Solar lighting - What do the specs really mean, how much light can I actually expect to get and for how long?

[Crossy]

Years ago I bought some solar garden lights.

 

They were not cheap, they were pretty useless.

The panels were tiny, the batteries cheap and the light level would be rivaled by a candle.

They worked well enough for marking the edge of the pond but didn't really provide "lighting".

The glimmer lasted about 8 hours when new.

The batteries finally failed after about 18 months.

 

Since then I've shied off solar lights, until now.

 

On the recommendation of another, well respected, member I bought a couple of these:-

 

 

For 660 Baht how badly wrong can it go?

 

In the box:-

• A 15W solar panel with a decently long lead and a weatherproof connector.
• The light itself, nicely made plastic moulding, sadly it's a sealed unit so no easy replacing of batteries
• Remote control with batteries
• Bolts for the panel and 4 handy expansion wall fittings.

 

The remote has several modes;-

• Off - Pretty obvious
• On - On all the time
• Auto - On when it gets dark, off when the sun wakes up
• 3H - On 3 hours **
• 5H - On 5 hours **
• 8H - On 8 hours **
• Dim 
• Bright

** it's currently unclear if this means it will light for X hours every night.

 

So what performance can I expect?

That 15W panel will generate about 50Watt hours in a reasonable day (our 300W panels are doing about 1000Watt hours).

The 20,000mAh battery (likely 3.3V) can store about 66Watt hours.

So the panel and battery are pretty well matched, good start ????

 

The main unit being sealed means that I can't actually verify the power of the LEDs (no way they're really "60W") so a spot of estimating.

If our 50Watt hours keeps the light on for the specified 8 hours that makes the LEDs 6.25W.

It's also in the right ball park for a 60W incandescent equivalent (explaining where the "60W" comes from).

 

More as testing proceeds.

 

 

 

[cleopatra2]

2 hours ago, Crossy said:

Years ago I bought some solar garden lights.

 

They were not cheap, they were pretty useless.

The panels were tiny, the batteries cheap and the light level would be rivaled by a candle.

They worked well enough for marking the edge of the pond but didn't really provide "lighting".

The glimmer lasted about 8 hours when new.

The batteries finally failed after about 18 months.

 

Since then I've shied off solar lights, until now.

 

On the recommendation of another, well respected, member I bought a couple of these:-

 

 

For 660 Baht how badly wrong can it go?

 

In the box:-

• A 15W solar panel with a decently long lead and a weatherproof connector.
• The light itself, nicely made plastic moulding, sadly it's a sealed unit so no easy replacing of batteries
• Remote control with batteries
• Bolts for the panel and 4 handy expansion wall fittings.

 

The remote has several modes;-

• Off - Pretty obvious
• On - On all the time
• Auto - On when it gets dark, off when the sun wakes up
• 3H - On 3 hours **
• 5H - On 5 hours **
• 8H - On 8 hours **
• Dim 
• Bright

** it's currently unclear if this means it will light for X hours every night.

 

So what performance can I expect?

That 15W panel will generate about 50Watt hours in a reasonable day (our 300W panels are doing about 1000Watt hours).

The 20,000mAh battery (likely 3.3V) can store about 66Watt hours.

So the panel and battery are pretty well matched, good start ????

 

The main unit being sealed means that I can't actually verify the power of the LEDs (no way they're really "60W") so a spot of estimating.

If our 50Watt hours keeps the light on for the specified 8 hours that makes the LEDs 6.25W.

It's also in the right ball park for a 60W incandescent equivalent (explaining where the "60W" comes from).

 

More as testing proceeds.

 

 

 

Your reasoning on the 60W is correct.

The actual Wattage quoted on Led  is Watt equal. The equivalent luminosity for a standard light.

[colinneil]

Well Crossy i have similar to the ones you just purchased.

My wife switches them on at around 21.30 and they are still working all night, going off at daylight.

Have been working fine for around 2 years.

