Quote Review - IA

[k-man21]

I have been quoted a 10.6 kw system for my house, in Iowa. The below is from Sunpro.

LG NeON2 375w panels, x28
Enphase IQ 7+ Microinverters.

Should fully offset my power bill. Over the past two years, we have used 14 MW of power, so the math adds up. Our utility does offer net-metering.

I have been quoted $40,500 for this system, pre tax credit. Any thoughts on the price, or quality of the products used here? I have two more companies coming out tomorrow for quotes, but I do like the warranty Sunpro offers. Any input on Sunpro as a company? I like that they are larger, so I am confident they will be around to honor their warranty.

I have already spoken to Purelight Power, and Sunpro provided a better system and pricing than them, so I'm not going to list that quote out.

The two companies coming out tomorrow are local, and one has already quoted me roughly half this cost over the phone, but I am not sure what panels they are using. They said SolarEdge was the inverter. Is there a panel or inverter you would recommend?

What questions should I be asking these guys? I have already signed with Sunpro, but I have until Saturday to cancel the contract, which I am leaning towards doing after hearing the local company's price.

[SunEagle]

Hello k-man21 and welcome to Solar Panel Talk

$40,500 seems high for that system. Even if you add up the panel wattage you get 10,500watts which is $3.86/watt. Although with those IQ+7 micro inverters you will not get the full 375 watts out of each panel so the cost per watt is even higher.

IMO I would get at least 3 to 6 quotes listing all material as well as any guaranteed kWh per year output claim.

[k-man21]

Hello k-man21 and welcome to Solar Panel Talk

$40,500 seems high for that system. Even if you add up the panel wattage you get 10,500watts which is $3.86/watt. Although with those IQ+7 micro inverters you will not get the full 375 watts out of each panel so the cost per watt is even higher.

IMO I would get at least 3 to 6 quotes listing all material as well as any guaranteed kWh per year output claim.

Thanks for the heads up. Two more quotes incoming tomorrow from recommended local companies. One quoted $22k over the phone for a 10.5 kW system, so that's much more in line, however, I don't know what equipment it is.

Is there any brand or model of equipment I should specifically avoid? I know they both said SolarEdge was the inverter brand. One company said 425w panels, the other one did not say but will let me see the options tomorrow.

My biggest concern with these other quotes is lower quality install/equipment. I know $40k is high, but it it high quality equipment with a top of the line warranty. I am not well informed with brands, equipment, etc, so any advice on stuff to avoid would be nice.

[SunEagle]

I would check out what an IQ+7 inverter will generate. Multiply that by the inverter number and that is your true system wattage. From there you divide that number into the total installation cost which is your quoted $/watt value.

IMO unless you have shading issues going with micro inverters may be a lot of added cost that a string inverter will work just as good.

[k-man21]

I would check out what an IQ+7 inverter will generate. Multiply that by the inverter number and that is your true system wattage. From there you divide that number into the total installation cost which is your quoted $/watt value.

IMO unless you have shading issues going with micro inverters may be a lot of added cost that a string inverter will work just as good.

Good info. I have zero shade, so no concerns there. I do like the ability for the rest of the panels to run if one goes down, instead of the whole system failing. Is that not super common?

[Ampster]

I would check out what an IQ+7 inverter will generate. Multiply that by the inverter number and that is your true system wattage. From there you divide that number into the total installation cost which is your quoted $/watt value.
......

The IQ7+ micro maxes out at 290 Watts. Glad to see someone else supports the use of AC inverter capacity to evaluate the cost per Watt of a system. As long as it is clear what denominator is used and that metric is used consistently to compare systems then I agree it represents the "true" cost per Watt.

[k-man21]

The IQ7+ micro maxes out at 290 Watts. Glad to see someone else supports the use of AC inverter capacity to evaluate the cost per Watt of a system. As long as it is clear what denominator is used and that metric is used consistently to compare systems then I agree it represents the "true" cost per Watt.

