Newbie Looking to Design my First Solar Panel System

[randomlife0]

Hi All. New to the site and to solar panels and am looking to design a solar panel system for my home.

Here are my notes/requirements:
- I live in Northern VA

 

[DThames]

Welcome.

 

[snoobler]

Seems like a VERY short list.

Link #5 in my sig for your solar availability.
Link #1 in my sig for your loads.

 

[randomlife0]

Ugh... Sorry, my dear daughter took over the keyboard while I was drafting this. Let's try again:

Here are my notes/requirements:
- Supply 100% of my electricity (or electricity costs)
- I live in Northern VA and recently cleared the trees around the house so there is minimal shading
- Conventional slope roof (~20 degrees), facing south-east (~45 degrees)
- We have dominion power with the option of Net Metering so I believe the most efficient option is Grid-Tied with no battery
- Previous evaluations from quotes I received put me at about an 7 KW system
- I am currently powering a 2 story single family home with standard (120/240) AC loads including:
- HVAC (Gas furnace, standard central AC), Gas hot water heater
- EV (Kona EV) with average of 100 miles a week
- Appliances: Washer, Dryer, Fridge, Stove (Gas range, electric oven), Dish washer, microwave, small fridge
- Electronics: 2 computers, 1 switch, 2 APs, 3 cameras
- Power tools (Dewalt flexvolt 20v/60v system) for yard work and DIY home projects
- We plan on the following additions/modifications in the next 1-5 years:
- Going all electric in the home: induction range, heat pump, electric water heater
- Obtaining another EV (overall mileage would increase by about 50 miles a week)
- Building pool and pool house (roughly 16' x 16')
- Adding a split mini to the garage and install computer equipment (2x Dell Rack servers)
- Improving insulation in the attic and exterior walls (currently pretty inefficient)
- Based on the upgrades I am thinking I will need to size up to about a 10 KW system (just a guestimate at this point)

Primary goals are to save $ and be eco-friendly. With the limited research that I started doing I believe I would need: Panels, Inverter, Cut-off, mounting/wiring, new meter (from electric co.). I was looking at LG panels based on reputation and cost per output but am open. I got a bit lost looking at inverters. I believe I only need a controller if I have a battery. Some future technology may allow using an EV as a backup battery and I would like to easily modify the system to support that or adding a traditional battery backup.

Couple of Initial Questions:
1. Does 10KW seem accurate/sufficient?
2. Is grid-tied w/ no battery the most efficient (cost effective/green) option?
3. Is my component list accurate? What am I missing?
4. What type of inverters should I be looking at (micro, single-phase, 3-phase)? What inverter brands should I look at (priority is reputation/value)?
5. What panel brand should I be looking at?
6. Anything else I should be considering?

Thanks in advance!

 

[snoobler]

1. You're just asking us to guess? We would have to look up and determine or guess at the power consumption of each item. I gave you the link to the energy audit. Please use it. In lieu of that, look at your electric bill for your kWh usage. Additionally, you need to use either link #5 or link #6 for your solar availability in your area.
2. efficient and cost effective/green aren't necessarily the same. With favorable net metering, grid-tie is the least costly.
3, 4. I'm not competent to advise regarding grid-tie components.
5. I would go with any common brand with the most favorable pricing. Avoid any obscure brand panels out of china.

 

[randomlife0]

Thanks for the quick response!
1. I will review the links. The original assessment (7KW) was based on my electric bill.
2. What I meant was the priorities are cost and environment from a long-term perspective.

 

[snoobler]

7kW is a power. kWh is your energy usage. Your kWh consumption and solar availability dictate your array size.

 

[DThames]

If I understand your roof situation (facing southeast) do you have any southwest facing roof, or do you have space for a ground mount array? Everything facing southeast would not be ideal.

How important is power if the grid were down?

 

[snoobler]

IMHO, you should likely head over to PVWatts (#6 in my signature) and play "what if" with a 7kW system and your panel orientation/tilt to see if you can actually generate the power you need. There are also tools to assess financial viability.