[CharlieH]

I bought this 90w version in a recent purchase a few months back. I liked that it had the panel built in and only one fix and no cables. It has operated very well and I am pleased with its performance, duration, luminosity etc to date. 

 

https://s.lazada.co.th/s.XqM9C

 

I have this set to come on at dusk, it stays at about 25% of power until something gets within about 3m of it and then full power on, its near a parking area so ideal as full is only needed whilst your there. Lasts right through the night til dawn no problem. Full remote multiple options.

 

Techie stuff : 15Ah  6v/18w

 

[bluesofa]

3 hours ago, Crossy said:

{snipped}

The 20,000mAh battery (likely 3.3V) can store about 66Watt hours.

Yes, I know that that batteries in more recent years are being listed in mAh, rather than Ah as I'm sure most of us were brought up to use.

Being cynical, I assume the continued use of a bigger number (20,000mAh instead if 20Ah) is to make people think it's more powerful.

 

About thirty years ago when loud cheap hi-fi's were popular, instead of being listed as Watts RMS there was a new term PMPO - Peak Maximum Power Output (in the UK anyway).
Why? Because it's a 'bigger number', to make people think it was more powerful, even though PMPO was the absolute highest output usually available for a fraction of a second. 75W RMS is can be considered as around 150W PMPO.

(OK, end of rant)

 

[Susco]

JD seems to be a renowned brand for solar lighting.

 

I have a set of these on the way for testing. For me they are intended for ambient light within the perimeter, but strange enough the very same light ( same brand and packaging) goes between 249 and 750 Baht on Lazada

 

https://www.lazada.co.th/products/sh-078-solar-cell-solar-light-led-solar-light-led-78-hvshops-i1419208911-s3656346739.html

 

[Crossy]

1 hour ago, bluesofa said:

About thirty years ago when loud cheap hi-fi's were popular, instead of being listed as Watts RMS there was a new term PMPO - Peak Maximum Power Output (in the UK anyway).

 

Ah yes, "Shopportunities" or "Scientific and Technical" in the back of the Sunday papers - This amazing hi-fi has a massive 100 Watts output (Total instantaneous peak music power - both channels driven), in reality about 4W RMS per channel.

 

There's a significant amount of "specmanship" going on, like the "60W" really being about 6W.

IMHO it's more than somewhat dishonest, the ordinary man in the street is going to think he can replace his 60W mains LED floodlight (which really will be 60W and b****y bright) with one of these and be severely disappointed.

 

That's not to say there's anything wrong with these lights, you just have to be aware of what you are going to get realistically and as the posts above show they do a sterling job in the right conditions.

 

[Susco]

5 hours ago, Crossy said:

• 3H - On 3 hours **
• 5H - On 5 hours **
• 8H - On 8 hours **
• Dim 
• Bright

** it's currently unclear if this means it will light for X hours every night.

 

If that setting would indeed work that way, that would be real positive, especially for my purpose, because who needs light within the perimeter after he went to bed. I haven't seen any other lights with that setting yet.

 

Would it be an option to add such a timer to an existing light?

 

The main requirements of course would be, it has to be small and cheap to build.

[Crossy]

A few thoughts to help you get the best out of your solar lighting.

 

When looking at solar lights immedately knock a zero off the purported wattage. That will approximate to the equivalent mains powered LED light of the same type (I've seen a couple of very optimistic specs where even that isn't enough).

 

The size of the panel is what determines how much / how long your illumination will be. A 30W panel will generate about 100 Watt-hours on a decent day if it's well positioned. If you don't see a spec for the panel you can approximate the power from the active area. Take the active area in cm² (you may have to estimate it from the photos) and multiply it by 0.015 to get Watts. Do some simple maths to determine how many Watt-hours your panel will make (multiply panel Watts by 3.3 to get Watt-hours per day).

