San Marcos San Diego new System Quick

[katass1031]

I joined the forum so I can talk to everyone a little bit more to get some more knowledge about the different types of panels and inverters that I have been presented with. So far, I have only 2 quotes, with 3 more on the way.

Option 1:
6.05kW
22 REC 275W
SE 5000W
$22250 ($3.67/w)

Option 2:
7.8kW
26 LG 300
26 Enphase 250
$29620 ($3.80/w)

I am not too concerned about the size as I can narrow that in better once I have some discussions with each vendor. Where I get confused is the different products. There are a lot of opinions and each vendor probably wants to sell what they get the most out of.

From the last 3 days of research, I really like the SolarEdge power optimizer solution. SMA with their Optimizer Global Peak also seems like a good idea. But Enphase worries me lately.

With respect to panels, does it really make a difference given you are getting a 25 yr warranty with most of them. Or do I want to go with something that has reputation?

Now in San Diego, what $/w should I be looking at? Can you negotiate with companies?

I feel like they are the experts and I don't want to tell them what I want, but it seems that there is good reputation for certain products here and if I can get them, then why now. I think most installers will do a good job. It is just finding the one that will be around for a while just in case something happens.

Thanks in advance.

[katass1031]

I'm also thinking that it may be better to go with an Electrical engineering firm rather than a solar firm as these business have been around and will be around regardless of solar and will always be looking into newer and better things.

[thejq]

I'm also thinking that it may be better to go with an Electrical engineering firm rather than a solar firm as these business have been around and will be around regardless of solar and will always be looking into newer and better things.

General electrical contractor that has been around for a long time (before Solar) is definitely a better choice. They will be around for a long time. In San Diego, $3.5/W for 5KW system seems to be the norm. Bigger systems may even be cheaper. Both SolarEdge (for shading and best performance) and SMA (for longevity, reputation and easy maintenance) are good choices. I could be worried about Enphase based on their financial outlook. If you have to get Enphase, maybe consider getting a few spare parts.

The most important part of your initial research is to know what you need in terms of sizing, financing options (if not paying cash) and where to install it. SDG&E charges $120/year minimum usage, so make you subtract that (in KWh terms) from your top level consumption estimation. Use http://pvwatts.nrel.gov/ to estimate the system size (by setting premium panel and 7% system loss as parameters). Try reducing excess consumption if possible, first.

BTW, none of your quotes seemed competitive for your system size. Also you're getting pretty close to NEM 1.0 cap set by SDG&E.

[katass1031]

Thanks for the reply. I will have to look into that PVWatts website more. I didn't quite understand it. But thanks for the tip on where to start.

[katass1031]

I will be paying cash so I assume I should tell them this so they give me the best price. I feel like the financing is like buying a car but in this case I am actually getting something after the term is up.

[katass1031]

I have only been in the house for 6 months and my average was 900 kWh per month. If I average in the next 6 months of winter that average comes down to 825kwh. I have been giving the vendors 9900 for my yearly supply.

Option 2 above really overestimated because he said I have two young kids who will use more energy. After my analysis, I figure in 5 years they will be in school and my wife will be back to work so the energy they use now is very close to max.

[katass1031]

As for the net metering, that is why I want to make a decision this week. Possible best chance to get in.

[thejq]

The PVWatt site allows you to put in your physical location, panel orientation (az. and tilt) to estimate your average yearly production, hence your system size. It should be the first thing you do. Most salesman will oversize your system so they can sell you more stuff. Cash will definitely get you the best pricing. What's your zip code and roof orientation? Personally I don't think 9.9MWh/year requires >6KW system unless your orientation is really bad. Check your PM for some more pointers.

[katass1031]

Thanks again. I was waiting to get to the elusive 10 posts.

[katass1031]

The PVWatt site allows you to put in your physical location, panel orientation (az. and tilt) to estimate your average yearly production, hence your system size. It should be the first thing you do. Most salesman will oversize your system so they can sell you more stuff. Cash will definitely get you the best pricing. What's your zip code and roof orientation? Personally I don't think 9.9MWh/year requires >6KW system unless your orientation is really bad. Check your PM for some more pointers.

Zip = 92069. Roof orientation SE and SW. Or do you need more info than that?

[thejq]

Since you have two roofs to work with, you need to run two estimates depending how many you can put on each roof. For example, pvwatts says 1 KW system in your area facing SW will produce roughly 1700 KWh/yr, and same system facing SE, 1647 KWh/yr. So using these basis, your available roof area, and panel wattage, you can calculate how big of a system you need to cover your usage (9900 KWh - $120/0.18 = 9233 KWh/yr, assuming you pay $0.18 per KWh). I'd recommend only cover 90-95% of that, since it's better to pay just a little than leaving $$$ on the table. But your money, your choice.

[katass1031]

Since you have two roofs to work with, you need to run two estimates depending how many you can put on each roof. For example, pvwatts says 1 KW system in your area facing SW will produce roughly 1700 KWh/yr, and same system facing SE, 1647 KWh/yr. So using these basis, your available roof area, and panel wattage, you can calculate how big of a system you need to cover your usage (9900 KWh - $120/0.18 = 9233 KWh/yr, assuming you pay $0.18 per KWh). I'd recommend only cover 90-95% of that, since it's better to pay just a little than leaving $$$ on the table. But your money, your choice.

Why would I want to subtract the $120 from the cost? If I actually use 9900 during the year and my system is only available for 9233, then I will owe 120 plus another 120.

[thejq]

Why would I want to subtract the $120 from the cost? If I actually use 9900 during the year and my system is only available for 9233, then I will owe 120 plus another 120.

No, $120 is the minimum USAGE. So if you use $0 (net zero), you pay $120, and anything < $120, you also pay $120. Of course, all these can change in the future.

[MKI]

The most important part of your initial research is to know what you need in terms of sizing, financing options (if not paying cash) and where to install it. SDG&E charges $120/year minimum usage, so make you subtract that (in KWh terms) from your top level consumption estimation. Use http://pvwatts.nrel.gov/ to estimate the system size (by setting premium panel and 7% system loss as parameters). Try reducing excess consumption if possible, first..

Hi, How is the minimum payment calculated if a system is overproducing? Thanks

[thejq]

Hi, How is the minimum payment calculated if a system is overproducing? Thanks

Don't do it! You will regret it. You will get paid $0.04/KWh (SDGE's wholesale price) for excess energy at true up time. So say, if you used 9000 KWh/yr and generated 10,000 KWh/yr, you will have 1,000 KWh in excess, and be paid $40 in credit against your minimum charge of $120. So you end up paying $80. But that's at a huge cost for so little pay back. eg. if the system is properly sized to to produce 9000-120/0.18 = 8333 KWh/yr, you will end up paying $120. But to reduce your payment by $40, you have to size it to generate 1,666KWh/yr (10,000-8,333) more ==> really bad decision and economics.