Purchased a NewPowa 150 Watt 12 volt panel on Amazon for 159.00 figuring that all the talk about raising tariffs mean prices will be going up soon. It was shipped for free and came well packaged and protected no scratches or dings. Today I tested it for out put using a multimeter around noon on a very sunny day.Short circuit current is listed at 9.17 Amps and I was seeing about 9.25 on a very cheap multimeter so I figure it is very close! I won't be installing it on the van roof until next spring when I purchase a new AGM Battery, but I have already purchased a cheap PWM Charge Controller that sis rated for 10 Amps and I am wondering if that is enough or if the Panel will damage it or cause it to run too hot? Anyone with experience care to comment? I'm working on a tight budget so MPPT is not really an option....Thanks!

If tariffs will be introduced, panel prices will go up by what - 10 or 15%? Unless Chinese ramp up the production and lower the cost (not a problem, given over-supply of under-paid labor) and prices will drop again. And, from what I hear, they ramp it up all the time, with govt being ambition-choked and the country fuel-starved. Or the govt will subsidize solar production like it did before - and they did, BIG time - so prices will drop again.I would be more concerned about adequate wattage (which 150W is likely not), safe install (considering your particular roof), and a controller that has both proper features and proper rating. 10A is barely enough for this panel. Should be 12A.

Isc of 9.17 on a 150w panel is fairly low-- "normal" might be more like 9.46, so I am suspecting your panel has a higher Voc. Some panels have near 23 instead of near 22, so their Iscs are lower.You won't see more than the Isc of the panel except briefly with occasional cloud edge effect. Or if it is really cold out. Your controller will be ok.Count on getting less than rated Isc amps when the panel is mounted flat, like on your roof, rather than tilted and aimed at the sun as when used as a portable panel. So the controller will have even more margin.If the PWM controller ever went over 10 amps, it would not fry right away. It takes a fair time to heat up and eventually fry.

BFL13 wrote:Isc of 9.17 on a 150w panel is fairly low-- "normal" might be more like 9.46, so I am suspecting your panel has a higher Voc. Some panels have near 23 instead of near 22, so their Iscs are lower.You won't see more than the Isc of the panel except briefly with occasional cloud edge effect. Or if it is really cold out. Your controller will be ok.Count on getting less than rated Isc amps when the panel is mounted flat, like on your roof, rather than tilted and aimed at the sun as when used as a portable panel. So the controller will have even more margin.If the PWM controller ever went over 10 amps, it would not fry right away. It takes a fair time to heat up and eventually fry.Thank you. This makes sense and when I had the panel flat it was putting out 5.75 or so...much better when pointed directly at the Sun. This was why I thought a 10 Amp would work initially. The battery has to go under my bed so I want an AGM and I think it will be a 120 AH model. I use very little electricity on this vehicle unless I change my fridge to a home style and think the 150 Watt will keep up with usage especially combined with the alternator when driving.

Not enough capacity for that panel. If there’s even a chance of adding a second 150 watts, buy a controller rated for 30 amps otherwise 20 would be okay, but wire for 30 regardless.

Do not go 120v only fridge if you can help it. Stick with propane if going off grid. You become a total slave to the 120v fridge for how much solar you are getting, and how much battery you can fit to the rig for how many days with no solar before the fridge can't stay cold. BTDT--no fun at all.---unless you also have a generator and a decent sized amps charger--which we didn't have in the TC. No room for that. :(Lesson is--any size rig-- if you go off grid with a res fridge, have a generator and a decent charger, or suffer. Do not expect sunshine every day.

Tested my new Solar Panel today | Good Sam Community

16 Replies

Almot
Explorer III
Oct 16, 2017
150W is very little. Especially if LP fridge has 12V thermostat.
And so is 120AH battery - very little, though very heavy. Get 2*100AH AGM in parallel, they will cycle shallow-er than a single 120AH and therefore will live longer.

For most people it makes sense getting as much solar wattage as possible. Unless you are in no-charging geographic area like BFL, where solar harvest can be so low that doubling the wattage won't change the picture.
BFL13
Explorer II
Oct 16, 2017
Do not go 120v only fridge if you can help it. Stick with propane if going off grid. You become a total slave to the 120v fridge for how much solar you are getting, and how much battery you can fit to the rig for how many days with no solar before the fridge can't stay cold.

BTDT--no fun at all.---unless you also have a generator and a decent sized amps charger--which we didn't have in the TC. No room for that. :(

Lesson is--any size rig-- if you go off grid with a res fridge, have a generator and a decent charger, or suffer. Do not expect sunshine every day.
Lwiddis
Explorer II
Oct 16, 2017
Not enough capacity for that panel. If there’s even a chance of adding a second 150 watts, buy a controller rated for 30 amps otherwise 20 would be okay, but wire for 30 regardless.
Traveler7
Explorer
Oct 16, 2017
BFL13 wrote:
Isc of 9.17 on a 150w panel is fairly low-- "normal" might be more like 9.46, so I am suspecting your panel has a higher Voc. Some panels have near 23 instead of near 22, so their Iscs are lower.

You won't see more than the Isc of the panel except briefly with occasional cloud edge effect. Or if it is really cold out. Your controller will be ok.

Count on getting less than rated Isc amps when the panel is mounted flat, like on your roof, rather than tilted and aimed at the sun as when used as a portable panel. So the controller will have even more margin.

If the PWM controller ever went over 10 amps, it would not fry right away. It takes a fair time to heat up and eventually fry.

Thank you. This makes sense and when I had the panel flat it was putting out 5.75 or so...much better when pointed directly at the Sun. This was why I thought a 10 Amp would work initially.

The battery has to go under my bed so I want an AGM and I think it will be a 120 AH model. I use very little electricity on this vehicle unless I change my fridge to a home style and think the 150 Watt will keep up with usage especially combined with the alternator when driving.
BFL13
Explorer II
Oct 16, 2017
Isc of 9.17 on a 150w panel is fairly low-- "normal" might be more like 9.46, so I am suspecting your panel has a higher Voc. Some panels have near 23 instead of near 22, so their Iscs are lower.

You won't see more than the Isc of the panel except briefly with occasional cloud edge effect. Or if it is really cold out. Your controller will be ok.

Count on getting less than rated Isc amps when the panel is mounted flat, like on your roof, rather than tilted and aimed at the sun as when used as a portable panel. So the controller will have even more margin.

If the PWM controller ever went over 10 amps, it would not fry right away. It takes a fair time to heat up and eventually fry.
Almot
Explorer III
Oct 16, 2017
If tariffs will be introduced, panel prices will go up by what - 10 or 15%? Unless Chinese ramp up the production and lower the cost (not a problem, given over-supply of under-paid labor) and prices will drop again. And, from what I hear, they ramp it up all the time, with govt being ambition-choked and the country fuel-starved. Or the govt will subsidize solar production like it did before - and they did, BIG time - so prices will drop again.

I would be more concerned about adequate wattage (which 150W is likely not), safe install (considering your particular roof), and a controller that has both proper features and proper rating. 10A is barely enough for this panel. Should be 12A.

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