 

The battery needs to be able to store all that energy. It's almost certainly specified in mA-hours, divide that by 1000 and multiply by 3.3 (3.3v battery) to get Watt-hours of storage. The number you get should be 10% or so larger than the Watt-hours you get from your panel.

 

Most of the lights say they'll operate for 8-10 hours on a full charge. If you divide the panel Watt-hours by 8 or 10 that should come to something like the Watts we saw in the first paragraph.

 

Your panel will generate the most power when it's angled slightly and facing south in full sun. If you're looking at lights with fixed panels consider how they will be orientated when your lights are installed, you may want to look at lights with separate, adjustable panels.

 

Also, check if your lights come apart reasonably easily, the batteries are likely the first things that are going to fail, if you can replace them that's a bonus. 

 

So, is it worth it?

 

The number one reason people go solar is ease of installation, no wiring to deal with just screw it to the wall or pole and you're good to go.

 

Also consider that they are not affected by power cuts, so if it's security lighting you're after this has to be a major plus.

 

Of course the energy is free so your power bill will be lower than it would be if you used mains lighting. Taking the lights in our OP. They are equivalent to about a 6W mains powered light. A 6W mains light would use 60 watt-hours per 10 hour night at a cost of 0.27 Baht. The lights cost 660 Baht each so they will pay for themselves in energy saving in 2444 nights - just under 7 years.

 

It may be worthwhile getting a bigger light than you need (with it's bigger panel and battery) then running it on "dim" to stretch the operating hours. Also the lights with "radar" (really PIR) which switch to "bright" when they detect a person will stretch the available energy (but watch the specs, some will use this to get away with a smaller panel and battery than an all-night spec. would use).

 

Worth it? As always it's up2u ???? 

 

Has Crossy been converted?

 

Possibly, our existing 25W CFL street lights are approaching 10 years old and the plastic housings are becoming cloudy so it's time for new ones. Madam is going though a "green" phase (I've been informed that our next vehicle will be pure EV) so replacing the street lights with solar ones will make her happy.

 

The "150W" version of these look promising 

https://www.lazada.co.th/products/i1330690542-s3321646144.html

the positioning of our light poles means the adjustable panels are a must.

 

 

 

 

 

 

[Susco]

On 11/28/2020 at 11:08 AM, Susco said:

 

 

My test light has arrived, so I have a few questions.

 

What direction should I point the solar panel? My idea was to have it horizontal, because the sun is most part of the day high in the sky, but I might be wrong.

 

The solar panel has a very matt surface. Is there a film I need to pull off?

 

It says output 5.5V 2.5W, is that the capacity of the panel?

 

Battery capacity is claimed to be 2000 mAh. Any way to check that, as the battery can be accessed.

 

Last but not least. Is there a way to build a small a miniature sized timer, which would shut down the battery output, on a set time after it get activated at night.

 

Let's say 7 hours after the photocell get activated it shut off and stays shut off for the next 7 hours.

 

 

[Crossy]

7 minutes ago, Susco said:

What direction should I point the solar panel? My idea was to have it horizontal, because the sun is most part of the day high in the sky, but I might be wrong.

 

The solar panel has a very matt surface. Is there a film I need to pull off?

 

It says output 5.5V 2.5W, is that the capacity of the panel?

 

Battery capacity is claimed to be 2000 mAh. Any way to check that, as the battery can be accessed.

 

Last but not least. Is there a way to build a small a miniature sized timer, which would shut down the battery output, on a set time after it get activated at night.

 

Let's say 7 hours after the photocell get activated it shut off and stays shut off for the next 7 hours.

 

 

Point your panel south tilted "slightly" (10-15^o).

 

Matt surface is normal, nothing to peel off unless it's obvious (none of mine have had film).

 

5V 2.5W will be the panel output.

 

Unless the battery is marked there's not much you can do to verify the capacity. Perhaps compare the physical size with similar batteries on AliExpress?

