Simple Solar For A Simpleton

[VirtualVagabond]

Just a quick update.

Firstly, thanks to everyone for the enormous input here.

Secondly, for some reason I haven't been getting the usual email notifications when posts have been made, so I thought this thread was dead.

I've ordered 600 watts in solar panels. This was an interesting exercize!
I drew out the real estate i had available and started searching for panels that would give me the most watts.
As it happens, Sun Power makes a 320W panel that fits exactly onto the area of our davits. I have space enough on either side of the doghouse sliding hatch for a 140W panel, so 280 there, and 600 all up and all out of the way.

BUT, Sun Power doesn't sell online or cater for DIY types at all. They only sell through their installers. Best price I could get was $900 for the one 320W panel, if I pick it up!

The Kyocera 315 W panel was a lot cheaper, doesn't fit as well, and shipping would be $268.

For the doghouse panels I found a 2 pack deal for 145W panels from DM Solar for $240. Sweet
Except they don't have any stock and also sell through Amazon, but they are out of stock too, and sell for somewhere in the region of $320-360 when they do.
The oriental gentleman assured me I could get the $240 from them, so it wasn't misleading advertising, but all their stock goes directly to Amazon, so I would have to pay for shipping from Amazon to them, and then from them to the east coast, making Amazon cheaper. Also Amazon would fill their own orders first before back orders for DM Solar, so he couldn't tell me when I'd get them!

When all else fails, check Ebay!

We eventually found someone selling a pack of 4 x 320W Sun Power, new, for $1280 plus $100 shipping.
They agreed to sell one for $320 + $100 shipping. I checked what else they had on sale and they happened to have 140W Solar Cynergy panels too.
Final deal was 3 new panels delivered to my door, ie 600 watts for $866.

Not a bad outcome at all.

Now I need to work out if I can do what Jimbo did and feed them directly into the 1125 AH battery bank, or if I have to go the route of controllers etc.

Vic

[noelex 77]

You cannot hook the sun power panel up directly. The higher voltage it means it needs an MPPT controler, otherwise you will waste a lot of power. Make sure the one you buy can handle the high voltage of this panel.

The cynergy panels are nominally 12v panels so they will need another regulator. You could regulate these with just a switch, but I would strongly recommend against this.

[Dsanduril]

BUT, Sun Power doesn't sell online or cater for DIY types at all

Disclosure - I do a fair amount of contract work for Sunpower.

The reason Sunpower doesn't cater to DIY is because their panels are just a little different, and have to be installed perfectly in order to maintain their top of the heap efficiency. If not properly installed they will lose efficiency over time more severely than other panels, and that hurts Sunpower's reputation.

As of last year Sunpower makes two types of panels, the standard series and the "N" series. The standard series have part number SPR-XXXE-..., the "N" series have part number SPR-XXXNE-...

The key difference is that the "N"series are made for transformerless inverters, and so are pretty much normal panels. The standard series, however, require that the positive side be grounded. This keeps the silicon mix used by Sunpower from polarizing (and reducing efficiency). When Sunpower installs these panels they either keep the positive side grounded whenever the panel is exposed to light, or they go back and depolarize the array at night using some techniques they don't discuss.

Grounding the positive side is next to impossible on a boat and in battery charging systems in general. Most (if not all) charge controllers pass the negative side of the panel straight through to the battery, and switch/control on the positive side. Thus the panel is not isolated from the system. On a boat the negative side is traditionally grounded to the engine block and the water. So, you can't ground the positive side of the panel unless you isolate the panel from the system, and even then you set up a huge electrolysis potential by grounding the positive side to the water near the boat. (Sunpower's standard panels are really designed for grid-tied use where the transformer in the inverter isolates the panels, and thus can have the positive side grounded).

Not trying to scare or dissuade. If you have "N" panels then no worries really. If you don't have "N" panels then they will still work, but their efficiency will not be as high as the product literature claims, and it will degrade over time more than other panels.

Sunpower Installation Manual

Sunpower Paper - Polarization

[sloopygirl]

Originally Posted by DeepFrz

And you thought this was going to be simple...

Great line! The uninitiated think that the cruising life is so carefree and wonders what we do all day. If they only knew!

[VirtualVagabond]

Originally Posted by Dsanduril

Disclosure - I do a fair amount of contract work for Sunpower.

The reason Sunpower doesn't cater to DIY is because their panels are just a little different, and have to be installed perfectly in order to maintain their top of the heap efficiency. If not properly installed they will lose efficiency over time more severely than other panels, and that hurts Sunpower's reputation.

