How to test a solar output direct from panel?

[Shadrack]

Hi Guys
An interesting thread. I have wired in a lead with an inline fuse connected directly to
Leisure battery. This makes it easy to plug in my portable(120w) panel.
I also retained a lead with big battery croc clips to use on engine battery and also other batteries on other vehicles should I need it.
I went through various tests at the time of installation. With my dvm connected in series on the amps range the dvm showed just a little over 2 amps charge. This was because the leisure batteries were already in a full state of charge.
I then found a very dull and tired battery from my garage and the current on that went up to 8.6amp. There was not a lot of sun around either..
I have used now on a few trips, each of a couple of days and they easily support the fridge and lights withought the need for hookup.
I don’t have an in-line amp meter whilst I use but the c/p will show 90% during the day with fridge and maybe a phone or iPad charger plugged in.
The rate of charge only goes up if the demand or load is there.

 

[MattBW]

The best I managed on the hottest day of the year was 7.1amps with fridge working hard and battery down to about 55%. It was putting more in than the fridge was taking out so I could go for extended off grid time with it.

Tried a half dead battery too wasn’t any higher for me.


Sent from my iPhone using Tapatalk

 

[Shadrack]

The best I managed on the hottest day of the year was 7.1amps with fridge working hard and battery down to about 55%. It was putting more in than the fridge was taking out so I could go for extended off grid time with it.

Tried a half dead battery too wasn’t any higher for me.


Sent from my iPhone using Tapatalk

I think that’s ok Matt. The panels themselves lose efficiency when they are hot, I have found with the solar I have on my house the best output is on a bright winters day were they are kept cooler. In the summer on a really hot day they have to be at least 15-20% down over a winters day.
Also I believe no panel is 100% efficient from new.

The fact that you can now keep up with the fridge probably running flat out has to make the panels worth the investment.
My panels at 120w allow me more than enough for my needs to be off grid.

 

[MattBW]

It was very very hot for the UK I must admit, about 32c at the time, I couldn't touch the panels very much.

Absolutely, .agree, they are a pretty good purchase. The Victron was almost the same cost as the panel itself but the functionality of it is superb. I have a bit of an addiction to watching all that free power going into my batteries.

I also noted that for the first time ever after a whole weekend on solar charging, the NASA BM1 (my other monitor) is showing the batteries as 99% full, never seen that once in 3 years, even when on hookup. Fridge running hard because of the 30c + temps (and van partially in sun) gave me confidence we will never be out of power in summer, probably spring and autumn too.

 

[Shadrack]

I don’t have any monitors whilst in use, only checked when setting up. With the separate lead with the croc clips I do check when I want to have a play.

In my younger days, clocks, oil and other gauges were a ‘must have’ in cars bikes etc. But as with age wisdom grows.... it’s hard, but I try to steer clear of gauges etc now. The more information... the more to worry about.
I do understand tho why you get a sense of achievement or satisfaction when you can physically see the freebie going to your batteries. My first year of my solar panels on the house I had readings and spreadsheets coming out of my ears.. Yes before you say ‘sad’, the novelty has worn off now.. It’s there.. It works.

I will add, my panels do have a regulator with over charge protection which is also fused, a must have I believe.