150W monocrystalline with PWM vs 200W polycrystalline with MPPT

[antobag]

That particular one has a USB output - which means it has electronics in it which would be drawing some amount of power.
Instead of that, I'd just wire in two car cigarette sockets.
And I'd probably get something that's direct wired, rather than clip-on. And with a built-in fuse.

Thanks foo1bar. What are the benefits it being direct wired over clip-on? Also, would it be dangerous to use one without a built-in fuse?

The best thing I've found on the internet in the UK is this: http://www.amazon.co.uk/Waterproof-C...ref=pd_cp_ce_1

Would I be able to wire 2 or 3 of these to the same battery?

An Amazon reviewer has mentioned that the cables are too small to be used with anything more than the supplied 2A fuse. How true is this? I would most likely need to have at least 5A going through (in order to get 60W to power my laptop (which runs at 90W max)).

[foo1bar]

If this is okay, would it also be possible to place a car charger splitter between the two

That particular one has a USB output - which means it has electronics in it which would be drawing some amount of power.
Instead of that, I'd just wire in two car cigarette sockets.
And I'd probably get something that's direct wired, rather than clip-on. And with a built-in fuse.

[antobag]

Thanks everyone. Looks like I'll definitely be going for the poly panels (I don't mind about the slightly larger size) and a small 150W PSW inverter that I'll use as rarely as possible.

It's very very likely that you don't need an inverter to power your laptop.
Without knowing the make/model of laptop can't guarantee, but many laptops have ability to be charged from a car charger. (and I think you were talking a 12V system, so a car charger would work)

I *can* guarantee that you can buy a laptop which has a car charger - and ones that have DC to DC power adapters.

In terms of using a DC-DC adapter, I can't seem to find anything that goes directly from the battery (ie. crocodile clips) to a laptop charger. Could/should I use the following?:
[My 12V Battery connected to:]
1) A battery to car charger adapter: http://www.amazon.co.uk/TRIXES-Batte.../dp/B005G39HLY
[connected to:]
2) An in-car laptop charger: http://www.amazon.co.uk/In-Car-Charg...laptop+charger
[connected to my laptop.]

If this is okay, would it also be possible to place a car charger splitter between the two (eg. http://www.amazon.co.uk/Ring-volt-In...cessory+socket) so that I can use multiple DC appliances on one battery? I know that the splitter is rated at 10A maximum (so 120W on 12V), but this should be enough for my needs. However, I'm just a bit concerned that adding so many different car-charger connections could end up causing some adverse effects.

Any more of your fantastic advice would be much appreciated!

[foo1bar]

That comes at quite a shock, I didn't realise the inverter would use so much power. In order to charge my laptop, I really do need to be using AC power (it's the only way I can plug my laptop in) - I assume I should use modified square wave in order to prevent the inverter from leeching all of my power?

It's very very likely that you don't need an inverter to power your laptop.
Without knowing the make/model of laptop can't guarantee, but many laptops have ability to be charged from a car charger. (and I think you were talking a 12V system, so a car charger would work)

I *can* guarantee that you can buy a laptop which has a car charger - and ones that have DC to DC power adapters.

Using your existing AC power adapter is probably the cheapest way to go - assuming you have to have AC power for other reasons anyhow.

[Johann]

I am completely new to solar power and I am considering buying a solar panel system for an off-grid hut in Wales, where I will be staying during the month of February. I require roughly 100 to 200 daily Watt-hours to power an LED light and a laptop on which I will be working. I have found two solar panels on ebay that seem to fit my needs, but as I have zero experience in buying solar panels, I thought I'd ask here before going ahead with the purchase.

Here are the two panels:

http://www.ebay.co.uk/itm/150W-solar-panel-kit-folding-monocrystalline-battery-charger-150W-caravan-12v-/301459750815?pt=UK_Gadgets&hash=item463066bf9f

http://www.ebay.co.uk/itm/2-100Watt-solar-panel-W-20A-MPPT-complete-Kit-for-RV-Boat-Home-System-12V-24V/390980292475?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D28111%26meid%3D018cd0a05ec24dbf876daf13696ac444%26pid%3D100009%26prg%3D11472%26rk%3D8%26rkt%3D10%26sd%3D301459750815

My main question is: Would it be better to buy the 150W monocrystalline panel with its included PWM charge controller, or the 200W polycrystalline panel with its MPPT charge controller? (Both controllers are rated at 20Ah). I know that monocrystalline panels are slightly more efficient, but I assume the extra 50W of panel would counter this. I've also heard that MPPT charge controllers are more efficient in systems of 150W and higher, and also in cold conditions (I will be using the panel in British winter at a reasonably high altitude). Taking this into consideration, which panel would be more suitable?

Any help would be much appreciated.

Antony

I got this from somewhere else, so this is not my work and credit needs to go to the creator.


Price

Monocrystalline solar cells cost more than polycrystalline for the same size.

Efficiency

Monocrystalline cells have a higher efficiency than polycrystalline cells due to the structure being made from one large crystal as opposed to many small ones. In addition to having an overall better efficiency, monocrystalline panels can perform up to 10% better than polycrystalline panels in high ambient temperatures.