 

You should be able to knock up a CMOS 555 (the standard 555 uses way too much power) based timer to do what you want without sucking too much of your valuable battery capacity. How to link it into the existing electronics is another matter entirely.

 

 

[sometimewoodworker]

40 minutes ago, Crossy said:

Unless the battery is marked there's not much you can do to verify the capacity. Perhaps compare the physical size with similar batteries on AliExpress

Humm BigClive would disagree.
 

The marking on the battery and literature often have very little to do with the actual capacity of the battery. For the average user actually confirming the capacity is, as you say, not very easy, but with a multi meter checking the load at intervals and run time of the light (and math) will get you to within 20% of the real capacity.
 

The weight of similar chemistry cells of the same size is often a reasonable guide to the gross capacity of a cell, in general the heavier the cell the higher the capacity.

 

Of course all of this requires that you actually have the items. 

[Crossy]

5 minutes ago, sometimewoodworker said:

The marking on the battery and literature often have very little to do with the actual capacity of the battery.

 

I can quite believe that fake batteries are out there just like fake flash cards.

[sometimewoodworker]

9 minutes ago, Crossy said:

 

I can quite believe that fake batteries are out there just like fake flash cards.

Just look at the 9900mAh 18650 cells for an example 

[Crossy]

14 minutes ago, sometimewoodworker said:

Just look at the 9900mAh 18650 cells for an example 

 

I wish I hadn't just looked on Lazada, scary ????

 

[Susco]

45 minutes ago, sometimewoodworker said:

The weight of similar chemistry cells of the same size is often a reasonable guide to the gross capacity of a cell, in general the heavier the cell the higher the capacity.

 

Any estimate what a 3.7V 2000 mAh battery should weigh on average?

[Crossy]

9 minutes ago, Susco said:

Any estimate what a 3.7V 2000 mAh battery should weigh on average?

 

I wouldn't stress over it unless you don't get the expected performance or the performance tails off rapidly.

 

[Rimmer]

On 11/28/2020 at 1:13 PM, Susco said:

 

If that setting would indeed work that way, that would be real positive, especially for my purpose, because who needs light within the perimeter after he went to bed. I haven't seen any other lights with that setting yet.

 

Would it be an option to add such a timer to an existing light?

 

The main requirements of course would be, it has to be small and cheap to build.

 

The time is set on the hand held remote control, point the control at the light and press the desired time you want the light to be on for, the light will flash at you which means it is set for that number of hours, nothing else need be done, I have several set on three hours only, the others I think are all on default Auto setting. 

 

The auto setting is the default meaning it comes on when it is dark and goes off when it is light, no need to use the controller.

 

I am not familiar with the new branding JDJINDIAN all mine are simply JD. 8860 with no S on the end of the cat number, the pictures of the light and the panel look identical to mine though.

 

 

 

[phetphet]

These are the ones that I have been thinking about buying for the side of our building.

 

https://www.lazada.co.th/products/mpow70-led-pirwall-lightip65garden-street-decor-i1603954406-s4378150412.html?spm=a2o4m.searchlist.list.13.5a4f601dsMwEAy&search=1

[Crossy]

11 minutes ago, Rimmer said:

The time is set on the hand held remote control, point the control at the light and press the desired time you want the light to be on for, the light will flash at you which means it is set for that number of hours, nothing else need be done, I have several set on three hours only, the others I think are all on default Auto setting. 

 

I thought that's what I did to mine last evening (set 3 hours) but the ruddy thing stayed on all night.

 

I'll try with an initial setting of "off" this evening, I think it was "Auto" before I set the time.

[Rimmer]

8 minutes ago, Crossy said:

 

I thought that's what I did to mine last evening (set 3 hours) but the ruddy thing stayed on all night.

 

I'll try with an initial setting of "off" this evening, I think it was "Auto" before I set the time.

 

Oh yes,  I think there is a mode to follow and I can't remember what it is, I tried doing with it off and with it on and with it on auto first but it took a few permutations to get it right.

