Solaredge P400 or P300 optimizers?

[reader2580]

Is there an advantage to P400 optimizers over P300 optimizers? The 300 watt 72 cell modules I am buying will work within the voltage specs of the P330.

The price difference is $1020 for me. I would definitely do P400 if the price difference was not so great.

[foo1bar]

Is there an advantage to P400 optimizers over P300 optimizers? The 300 watt 72 cell modules I am buying will work within the voltage specs of the P330.

The price difference is $1020 for me. I would definitely do P400 if the price difference was not so great.

Make sure it's within voltage spec on a clear cold morning. ie. that when you include temperature it's still in spec.

[reader2580]

Here are the specs on the panels:

STC Maximum voltage (Vmp) - 36.6 volts
STC Open circuit voltage (Voc) - 44.8 volts

NOCT Maximum voltage (Vmp) 33.4 volts
NOCT Open circuit voltage (Voc) - 41.9 volts

The P300 specs say that Voc needs to be under 48 volts.

[foo1bar]

Here are the specs on the panels:

...

The P300 specs say that Voc needs to be under 48 volts.

What's the Voc at the temperatures you're likely to see on a winter morning?
What's the temperature you're likely to see?
What's the temperature coefficient of the module?

If I were you I would see if Solaredge can give me guidance on whether the module I'm looking at will be useable with the P300 in my location.

[littleharbor]

With a STC Voc of 44.8 You are very likely to over volt a P300 with those panels unless you live in the tropics. P300 aren't for 72 cell modules.

[reader2580]

Darn it, I guess that means a redesign of my system then. I am already at the limit of what I want to spend on the system. (Yes, I added money for contingencies.) I'll have to reduce the number of panels to reduce the total system cost. I'll have to go with the P400 optimizers.

[GRickard]

How many panels are you looking to install? I'm seeing $54 ($49.87 sale) for the P300 and $60.93 ($55.96 sale) for the P400. It would take 170 panels to make the $1020 difference.

[reader2580]

How many panels are you looking to install? I'm seeing $54 ($49.87 sale) for the P300 and $60.93 ($55.96 sale) for the P400. It would take 170 panels to make the $1020 difference.

34 panels. I found a source for the P300 optimizers for $45 versus $61 at Renvu for the P400. I did the math wrong and the difference is only $544 so not quite so bad.

Renvu shows them for $56, but they mention that price is for projects. I need to call them, but I am assuming I have to buy my entire project from them to get that price.

[foo1bar]

Renvu shows them for $56, but they mention that price is for projects. I need to call them, but I am assuming I have to buy my entire project from them to get that price.

I would buy all the PV equipment from one retailer.
Modules + inverter + optimizers (and maybe +racking)

1> You're probably not going to save much once you include freight.
2> It gives you one "neck to strangle". Avoids the whole argument of "it's his fault not mine"

[reader2580]

I would buy all the PV equipment from one retailer.
Modules + inverter + optimizers (and maybe +racking)

1> You're probably not going to save much once you include freight.
2> It gives you one "neck to strangle". Avoids the whole argument of "it's his fault not mine"

I really need the system price to come in at no more than $11,000 all in (before tax credits). Equipment with racking is coming in at $9000. No labor costs and only an electrical permit. I think I can do the rest for $2,000 since it is ground mount. This is for a 10,200 watt system. I might step back to a 6,000 watt system to save on costs.

The only vendor I can find that carries the racking and everything else from a single vendor comes in at $15,000 for just the equipment for the 10,000 watt system.

I am planning to use Patriot Solar ballasted ground mount racks. The various places I talked to said because of the soil type I would need enormous footings for a lot of the rack systems. Most of them talked about 24" concrete footings up to 8 feet deep. 24" footings would require bringing in a contractor as the average DIY guy can't rent a 24" auger.

[reader2580]

When I started planning my solar system I was hoping to spend about $7,000 for a 14 panel system that put out about 4,200 watts. I then found a deal on fairly cheap pallets of 20 panels for a 6,100 watt system, but it turns out they don't sell to homeowners.

I found another deal for cheap pallets of either 20 or 34 panels and they will sell to homeowners with reasonable shipping. (The same vendor will sell the inverter and optimizers for about 10% more than Renvu.com.) That is how I got up to a 10,200 watt system. I will spend more up front, but my production would be enough that even if the power company starts only paying wholesale rates for power I could cover my entire electric bill.