Size

Since monocrystalline panels are more efficient per area, the size of the solar panel is less than a polycrystalline solar panel for the same wattage. If you are limited on size and want to get the most energy possible, monocrystalline panels are the better choice.

Looks

In terms of looks, monocrystalline panels have a nice uniform color and have a more circular cell shape. Polycrystalline cells are in squares and have inconsistencies in the color sort of like granite.

Longevity

Even though a monocrystalline panel has the potential to last up to 50 years, most warranties only go up to 25 years which polycrystalline panels are able to reach just fine.

Overall, the production process for monocrystalline silicon is mature, and the process for polycrystalline in still maturing. As purity and process tolerances for polycrystalline Si improves, the performance gaps between the two are narrowing.

[Mike90250]

I'll quote myself about inverters:

Pure sine vs Mod sine inverters. Pure sine are less efficient at the 12V end, because of losses creating a nice sine wave. All gear works great on pure sine.

Mod sine is a bit more efficient on the 12V end because it's a much simpler circuit, BUT powering loads with mod sine can cause problems with some (portable tool rechargers are sometimes very picky about their power) devices, problems with motors - motors buzz, get hotter from the harmonics and draw MORE power when on mod sine. Small device wall wart power supplies can overheat on mod sine, and you have to replace them, or put the smoke back inside the parts.

Incandescent lights, and heating appliances are about the only thing that don't care about mod OR pure power.

[jimindenver]

There are other advantages to using PSW over MSW. Your computer uses a brick to charge with, that brick will be much cooler in use with PSW. The microwave will run better and motors will start easier.

Going PSW on the small side doesn't have to cost a arm and a leg. It's the big PSW inverters that can break the bank. There are cheapies but you have to get one the size of a bus to run a 500w load. They have high idle draws and break it and it is disposable as the warranty isn't worth the paper it's written on.

I use a Powerbright MSW 150w inverter for my TV, satellite and phone charger and while nothing has died, the charger and satellite box sure do get warmer than normal. I'll upgrade to a Morningstar 300w PSW that is fan less. Not having to listen to the fan will be worth the upgrade in its self.

[antobag]

Okay, so it seems there are two different lines of thought regarding the power usage of inverters in this thread:

The modified sine wave inverter will need more power or take more power from your battery bank to give your device the necessary wattage that it needs to operate. A full sine wave inverter may need less power from your battery bank to do the same amount of work.

those pure sine wave inverters use much more power than their modified square wave equivalents.

I'm guessing it all boils down to how I'll be using the inverter. Considering that I'll be powering a standard laptop (runs at a rate of about 30-40W) and an LED light (4W), is it possible to estimate which type of inverter would result in the lowest consumption of power? Does the inverter's wattage rating affect the amount of power it consumes (ie. should I go for the lowest wattage possible for my needs)?

[Johann]

''''Sorry, I'm a bit confused here. Are you saying that the modified sine wave inverter will provide me with more power, or that it will use up more power? Apologies if I'm being a bit slow, this is all very new to me.''''

The modified sine wave inverter will need more power or take more power from your battery bank to give your device the necessary wattage that it needs to operate. A full sine wave inverter may need less power from your battery bank to do the same amount of work. Here is a youtube clip that may show you this better. https://www.youtube.com/watch?v=wimT...BnrLfeIe1tdgSQ

[antobag]

Many thanks for all of your replies. I've tried to respond to all of them:

If you only need this for February I wonder what a month of gas would cost you?

We also hope to use the solar panels later on our house (my dad and I are really interested in off-grid living and we've always wanted to buy solar panels), so my off-grid stint in Wales in February is a sort of "testing period" for later. I did consider only using a generator but I'd love to be able to rely on solar as much as possible. I guess one of my main reasons for doing it are for the challenge and the satisfaction of setting it all up.

The thing you would get with higher voltage is less power lost due to voltage drop, so how far between your panels and charge controller?

I'm pretty sure the charge controller will be right next to the panels, so I guess I don't need to worry about this.

Well I don't know a thing about audio equipment but the inverter idles at .6 amps so at 12 volts that's 7.2 watts which over 24 hours is 172.8 Wh. So without even doing anything you could spend more power than your bringing in if you leave the inverter on.

That comes at quite a shock, I didn't realise the inverter would use so much power. In order to charge my laptop, I really do need to be using AC power (it's the only way I can plug my laptop in) - I assume I should use modified square wave in order to prevent the inverter from leeching all of my power?

In addition to feeding through inadequate filters in the DC power supplies, the MSW will radiate interference from the AC lines and from the inverter itself. That will affect audio if you use unshielded cables or run them too close to your AC wiring, and it can affect radio and TV reception in particularly bad cases.

I am now thinking that any time I am making an audio recording, I could run the laptop on its own battery power. This should avoid any interference with the audio. When mixing/editing/etc, I guess I will just have to make do with hearing interference over my headphones.

If using a Modified sine wave inverter, you will/may be using a lot more power for powering an device than if you would be using a full sine wave inverter.

Sorry, I'm a bit confused here. Are you saying that the modified sine wave inverter will provide me with more power, or that it will use up more power? Apologies if I'm being a bit slow, this is all very new to me.

