How to make new construction solar ready?

[renormalize]

Per my recent thread "Seeking opinions on a Sunpower vs. Kyocera system quote in New Mexico...", I am weighing the economics of installing solar PV power on the flat garage roof of my new home (currently under construction). But should I decide to postpone a PV system at this time, I would nonetheless like to make my home "solar ready" while the walls and roof are still open and accessible. Off the top of my head, I imagine that at least the following items are required:

--Solar panel mounting standoffs incorporated into garage roof during construction (but not needed if I end up with ballast mount).
--Conduit between roof and garage interior to route future wiring for DC, AC, and/or data.
--Prewired location inside garage for inverter and/or data hub.
--Prewired blank meter box outside garage near grid-meter for eventual install of net-meter.
--Others?

I favor "solar ready" because I'm guessing it doesn't add too much cost during new construction and it allows me to keep my future options open. Do you think it's reasonable to solicit bids for this work from a solar installer or even the builder's roofer and electrician? Is there some "cookbook recipe" for making construction PV ready that I can share with my builder?

[foo1bar]

I imagine that at least the following items are required:

--Solar panel mounting standoffs incorporated into garage roof during construction (but not needed if I end up with ballast mount).
--Conduit between roof and garage interior to route future wiring for DC, AC, and/or data.
--Prewired location inside garage for inverter and/or data hub.
--Prewired blank meter box outside garage near grid-meter for eventual install of net-meter.
--Others?

I'd figure out where you want the inverter to be.
Then how to get the wires from the array to the inverter (conduit to the roof - maybe to a jbox in the parapet?)
In doing the flat roof, I'd make sure that it'd be able to support a ballast mount. Or I've read on here about people mounting off the parapets to be above a flat roof.
I'd run CAT6 wires to each room from a spot where you can put a network switch - probably to each side for bigger rooms and living room, and an extra 2 CAT6 to the spot where you'd likely have a computer hooked up. Or do "structured wiring" (usually 2 CAT6, 2 RG6, and fiberoptic in one cable)
Lastly, put in the AC wires from inverter to the main panel and make sure the panel can handle the power from the inverter. (Can be conduit and install the wires after, or could be wires that for now are to a "welder outlet") When doing that, you will want to make sure the wires are big enough so you aren't yanking it out to put in bigger ones.) If not having an idea of how big a system you're going to do, I'd probably make sure you could do a 60A PV breaker and size the wiring for that.

[gmanInPA]

If you're planning on having a grid-interactive system vs a grid-tied system, i'd go ahead and have all your critical loads circuits placed in a separate sub-panel off of the main. If I built a new home, I'd do this either way because even if you use grid-tied solar, you could then connect a generator to a critical loads panel and have a nice emergency back-up system. Some would say "just get a whole-house standby generator"... which one can do, but you'll spend more on a generator and more on fuel doing so vs powering only what is critical - which can be an awful lot.

[organic farmer]

In some areas [like mine] an on-grid house with a whole-house generator will consume a lot more in fuel over 10 years of use, than a solar system would cost.

[gmanInPA]

In some areas [like mine] an on-grid house with a whole-house generator will consume a lot more in fuel over 10 years of use, than a solar system would cost.

Hi organic farmer - I am not anti-off-grid by any means just to be clear. I was advocating the generator to run critical circuits if renormalize was expecting to be otherwise grid-tied, in which case PV would provide no grid-down support other than a convenience outlet or two. If building a new place with an expectation to have either generator or battery/inverters/pv support, I stick by my opinion that a separate critical loads panel would be a good thing to setup while the house is being built vs fiddling with circuits after the fact.

I'd like to know more about your context and location and how you've concluded that batteries and PV are less expensive than a generator. I don't mean that as a challenge - I'm really interested to know more about that and I'm sure others would be also

Again - I'm not advocating a generator instead of PV - only as a backup for someone who has a grid-tied system because they would not otherwise have the hardware necessary for using PV in a grid-down scenario. Hopefully those who have an off-grid or backup system already know they need one for some extra support. If you've been able to successfully run off-grid without a generator, I suspect you're in a very small minority of solar users.

[organic farmer]

... I was advocating the generator to run critical circuits if renormalize was expecting to be otherwise grid-tied, in which case PV would provide no grid-down support other than a convenience outlet or two. If building a new place with an expectation to have either generator or battery/inverters/pv support, I stick by my opinion that a separate critical loads panel would be a good thing to setup while the house is being built vs fiddling with circuits after the fact.

I get it, and I agree.

I served 20 years on Active Duty mostly on subs. Every electric circuit on a sub is keyed to various priorities. The availability of power determines which systems are allowed to operate.

Living off-grid is very similar. Mid-day when batteries are charged and solar-panels are still putting out wattage, I can run everything appliance and power tool in the house. But at night and after the batteries have drained down a bit, you want to operate very few things.

We have chest-freezers that are on timers to only run from 8am to 4pm. They do not need to run any more than that to maintain temp, and I do not want them running at night [on battery].