As of last year Sunpower makes two types of panels, the standard series and the "N" series. The standard series have part number SPR-XXXE-..., the "N" series have part number SPR-XXXNE-...

The key difference is that the "N"series are made for transformerless inverters, and so are pretty much normal panels. The standard series, however, require that the positive side be grounded. This keeps the silicon mix used by Sunpower from polarizing (and reducing efficiency). When Sunpower installs these panels they either keep the positive side grounded whenever the panel is exposed to light, or they go back and depolarize the array at night using some techniques they don't discuss.

Grounding the positive side is next to impossible on a boat and in battery charging systems in general. Most (if not all) charge controllers pass the negative side of the panel straight through to the battery, and switch/control on the positive side. Thus the panel is not isolated from the system. On a boat the negative side is traditionally grounded to the engine block and the water. So, you can't ground the positive side of the panel unless you isolate the panel from the system, and even then you set up a huge electrolysis potential by grounding the positive side to the water near the boat. (Sunpower's standard panels are really designed for grid-tied use where the transformer in the inverter isolates the panels, and thus can have the positive side grounded).

Not trying to scare or dissuade. If you have "N" panels then no worries really. If you don't have "N" panels then they will still work, but their efficiency will not be as high as the product literature claims, and it will degrade over time more than other panels.

Sunpower Installation Manual

Sunpower Paper - Polarization

Just when everything was humming along so sweetly!
SPR-320E-WHT-D
I guess that says it all.

So in this case I will just install the panel with negative grounding along with the others and accept that the panel will degrade more rapidly than conventional panels.
Is this correct?
Any particular instalation details I should cater for?

Quite frankly, if I get 5 years out of the panel it will still have been a good deal.

Vic

[VirtualVagabond]

Originally Posted by noelex 77

You cannot hook the sun power panel up directly. The higher voltage it means it needs an MPPT controler, otherwise you will waste a lot of power. Make sure the one you buy can handle the high voltage of this panel.

The cynergy panels are nominally 12v panels so they will need another regulator. You could regulate these with just a switch, but I would strongly recommend against this.

This is pretty much what I was expecting. I was just hoping electricity may have changed in the last week or so

I have an Outback Inverter/charger. Is there any advantage or otherwise in going for the Outback MPPT controller? (assuming high voltage abilities).

Does the MPPT Controller link up completely seperately to the charger/ inverter?
Solar panels -> MPPT Controller -> Battery bank

Or does the MPPT controller need to be hooked up with the inverter/charger somehow so they all play nicely together?

Vic

[Dsanduril]

The panel is still a good deal, it will still put out power, just not quite the quoted output, and Sunpower won't want to use you as a reference. But it fits where you have the space, so...

As Noelex 77 said above, you definitely need a controller on the Sunpower module that can deal with it correctly. The Vmp on the module is 54.7V and the Voc is 64.8V. The controller will down-convert that to 14.4V for the batteries.

The Solar Cynergy panels have Vmp = 18.1 and Voc = 21.8. You could probably run those into the batteries directly, but you will sacrifice about 20% of the power during bright sun conditions by operating them at 14.4V. Because of your daily usage you could probably run them uncontrolled and not risk overcharging. Unfortunately, if you do want to control them to get the maximum power you will need a separate controller from the Sunpower controller. To run them uncontrolled you will need to make sure that your batteries are not fully topped up when the sun is out, otherwise you risk driving the voltage as high as the Voc (but only if your batteries are at 100% charge).

[noelex 77]

Originally Posted by Dsanduril

Disclosure - I do a fair amount of contract work for Sunpower.

The reason Sunpower doesn't cater to DIY is because their panels are just a little different, and have to be installed perfectly in order to maintain their top of the heap efficiency. If not properly installed they will lose efficiency over time more severely than other panels, and that hurts Sunpower's reputation.

Great information and thanks for links.

I am a little concerned about the long term durability of the Anti reflection coating applied to many of these high performance panels. The large temperature differences are very hard on AR coatings and boats have the adittional problem of abrasive salt.

Is this a valid concern or not a significant issue?

[Dsanduril]

I am a little concerned about the long term durability of the Anti reflection coating applied to many of these high performance panels. The large temperature differences are very hard on AR coatings and boats have the adittional problem of abrasive salt.

Is this a valid concern or not a significant issue?

Short answer, I don't know.

