New panels for my array.

ILFE · January 2014

Greetings:-

Depending on my budget over the next month or so, I am going to expand my solar array. One reason for doing this is, I will be receiving a "Kid" controller from Midnite. Anyway, I would like to go with 9 new panels, bringing my total to 12. But, I probably will have to go for a more realistic affordable number, like 5, bringing the total to 8.

So, two strings of 4 panels would be the best way to go here, I am assuming?

=========

Also, since my first three panels are 100 watts each, I figured I would just stay with the same size, rather than going for larger panels. I have three reasons for doing this. Not sure if they are correct reasons, though?

1. Since I started with this size, stay with this size.
2. Same specifications. (Also. I have enough room for them on the roof.)
3. If a 100 watts panel stops functioning, I would only lose 100 watts, not 250 or 300.

vtmaps · January 2014

Re: New panels for my array.

ILFE wrote: »

I will be receiving a "Kid" controller from Midnite. Anyway, I would like to go with 9 new panels, bringing my total to 12. But, I probably will have to go for a more realistic affordable number, like 5, bringing the total to 8.

I think that 8 panels in a 12 volt system will exceed the capacity of the kid controller.

ILFE wrote: »

Also, since my first three panels are 100 watts each, I figured I would just stay with the same size, rather than going for larger panels. I have three reasons for doing this. Not sure if they are correct reasons, though?

1. Since I started with this size, stay with this size.
2. Same specifications. (Also. I have enough room for them on the roof.)
3. If a 100 watts panel stops functioning, I would only lose 100 watts, not 250 or 300.

You have true 12 volt panels. They tend to be expensive in dollars per watt. Once you have a MPPT controller you can use grid-tie panels which are much less expensive. My advice: keep you 3 panels on your PWM controller and buy new grid-tie panels for your new Kid.

--vtMaps

ILFE · January 2014

Re: New panels for my array.

vtmaps wrote: »

You have true 12 volt panels. They tend to be expensive in dollars per watt. Once you have a MPPT controller you can use grid-tie panels which are much less expensive. My advice: keep you 3 panels on your PWM controller and buy new grid-tie panels for your new Kid.

Panels here tend to get very costly, very fast. What size would you suggest I try to go with? 250w? 300w? Getting anything over about 135 watts is going to have to be special ordered. Most Cambodians simply do not have the funds to pay for larger panels. So, most companies do not stock them, for that primary reason.

BB. · January 2014

Re: New panels for my array.

In the end, it is the overall cost of the system (solar panels + shipping + cost of MPPT type charge controllers for "non-battery standard" solar panels).

The one nice thing about larger solar panels is that they require less electrical connections and can use smaller gauge wire from the array to the charge controller--Very nice if you have to install the array some distance away.

The problem with >>100 Watt panels is cost of shipping and MPPT charge controllers... Sometimes, it just does not make economic sense to use larger format panels. All depends on your needs and local economy.

-Bill

ILFE · January 2014

Re: New panels for my array.

BB, your post is a good part of why I have been wanting to continue with 100 watts panels. I do not know if I can justify purchasing larger panels. I figure at $135 USD per panel, it isn't too bad - for Cambodia. But, I will try to negotiate a bit lower price when we go back to talk about another purchase with the supplier.

In this case, we are off-grid whether we want to be or not. The mains power generated here is so nasty that I would not want to be grid-tied anyway. Not to mention, I am not overly concerned about earning credits for power generated. We are just happy being able to use the power generated for ourselves. Here, the grid, fairly often, can be down as much as it is up. Since installing our solar array, we have not had any power cuts. Water service is quite similar to power - not reliable. This is why we have rainwater harvesting for our water needs.

Anyway, the bottom line here is, if we want power at the farm, we have to go with solar. No ifs, ands, or buts, because no utilities offered anyway - none. Solar is the only dependable source of power that we have available to us year round. Of course, I may be singing a different tune after a solid week of cloudy, rainy skies during this upcoming rainy season. (Rainy season will start here around the end of April to the first of May, and last until October / November.) That is why I want to get going with my next stage of extending the array. I want to, hopefully, have enough panels "in the air", to collect what light we can during the day, cloudy, rain, or shine.

The array, by the way, is on top of the little farm house, on the salt box style roof. The cables are no longer than about three meters from the array to the controller. So, ten feet is all we are looking at here.

Anyway, since I want to stay at 12vdc, I guess I will just add one more panel to the current array, until I can sort out what to do with the other controller.

BB. · January 2014

Re: New panels for my array.

You probably are better staying with smaller format panels... The 200 watt and larger panels are "big" and require vary careful packing and shipping. It is expensive in the US just sending via pallets on truck depot to depot. Sending a couple panels via "best way" will stand a good chance of ending up as modern art (broken safety glass held by flexible backing in a twisted aluminum frame).

You can always put small format panels in series for higher voltage for 24/48 volt battery banks and MPPT controllers that will take Vmp-array upwards of 100 VDC (and some models/brands even higher voltages). They will work fine--Just a bit more electrical connections/fusing + array mounting hardware--Hardly the end of the world (which sounds like it might be around the corner anyway...

:roll:

).

-Bill

westbranch · January 2014

Re: New panels for my array.

I stayed with the smaller format precisely because of the size of the higher watt panels. I wanted something I could handle alone.
You could see what local suppliers have in the larger size and use that as a negotiating point, for a small reduction on the 100+ size.
Don't let the lure of a lower price be your only factor as you stated, attractive as it may be.

ILFE · January 2014

Re: New panels for my array.

One thing learned on this site, prior to even beginning this venture, was to match the panels as closely as possible when expanding the system.

@ Bill - I could have ordered some Yingli panels at a decent rate, getting 285 watts panels shipped to me for less than $1.00 per watt, in my hands. However, them getting broken in shipment from Singapore, dealing with customs, etc., just didn't seem worth it. If I get a panel from the dealer in town, I can just return the panel to her if anything is wrong with it.

New panels for my array.

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