... I'd like to know more about your context and location and how you've concluded that batteries and PV are less expensive than a generator. I don't mean that as a challenge - I'm really interested to know more about that and I'm sure others would be also

Again - I'm not advocating a generator instead of PV - only as a backup for someone who has a grid-tied system because they would not otherwise have the hardware necessary for using PV in a grid-down scenario. Hopefully those who have an off-grid or backup system already know they need one for some extra support. If you've been able to successfully run off-grid without a generator, I suspect you're in a very small minority of solar users.

I live rural in a forest. Grid power in our township normally goes down 2 or 3 times every month. Every home here that uses electricity has at least one generator. I have neighbors who consume $100 to $150 a month in generator fuel, along with their utility bill, and whatever it cost them to install the generator.

We have one neighbor who is in a 20-year lease contract with a net-metering solar-power setup. They still have to run their generator when the grid is down. They still have a monthly utility bill. And now they also have a monthly payment for the lease contract on their solar array [Our state does not require utility companies to pay home-owners for power home-owners put onto the grid, so you can not 'get money back'].

I spent a little under $20k for our solar power setup with battery bank. I see generators that go up to $5k. Now that my solar system is up, I am no longer consume generator fuel every month. I use grid power as an Aux-input for my system. If my battery is low, and if the grid is up that night, than I can still use grid power.

Most people pay out for the cost of a generator, and then the monthly expenses of it's fuel, plus they still have the utility bill, I think that within 10 years I will be ahead.



I think that it makes sense, if you have appliances that you only want ran during day-light, then put those appliances onto a solar power circuit. It would reduce how much stuff you are powering from grid power.

[gmanInPA]

I have a similarly-sized system, but we don't get enough sun here for me to not require a generator to assist in recharging my batteries - though they do extend the fuel quite a bit. If I add up the cost to run the generator I still think it would be slightly less than the PV per kWh. I don't see them as an either/or personally, but think you have to find the mix that fits your needs vs budget. There's a point where a bigger battery bank makes little sense compared to a generator and stored fuel. Having both is nice because a system can be adjusted as variables change.

[SunEagle]

Living off grid requires people to make changes in their lives mostly how and when to use their electrical appliances.

People who do not have a regimentation like organic farmer probably make poor choices and run their appliances whenever they want to thus requiring also running their gen set and burning fuel.

If you can find ways to only use your appliances when you have the sun then you can save your gen fuel.

If you can't resist doing a load of cloths at night then you spend you money on a bigger battery system or more fuel.

[organic farmer]

People say that everyone kills their first battery bank after 10 years. It is only on their second battery banks that they have figured out how to get a battery to last longer.

My question is: Is it this regimentation that allows batteries to live longer?

[Mike90250]

pre place ample sized conduit for the AC and DC wiring, with spaces to put the breakout, cutoff, and safety boxes - 2016 NEC code. When you install the gear, hope the same code applies and you can use the conduit . Mark rafter location at the eves and peak of the roof (use a quarter size dots of white roof cement to mark)

[SunEagle]

People say that everyone kills their first battery bank after 10 years. It is only on their second battery banks that they have figured out how to get a battery to last longer.

My question is: Is it this regimentation that allows batteries to live longer?

Losing your first battery system could very well be a good reason to take care of the second set.

Although I was referring to your regimentation as having the ability & will to not use your appliances when the batteries were the only power source. IMO that takes determination and some skill.

[gmanInPA]

I've experienced some of the benefits to regimentation of use also - but can't entirely do so - namely because of our well system which maintains a buffering tank by pumping every x minutes for x seconds. There's q bit of draw-down by doing so. I love the freezer idea. I once used a chest freezer and a thermostat controlled relay as a refrigerator. It consumed about something like $12/year in power at the time. One question about the freezers though... wouldn't a chest freezer only power on anyway (without need of timers) if internal temperatures demanded so?

[inetdog]

I've experienced some of the benefits to regimentation of use also - but can't entirely do so - namely because of our well system which maintains a buffering tank by pumping every x minutes for x seconds. There's q bit of draw-down by doing so. I love the freezer idea. I once used a chest freezer and a thermostat controlled relay as a refrigerator. It consumed about something like $12/year in power at the time. One question about the freezers though... wouldn't a chest freezer only power on anyway (without need of timers) if internal temperatures demanded so?

Two factors involved in putting freezers on a timer:

1. If the freezer is powered off long enough (i.e. overnight) you can pretty well assume that the thermostat will be calling for refrigeration by morning and so all freezers and refrigerators will try to start at the same time if a single timer is used.
2. Frost Free refrigerators and freezers usually go into a defrost cycle at a factory set interval. The defrost timer (usually) kicks in on the basis of elapsed time rather than compressor run time.
To avoid the chance of missing a needed defrost cycle in the event of temporary power loss, many such timers will go straight into the defrost cycle when power is applied and then hold off for the preset interval before doing it again.