I can't say I have a lot of knowledge in that regard, I work more on the electrical side of things. I can say that I don't think the temperature issues are any greater than on land. We install panels in the Southern California desert that experience below freezing ambient temperatures in the winter and > 100F in the summer. The operating temperature of the panels is generally 45-50F above ambient (not unusual to see 150F on the back of the module on a summer day). The panels cycle through that temperature range every day (at dawn they are usually a few degrees below ambient because of a variety of factors). Pretty much all the HE panel makers warrant performance of at least 80% out to 25 years, but since they haven't been in use that long....

The question to me would be what are the additional issues related to humidity and salt that would be encountered through those heating cycles when installed on a boat, and I simply don't have any information in that regard. If I come across any (publicly available) I'll post it, but not something I run in to on my side of the work.

[VirtualVagabond]

Originally Posted by Dsanduril

The panel is still a good deal, it will still put out power, just not quite the quoted output, and Sunpower won't want to use you as a reference. But it fits where you have the space, so...

As Noelex 77 said above, you definitely need a controller on the Sunpower module that can deal with it correctly. The Vmp on the module is 54.7V and the Voc is 64.8V. The controller will down-convert that to 14.4V for the batteries.

The Solar Cynergy panels have Vmp = 18.1 and Voc = 21.8. You could probably run those into the batteries directly, but you will sacrifice about 20% of the power during bright sun conditions by operating them at 14.4V. Because of your daily usage you could probably run them uncontrolled and not risk overcharging. Unfortunately, if you do want to control them to get the maximum power you will need a separate controller from the Sunpower controller. To run them uncontrolled you will need to make sure that your batteries are not fully topped up when the sun is out, otherwise you risk driving the voltage as high as the Voc (but only if your batteries are at 100% charge).

I didn't realise I'd need 2 controllers.
I figured they'd be smart enough to suck in whatever solar input came their way and shunt it out to the batteries at 14.4V.

If the Sunpower HAS to have a controller that is obviously the starting point. Would you happen to know a few brands that would handle the 54.7 Vmpp for me to look at?

Vic

[noelex 77]

Originally Posted by VirtualVagabond

This is pretty much what I was expecting. I was just hoping electricity may have changed in the last week or so

I have an Outback Inverter/charger. Is there any advantage or otherwise in going for the Outback MPPT controller? (assuming high voltage abilities).

Does the MPPT Controller link up completely seperately to the charger/ inverter?
Solar panels -> MPPT Controller -> Battery bank

Or does the MPPT controller need to be hooked up with the inverter/charger somehow so they all play nicely together?

Vic

Sorry I missed your post Vic
There are not many advantages in going for an Outback controller, given that you have the same brand inverter /charger. The only advantage I can see in your case is the addition of an Outback mate could report the performance of both the inverter and solar system. It can also be used to turn the inverter off and on etc
Most of the good controlers that will accept the voltage of the Sunpower panels are expensive ( make sure you use Vsc which I think is close to 60v for the Sunpower panels, sometimes the voltage can go slightly over Vsc and most regulators will be immediately damaged if you exceed their voltage).

I think the Outback FM60, given your system, would be my choice, but it's expensive, particularly as you will need another controller for the lower voltage panels.

The Rogue is my normal recommendation for this sized panel

Rogue Power Technologies

But it is close to the limits of its performance and I would email the designer and check its OK, although his specs are very conservative so I think you will be OK. It's a lot cheaper than the Outback and close in its MPP tracking ability, although with reduced ability to accept larger panels.

[Stu Jackson]

Back to the ALTERNATOR issue

Don't know if you've sorted it out yet, but the only way I figured my system out was to draw a wiring diagram.

Here's ours, may help you some.

Alternator Regulator Wiring Diagrams (all three)

[Dsanduril]

Or does the MPPT controller need to be hooked up with the inverter/charger somehow so they all play nicely together?

Vic,

For the most part, given the electrical usage described earlier in this thread, I don't think you will have to worry too much about making things play nice. It appears that you typically operate at 60-70% state of charge, which means your batteries are willing to soak up all the power you can deliver.

What can happen is that if one charger/controller starts first, it may raise the voltage into the 13.8-14.2V (typical) range while in acceptance charging mode. When the second charger/controller comes online it may see this as the batteries being fully charged and move into reduced power float mode. This can usually be dealt with by monkeying around a little with the float and acceptance voltages on the controllers (like setting the smaller controller to have both float and acceptance at 14.4V).

Would you happen to know a few brands that would handle the 54.7 Vmpp for me to look at?

