve a current above about 1.5 amps anywhere from max volts down to 15 volts they tend to give up looking for a max power point and just sit at 15 volts. If you have the panels in parallel than1.5 amps is easily reached even in low light, in series it is much harder to get 1.5 amps.  On a dull day in winter the controller can stay at 15 volts all day. My tracer will usually be at 15 volts early in the morning in winter. I switch the panel connection off and then back on and watch as the controller volts goes from 63 down to 15, unless there is a step where the current is well over one amp it will stick on 15 volts, if it finds a step where the current is higher it then switches back to that voltage (often 53 in my case) and hunts up and down from that point (MPPT).  I have 600 watts in two serial sets of 3 and the two sets in parallel, tracer 40 amp controller.

[jenevers]

Thanks Dettling, that sounds like what’s happening.