Interesting, I didn't know that at all. So this system would underperform their estimate then?

[k-man21]

I have attached our monthly use showing everything back to January of 2020. What size system would you recommend to offset 100% of our use? Our utility offers net metering, but once a year, any extra credits are taken back to the "general fund," to lower everyone's costs. It works out best to offset exactly 100% of our use, and no more. I would prefer to go a bit over 100%, since we just had a second daughter, and our use will most likely go up. We are also planning on an electric car in the next few years. Screen Shot 2021-11-18 at 10.17.57 AM.png

[Ampster]

Interesting, I didn't know that at all. So this system would underperform their estimate then?

It would depend on what assumptions they made. Most panels rarely put out their rating so that constraint may not effect your overall performance. Have you gone to PV Watts and modeled your system? That will give you another number to compare with.
For what it is worth my system uses 345 Watt panels with IQ7+ Micros. I did a quick check and the savings was not worth going to 300 Watt panels. My system was not completed until August so I did not get any data for The longest solar day in June. I expect to see some clipping as I did on a cooler clear day in August but it was not significant.

[k-man21]

I have tried PV Watts but I'm a simpleton using that thing, no idea what it's asking

[k-man21]

Trying it now:

DC System Size: 10.6 kW
Module: Premium
Array type: Roof mount
System Losses: 14.8% (default)
Tilt: 20 Degree (default)
Azimuth: 180 degree (default)

Retail Electricity rate: $0.088 per kW/h

Here are the results from the above:

[SunEagle]

Good info. I have zero shade, so no concerns there. I do like the ability for the rest of the panels to run if one goes down, instead of the whole system failing. Is that not super common?

The earlier models of the micro seem to have failed due to too much heat or electronic failure. The newer models seem to last a lot longer but sill still limit the panel wattage to the maximum output they are rated for. A string inverter may fail or may last longer then all of the micros.

I still say that unless you need the micro (due to shade) or can get them for a lower price then a string inverter handling the same kw load I would go with a quality string type. But again it still depends on the overall cost and expectations of what you want your system to do.

[k-man21]

The earlier models of the micro seem to have failed due to too much heat or electronic failure. The newer models seem to last a lot longer but sill still limit the panel wattage to the maximum output they are rated for. A string inverter may fail or may last longer then all of the micros.

I still say that unless you need the micro (due to shade) or can get them for a lower price then a string inverter handling the same kw load I would go with a quality string type. But again it still depends on the overall cost and expectations of what you want your system to do.

Help me out a bit. What situations would the micro be better? Our roof would definitely get hot in the summer, we regularly see 100s, and our shingles are dark grey.

I want a system that is minimal maintenance long term, roof mounted, and can offset 100% of our yearly electrical use. I want an app to monitor production, and I want a good warranty from a company that will be around long term. Quality equipment is a requirement, I just don't know how to define "quality."

[SunEagle]

Help me out a bit. What situations would the micro be better? Our roof would definitely get hot in the summer, we regularly see 100s, and our shingles are dark grey.

I want a system that is minimal maintenance long term, roof mounted, and can offset 100% of our yearly electrical use. I want an app to monitor production, and I want a good warranty from a company that will be around long term. Quality equipment is a requirement, I just don't know how to define "quality."

I believe the newer model of the micro can handle more heat and do not have early death syndrome like the earlier models did.

So again if the cost of 28 micros = XXX and a quality (name brand) 10kw string inverter = YYY. Then if XXX is about the same or not much more then YYY I would go with the micros. But if XXX is much more then YYY I would go with the string inverter.

[k-man21]

I believe the newer model of the micro can handle more heat and do not have early death syndrome like the earlier models did.

So again if the cost of 28 micros = XXX and a quality (name brand) 10kw string inverter = YYY. Then if XXX is about the same or not much more then YYY I would go with the micros. But if XXX is much more then YYY I would go with the string inverter.

Thanks! What would a name brand string inverter be? I am not familiar with the best brands in the field. I will report back on the decision tomorrow.