[foo1bar]

Most of them talked about 24" concrete footings up to 8 feet deep. 24" footings would require bringing in a contractor as the average DIY guy can't rent a 24" auger.

sounds like BS to me.
I wouldn't expect 8' deep and 24" diameter being necessary. Maybe if you have major frost heave and the frostline is normally 6-7' down. (which it isn't in most places)
Even then I'd think a 18" (or smaller) hole would be work.

But in any case, you can rent a mini-excavator.
24" wide, 8' long, 4' deep is doable in a day in almost any soil.
And I think 8' deep doable in soils that don't just collapse in when you dig that deep.
And rental for that will probably be less than $500.

You could probably do tube forms without much problem into those trenches and then backfill around the forms if that works for you - and that'd save some costs in concrete needed.

I found another deal for cheap pallets of either 20 or 34 panels and they will sell to homeowners with reasonable shipping.

Are you going to be happy with that choice?
If so - go for it. It's your money to spend as you see fit.


Personally I'd find out how long I could rely on the net metering.
(Probably 10-20 years)
Then I'd make sure my payoff timeframe is well within that. (at $2/W it very likely is in the continental US)
And I'd target just slightly more kW system than needed to pay very little to the utility.

Oversizing so that you get wholesale rates is just a waste of money.
The panels will be cheaper in 10 years, so why pay for them now and not get enough economic benefit out of it.



Also - since you're building a larger system
And you're looking to make it be ground mount.
I would seriously look at a normal string inverter.
Solaredge is great - I have one myself. But for a ground mount I think the payback is likely to favor a string inverter.
Usually ground mounts don't have multiple angles and numerous partial shading issues (like from 2nd floor shading modules on the roof of a first floor)

[foo1bar]

The only vendor I can find that carries the racking and everything else from a single vendor comes in at $15,000 for just the equipment for the 10,000 watt system.

32 of the 310W csun panels: $4752
32 P400-5 optimizers: $1952
10kW solaredge inverter: $1720
Racking: $2000 (guesstimate - probably high for not including pipe, cement, equipment rental
Shipping: $600

In all - $11k for 9.9kW system = $1.11/W

When I started planning my solar system I was hoping to spend about $7,000 for a 14 panel system that put out about 4,200 watts.

I'd recommend going back to that if that is going to meet your needs (from a net metering/economic view) for the next 10 years.

Maybe go to 345W/module system with 12 modules (72 cell solarworld 345W are $.65/W at renvu at the moment)
Add in a smaller inverter and the lower number of optimizers and I think you'll have the system paid off by the savings significantly faster.
And still be in a good shape for 10+ years to come.

[reader2580]

32 of the 310W csun panels: $4752
32 P400-5 optimizers: $1952
10kW solaredge inverter: $1720
Racking: $2000 (guesstimate - probably high for not including pipe, cement, equipment rental
Shipping: $600

In all - $11k for 9.9kW system = $1.11/W


I'd recommend going back to that if that is going to meet your needs (from a net metering/economic view) for the next 10 years.

Maybe go to 345W/module system with 12 modules (72 cell solarworld 345W are $.65/W at renvu at the moment)
Add in a smaller inverter and the lower number of optimizers and I think you'll have the system paid off by the savings significantly faster.
And still be in a good shape for 10+ years to come.

My total electric bill for a year with solar access fees will be $936. A 6 KW system would generate $1038 in electricity per PVWATTS. Payback would probably be 7 years or so at current electric rates. If I did 10 KW I could pay off the system in five years and make money after that as long as net metering is in effect.

I would have to buy another inverter to add more panels down the road. The panels may cost less down the road, but racking probably will go up in price,

The panels I am planning to buy are quite a bit less than any of the prices you listed.

[J.P.M.]

My total electric bill for a year with solar access fees will be $936. A 6 KW system would generate $1038 in electricity per PVWATTS. Payback would probably be 7 years or so at current electric rates. If I did 10 KW I could pay off the system in five years and make money after that as long as net metering is in effect.

I would have to buy another inverter to add more panels down the road. The panels may cost less down the road, but racking probably will go up in price,

The panels I am planning to buy are quite a bit less than any of the prices you listed.

I'd be skeptical of the $$ figures you get from PVWatts. A PITA, but I've found getting familiar with how you are charged for energy and generating your own savings per kWh is much more reliable than the PVWatts cost/kWh for POCO power.