 

[randomlife0]

If I understand your roof situation (facing southeast) do you have any southwest facing roof, or do you have space for a ground mount array? Everything facing southeast would not be ideal.

The house is facing NW and so the backyard roof facing SE is our best bet, PVWatts confirms this. S or SW did show a small increase but currently it is not feasible to do a ground mount.

How important is power if the grid were down?

Power without the grid would be nice to have, not a must. I would have to evaluate the cost. Maybe doing something where you only power critical loads (HVAC, Fridge, etc.) might be an option if it is cost effective.

IMHO, you should likely head over to PVWatts (#6 in my signature) and play "what if" with a 7kW system and your panel orientation/tilt to see if you can actually generate the power you need. There are also tools to assess financial viability.

Thanks for the reference to the PVWatts tool, it is very useful. I adjusted to a 8kW system and came up with 10655 kWh/year which is close to last years bill (12733kWh). Last years bill is likely skewed due to issues with our HVAC system. The years before we were around 9000 kWh.

 

[randomlife0]

To better prepare for a potential future scenario of adding a battery or using an EV, I was researching battery backup and how 3 phase complicates things and came across this article:

Don't Add Batteries To A 3-Phase Home Before Reading This

If you have a 3 phase home and want to add solar batteries, you need to be really careful. If your installer chooses the wrong design your bill savings will be crippled and your backup ineffective. Here's what you need to know to get it right.

www.solarquotes.com.au

It's seems that there are a lot of options. I like the idea of a single phase hybrid inverter (#3) or single phase inverter and add a battery inverter later (#7).

Questions:
1. Should I just plan my best solution now and cross the battery bridge when I get there?
2. Are there advantages to getting a 3-phase inverter without using a battery? Single phase is cheaper correct?
3. What are good brands for inverters?

 

[DThames]

Is your home 3 phase?

 

[randomlife0]

Is your home 3 phase?

I was told before that it is 3 phase however that seems very unlikely.

I had someone do a survey recently and they the said it is very uncommon to have 3-phase residential in my area and the meter showing 3w confirms this.

Is this accurate?

 

[snoobler]

Unless you have a beastly mill or lathe or other heavy equipment in your garage, essentially impossible you have 3-phase.

 

[DThames]

A normal residence in the US will have 240v split phase, where they center tap the transformer secondary to ground and the two ends of the secondary give you the 240v. The 120v comes from the center to either end of the transformer secondary.

A three phase system will have two or three transformers feeding into your service. If you beg, plead, and pay extra you might get three phase if you have a garage/shop with 3 phase motors that you need to power. This normally seen in commerical accounts, farms, factories, etc If you want to run 240v loads look for a split phase inverter or inverters that can be coupled together to supply 230v-240v in a split phase configuration.

 

[randomlife0]

Understood. Thanks for the info and sorry for the distraction...

The recent quote I received had SolarEdge optimizers and inverter. I was also looking at micro inverters from Enphase.

Are these good options? Are there other options I should consider?

Currently I am thinking I will design the system with a battery backup and modify later if needed.

 

[DThames]

Enphase has a battery system with their micro inverters. Micro inverters normally are straight grid tied (very simple install) and you have no option for emergency power. I have a micro inverter system (not Enphase) that makes more power than I use, which was my design goal. I have no reason for batteries other than an emergency (grid off) situation, which is pretty rare for us. I ended up with some extra panels and I am building a battery/inverter that could run my freezer, wife's CPAP, and other light loads overnight. I also have a generator that I plan to use for heavier loads. But for me, batteries are just an expense with little value, because my grid tie agreement with the power company is ideal. Be sure to assign proper value to your design goals. Batteries for load shifting, peak shaving, etc would be a different size than for emergency only use (in most cases).

 

[TRW]

Randomlife0, There are many in this boat, so I hope to see the follow up and how this works out! I appreciate all the info, hoping for more.