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Panels Charging?

Toolworker

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Sep 30, 2020
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Do today's solar panels put out full power as soon as they're hooked up, or do they ramp up for some hours?

A contractor removed and replaced my 14 year old solar panels. When he turned them on, I saw they were not putting out full power. He said they had to "charge up" for most of a day before reaching full power, and he left.

That sounded fishy to me, but I thought maybe today's panels have more electronics than my old ones. So I thought I'd check before deciding he was just shining me on.

(From my metering, it's clear that one of my three strings is not working.)
 
If you could expose them to full light, the often cited 1kW / sqm, they would produce full power at connection. Actual light falling on the panel will vary across the day as the sun moves across the sky and power output will track that.

'Charge up' is a really terrible way of describing it, but he may have been dumbing it down (no offense is intended here) for your benefit. Of course he may also just have been making up any excuse that will let him escape before you pin him down and fix any issues.
 
What time was it that he said that? Panels "charging up" is not a thing, but he may have meant it was morning and the sun wasn't bright enough yet for full power.
 
It was about 11 am, at which hour my array has been putting out 1600w or so in good sunlight this month. But it was only putting out 1200w.

So I told him something was wrong. He said it had to "charge up" and I should wait until the end of the day. Yes, he was dumbing it down - but for his benefit, not mine.

Washing the panels added about 12% to the output, so it should have been putting out 1800w. It was putting out 1200w. There are three strings. Do the math.

So you've answered my question - thanks. Now to get him back and see what else he says.
 
It is very rare to get actual full rated power out of your panels. You don't say how many watts the array is rated at, so we can't tell if you are already taking this into account. As I'm sure you know, the angle and direction will have a big impact, as can temperature and obviously brightness. So if it was an 1800W array, 1200W isn't bad if everything isn't perfect.
 
Do today's solar panels put out full power as soon as they're hooked up, or do they ramp up for some hours?

A contractor removed and replaced my 14 year old solar panels. When he turned them on, I saw they were not putting out full power. He said they had to "charge up" for most of a day before reaching full power, and he left.

That sounded fishy to me, but I thought maybe today's panels have more electronics than my old ones. So I thought I'd check before deciding he was just shining me on.

(From my metering, it's clear that one of my three strings is not working.)
Why did you replace your 14 year old panels?
 
Good question. I didn't think about it until the contractor - actually a sub-contractor - was here to remove them for a reroofing. I talked to him about replacing them, but wasn't impressed with him and didn't trust him (he kept trying to upsell me services).

But the panels are still putting out 85% of their original output. And I've got a data recording setup that would have to be reinvented unless I could use the original inverter. And I didn't want to start researching a whole new project at that stage.

In retrospect, I could have gotten an allowance from the roofer for not having to R&R the array, which would have paid a good chunk of the cost to replace them. And I could have researched it during the week that the panels were down.
 
Oh, maybe one of us misunderstood. I should have said they removed and reinstalled the panels for a reroofing.

Were you asking why did I reinstall them? Or did you think I tossed and replaced them?
 
I thought they were new too. Reinstalling original ones. Totally different story. I was wondering why washing new panels gave you such an improvement. All making more sense. Yah, the guy's a hack and was BSing you to get away.
 
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