Converting part of a house

System

Is it "right" and does it meet code to disconnect a leg from my grid breaker box and put that leg on a battery/solar system? I'm looking at doing this to the bedroom or TV/stereo room section. Later on maybe adding another leg.

Any and all ideas, advise, do's and don't's will be appreciated.

tsp

sawmill

Re: Converting part of a house

You might want to consider using a transfer switch for your solar circuits. Keep in mind that some inverters are not compatible with a shared grid neutral and ground.

BB.

Re: Converting part of a house

Yes, you could probably do this, however, you will need a true sine wave inverter designed for a US style grounded neutral system. An inexpensive modified square wave inverter probably would not work--not sure how code would treat it though...

Your best bet would be to get an inverter that has an internal transfer switch (usually includes an internal battery charger too). It would switch automatically when batteries were charged or if AC mains fail. Unless you have an excess of solar, you should plan on using AC main power when the batteries get discharged.

The real question is what do you want to do... A grid tied solar system is less expensive to install/maintain (no batteries) and can get state and Federal rebates/tax credits to reduce your costs.

An off-grid system (like you have described) is not able to receive rebates.

A hybrid Grid Tie / Off-Grid / Backup system is also available, rebates available, but is not cheap to install or easy to expand later (battery banks don't work well with old and new batteries mixed in the same bank).

-Bill

lamplight

Re: Converting part of a house

home power had an article called take your bedroom off the grid, this is a link that i found after a quick search, i think it is the same article not sure:
http://www.environmental-expert.com/resultEachArticlePDF.aspx?cid=9873&idmainpage=0&level=0&codi=12991

absolutely its possible and is a great way to start slow with solar (that is about its main advantage to Bills solid points about grid tie's advantage.

thats how i started and now have a separate AC outlet in my home office , sunny weather: plug into the solar, rainy plug into the grid (as the small offgrid setup isnt sized to run the office for many days without sun, but it CAN do it for a couple days). im using the sun now

niel

Re: Converting part of a house

i seem to recall a hp article about taking your office off grid too, but i suppose a bedroom to normally be easier and cheaper as not much is used there for the majority of homes.

Windsun

Re: Converting part of a house

We are not fans of these "partial conversions".

Because they are nearly always battery based and require sine wave inverters, they are almost never cost effective, nor do they usually save any appreciable amount of energy. And because of all the extra components you need, such as the batteries, extra wiring and panels, you are not really being all that "green". And if you are producing more power than needed, it is usually just wasted.

Grid tie systems are nearly always much more cost effective, more reliable, much simpler, and work on the ENTIRE energy bill all the time.

niel

Re: Converting part of a house

i agree with you, but somebody may do it this way anyway due to limited funds or some other reason.

Windsun

Re: Converting part of a house

For about the same or less they could get one of those little sunnyboy 700's and 3-4 panels

lamplight

Re: Converting part of a house

I looked at those too, considering taking my small offgrid system online. in my case w/3 sharp 24v 175w panels i thought i would have had to buy a 4th panel to meet the minimum specs. forget details but i bet comparing both side by side would be very close cost, but only assuming that the battery system was as big as the minimum size of the sunnyboy700 system requirements.

looking at the sba700 specs it lists 3 scenarios for voltage ranges, am i reading that right as 3 scenarios for the same device or are there 3 subversions of the unit?

i do like knowing that i have some power to work with when the grid is out. gridtie w/batts backup sized large enough to be useful definitely would tip the scales.

niel

Re: Converting part of a house

matt,
3 of your sharps will work as the vp of each pv is 35.4v so multiplying by 3 gives you 106.2v. 2 of them wouldn't as that is 70.8v and below the 73v min.