Any suggestions for a reliable 500 Watt or 2.5 kWh/Day Kit - with portablity in mind

[KenTechno]

Happy New Year ALL!. I'm new to the site as well.

First task is to build a reasonably Large emergency solar system (so Harbor Freight won't make the cut. Goal is a PV Solar System 2.5kWh/Day (Thinking 4x120+Watt Panels - maybe a second back-up, to the back-up), with a 5-Day Potential Battery Reserves Back-up, for Blizzards & other Natural emergencies/Power outages. Thought I lost my original post so re-typing some details in this post area.

Any experience in the market for such products with a Pure Sine-Wave Inverter, and Listed Components under $1,500 would be great. Looking at a Kit or Self-Build, because everything else is either too underpowered or well over a couple thousand, esp with batteries and Pure-Sine Wave Inverters added. Looking for scale-ability on the addition of Panels & String type Inverter as well, to handle 1500Watts/Hr.

About my skills, I'm probably an Intermediate to early Advanced with wire soldering and electronics, decent skills at basic wiring so can be flexible on the build requirements. I'm now where near a Master carpenter or electrician, but I can pick-up pretty fast with some wiring diagrams and guidance.

Looking forward to your recommendations, tips & tricks, advice.

Thanks,
Ken

P.S. Was originally thinking of 2x250 Watt Panels. But the ones I've seen so far are 2.5-3 Feet wide x 5-6feet Long

[Naptown]

For back up purposes and to try to keep in that budget.
Use 60 or 72 cell grid tie panels in the 225-250W range Big but the best bang for the dollar.
Get a good (Midnight, outback, Morningstar) MPPT charge controller.
Don't even think of doing a 12V system 24 would be minimum 48 even better.
So say 2 250W panels at about a buck a watt. $500
Morningstar Tristar MPPT 45A controller $400 There is some room for expansion in this Don't go cheap here
2 (for 24V) or 4 (for 48V) cheap marine batteries 150ah (YOU WILL DESTROY YOUR FIRST SET SO GO CHEAP ON THESE) $300 - $600
Inverter too many possibilities but none that are of any quality are cheap.

[Naptown]

Use this to calculate system requirementsOff grid calculator excel 97 version (2).zip

[SunEagle]

For back up purposes and to try to keep in that budget.
Use 60 or 72 cell grid tie panels in the 225-250W range Big but the best bang for the dollar.
Get a good (Midnight, outback, Morningstar) MPPT charge controller.
Don't even think of doing a 12V system 24 would be minimum 48 even better.
So say 2 250W panels at about a buck a watt. $500
Morningstar Tristar MPPT 45A controller $400 There is some room for expansion in this Don't go cheap here
2 (for 24V) or 4 (for 48V) cheap marine batteries 150ah (YOU WILL DESTROY YOUR FIRST SET SO GO CHEAP ON THESE) $300 - $600
Inverter too many possibilities but none that are of any quality are cheap.

Naptown

Do have any experience with either Whistler or Cobra inverters. They are cheap ($100 to $200) but I am not sure how reliable.

[Naptown]

Naptown

Do have any experience with either Whistler or Cobra inverters. They are cheap ($100 to $200) but I am not sure how reliable.

no i do not

[SunEagle]

no i do not

They only except 12v inputs so not a good item for the desired 48v system.

I have a 400 watt cobra that I picked up year ago which I planed to be used connected to my truck battery when I need to run a RC plane battery charger. I have not really used it much and was wondering if anyone had good/bad experience with one.

I have seen Whistler which makes units from 1000 watt to 3000 watt but again they are for 12 volts input systems which is far from ideal for a good Solar PV system. Just curious about their quality.

[Sunking]

Do have any experience with either Whistler or Cobra inverters. They are cheap ($100 to $200) but I am not sure how reliable.

They are just cheap Truck Stop variety inverters made for mobile applications where the vehicle alternator does most of the work. Basically that is what any 12 volt inverter is made for. Very few are quality. Ones made for Solar Home PV are going to be 24 and 48 volts.