 

Been a long time now but I think one light never did take the time schedule so I ended up moving it somewhere else.

 

Oh and I now have a box full of those ridicules over size brass plugs they give you with the light, I found a couple of six or eight screws with washers to take up the enormous holes works just fine.

[sometimewoodworker]

1 hour ago, Susco said:

 

Any estimate what a 3.7V 2000 mAh battery should weigh on average?

That is not possible to say as you haven’t given a form factor of the battery & even if you did you will only get a general guide that a heavier battery is likely to last longer, given that everything else is equal.

[simon43]

One common problem about led lights, (and I understand that this problem wont' be significant for the vast majority of people), is that the power supply unit typically creates a huge amount of RFI - radio frequency interference.  Spikes of RF transmissions that swamp the radio spectrum from shortwave frequencies, all the way up to 1 GHz and higher.  (I know - I've monitored these).

 

I'm a radio amateur, and have a strong dislike for led units for reasons of the RFI.  There is (was) an led street-light right outside my house, but it met with an 'accident'.....

 

But accidents seem unlikely for the other led lights further up the road.  When I'm using my radio gear around sunrise, I have to wait until the led lights switch off - the reduction in RFI is amazing and distant signals can be heard again.

[Muhendis]

On the subject of  60W incandescent light. The 60W is power consumption and totally unrelated to the amount of actual light as I'm sure you already know. The number to take into consideration is LM (lumens). Decent outdoor lighting would be upwards of 1,000 lm in my opinion which is about what you would get from an 80W filament lamp. If the advert fails to mention how many lumens you get then its not bright enough to do what they say.

 

[carlyai]

21 hours ago, sometimewoodworker said:

Just look at the 9900mAh 18650 cells for an example 

So you are saying that no way is this battery 9.9 Ah? 

[Crossy]

9 minutes ago, carlyai said:

So you are saying that no way is this battery 9.9 Ah? 

 

Anything over about 3600mAh in an 18650 format cell is going to be suspect.

 

Of course there's nothing to stop larger capacity packs being made from multiple cells.

 

[sometimewoodworker]

34 minutes ago, carlyai said:

So you are saying that no way is this battery 9.9 Ah? 

Yes. It’s very likely that it isn’t even 1Ah

[George Aylesham]

On 11/28/2020 at 10:10 AM, colinneil said:

Well Crossy i have similar to the ones you just purchased.

My wife switches them on at around 21.30 and they are still working all night, going off at daylight.

Have been working fine for around 2 years.

My experience too - they work really well but I suspect that battery technology has really matured over the past couple of years.

[sometimewoodworker]

43 minutes ago, Crossy said:

Anything over about 3600mAh in an 18650 format cell is going to be suspect.

I fairly sure that if it’s a lithium ion cell then it’s a fake number or a dangerous fire hazard.

[Susco]

I tested my lamps last night for only a few minutes to check the brightness, and that was very satisfying. Since yesterday was a cloudy day, I decided to charge them for a second day before testing the endurance.

 

These are some observations so far,

 

- Brightness is good, even at dimmed all night strength it is sufficient for my purpose.

 

- I watched a customer feedback video, where I noticed he covered the solar panel, and the lights would turn on without covering the photocell. Tried this just here during day time and got the same result. Covering only the photocell would not activate the lights.

Is this normal behaviour?

 

- Shopee and Lazada definitely need to get their act together. The model of the light is SH-078, entering that in the search bar of Shopee gives me 6 results from 225 to 295 Baht. In Lazada  that gives 11 results from 279 to 790 Baht, all with the same package pictured as I received.

 

Now giving SH-078 in Google shows me a Thai website which has a Shopee listing at 160 Baht.

If I click on that listing, I'm taken to the Shopee Thailand website, and from that listing by clicking suggested items at the bottom, I can find at least 6 other sellers selling the product, all below 200 Baht. All listing have the item in stock

So why is it impossible to find these in the Shopee search?