Many of the MPPT controllers are fine with these voltage levels, and you are somewhat married to an MPPT controller on the Sunpower panel, because you need to reduce the voltage. The Outback units go to 150V max, 145V max in operation. Most of the BlueSky units want a maximum Voc of 57V, so they aren't appropriate. MorningStar makes a [EDIT]TriStar, Sunsaver not rated > 200W @ 12V[EDIT] model that goes to 75V. Since you have the Outback inverter/charger I would give them a call and see if there is any easy way to integrate things (or see if anyone here has thoughts on that).

I figured they'd be smart enough to suck in whatever solar input came their way and shunt it out to the batteries at 14.4V.

The way the MPPT controllers work is by driving the voltage on the panels up and down, measuring the voltage and current to get the total power, and doing that over and over again, raising or lowering the panel voltage slightly each time to see if they are at the maximum power point. For that to work, the voltage for maximum power has to be the same for all of the panels connected to the controller. You can connect multiple panels of the same type in parallel and as long as the panels are operating under the same conditions (same tilt, orientation, shading) the controller will be happy with all of them.

For your situation, if you had three of the 140W panels you might be able to connect those panels in series to get a Vmp of 54.3V, which compares pretty well with the Vmp of the Sunpower panel. Got a place to put one more? You could then connect the string of 140W panels in parallel with the Sunpower panel into a single controller and probably get reasonable controller accuracy. Short of that, you probably need two controllers. If cost becomes a real issue you might consider a PWM controller for the 140s. You'll lose a little output (hard to predict exactly) but it will also cost you less (I don't necessarily recommend that, I'm an MPPT fan, but I recognize not everyone wants to spend the $).

[VirtualVagabond]

Originally Posted by noelex 77

Sorry I missed your post Vic
There are not many advantages in going for an Outback controller, given that you have the same brand inverter /charger. The only advantage I can see in your case is the addition of an Outback mate could report the performance of both the inverter and solar system. It can also be used to turn the inverter off and on etc
Most of the good controlers that will accept the voltage of the Sunpower panels are expensive ( make sure you use Vsc which I think is close to 60v for the Sunpower panels, sometimes the voltage can go slightly over Vsc and most regulators will be immediately damaged if you exceed their voltage).

I think the Outback FM60, given your system, would be my choice, but it's expensive, particularly as you will need another controller for the lower voltage panels.

The Rogue is my normal recommendation for this sized panel

Rogue Power Technologies

But it is close to the limits of its performance and I would email the designer and check its OK, although his specs are very conservative so I think you will be OK. It's a lot cheaper than the Outback and close in its MPP tracking ability, although with reduced ability to accept larger panels.

Unfortunately Marc at Rogue Power says their one would not be a good match. He has one coming out at the end of the year that would do it, but unfortunately we will be on our way before then.

The price of the Outback sure does make your eyes water

Vic

[VirtualVagabond]

Originally Posted by Dsanduril

Vic,

For the most part, given the electrical usage described earlier in this thread, I don't think you will have to worry too much about making things play nice. It appears that you typically operate at 60-70% state of charge, which means your batteries are willing to soak up all the power you can deliver.

Many of the MPPT controllers are fine with these voltage levels, and you are somewhat married to an MPPT controller on the Sunpower panel, because you need to reduce the voltage. The Outback units go to 150V max, 145V max in operation. Most of the BlueSky units want a maximum Voc of 57V, so they aren't appropriate. MorningStar makes a [EDIT]TriStar, Sunsaver not rated > 200W @ 12V[EDIT] model that goes to 75V. Since you have the Outback inverter/charger I would give them a call and see if there is any easy way to integrate things (or see if anyone here has thoughts on that).


For your situation, if you had three of the 140W panels you might be able to connect those panels in series to get a Vmp of 54.3V, which compares pretty well with the Vmp of the Sunpower panel. Got a place to put one more? You could then connect the string of 140W panels in parallel with the Sunpower panel into a single controller and probably get reasonable controller accuracy. Short of that, you probably need two controllers. If cost becomes a real issue you might consider a PWM controller for the 140s. You'll lose a little output (hard to predict exactly) but it will also cost you less (I don't necessarily recommend that, I'm an MPPT fan, but I recognize not everyone wants to spend the $).

Unfortunately I can't fit another 140 watt panel on without an unaceptable overhang.
I emailed Morningstar with the panel specs and they have advised me one of their techies will get back to me with controllers in their product line that would cope with it.

Panel are due to arrive on Friday so I'd better choose a controller soon.

Given the cost of controllers, I'm inclined to have the controller for the 320 W panel, and feed the 140 W panels in directly to the battery bank.
It's my understanding that this should be ok because we're not likely to over charge the battery bank.

Vic