[KenTechno]

Great Solar Back-up Generator Ideas! thxs

For back up purposes and to try to keep in that budget.
Use 60 or 72 cell grid tie panels in the 225-250W range Big but the best bang for the dollar.
Get a good (Midnight, outback, Morningstar) MPPT charge controller.
Don't even think of doing a 12V system 24 would be minimum 48 even better.
So say 2 250W panels at about a buck a watt. $500
Morningstar Tristar MPPT 45A controller $400 There is some room for expansion in this Don't go cheap here
2 (for 24V) or 4 (for 48V) cheap marine batteries 150ah (YOU WILL DESTROY YOUR FIRST SET SO GO CHEAP ON THESE) $300 - $600
Inverter too many possibilities but none that are of any quality are cheap.

Awesome!

Questions:

Presuming the individual Solar cells are 6x6 (used in non-obstructed True South Facing Locations). Other than space savings at the cost of a slightly higher panel, is there an advantage to higher energy density (60cell/250 Watt vs 72cell/250 watt). Thought I saw a Manufacturer (German, maybe now having Mfg in China) touting Monocrystalline PVs with 19.5% efficiency with cells producing 280 watts/Panel (4.7V/cell, 30+V - Rated 38+V Open Voltage Panels. Independent Lab Certified +/-3%)?

Thanks also for the very useful advice & great sanity checks! I was debating weather to go with an over-sized 24V vs. 48V Inverter, could always swap-into the Full House when that gets done later. Figured a higher voltage would squeeze out better conversion efficiencies as well (simultaneously giving less heat losses). Was thinking of an integrated Charge-Controller & String Inverter. Read a post reported offsite by a Xantrex Certified Warranty Repair Center that they had have reduced their warranty period over the last few years and making the key parts non-Repair Center replaceable (may have been for Pro-series only though). Will check out the Morningstar Tristar, didn't realize they could be had to $400s!

Thanks Again
- Ken

[Naptown]

Actually if you look at them and the physical size for the same wattage a 60 and 72 cell are about identical in size (Sunpower excepted) the big difference is in output voltage. A 72 cell module is almost perfectly matched to charge a 24V battery. Two in series charges a 48V battery.

[Mike90250]

Another way to look at it, is the batteries start to degrade when they leave the factory, and even in the best service conditions, will need replacement before 10 years. What would a propane fed generator in the 3-5KW power class cost, with a weeks supply of propane? PV's DON't generate power in cloudy conditions - I'm running my generator daily to keep my batteries up. If you drain the batteries completely, you will destroy them quickly.

[KenTechno]

Is there an advantage of 3.7V vs 3.7 volt/Cell

Actually if you look at them and the physical size for the same wattage a 60 and 72 cell are about identical in size (Sunpower excepted) the big difference is in output voltage. A 72 cell module is almost perfectly matched to charge a 24V battery. Two in series charges a 48V battery.

Hi Rich
So for a 60 cell Panel with 4.667V (280 watts) and a 72 cell panel with 3.889V (280 Watts) - Both panels being the same size, is there any advantage of one over the other? what about any specific conditions, such as cloudy/shading?

Also, curious if anyone has noticed differences in Panel Output Production - based on Monocrystalline vs Polycrystalline Panels? Of Blue Polys vs Dark Blue/Black Polys? - Seems that under cloudy skies, the lighter blue Polys should out perform the Black Monocrystallines, due to different light spectrum characteristics.

Thanks again!

[Naptown]

60 or 72 depends on the charge controller you are using. A 72 cell will work well with a Pwm cc IF USING 24v 2 in series will work with a 48V battery with minimal losses.
the voltage or amperage numbers you just posted are not within any reasonable realm of possibility.
At VMP each cell in a panel will produce approximately .5V
Your numbers do not make sense or your are mis reading them.
Performance is actually a different animal. What you are really talking about is efficiency and degredation.
All cells degrade with time. Boron doped cells will degrade about 3% in the first 30 days of sun exposure and stabilize.
Phosphorous doped cells will degrade a bit slower. and is dependant on the location of the P-n junction