I can also vouch for the Eco-worthy 20 amp MPPT controller. I got my forst one shortly after they came out and have been happy since.

On Poly vs mono panels. Set one of each with matching wattage out in the sun. Their numbers will be similar until the lightest of cloud covers come in. When that happens the Poly drops its output depending on how thick the cloud cover is. The Mono's take a swan dive as soon as any cloud cover exist. My Bosch 245w mono will drop to 2.38a with any cover, My 230w Schott poly will put out 4a in pea soup thick enough that I'm really only pointing the panel at the brightest point in the clouds. The mono system is asleep at that point. Those four amps kept us off the generator by stretch our battery on a cloudy day sandwiched between two freezing nights.

Thanks jimindenver, it's really helpful to hear some personal experiences. It seems that the MPPT controller with the poly panels would be the best choice for me then.

[jimindenver]

I can also vouch for the Eco-worthy 20 amp MPPT controller. I got my forst one shortly after they came out and have been happy since.

On Poly vs mono panels. Set one of each with matching wattage out in the sun. Their numbers will be similar until the lightest of cloud covers come in. When that happens the Poly drops its output depending on how thick the cloud cover is. The Mono's take a swan dive as soon as any cloud cover exist. My Bosch 245w mono will drop to 2.38a with any cover, My 230w Schott poly will put out 4a in pea soup thick enough that I'm really only pointing the panel at the brightest point in the clouds. The mono system is asleep at that point. Those four amps kept us off the generator by stretch our battery on a cloudy day sandwiched between two freezing nights.

[Johann]

In addition to feeding through inadequate filters in the DC power supplies, the MSW will radiate interference from the AC lines and from the inverter itself. That will affect audio if you use unshielded cables or run them too close to your AC wiring, and it can affect radio and TV reception in particularly bad cases.

If using a Modified sine wave inverter, you will/may be using a lot more power for powering an device than if you would be using a full sine wave inverter.

[inetdog]

The main reason I was going for pure sine wave was because I heard that modified square wave inverters can make a slight buzzing sound when using audio equipment (I'll be recording audio with microphones, electric guitar, etc). BUT I've just realised that nearly all of my audio equipment runs through an interface that is powered by the usb port in my laptop, so it is never directly powered by the mains. Would it still be affected by the buzzing?

In addition to feeding through inadequate filters in the DC power supplies, the MSW will radiate interference from the AC lines and from the inverter itself. That will affect audio if you use unshielded cables or run them too close to your AC wiring, and it can affect radio and TV reception in particularly bad cases.

[Bucho]

Haha yes, albeit rare! I've estimated that I'll get slightly less than an hour's worth of usable sunshine daily, so the 200W solar panels should provide about 170W per day.

That's a very short period of sun and I recall spending a week in England where I never did see the sun. What I'm trying to get at is if you need to have dependable power well you'll realistically need a generator and since you need the generator anyway....

If you only need this for February I wonder what a month of gas would cost you?

Also, I've heard that in order to make the full use of MPPT charge controllers, the array voltage should be substantially higher than the battery voltage. Would the 100Ah battery be okay for this?

I'm not familiar with your battery but if you're talking about wiring your panels in series I don't think that gets you anything battery-wise. The thing you would get with higher voltage is less power lost due to voltage drop, so how far between your panels and charge controller?

The main reason I was going for pure sine wave was because I heard that modified square wave inverters can make a slight buzzing sound when using audio equipment (I'll be recording audio with microphones, electric guitar, etc). BUT I've just realised that nearly all of my audio equipment runs through an interface that is powered by the usb port in my laptop, so it is never directly powered by the mains. Would it still be affected by the buzzing?

Well I don't know a thing about audio equipment but the inverter idles at .6 amps so at 12 volts that's 7.2 watts which over 24 hours is 172.8 Wh. So without even doing anything you could spend more power than your bringing in if you leave the inverter on.

[antobag]

I suspect that polycrystalline is not only ok for you but better. Polycrystalline will still give you their rated power, they're just a little bigger than more efficient technology. So it you were covering that hut in panels trying to get the most power you could then sure efficiency would matter but to you it's just throwing money away to make your panels slightly smaller.

Perfect, thanks for the clarification.

Does Wales get sun in February?

Haha yes, albeit rare! I've estimated that I'll get slightly less than an hour's worth of usable sunshine daily, so the 200W solar panels should provide about 170W per day. Also, I've heard that in order to make the full use of MPPT charge controllers, the array voltage should be substantially higher than the battery voltage. Would the 100Ah battery be okay for this?

Laptops and light bulbs don't need pure sine wave, you could go much cheaper. Which would also be better for you as those pure sine wave inverters use much more power than their modified square wave equivalents.

The main reason I was going for pure sine wave was because I heard that modified square wave inverters can make a slight buzzing sound when using audio equipment (I'll be recording audio with microphones, electric guitar, etc). BUT I've just realised that nearly all of my audio equipment runs through an interface that is powered by the usb port in my laptop, so it is never directly powered by the mains. Would it still be affected by the buzzing?